| Insects | Aaa water treader bug | Cavaticovelia aaa | Not Listed | Species of Concern | | HI |
| Arachnids | Aalbu's cave pseudoscorpion | Archeolarca aalbui | Not Listed | Species of Concern | | CA |
| Snails | Aardhals springsnail | Pyrgulopsis aardahli | Not Listed | Species of Concern | | CA |
| Flowering Plants | Aase's onion | Allium aaseae | Not Listed | Species of Concern | | ID |
| Flowering Plants | Abajo daisy | Erigeron abajoensis | Not Listed | Resolved Taxon | | UT |
| Birds | Abbott's booby | Papasula (=Sula) abbotti | Listed | Endangered | | |
| Flowering Plants | Abbott's bush-mallow | Malacothamnus abbottii | Not Listed | Species of Concern | | CA |
| Insects | Abellan hydropsyche caddisfly | Ceratopsyche abella | Not Listed | Species of Concern | | OR |
| Flowering Plants | Aboriginal Prickly-apple | Harrisia (=Cereus) aboriginum (=gracilis) | Listed | Endangered | | FL |
| Flowering Plants | Absaroka beardtongue | Penstemon absarokensis | Not Listed | Resolved Taxon | | WY |
| Birds | Acadian Flycatcher | Empidonax virescens | Not Listed | Species of Concern | | |
| Crustaceans | A Cave Obligate amphipod | Stygobromus obscurus | Not Listed | Resolved Taxon | | |
| Arachnids | A Cave Obligate Harvestman | Cryptobunus cavicolus | Not Listed | Resolved Taxon | | |
| Arachnids | A Cave Obligate Harvestman | Hesperonemastoma packardi | Not Listed | Resolved Taxon | | |
| Arachnids | A Cave Obligate Pseudoscorpion | Tyrannochthonius troglodytes | Not Listed | Resolved Taxon | | |
| Crustaceans | A Cave Obligate Shrimp | sphaeromicola moria | Not Listed | Resolved Taxon | | |
| Reptiles | Acklins ground iguana | Cyclura rileyi nuchalis | Listed | Threatened | | |
| Flowering Plants | Acoma fleabane | Erigeron acomanus | Not Listed | Resolved Taxon | | NM |
| Snails | Acorn rams-horn | Planorbella multivolvis | Not Listed | Species of Concern | | MI |
| Clams | Acornshell | Epioblasma haysiana | Not Listed | Resolved Taxon | | AL, TN, VA |
| Flowering Plants | Acuña Cactus | Echinomastus erectocentrus var. acunensis | Listed | Endangered | | AZ |
| Snails | Acute elimia | Elimia acuta | Petitioned for Listing, Under Review | Under Review | | AL, TN |
| Mammals | Addax | Addax nasomaculatus | Listed | Endangered | | |
| Flowering Plants | Adder's-mouth | Malaxis brachypoda | Not Listed | Species of Concern | | CA |
| Flowering Plants | Addison's virgin's bower | Clematis addisonii | Not Listed | Species of Concern | | VA |
| Flowering Plants | Adobe desert-parsley | Lomatium concinnum | Not Listed | Species of Concern | | CO |
| Flowering Plants | Adobe navarretia | navarretia nigelliformis ssp. nigelliformis | Not Listed | Species of Concern | | |
| Flowering Plants | Adobe sanicle | Sanicula maritima | Not Listed | Species of Concern | | CA |
| Flowering Plants | Adobe yampah | Perideridia pringlei | Not Listed | Resolved Taxon | | CA |
| Fishes | Adriatic sturgeon | Acipenser naccarii | Listed | Endangered | | |
| Insects | Adytum megalagrion damselfly | Megalagrion adytum | Not Listed | Species of Concern | | HI |
| Flowering Plants | A`e | Zanthoxylum dipetalum var. tomentosum | Listed | Endangered | | HI |
| Flowering Plants | A`e | Zanthoxylum hawaiiense | Listed | Endangered | | HI |
| Flowering Plants | A`e | Zanthoxylum oahuense | Listed | Endangered | | HI |
| Flowering Plants | A`e | Zanthoxylum semiarticulatum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | A`e | Zanthoxylum skottsbergii | Not Listed | Resolved Taxon | | HI |
| Snails | A Freshwater Snail | Pyrgulopsis bedfordensis | Not Listed | Resolved Taxon | | |
| Fishes | African coelacanth | Latimeria chalumnae | Listed | Threatened | | |
| Reptiles | African dwarf crocodile | Osteolaemus tetraspis tetraspis | Listed | Endangered | | |
| Mammals | African elephant | Loxodonta africana | Listed | Threatened | | |
| Birds | African penguin | Spheniscus demersus | Listed | Endangered | | |
| Reptiles | African slender-snouted crocodile | Crocodylus cataphractus | Listed | Endangered | | |
| Amphibians | African viviparous toads | Nectophrynoides spp. | Listed | Endangered | | |
| Mammals | African wild ass | Equus africanus | Listed | Endangered | | |
| Mammals | African wild dog | Lycaon pictus | Listed | Endangered | | |
| Snails | Agate rocksnail | Leptoxis clipeata | Not Listed | Resolved Taxon | | AL |
| Snails | Agave Threeband | Humboldtiana agavophila | Not Listed | Resolved Taxon | | |
| Flowering Plants | `Ahakea | Bobea sandwicensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ahakea | Bobea timonioides | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ahart's dwarf rush | Juncus leiospermus var. ahartii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Ahart's whitlow-wort | Paronychia ahartii | Not Listed | Species of Concern | | CA |
| Flowering Plants | `Ahinahina | Argyroxiphium sandwicense ssp. macrocephalum | Listed | Threatened | | HI |
| Flowering Plants | `Ahinahina | Argyroxiphium sandwicense ssp. sandwicense | Listed | Endangered | | HI |
| Insects | Ahinahina long-horned beetle | Plagiithmysus swezeyanus | Not Listed | Species of Concern | | HI |
| Fishes | Aholehole Kai | Kuhlia sandvicensis | | Not Listed | | |
| Fishes | Aholehole Mauka | Kuhlia xenura | | Not Listed | | |
| Flowering Plants | A Hornwort | Aspiromitus appalachianus | Not Listed | Species of Concern | | |
| Flowering Plants | `Aiakeakua, popolo | Solanum sandwicense | Listed | Endangered | | HI |
| Flowering Plants | `Aiea | Nothocestrum breviflorum | Listed | Endangered | | HI |
| Flowering Plants | `Aiea | Nothocestrum latifolium | Listed | Endangered | | HI |
| Flowering Plants | `Aiea | Nothocestrum longifolium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Aiea | Nothocestrum peltatum | Listed | Endangered | | HI |
| Flowering Plants | Ajo rock-daisy | Perityle ajoensis | Not Listed | Resolved Taxon | | AZ |
| Birds | Akekee | Loxops caeruleirostris | Listed | Endangered | | HI |
| Birds | akiapolaau | Hemignathus wilsoni | Listed | Endangered | | HI |
| Birds | Akikiki | Oreomystis bairdi | Listed | Endangered | | HI |
| Birds | `Akohekohe (crested honeycreeper) | Palmeria dolei | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Chamaesyce arnottiana | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Akoko | Chamaesyce atrococca | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Akoko | Chamaesyce celastroides tomentella | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Akoko | Chamaesyce olowaluana | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Akoko | Chamaesyce remyi hanaleiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Akoko | Chamaesyce skottsbergii vaccinioides | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Akoko | Chamaesyce sparsiflora | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Akoko | Euphorbia celastroides var. kaenana | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia deppeana | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia eleanoriae | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia haeleeleana | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia herbstii | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia kuwaleana | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia remyi var. kauaiensis | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia remyi var. remyi | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia rockii | Listed | Endangered | | HI |
| Flowering Plants | `Akoko | Euphorbia skottsbergii var. skottsbergii | Listed | Endangered | | HI |
| Flowering Plants | 'Akoko | Euphorbia halemanui | Listed | Endangered | | HI |
| Flowering Plants | `aku | Cyanea tritomantha | Listed | Endangered | | HI |
| Flowering Plants | `aku`aku | Cyanea platyphylla | Listed | Endangered | | HI |
| Fishes | Akupa Sleeper, `O`Opu Akupa | Eleotris sandwicensis | | Not Listed | | |
| Flowering Plants | Ala`a | Pouteria hotteana | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Ala`a | Pouteria sandwicensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ala `ala wai nui | Peperomia subpetiolata | Listed | Endangered | | HI |
| Fishes | Ala balik (trout) | Salmo platycephalus | Listed | Endangered | | |
| Mammals | Alabama beach mouse | Peromyscus polionotus ammobates | Listed | Endangered | | AL |
| Flowering Plants | Alabama Canebrake Pitcher Plant | Sarracenia rubra ssp. alabamensis | Listed | Endangered | | AL |
| Crustaceans | Alabama Cave crayfish | Cambarus jonesi | | Not Listed | | AL |
| Fishes | Alabama cavefish | Speoplatyrhinus poulsoni | Listed | Endangered | | AL |
| Crustaceans | Alabama cave shrimp | Palaemonias alabamae | Listed | Endangered | | AL |
| Fishes | Alabama channel darter | Percina sp. | Not Listed | Species of Concern | | AL |
| Clams | Alabama Clubshell | Pleurobema troschelianum | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | Alabama croton | Croton alabamensis alabamensis | Not Listed | Species of Concern | | AL, TN |
| Flowering Plants | Alabama glade cress | Leavenworthia alabamica ssp. alabamica | Not Listed | Resolved Taxon | | AL |
| Clams | Alabama hickorynut | Obovaria unicolor | Proposed for Listing | Proposed Endangered | | AL, MS |
| Flowering Plants | Alabama jamesianthus | Jamesianthus alabamensis | Not Listed | Species of Concern | | AL |
| Clams | Alabama lampmussel | Lampsilis virescens | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Alabama lampmussel | Lampsilis virescens | Listed | Endangered | | AL, MS, TN |
| Flowering Plants | Alabama larkspur | Delphinium alabamicum | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | Alabama Leather Flower | Clematis socialis | Listed | Endangered | | AL, GA |
| Reptiles | Alabama Map turtle | Graptemys pulchra | Listed | Similarity of Appearance (Threatened) | | AL, GA, MS |
| Clams | Alabama moccasinshell | Medionidus acutissimus | Listed | Threatened | | AL, GA, MS, TN |
| Clams | Alabama pearlshell | Margaritifera marrianae | Listed | Endangered | | AL |
| Clams | Alabama rainbow | Villosa nebulosa | Petitioned for Listing, Under Review | Under Review | | AL, GA, NC, TN |
| Reptiles | Alabama red-bellied turtle | Pseudemys alabamensis | Listed | Endangered | | AL, MS |
| Flowering Plants | Alabama sandwort | Arenaria alabamensis | Not Listed | Resolved Taxon | | AL, GA, NC |
| Fishes | Alabama shad | Alosa alabamae | Petitioned for Listing, Under Review | Under Review | | GA |
| Clams | Alabama spike | Elliptio arca | Petitioned for Listing, Under Review | Under Review | | AL, GA, LA, MS, TN |
| Fishes | Alabama Spotted Bass | Micropterus henshalli | | Not Listed | | |
| Ferns and Allies | Alabama streak-sorus fern | Thelypteris pilosa var. alabamensis | Listed | Threatened | | AL |
| Fishes | Alabama sturgeon | Scaphirhynchus suttkusi | Listed | Endangered | | AL |
| Snails | Alabama vertigo | Vertigo alabamensis | Not Listed | Species of Concern | | AL |
| Crustaceans | Alabama well amphipod | Stygobromus smithi | Not Listed | Species of Concern | | AL |
| Crustaceans | Alachua Light Fleeting Cave crayfish | Procambarus lucifugus ssp. alachua | | Not Listed | | |
| Mammals | Alameda Island mole | Scapanus latimanus parvus | Not Listed | Species of Concern | | CA |
| Reptiles | Alameda whipsnake (=striped racer) | Masticophis lateralis euryxanthus | Listed | Threatened | | CA |
| Flowering Plants | Alamo beardtongue | Penstemon alamosensis | Not Listed | Species of Concern | | NM, TX |
| Insects | Alamosa satyr butterfly | Cercyonis meadii alamosa | Not Listed | Resolved Taxon | | CO |
| Snails | Alamosa springsnail | Tryonia alamosae | Listed | Endangered | | NM |
| Flowering Plants | Alani | Melicope adscendens | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope balloui | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope christophersenii | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope cruciata | Not Listed | Species of Concern | | HI |
| Flowering Plants | Alani | Melicope degeneri | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope haleakalae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Alani | Melicope haupuensis | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope hawaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Alani | Melicope hiiakae | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope kavaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Alani | Melicope knudsenii | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope lydgatei | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope macropus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Alani | Melicope makahae | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope mucronulata | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope munroi | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope nealae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Alani | Melicope obovata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Alani | Melicope orbicularis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Alani | Melicope ovalis | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope ovata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Alani | Melicope pallida | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope paniculata | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope puberula | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope quadrangularis | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope reflexa | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope saint-johnii | Listed | Endangered | | HI |
| Flowering Plants | Alani | Melicope sandwicensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Alani | Melicope wailauensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Alani | Melicope zahlbruckneri | Listed | Endangered | | HI |
| Birds | Alaotra Grebe | Tachybaptus rufolavatus | Listed | Endangered | | |
| Flowering Plants | Alaskan glacier buttercup | Ranunculus glacialis ssp. alaskensis | | Not Listed | | AK |
| Flowering Plants | Alaska rein orchid | Platanthera unalascensis maritima | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Crustaceans | Albermarle crayfish | Procambarus medialis | Not Listed | Species of Concern | | NC |
| Birds | Aldabra Warbler (old world warbler) | Nesillas aldabranus | Listed | Endangered | | |
| Birds | Aleutian Canada goose | Branta canadensis leucopareia | Delisted | Recovery | | AK, CA, NV, OR, WA |
| Flowering Plants | Aleutian chickweed | Cerastium aleuticum | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | Aleutian saxifrage | Saxifraga aleutica | Not Listed | Resolved Taxon | | AK |
| Ferns and Allies | Aleutian shield fern | Polystichum aleuticum | Listed | Endangered | | AK |
| Birds | Aleutian Tern | Onychoprion aleuticus | | Not Listed | | |
| Flowering Plants | Aleutian wormwood | Artemisia aleutica | Not Listed | Resolved Taxon | | AK |
| Fishes | alewife | Alosa pseudoharengus | Not Listed | Status Undefined | | |
| Clams | Alewife Floater | Utterbackiana implicata | | Not Listed | | |
| Mammals | Alexander Archipelago wolf | Canis lupus ligoni | Not Listed | Resolved Taxon | | AK |
| Insects | Alexander's rhyacophilan caddisfly | Rhyacophila alexanderi | Not Listed | Species of Concern | | MT |
| Flowering Plants | Alexander's rock-aster | Eurybia avita | Not Listed | Species of Concern | | NC |
| Birds | Algerian nuthatch | Sitta ledanti | Listed | Endangered | | |
| Flowering Plants | Algodoncillo | Psiguria cookiana | Not Listed | Species of Concern | | PR, VI |
| Insects | Algodones croton jewel beetle | Agrilus harenus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Algodones Dunes sunflower | Helianthus niveus tephrodes | Not Listed | Species of Concern | | AZ, CA |
| Insects | Algodones white wax jewel beetle | Prasinalia imperialis | Not Listed | Resolved Taxon | | |
| Insects | Algondones sand jewel beetle | Lepismadora algodones | Not Listed | Resolved Taxon | | |
| Snails | Alifan Tree snail | Partula salifana | Not Listed | Species of Concern | | GU |
| Flowering Plants | A Liverwort | Porella wataugensis | Not Listed | Species of Concern | | NC |
| Flowering Plants | Alkali mariposa lily | Calochortus striatus | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Alkali milk-vetch | Astragalus tener var. tener | Not Listed | Species of Concern | | |
| Insects | Alkali skipper | Pseudocopaeodes eunus eunus | | Not Listed | | CA |
| Flowering Plants | Alleghany plum | Prunus alleghaniensis | Not Listed | Species of Concern | | CT, DE, MD, MI, NJ, PA, VA, WV |
| Insects | Alleghany snaketail | Ophiogomphus incurvatus alleghaniensis | Not Listed | Status Undefined | | AL, GA, TN, VA, WV |
| Mammals | Alleghany woodrat | Neotoma magister | Not Listed | Resolved Taxon | | VA |
| Crustaceans | Allegheny cave amphipod | Stygobromus allegheniensis | Not Listed | Resolved Taxon | | MD, NY, PA |
| Crustaceans | Allegheny Mountain Mudbug | Cambarus fetzneri | | Not Listed | | |
| Mammals | Allen's 13-lined ground squirrel | Spermophilus tridecemlineatus alleni | Not Listed | Species of Concern | | WY |
| Mammals | Allen's big-eared bat | Idionycteris phyllotis | Not Listed | Species of Concern | | AZ, CA, CO, NM, NV, UT |
| Reptiles | Allen's Cay iguana | Cyclura cychlura inornata | Listed | Threatened | | |
| Birds | Allen's Hummingbird | Selasphorus sasin | Not Listed | Species of Concern | | |
| Fishes | Alligator Gar | Atractosteus spatula | | Not Listed | | |
| Reptiles | Alligator snapping turtle | Macrochelys temminckii | Proposed for Listing | Proposed Threatened | | AL, AR, FL, GA, IL, KS, KY, LA, MO, MS, OK, TN, TX |
| Fishes | almaco jack | Seriola rivoliana | | Not Listed | | |
| Flowering Plants | Alpine bluet | Houstonia caerulea faxonorum | Not Listed | Resolved Taxon | | NH |
| Flowering Plants | Alpine braya | Braya humilis ventosa | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Alpine County cryptantha | Cryptantha crymophila | Not Listed | Resolved Taxon | | CA |
| Snails | Alpine Mountainsnail | Oreohelix alpina | Not Listed | Resolved Taxon | | |
| Flowering Plants | Alpine streptanthus | Streptanthus gracilis | Not Listed | Resolved Taxon | | CA |
| Insects | Alsea ochrotrichian micro caddisfly | Ochrotrichia alsea | Not Listed | Resolved Taxon | | OR |
| Clams | Altamaha arc-mussel | Alasmidonta arcula | | Not Listed | | GA |
| Clams | Altamaha lance | Elliptio shepardiana | Not Listed | Species of Concern | | GA |
| Fishes | Altamaha shiner | Cyprinella xaenura | | Not Listed | | GA |
| Clams | Altamaha Spinymussel | Elliptio spinosa | Listed | Endangered | | GA |
| Birds | Altamira Oriole | Icterus gularis | Not Listed | Species of Concern | | |
| Flowering Plants | Alverson's foxtail cactus | Coryphantha vivipara alversonii | Not Listed | Species of Concern | | CA |
| Fishes | Alvord chub | Siphateles alvordensis | Not Listed | Species of Concern | | NV, OR |
| Fishes | Alvord cutthroat trout | Oncorhynchus clarki ssp. | Not Listed | Resolved Taxon | | CA, NV, OR |
| Fishes | Ama (Black Mullet) | Mugil cephalus | | Not Listed | | |
| Flowering Plants | Amador rush-rose | Helianthemum scoparium | Not Listed | Resolved Taxon | | CA |
| Birds | Amak song sparrow | Melospiza melodia amaka | Not Listed | Resolved Taxon | | AK |
| Mammals | Amak tundra vole | Microtus oeconomus amakensis | Not Listed | Species of Concern | | AK |
| Fishes | Amargosa Canyon speckled dace | Rhinichthys osculus ssp. | Not Listed | Species of Concern | | CA |
| Insects | Amargosa naucorid | Pelocoris shoshone amargosa | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Amargosa niterwort | Nitrophila mohavensis | Listed | Endangered | | NV |
| Flowering Plants | Amargosa penstemon | Penstemon fruticiformis amargosae | Not Listed | Species of Concern | | CA, NV |
| Fishes | Amargosa Pupfish | Cyprinodon nevadensis | | Not Listed | | |
| Fishes | Amargosa River Pupfish | Cyprinodon nevadensis amargosae | | Not Listed | | |
| Mammals | Amargosa southern pocket gopher | Thomomys umbrinus amargosae | Not Listed | Resolved Taxon | | CA |
| Fishes | Amargosa speckled dace | Rhinichthys nevadensis nevadensis | Petitioned for Listing, Under Review | Under Review | | NV |
| Amphibians | Amargosa toad | Bufo nelsoni | Petitioned for Listing, Under Review | Under Review | | NV |
| Snails | Amargosa tryonia | Tryonia variegata | Not Listed | Resolved Taxon | | CA, NV |
| Mammals | Amargosa vole | Microtus californicus scirpensis | Listed | Endangered | | CA |
| Flowering Plants | Amarillo mato | Caesalpinia culebrae | Not Listed | Species of Concern | | PR, VI |
| Insects | A Mayfly | Baetodes alleni | Not Listed | Resolved Taxon | | |
| Mammals | Amazonian manatee | Trichechus inunguis | Listed | Endangered | | |
| Fishes | Amber darter | Percina antesella | Listed | Endangered | | GA, TN |
| Insects | Ambiguous eopenthes click beetle | Eopenthes ambiguus | Not Listed | Species of Concern | | HI |
| Reptiles | American alligator | Alligator mississippiensis | Listed | Similarity of Appearance (Threatened) | Recovery | AR, FL, NC, OK, TX |
| Birds | American Avocet | Recurvirostra americana | Not Listed | Species of Concern | | |
| Mammals | American badger | Taxidea taxus | Not Listed | Species of Concern | | |
| Mammals | American Bison | Bison bison | | Not Listed | | |
| Birds | American bittern | Botaurus lentiginosus | Not Listed | Species of Concern | | |
| Mammals | American black bear | Ursus americanus | Not Listed | Resolved Taxon | | MS |
| Fishes | American Brook Lamprey | Lethenteron appendix | | Not Listed | | |
| Insects | American bumble bee | Bombus pensylvanicus | Petitioned for Listing, Under Review | Under Review | | |
| Insects | American burying beetle | Nicrophorus americanus | Listed | Experimental Population, Non-Essential | | MO |
| Insects | American burying beetle | Nicrophorus americanus | Listed | Threatened | | AR, KS, MA, NE, OH, OK, RI, SD, TX |
| Flowering Plants | American chaffseed | Schwalbea americana | Listed | Endangered | | AL, FL, GA, LA, MA, NC, NJ, PA, SC, TX |
| Flowering Plants | American chestnut | Castanea dentata | Not Listed | Status Undefined | | |
| Insects | American chestnut nepticulid moth | Ectodemia castaneae | Not Listed | Species of Concern | | MD |
| Crustaceans | American clam shrimp | Limnadia lenticularis | Not Listed | Species of Concern | | |
| Birds | American Coot | Fulica americana americana | Not Listed | Species of Concern | | |
| Reptiles | American crocodile | Crocodylus acutus | Listed | Endangered | | |
| Reptiles | American crocodile | Crocodylus acutus | Listed | Threatened | | FL |
| Birds | American Dipper | Cinclus mexicanus | Not Listed | Species of Concern | | |
| Birds | American Dipper | Cinclus mexicanus unicolor | Not Listed | Resolved Taxon | | |
| Flowering Plants | American dry rock moss | Grimmia americana | Not Listed | Resolved Taxon | | NV |
| Fishes | American eel | Anguilla rostrata | Not Listed | Resolved Taxon | | |
| Birds | American Flamingo | Phoenicopterus ruber | Not Listed | Species of Concern | | |
| Flowering Plants | American ginseng | Panax quinquefolius | Not Listed | Resolved Taxon | | |
| Birds | American Golden-Plover | Pluvialis dominica | Not Listed | Species of Concern | | |
| Ferns and Allies | American hart's-tongue fern | Asplenium scolopendrium var. americanum | Listed | Threatened | | AL, GA, MI, NM, NY, TN |
| Birds | American Kestrel | Falco sparverius paulus | Not Listed | Species of Concern | | |
| Mammals | American Marten | Martes americana | | Not Listed | | |
| Birds | American Oystercatcher | Haematopus palliatus | Not Listed | Species of Concern | | |
| Birds | American peregrine falcon | Falco peregrinus anatum | Delisted | Recovery | | AZ, CO, OK |
| Mammals | American pika | Ochotona princeps | Not Listed | Resolved Taxon | | CO |
| Insects | American sandburrowing mayfly | Dolania americana | Not Listed | Species of Concern | | |
| Fishes | American shad | Alosa sapidissima | Not Listed | Species of Concern | | |
| Birds | American swallow-tailed kite | Elanoides forficatus forficatus | Not Listed | Resolved Taxon | | |
| Birds | American White Pelican | pelecanus erythrorhynchos | Not Listed | Species of Concern | | |
| Insects | A millipede | Polydesmus cavicola | Not Listed | Resolved Taxon | | |
| Fishes | Amistad gambusia | Gambusia amistadensis | Delisted | Extinction | | TX |
| Flowering Plants | Ammon's tortula | Tortula ammonsiana | Not Listed | Species of Concern | | NC, TN, WV |
| Insects | Amphibious caddisfly | Desmona bethula | Not Listed | Species of Concern | | CA |
| Snails | Ample elimia | Elimia ampla | | Not Listed | | AL |
| Birds | Amsterdam Albatross | Diomedia amsterdamensis | Listed | Endangered | | |
| Fishes | Amur Sturgeon | Acipenser schrenckii | Proposed for Listing | Proposed Endangered | | |
| Mammals | Anacapa deer mouse | Peromyscus maniculatus anacapae | Not Listed | Resolved Taxon | | CA |
| Mammals | Anastasia Island beach mouse | Peromyscus polionotus phasma | Listed | Endangered | | FL |
| Mammals | Anastasia Island cotton mouse | Peromyscus gossypinus anastasae | Not Listed | Resolved Taxon | | |
| Mammals | Anastasia Island mole | Scalopus aquaticus anastasae | Not Listed | Resolved Taxon | | |
| Flowering Plants | `Anaunau | Lepidium arbuscula | Listed | Endangered | | HI |
| Flowering Plants | `Anaunau | Lepidium bidentatum o-waihiense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Anaunau | Lepidium serra | Not Listed | Species of Concern | | HI |
| Insects | Ana wingless thread bug | Nesidiolestes ana | Not Listed | Species of Concern | | HI |
| Crustaceans | Anchialine pool shrimp | Antecaridina lauensis | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Anchialine pool shrimp | Metabetaeus lohena | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Anchialine pool shrimp | Palaemonella burnsi | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Anchialine pool shrimp | Vetericaris chaceorum | Listed | Endangered | | HI |
| Crustaceans | Anchialine pool Shrimp | Calliasmata pholidota | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Anchialine pool Shrimp | Procaris hawaiana | Listed | Endangered | | HI |
| Snails | Anchialine Pool Snail | Neritilia hawaiiensis | Not Listed | Species of Concern | | HI |
| Insects | Ancient ant | Smithistruma reliquia | Not Listed | Species of Concern | | CA |
| Birds | Ancient Murrelet | Synthliboramphus antiquus | Not Listed | Species of Concern | | |
| Mammals | Andean cat | Felis jacobita | Listed | Endangered | | |
| Birds | Andean condor | Vultur gryphus | Listed | Endangered | | |
| Birds | Andean flamingo | Phoenicoparrus andinus | Listed | Endangered | | |
| Flowering Plants | Anderson's brachymenium | Brachymenium andersonii | Not Listed | Species of Concern | | NC |
| Flowering Plants | Anderson sedge | Carex micropoda | Not Listed | Resolved Taxon | | AK |
| Insects | Andrenid bee | Perdita glamis | Not Listed | Resolved Taxon | | |
| Insects | Andrenid Bee | Perdita algondones | Not Listed | Resolved Taxon | | |
| Insects | Andrenoid yellow-faced bee | Hylaeus andrenoides | Not Listed | Species of Concern | | HI |
| Insects | Andrews' dune scarab beetle | Pseudocotalpa andrewsi | Not Listed | Resolved Taxon | | CA |
| Birds | Andrew's frigatebird | Fregata andrewsi | Listed | Endangered | | |
| Insects | Andrew's marble butterfly | Euchloe hyantis andrewsi | Not Listed | Species of Concern | | CA |
| Reptiles | Andros Island ground iguana | Cyclura cychlura cychlura | Listed | Threatened | | |
| Reptiles | Anegada ground iguana | Cyclura pinguis | Listed | Endangered | | |
| Fishes | Angel shark | Squatina squatina | Listed | Endangered | | |
| Clams | Angled riffleshell | Epioblasma biemarginata | Not Listed | Resolved Taxon | | AL, TN |
| Crustaceans | Angular Dwarf crayfish | Cambarellus lesliei | Petitioned for Listing, Under Review | Under Review | | AL, MS |
| Snails | Angular pebblesnail | Somatogyrus biangulatus | Not Listed | Species of Concern | | AL |
| Reptiles | Angulated tortoise | Geochelone yniphora | Listed | Endangered | | |
| Birds | Anianiau | Magumma parva | Not Listed | Species of Concern | | |
| Insects | Animas minute moss beetle | Limnebius aridus | Not Listed | Species of Concern | | NM |
| Snails | animas mountains tubeshell | holospira animasensis | Not Listed | Resolved Taxon | | |
| Snails | Animas Peak Woodlandsnail | Ashmunella animasensis | Not Listed | Resolved Taxon | | |
| Mammals | Animas southern pocket gopher | Thomomys umbrinus emotus | Not Listed | Resolved Taxon | | NM |
| Snails | Animas Talussnail | Sonorella animasensis | Not Listed | Resolved Taxon | | |
| Birds | Anjouan Island sparrowhawk | Accipiter francesii pusillus | Listed | Endangered | | |
| Birds | Anjouan scops owl | Otus rutilus capnodes | Listed | Endangered | | |
| Insects | Annectans rhopalid bug | Ithamar annectans | Not Listed | Species of Concern | | HI |
| Insects | Annointed sallow noctuid moth | Pyreferra ceromatica | Not Listed | Species of Concern | | |
| Crustaceans | Anomalous spring amphipod | Crangonyx anomalus | Not Listed | Resolved Taxon | | IN, KY, OH |
| Insects | Anomalous yellow-faced bee | Hylaeus anomala | Not Listed | Species of Concern | | HI |
| Insects | A Notodontid moth | Crinodes mcfarlandi | Not Listed | Resolved Taxon | | |
| Insects | A Notodontid moth | Heterocampa sp. 1 nr. amanda | Not Listed | Resolved Taxon | | |
| Insects | A Notodontid moth | Litodonta sp. 1 nr. alpina | Not Listed | Resolved Taxon | | |
| Insects | A Notodontid moth | ursia species | Not Listed | Status Undefined | | |
| Insects | A Notodontid Moth | Heterocampa rufinans | Not Listed | Resolved Taxon | | |
| Mammals | Antelope Island pocket gopher | Thomomys umbrinus nesophilus | Not Listed | Species of Concern | | UT |
| Insects | Anthony blister beetle | Lytta mirifica | Not Listed | Species of Concern | | NM |
| Flowering Plants | Anthony Peak lupine | Lupinus antoninus | Not Listed | Species of Concern | | CA |
| Snails | Anthony's riversnail | Athearnia anthonyi | Listed | Experimental Population, Non-Essential | | TN |
| Snails | Anthony's riversnail | Athearnia anthonyi | Listed | Experimental Population, Non-Essential | | AL |
| Snails | Anthony's riversnail | Athearnia anthonyi | Listed | Endangered | | AL, GA, TN |
| Insects | Anthricinan yellow-faced bee | Hylaeus anthracinus | Listed | Endangered | | HI |
| Fishes | Antillean Manatee | Trichechus manatus manatus | Proposed for Listing | Proposed Endangered | | |
| Birds | Antillean Mango | Anthracothorax dominicus | Not Listed | Species of Concern | | |
| Birds | Antillean Mango | Anthracothorax dominicus aurulentus | Not Listed | Species of Concern | | |
| Insects | Antioch andrenid bee | Perdita scitula antiochensis | Not Listed | Species of Concern | | CA |
| Insects | Antioch cophuran robberfly | Cophura hurdi | Not Listed | Species of Concern | | CA |
| Insects | Antioch Dunes anthicid | Anthicus antiochensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Antioch Dunes evening-primrose | Oenothera deltoides ssp. howellii | Listed | Endangered | | CA |
| Insects | Antioch Dunes shieldback katydid | Neduba extincta | Not Listed | Resolved Taxon | | CA |
| Insects | Antioch Dune weevil | Dysticheus rotundicollis | Not Listed | Resolved Taxon | | CA |
| Insects | Antioch efferian robberfly | Efferia antiochi | Not Listed | Species of Concern | | CA |
| Insects | Antioch mutillid wasp | Myrmosula pacifica | Not Listed | Species of Concern | | CA |
| Insects | Antioch potter wasp | Microdynerus arenicolus | Not Listed | Resolved Taxon | | AZ, CA, NV |
| Insects | Antioch sphecid wasp | Philanthus nasalis | Not Listed | Species of Concern | | CA |
| Flowering Plants | `Anunu | Sicyos albus | Listed | Endangered | | HI |
| Flowering Plants | `Anunu | Sicyos cucumerinus | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Anunu | Sicyos macrophyllus | Listed | Endangered | | HI |
| Arachnids | Anza Borrego blind harvestman | Sitalcina borregoensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Apache Pass rubberweed | Hymenoxys ambigens var. floribunda | Not Listed | Resolved Taxon | | AZ |
| Insects | Apache silverspot butterfly | Speyeria nokomis apacheana | Not Listed | Resolved Taxon | | CA, NV |
| Snails | Apache Talussnail | Sonorella apache | Not Listed | Resolved Taxon | | |
| Fishes | Apache trout | Oncorhynchus apache | Delisted | Recovery | | AZ, NM |
| Flowering Plants | Apache wild-buckwheat | Eriogonum apachense | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Apalachicola doll's daisy | Boltonia apalachicolensis | Not Listed | Species of Concern | | |
| Clams | Apalachicola floater | Anodonta heardi | Not Listed | Status Undefined | | AL, GA |
| Reptiles | Apalachicola king snake | Lampropeltis getula meansi | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Apalachicola rosemary | Conradina glabra | Listed | Endangered | | FL |
| Insects | Apalachicola twilight skimmer | Neurocordulia clara | Not Listed | Species of Concern | | |
| Flowering Plants | Apalachicola wild indigo | Baptisia megacarpa | Not Listed | Resolved Taxon | | GA |
| Birds | 'Apapane | Himatione sanguinea | Not Listed | Species of Concern | | |
| Reptiles | Apaporis River caiman | Caiman crocodilus apaporiensis | Listed | Endangered | | |
| Mammals | Apennine chamois | Rupicapra rupicapra ornata | Listed | Endangered | | |
| Flowering Plants | Aphanisma | Aphanisma blitoides | Not Listed | Species of Concern | | CA |
| Insects | Aphodius tortoise commensal scarab | Aphodius troglodytes | Not Listed | Species of Concern | | |
| Arachnids | (Aphrastochthonius) pseudoscorpion | aphrastochthonius | Not Listed | Species of Concern | | |
| Flowering Plants | Aplokating-palaoan | Psychotria malaspinae | Listed | Endangered | | GU |
| Flowering Plants | Apoda | Pelea parvifolia apoda | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Appalachian Adder's-mouth | Malaxis bayardii | Not Listed | Species of Concern | | NC |
| Birds | Appalachian Bewick's wren | Thryomanes bewickii altus | Not Listed | Species of Concern | | VA |
| Crustaceans | Appalachian Cave crayfish | Orconectes packardi | Not Listed | Status Undefined | | KY |
| Mammals | Appalachian cottontail rabbit | Sylvilagus obscurus | Not Listed | Status Undefined | | VA |
| Lichens | Appalachian dust bunnies | Lepraria lanata | Not Listed | Species of Concern | | |
| Clams | Appalachian elktoe | Alasmidonta raveneliana | Listed | Endangered | | NC, SC, TN |
| Ferns and Allies | Appalachian Fissidens moss | Fissidens appalachensis | Not Listed | Status Undefined | | NC, TN |
| Clams | Appalachian monkeyface (pearlymussel) | Theliderma sparsa | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Appalachian monkeyface (pearlymussel) | Theliderma sparsa | Listed | Endangered | | TN, VA |
| Insects | Appalachian snaketail | Ophiogomphus incurvatus | Not Listed | Status Undefined | | AL, GA, KY, MD, NC, PA, VA, WV |
| Crustaceans | Appalachian Valley cave amphipod | Crangonyx antennatus | Not Listed | Resolved Taxon | | AL, IL, TN, VA |
| Flowering Plants | Applegate's milk-vetch | Astragalus applegatei | Listed | Endangered | | OR |
| Flowering Plants | Applegate stonecrop | Sedum oblanceolatum | Not Listed | Species of Concern | | CA, NV, OR |
| Snails | Aqua Dulce Talussnail | Sonorella meadi | Not Listed | Resolved Taxon | | |
| Flowering Plants | Aquarius paintbrush | Castilleja aquariensis | Not Listed | Resolved Taxon | | UT |
| Reptiles | Aquatic box turtle | Terrapene coahuila | Listed | Endangered | | |
| Snails | Aquatic snail | valvata mergella | Not Listed | Species of Concern | | |
| Mammals | Arabian gazelle | Gazella gazella | Listed | Endangered | | |
| Mammals | Arabian oryx | Oryx leucoryx | Listed | Endangered | | |
| Birds | Arabian ostrich | Struthio camelus syriacus | Listed | Endangered | | |
| Mammals | Arabian tahr | Hemitragus jayakari | Listed | Endangered | | |
| Mammals | Aransas short-tailed shrew | Blarina hylophaga plumbea | Not Listed | Species of Concern | | TX |
| Insects | Arapahoe snowfly | Arsapnia arapahoe | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Aravaipa sage | Salvia amissa | Not Listed | Species of Concern | | AZ |
| Insects | Arbuckle Cave ground beetle | Horologion speokites | Not Listed | Species of Concern | | WV |
| Insects | Archbold anomalan scarab | Anomala eximia | Not Listed | Species of Concern | | |
| Snails | Archer's toothed land snail | Fumonelix archeri | Not Listed | Resolved Taxon | | TN |
| Fishes | Arctic Char | Salvelinus alpinus | | Not Listed | | |
| Fishes | Arctic Cisco | Coregonus autumnalis | | Not Listed | | |
| Fishes | Arctic grayling | Thymallus arcticus | | Not Listed | | |
| Fishes | Arctic grayling | Thymallus arcticus | Not Listed | Resolved Taxon | | MT |
| Fishes | Arctic Lamprey | Lethenteron camtschaticum | | Not Listed | | |
| Birds | Arctic peregrine Falcon | Falco peregrinus tundrius | Delisted | Recovery | | |
| Flowering Plants | Arctic sage | Artemisia senjavinensis | Not Listed | Resolved Taxon | | AK |
| Birds | Arctic Tern | Sterna paradisaea | Not Listed | Species of Concern | | |
| Insects | Arctiidae arctia | Arctia speciesone | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Arcuate bush mallow | malacothamnus arcuatus | Not Listed | Species of Concern | | |
| Insects | Arduous eopenthes click beetle | Eopenthes arduus | Not Listed | Species of Concern | | HI |
| Mammals | Argali | Ovis ammon | Listed | Threatened | | |
| Mammals | Argali | Ovis ammon | Listed | Endangered | | |
| Fishes | Argentine angelshark | Squatina argentina | Listed | Endangered | | |
| Insects | Argo ephemerellan mayfly | Ephemerella argo | Not Listed | Species of Concern | | GA, IL, IN, SC |
| Flowering Plants | Argyle Canyon Phacelia | Phacelia argylensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Arid northern clarkia | Clarkia borealis arida | Not Listed | Species of Concern | | CA |
| Flowering Plants | Arizona agave | Agave arizonica | Delisted | Original Data in Error - Not a listable entity | | AZ |
| Birds | Arizona Bell's vireo | Vireo bellii arizonae | Not Listed | Resolved Taxon | | AZ, CA, NV, UT |
| Mammals | Arizona black-tailed prairie dog | Cynomys ludovicianus arizonensis | Not Listed | Species of Concern | | AZ, NM, TX |
| Flowering Plants | Arizona brome | Bromus arizonicus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Arizona bugbane | Cimicifuga arizonica | Not Listed | Resolved Taxon | | AZ |
| Crustaceans | Arizona cave amphipod | Stygobromus arizonensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Arizona Cliffrose | Purshia (=Cowania) subintegra | Listed | Endangered | | AZ |
| Flowering Plants | Arizona eryngo | Eryngium sparganophyllum | Listed | Endangered | | AZ |
| Insects | Arizona giant sand treader cricket | Daihinibaenetes arizonensis | Not Listed | Species of Concern | | AZ |
| Reptiles | Arizona Gilbert's skink | Eumeces gilberti arizonensis | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Arizona hedgehog cactus | Echinocereus arizonicus ssp. arizonicus | Listed | Endangered | | AZ |
| Flowering Plants | Arizona leatherflower | Clematis hirsutissima arizonica | Not Listed | Resolved Taxon | | |
| Flowering Plants | Arizona Monkshood | Aconitum infectum | Not Listed | Resolved Taxon | | |
| Mammals | Arizona montane vole | Microtus montanus arizonensis | Not Listed | Resolved Taxon | | AZ, NM |
| Mammals | Arizona Myotis | Myotis occultus | Not Listed | Species of Concern | | |
| Reptiles | Arizona night lizard | Xantusia vigilis arizonae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Arizona prickle-poppy | Argemone arizonica | Not Listed | Resolved Taxon | | AZ |
| Reptiles | Arizona ridge-nosed rattlesnake | Crotalus willardi willardi | Not Listed | Resolved Taxon | | AZ |
| Mammals | Arizona shrew | Sorex arizonae | Not Listed | Species of Concern | | AZ, NM |
| Flowering Plants | Arizona star leaf | Choisya arizonica | Not Listed | Resolved Taxon | | AZ |
| Reptiles | Arizona striped whiptail | Aspidoscelis inornatus arizonae | | Not Listed | | |
| Amphibians | Arizona toad | Anaxyrus microscaphus | Petitioned for Listing, Under Review | Under Review | | AZ, CA, NM, NV, OR, UT |
| Amphibians | Arizona Treefrog | Hyla wrightorum | Not Listed | Resolved Taxon | | AZ |
| Insects | Arizona water penny | Psephenus arizonensis | Not Listed | Species of Concern | | AZ |
| Mammals | Arizona water shrew | Sorex palustris navigator | Not Listed | Resolved Taxon | | AZ |
| Insects | Arizona wetsalts Tiger Beetle | Cicindela haemorrhagica arizonae | Not Listed | Resolved Taxon | | |
| Flowering Plants | Arizona willow | Salix arizonica | Not Listed | Resolved Taxon | | AZ |
| Birds | Arizona Woodpecker | Dryobates arizonae | Not Listed | Species of Concern | | |
| Reptiles | Arizona yellow mud turtle | Kinosternon flavescens arizonense | Not Listed | Resolved Taxon | | AZ |
| Insects | Arkansas agapetus caddisfly | Agapetus medicus | Not Listed | Species of Concern | | AR |
| Clams | Arkansas Broken-Ray | Lampsilis reeveiana | | Not Listed | | |
| Fishes | Arkansas darter | Etheostoma cragini | Not Listed | Resolved Taxon | | AR, CO, KS, MO, OK |
| Clams | Arkansas fatmucket | Lampsilis powellii | Listed | Threatened | | AR |
| Snails | Arkansas mudalia | Leptoxis arkansensis | Not Listed | Resolved Taxon | | AR, MO |
| Flowering Plants | Arkansas River feverfew | Parthenium tetraneuris | Not Listed | Species of Concern | | CO |
| Fishes | Arkansas River shiner | Notropis girardi | Listed | Threatened | | KS, NM, OK, TX |
| Snails | Arkansas Wedge | Triodopsis occidentalis | Not Listed | Species of Concern | | AR |
| Mammals | Armenian Whiskered Bat | Myotis hajastanicus | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Armored rocksnail | Lithasia armigera | Not Listed | Species of Concern | | AL, IN, KY, TN |
| Snails | Armored snail | Marstonia pachyta | Listed | Endangered | | AL |
| Flowering Plants | Aroostook sedge | Carex sterilis | Not Listed | Resolved Taxon | | ME |
| Fishes | Arrowleaf Falsepickerelweed | Monochoria hastata | | Not Listed | | |
| Amphibians | Arroyo (=arroyo southwestern) toad | Anaxyrus californicus | Listed | Endangered | | CA |
| Fishes | Arroyo chub | Gila orcuttii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Arroyo de la Cruz manzanita | Arctostaphylos cruzensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Arroyo de la Cruz mariposa lily | Calochortus clavatus recurvifolius | Not Listed | Species of Concern | | CA |
| Flowering Plants | Arroyo Seco bush-mallow | Malacothamnus palmeri lucianus | Not Listed | Species of Concern | | CA |
| Insects | Artesian agapetus caddisfly | Agapetus artesus | Not Listed | Species of Concern | | MO |
| Reptiles | Aruba Island rattlesnake | Crotalus unicolor | Listed | Threatened | | |
| Birds | Ash-breasted tit-tyrant | Anairetes alpinus | Listed | Endangered | | |
| Flowering Plants | Ash Creek ivesia | Ivesia paniculata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Ashe's magnolia | Magnolia ashei | Not Listed | Species of Concern | | |
| Flowering Plants | Ash-grey paintbrush | Castilleja cinerea | Listed | Threatened | | CA |
| Flowering Plants | Ashland Lupine | Lupinus aridus ssp. ashlandensis | Not Listed | Resolved Taxon | | CA, NV, OR |
| Mammals | Ashland shrew | Sorex trigonirostris | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Ashland thistle | Cirsium ciliolatum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Fishes | Ash Meadows Amargosa pupfish | Cyprinodon nevadensis mionectes | Listed | Endangered | | NV |
| Flowering Plants | Ash Meadows blazingstar | Mentzelia leucophylla | Listed | Threatened | | NV |
| Flowering Plants | Ash Meadows gumplant | Grindelia fraxinipratensis | Listed | Threatened | | NV |
| Flowering Plants | Ash Meadows ivesia | Ivesia kingii var. eremica | Listed | Threatened | | NV |
| Flowering Plants | Ash Meadows ladies'-tresses | Spiranthes infernalis | Not Listed | Species of Concern | | NV |
| Flowering Plants | Ash meadows milk-vetch | Astragalus phoenix | Listed | Threatened | | NV |
| Mammals | Ash Meadows montane vole | Microtus montanus nevadensis | Not Listed | Species of Concern | | NV |
| Insects | Ash Meadows naucorid | Ambrysus amargosus | Listed | Threatened | | NV |
| Snails | Ash Meadows pebblesnail | Pyrgulopsis erythropoma | Not Listed | Resolved Taxon | | NV |
| Fishes | Ash Meadows poolfish | Empetrichthys merriami | Not Listed | Resolved Taxon | | NV |
| Fishes | Ash Meadows speckled dace | Rhinichthys osculus nevadensis | Listed | Endangered | | NV |
| Flowering Plants | Ash Meadows sunray | Enceliopsis nudicaulis var. corrugata | Listed | Threatened | | NV |
| Flowering Plants | Ash penstemon | Penstemon cinicola | Not Listed | Resolved Taxon | | CA, NV, OR |
| Fishes | Ashy darter | Etheostoma cinereum | Not Listed | Resolved Taxon | | AL, GA, KY, TN, VA |
| Flowering Plants | Ashy dogweed | Thymophylla tephroleuca | Listed | Endangered | | TX |
| Clams | ashy pebblesnail | Fluminicola fuscus | | Not Listed | | OR, WA |
| Flowering Plants | Ashy phacelia | Phacelia distans | Not Listed | Species of Concern | | CA |
| Lichens | Ashy spike-moss | selaginella cinerascens | Not Listed | Species of Concern | | |
| Birds | Ashy Storm-petrel | Hydrobates homochroa | Not Listed | Resolved Taxon | | CA |
| Fishes | Asian bonytongue | Scleropages formosus | Listed | Endangered | | |
| Mammals | Asian elephant | Elephas maximus | Listed | Endangered | | |
| Mammals | Asian golden (=Temmnick's) cat | Catopuma (=Felis) temminckii | Listed | Endangered | | |
| Mammals | Asian tapir | Tapirus indicus | Listed | Endangered | | |
| Mammals | Asian wild ass | Equus hemionus | Listed | Endangered | | |
| Insects | A Spur-throat Grasshopper | Melanoplus magdalenae | Not Listed | Resolved Taxon | | |
| Insects | Assimulans yellow-faced bee | Hylaeus assimulans | Listed | Endangered | | HI |
| Insects | A stonefly | Capnia arapahoe | Not Listed | Resolved Taxon | | |
| Insects | A stonefly | Sweltsa cristata | Not Listed | Resolved Taxon | | |
| Insects | Atascodero june beetle | Polyphylla nubila | Not Listed | Species of Concern | | CA |
| Insects | Athens long-horned caddisfly | Triaenodes phalacris | Not Listed | Resolved Taxon | | OH |
| Birds | Atitlan grebe | Podilymbus gigas | Listed | Endangered | | |
| Fishes | Atlantic Croaker | Micropogonias undulatus | | Not Listed | | |
| Mammals | Atlantic humpback dolphin | Sousa teuszii | Listed | Endangered | | |
| Fishes | Atlantic Menhaden | Brevoortia tyrannus | | Not Listed | | |
| Clams | Atlantic pigtoe | Fusconaia masoni | Listed | Threatened | | NC, VA |
| Birds | Atlantic Puffin | Fratercula arctica | Not Listed | Species of Concern | | ME |
| Fishes | Atlantic salmon | Salmo salar | Listed | Endangered | | ME |
| Fishes | Atlantic salmon | Salmo salar | Not Listed | Resolved Taxon | | |
| Fishes | Atlantic salmon | Salmo salar | Not Listed | Resolved Taxon | | ME |
| Reptiles | Atlantic salt marsh snake | Nerodia clarkii taeniata | Listed | Threatened | | FL |
| Fishes | Atlantic sturgeon | Acipenser oxyrinchus oxyrinchus | Listed | Endangered | | |
| Fishes | Atlantic sturgeon | Acipenser oxyrinchus oxyrinchus | Listed | Endangered | | |
| Fishes | Atlantic sturgeon | Acipenser oxyrinchus oxyrinchus | Listed | Threatened | | |
| Fishes | Atlantic sturgeon | Acipenser oxyrinchus oxyrinchus | Listed | Endangered | | |
| Fishes | Atlantic sturgeon | Acipenser oxyrinchus oxyrinchus | Listed | Endangered | | |
| Snails | Atlas pebblesnail | Somatogyrus humerosus | Not Listed | Species of Concern | | AL |
| Insects | Atossa fritillary | Speyeria adiaste atossa | Not Listed | Resolved Taxon | | CA |
| Birds | Attwater's greater prairie-chicken | Tympanuchus cupido attwateri | Listed | Endangered | | TX |
| Flowering Plants | Atwood's catseye | Cryptantha atwoodii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Auburua Ranch jewelflower | Streptanthus insignis lyonii | Not Listed | Species of Concern | | CA |
| Birds | Audouin's gull | Larus audouinii | Listed | Endangered | | |
| Birds | Audubon's oriole | Icterus graduacauda audubonii | Not Listed | Species of Concern | | TX |
| Birds | Audubon's Oriole | Icterus graduacauda | Not Listed | Species of Concern | | |
| Birds | Audubon's Shearwater | Puffinus lherminieri | Not Listed | Species of Concern | | |
| Birds | Aukland Island rail | Rallus pectoralis muelleri | Listed | Endangered | | |
| Flowering Plants | Aupaka | Isodendrion hosakae | Listed | Endangered | | HI |
| Flowering Plants | Aupaka | Isodendrion laurifolium | Listed | Endangered | | HI |
| Flowering Plants | Aupaka | Isodendrion longifolium | Listed | Threatened | | HI |
| Flowering Plants | Auricled twayblade | Listera auriculata | Not Listed | Resolved Taxon | | ME, MI, MN, NH, NY, VT, WI |
| Flowering Plants | Auriculate false-foxglove | Agalinis auriculata | Not Listed | Species of Concern | | AR, IL, IN, KS, MD, MI, MN, MO, MS, OH, OK, PA, SC, TN, TX, VA, WI, WV |
| Amphibians | Austin blind Salamander | Eurycea waterlooensis | Listed | Endangered | | TX |
| Flowering Plants | Austin's popcornflower | Plagiobothrys austiniae | Not Listed | Species of Concern | | |
| Birds | Australasian Swamphen | Porphyrio melanotus samoensis | Not Listed | Species of Concern | | |
| Mammals | Australian native mouse | Notomys aquilo | Listed | Endangered | | |
| Mammals | Australian native mouse | Zyzomys pedunculatus | Listed | Endangered | | |
| Flowering Plants | Autumn Buttercup | Ranunculus aestivalis (=acriformis) | Listed | Endangered | | UT |
| Mammals | Avahi | Avahi laniger (entire genus) | Listed | Endangered | | |
| Flowering Plants | Aven Nelson's phacelia | Phacelia anelsonii | Not Listed | Resolved Taxon | | CA, NV, UT |
| Flowering Plants | Avon Park harebells | Crotalaria avonensis | Listed | Endangered | | FL |
| Flowering Plants | Awapa Daisy | Erigeron awapensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | `Awikiwiki | Canavalia molokaiensis | Listed | Endangered | | HI |
| Flowering Plants | `Awikiwiki | Canavalia napaliensis | Listed | Endangered | | HI |
| Flowering Plants | `Awikiwiki | Canavalia pubescens | Listed | Endangered | | HI |
| Flowering Plants | Awiwi | Schenkia sebaeoides | Listed | Endangered | | HI |
| Flowering Plants | 'Awiwi | Kadua cookiana | Listed | Endangered | | HI |
| Flowering Plants | Awned bentgrass | Agrostis microphylla | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Awned meadowbeauty | Rhexia aristosa | Not Listed | Species of Concern | | AL, DE, GA, NC, NJ, SC |
| Mammals | Aye-aye | Daubentonia madagascariensis | Listed | Endangered | | |
| Fishes | Ayumodoki (loach) | Hymenophysa curta | Listed | Endangered | | |
| Birds | Azores wood pigeon | Columba palumbus azorica | Listed | Endangered | | |
| Flowering Plants | Aztec gilia | Aliciella formosa | Petitioned for Listing, Under Review | Under Review | | NM |
| Mammals | Babirusa | Babyrousa babyrussa | Listed | Endangered | | |
| Birds | Bachman's Sparrow | Peucaea aestivalis | Not Listed | Species of Concern | | VA |
| Birds | Bachman's warbler (=wood) | Vermivora bachmanii | Delisted | Extinction | | FL, SC |
| Mammals | Bactrian camel | Camelus bactrianus | Listed | Endangered | | |
| Mammals | Bactrian deer | Cervus elaphus bactrianus | Listed | Endangered | | |
| Flowering Plants | Badlands wild-buckwheat | Eriogonum hylophilum | Not Listed | Resolved Taxon | | UT |
| Snails | Badwater snail | Assiminea infima | Not Listed | Species of Concern | | CA |
| Birds | Bahaman or Cuban parrot | Amazona leucocephala | Listed | Endangered | | |
| Insects | Bahama swallowtail butterfly | Heraclides andraemon bonhotei | Delisted | Original Data in Error - Act Amendment | | |
| Flowering Plants | Bailey's ballmoss | Tillandsia baileyi | Not Listed | Species of Concern | | TX |
| Flowering Plants | Baird's evening primrose | Camissonia bairdii | Not Listed | Resolved Taxon | | |
| Birds | Baird's Sparrow | Centronyx bairdii | Not Listed | Resolved Taxon | | CO, ID, KS, MN, MO, MT, ND, NE, NM, OK, SD, TX, WY |
| Flowering Plants | Bakersfield cactus | Opuntia treleasei | Listed | Endangered | | CA |
| Flowering Plants | Bakersfield saltbush | Atriplex tularensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Baker's larkspur | Delphinium bakeri | Listed | Endangered | | CA |
| Mammals | Baker's Llano pocket gopher | Geomys texensis bakeri | Not Listed | Species of Concern | | TX |
| Flowering Plants | Baker's manzanita | Arctostaphylos bakeri bakeri | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Baker's meadowfoam | Limnanthes bakeri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Baker's rhododendron | Rhododendron bakeri | Not Listed | Resolved Taxon | | AL, GA, KY, NC, TN, VA |
| Insects | Baker Station cave beetle | Pseudanophthalmus insularis | Not Listed | Resolved Taxon | | TN |
| Reptiles | Baker's worm lizard | Amphisbaena bakeri | Not Listed | Resolved Taxon | | PR, VI |
| Insects | Baking Powder Flat blue | Euphilotes bernardino minuta | Not Listed | Resolved Taxon | | NV |
| Crustaceans | Balcones cave amphipod | Stygobromus balconis | Not Listed | Species of Concern | | TX |
| Snails | Balcones Ghostsnail | Balconorbis uvaldensis | Not Listed | Resolved Taxon | | |
| Clams | Balcones spike | Fusconaia iheringi | Listed | Endangered | | TX |
| Conifers and Cycads | Bald Cypress | Taxodium distichum | | Not Listed | | |
| Birds | Bald Eagle | Haliaeetus leucocephalus | Not Listed | Resolved Taxon | | AZ |
| Birds | Bald Eagle | Haliaeetus leucocephalus | Delisted | Recovery | | AL, AR, AZ, CO, IN, KY, MT, OH, PA, SC, TN, TX, VA, WY |
| Birds | Bald Eagle | Haliaeetus leucocephalus | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Bald grass | Sporobolus vaginiflorus var. ozarkanus | Not Listed | Resolved Taxon | | AL, IL, IN, KY, LA, MO, MS, OK, TN, TX |
| Flowering Plants | Baldwin Lake linanthus | Linanthus killipii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Ballhead, Thompson's waterleaf | Hydrophyllum capitatum thompsonii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | Ballona cinquefoil | Potentilla multijuga | Not Listed | Species of Concern | | CA |
| Insects | Balmorhea damselfly | Argia sp. | Not Listed | Species of Concern | | TX |
| Insects | Balmorhea saddle-case caddisfly | Protoptila balmorhea | Not Listed | Species of Concern | | AZ, TX |
| Flowering Plants | Balsam Mountain Gentian | Gentiana latidens | Not Listed | Species of Concern | | NC |
| Flowering Plants | Balsam Mountain Hawthorn | Crataegus oreophila | Not Listed | Species of Concern | | NC |
| Birds | Baltimore Oriole | Icterus galbula | Not Listed | Species of Concern | | |
| Mammals | Baluchistan bear | Ursus thibetanus gedrosianus | Listed | Endangered | | |
| Birds | Bananal tyrannulet | Serpophaga araguayae | Not Listed | Status Undefined | | |
| Snails | Banbury Springs limpet | Idaholanx fresti | Listed | Endangered | | ID |
| Snails | Banbury Springs Limpet | Lanx sp. | | Not Listed | | |
| Insects | Banded bog skimmer | Williamsonia lintneri | Not Listed | Species of Concern | | CT, DE, MA, NH, NJ, NY, RI |
| Birds | Banded cotinga | Cotinga maculata | Listed | Endangered | | |
| Fishes | Banded Darter | Etheostoma zonale | | Not Listed | | |
| Snails | Banded elimia | Elimia fascinans | Not Listed | Species of Concern | | AL |
| Reptiles | Banded gila monster | Heloderma suspectum cinctum | Not Listed | Species of Concern | | AZ, CA, NV, UT |
| Mammals | Banded hare wallaby | Lagostrophus fasciatus | Listed | Endangered | | |
| Snails | banded juga | Juga newberryi | Not Listed | Status Undefined | | OR |
| Fishes | Banded Killifish | Fundulus diaphanus | | Not Listed | | |
| Fishes | Banded Sculpin | Cottus carolinae | | Not Listed | | |
| Birds | Banded wattle-eye | Platysteira laticincta | Listed | Endangered | | |
| Fishes | bandfin darter | Etheostoma zonistium | Not Listed | Species of Concern | | |
| Arachnids | Bandit Cave spider | Cicurina bandida | Not Listed | Resolved Taxon | | TX |
| Birds | Band-rumped Storm-petrel | Hydrobates castro | Listed | Endangered | | HI, UM |
| Birds | Band-rumped Storm-Petrel | Hydrobates castro | Not Listed | Species of Concern | | |
| Birds | Band-tailed pigeon | patagioenas fasciata | Not Listed | Species of Concern | | |
| Fishes | Banggai cardinalfish | Pterapogon kauderni | Listed | Threatened | | |
| Fishes | Bankhead darter | Percina sipsi | Petitioned for Listing, Under Review | Under Review | | AL |
| Flowering Plants | Bank monkeyflower | Mimulus clivicola | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Birds | Bank swallow | riparia riparia | Not Listed | Species of Concern | | |
| Birds | Bannerman's turaco | Tauraco bannermani | Listed | Endangered | | |
| Fishes | Bantam Sunfish | Lepomis symmetricus | | Not Listed | | |
| Mammals | Banteng | Bos javanicus | Listed | Endangered | | |
| Birds | Barbados yellow warbler (=wood) | Dendroica petechia petechia | Listed | Endangered | | |
| Insects | Barbara Ann's tiger beetle | Cicindela politula barbarannae | Not Listed | Resolved Taxon | | TX |
| Mammals | Barbary deer | Cervus elaphus barbarus | Listed | Endangered | | |
| Mammals | Barbary hyena | Hyaena hyaena barbara | Listed | Endangered | | |
| Mammals | Barbary serval | Leptailurus (=Felis) serval constantina | Listed | Endangered | | |
| Mammals | Barbary stag | Cervus elaphus barbarus | Listed | Endangered | | |
| Flowering Plants | Barbed rattlesnake root | Prenanthes barbata | Not Listed | Species of Concern | | AL, AR, GA, KY, LA, TN, TX |
| Flowering Plants | Barberry-leaved hawthorn | Crataegus berberifolia | Not Listed | Resolved Taxon | | LA, TX |
| Insects | Barber's Point oliarus planthopper | Oliarus myoporicola | Not Listed | Species of Concern | | HI |
| Reptiles | Barbour's map turtle | Graptemys barbouri | Listed | Similarity of Appearance (Threatened) | | AL, FL, GA |
| Reptiles | Barefoot gecko | Coleonyx switaki | Not Listed | Species of Concern | | CA |
| Snails | Barfoot Woodlandsnail | Ashmunella esuritor | Not Listed | Resolved Taxon | | |
| Flowering Plants | Bariaco | Trichilia triacantha | Listed | Endangered | | PR |
| Flowering Plants | Barneby catseye | Cryptantha barnebyi | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Barneby milk-vetch | Astragalus barnebyi | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Barneby reed-mustard | Schoenocrambe barnebyi | Listed | Endangered | | UT |
| Flowering Plants | Barneby ridge-cress | Lepidium barnebyanum | Listed | Endangered | | UT |
| Mammals | Barnes' pika | Ochotona princeps barnesi | Not Listed | Species of Concern | | UT |
| Birds | Barn Owl | Tyto alba | Not Listed | Species of Concern | | |
| Birds | Barn Swallow | Hirundo rustica | Not Listed | Species of Concern | | |
| Flowering Plants | Barratt's sedge | Carex barrattii | Not Listed | Resolved Taxon | | AL, CT, DE, MD, NC, NJ, NY, PA, TN, VA |
| Mammals | Barred bandicoot | Perameles bougainville | Listed | Endangered | | |
| Amphibians | Barred Tiger Salamander | Ambystoma mavortium | | Not Listed | | |
| Birds | Barred-wing rail | Rallus poecilopterus | Not Listed | Resolved Taxon | | |
| Insects | Barrens bluet damselfly | Enallagma recurvatum | Not Listed | Resolved Taxon | | DE, MA, NJ, NY |
| Insects | Barrens Dagger Moth | Acronicta albarufa | Not Listed | Species of Concern | | AR, CO, CT, DE, GA, MA, MO, NC, NJ, NM, NY, OH, PA |
| Fishes | Barrens darter | Etheostoma forbesi | Proposed for Listing | Proposed Endangered | | TN |
| Clams | Barrens heelsplitter | Lasmigona sp. | Not Listed | Species of Concern | | TN |
| Insects | Barrens sedge leafhopper | Limotettix sp. | Not Listed | Species of Concern | | MD |
| Fishes | Barrens topminnow | Fundulus julisia | Listed | Endangered | | TN |
| Reptiles | Barrington land iguana | Conolophus pallidus | Listed | Endangered | | |
| Crustaceans | Barr's amphipod | Stygobromus cherylae | | Not Listed | | |
| Crustaceans | Barr's cave amphipod | Stygobromus barri | Not Listed | Species of Concern | | MO |
| Flowering Plants | Barstow wooly-sunflower | Eriophyllum mohavense | Not Listed | Species of Concern | | CA |
| Birds | Bar-tailed Godwit | Limosa lapponica | Not Listed | Species of Concern | | |
| Birds | Bar-tailed pheasant | Syrmaticus humaie | Listed | Endangered | | |
| Snails | Barton Cavesnail | Stygopyrgus bartonensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Barton Flats horkelia | Horkelia wilderae | Not Listed | Species of Concern | | CA |
| Amphibians | Barton Springs salamander | Eurycea sosorum | Listed | Endangered | | TX |
| Insects | Bartram's hairstreak Butterfly | Strymon acis bartrami | Listed | Endangered | | FL |
| Flowering Plants | Bartram's ixia | Calydorea coelestina | Not Listed | Resolved Taxon | | |
| Flowering Plants | Bartram's stonecrop | Graptopetalum bartramii | Listed | Threatened | | AZ |
| Snails | Bartsch Holospira | Holospira yucatanensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Basalt daisy | Erigeron basalticus | Not Listed | Resolved Taxon | | WA |
| Snails | Basalt Juga | Juga sp | Not Listed | Resolved Taxon | | OR, WA |
| Flowering Plants | Basin bellflower | Campanula reverchonii | Not Listed | Resolved Taxon | | TX |
| Crustaceans | Bastrop Crayfish | Procambarus texanus | Not Listed | Resolved Taxon | | |
| Crustaceans | Bat Cave isopod | Caecidotea macropropoda | Not Listed | Species of Concern | | OK |
| Crustaceans | Bath County cave amphipod | Stygobromus mundus | Not Listed | Species of Concern | | VA |
| Fishes | Bat Ray | Myliobatis californica | | Not Listed | | |
| Birds | Bay-breasted Warbler | Setophaga castanea | Not Listed | Species of Concern | | |
| Insects | Bay checkerspot butterfly | Euphydryas editha bayensis | Listed | Threatened | | CA |
| Flowering Plants | Bay matchweed | Gutierrezia californica | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Bayou Bodcau crayfish | Bouchardina robisoni | Not Listed | Status Undefined | | AR |
| Fishes | Bayou darter | Etheostoma rubrum | Listed | Threatened | | MS |
| Insects | Bay skipper | Euphyes bayensis | Not Listed | Resolved Taxon | | MS, TX |
| Amphibians | Bay Springs salamander | Plethodon ainsworthi | Not Listed | Resolved Taxon | | |
| Flowering Plants | Beach, Grave's plum | Prunus maritima gravesii | Not Listed | Resolved Taxon | | CT |
| Flowering Plants | Beach jacquemontia | Jacquemontia reclinata | Listed | Endangered | | FL |
| Flowering Plants | Beach layia | Layia carnosa | Listed | Threatened | | CA |
| Flowering Plants | Beach spectacle-pod | Dithyrea maritima | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Beach, Virginian pinweed | Lechea maritima virginica | Not Listed | Resolved Taxon | | VA |
| Mammals | Beach vole | Microtus breweri | Not Listed | Species of Concern | | MA |
| Snails | Beaked Cavesnail | Phreatodrobia rotunda | Not Listed | Resolved Taxon | | |
| Flowering Plants | Beaked clarkia | Clarkia rostrata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Beaked tracyina | Tracyina rostrata | Not Listed | Resolved Taxon | | CA |
| Snails | Bearded Mountainsnail | Oreohelix barbata | Not Listed | Resolved Taxon | | |
| Flowering Plants | Bearded popcornflower | Plagiobothrys hystriculus | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Bearded red crayfish | Procambarus pogum | Not Listed | Resolved Taxon | | MS |
| Mammals | bearded Seal | Erignathus barbatus nauticus | Listed | Threatened | | |
| Mammals | bearded Seal | Erignathus barbatus nauticus | Listed | Threatened | | |
| Flowering Plants | beardless chinchweed | Pectis imberbis | Listed | Endangered | | AZ |
| Flowering Plants | Bear gum | Nyssa ursina | Not Listed | Status Undefined | | |
| Fishes | Bear Lake Sculpin | Cottus extensus | Not Listed | Resolved Taxon | | |
| Fishes | Bear Lake Whitefish | Prosopium abyssicola | Not Listed | Resolved Taxon | | |
| Snails | Bearmouth mountainsnail | Oreohelix spthree | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | Bear Valley milk-vetch | Astragalus lentiginosus ursinus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Bear Valley phlox | Phlox dolichantha | Not Listed | Species of Concern | | CA |
| Flowering Plants | Bear Valley pyrrocoma | Pyrrocoma uniflora gossypina | Not Listed | Species of Concern | | CA |
| Flowering Plants | Bear Valley sandwort | Arenaria ursina | Listed | Threatened | | CA |
| Flowering Plants | Bear Valley wooly-pod | Astragalus leucolobus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Beath milk-vetch | Astragalus beathii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Beatley buckwheat | Eriogonum beatleyae | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Beatley milk-vetch | Astragalus beatleyae | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Beatley phacelia | Phacelia beatleyae | Not Listed | Species of Concern | | NV |
| Flowering Plants | Beatley's clover | Trifolium andersonii beatleyae | Not Listed | Resolved Taxon | | CA, NV |
| Crustaceans | Beautiful crayfish | Cambarus speciosus | Not Listed | Status Undefined | | GA |
| Flowering Plants | Beautiful goetzea | Goetzea elegans | Listed | Endangered | | PR |
| Flowering Plants | Beautiful Hulsea | Hulsea vestita ssp. callicarpha | Not Listed | Species of Concern | | CA |
| Arachnids | Beautiful Parachute Spider | Poecilotheria formosa | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Beautiful pawpaw | Deeringothamnus pulchellus | Listed | Endangered | | FL |
| Fishes | Beautiful shiner | Cyprinella formosa | Listed | Threatened | | AZ |
| Insects | Beaver Cave beetle | Pseudanophthalmus major | Not Listed | Resolved Taxon | | KY |
| Mammals | Beaver (Mongolian) | Castor fiber birulai | Listed | Endangered | | |
| Flowering Plants | Beaver Mountain Groundsel | Packera castoreus | Not Listed | Resolved Taxon | | |
| Snails | Beaver pond marstonia | Pyrgulopsis castor | Not Listed | Species of Concern | | GA |
| Snails | Beaverpond marstonia | Marstonia castor | Not Listed | Resolved Taxon | | GA |
| Birds | Beck's petrel | Pseudobulweria becki | Not Listed | Status Undefined | | |
| Arachnids | Bee Creek Cave harvestman | Texella reddelli | Listed | Endangered | | TX |
| Flowering Plants | Beegum onion | Allium hoffmanii | Not Listed | Resolved Taxon | | CA |
| Insects | Beer's false water penny | Acneus beeri | Not Listed | Species of Concern | | OR |
| Insects | Beetle | Cyclocephala wandae | Not Listed | Resolved Taxon | | |
| Insects | Behren's silverspot butterfly | Speyeria zerene behrensii | Listed | Endangered | | CA |
| Reptiles | Belding's orange-throated whiptail | cnemidophorus hyperythrus ssp. beldingi | Not Listed | Species of Concern | | |
| Birds | Belding's Savannah Sparrow | Passerculus sandwichensis beldingi | Not Listed | Species of Concern | | CA |
| Insects | Belfragi's chlorochroan bug | Chlorochroa belfragii | Not Listed | Species of Concern | | IA, IL, NE, SD |
| Insects | Belkin's dune tabanid fly | Brennania belkini | Not Listed | Resolved Taxon | | CA |
| Insects | Beller's ground beetle | Agonum belleri | Not Listed | Species of Concern | | OR, WA |
| Flowering Plants | Bellinger's meadowfoam | Limnanthes floccosa bellingeriana | Not Listed | Species of Concern | | CA, NV, OR |
| Birds | Bell's sage sparrow | Amphispiza belli belli | Not Listed | Species of Concern | | CA |
| Birds | Bells Sparrow | Artemisiospiza belli | Not Listed | Species of Concern | | |
| Flowering Plants | Bell's Twinpod | Physaria bellii | Not Listed | Species of Concern | | CO |
| Birds | Bell's Vireo | Vireo bellii | Not Listed | Species of Concern | | |
| Crustaceans | belted crayfish | Faxonius harrisonii | | Not Listed | | |
| Birds | Belted Kingfisher | Megaceryle alcyon | Not Listed | Species of Concern | | |
| Fishes | Beluga sturgeon | Huso huso | Listed | Threatened | | |
| Mammals | beluga whale | Delphinapterus leucas | Listed | Endangered | | |
| Insects | (Bembidion gordoni) ground beetle | bembidion gordoni | Not Listed | Species of Concern | | |
| Insects | (Bembidion stillaguamish) ground beetle | bembidion stillaguamish | Not Listed | Species of Concern | | |
| Insects | (Bembidion viator) ground beetle | bembidion viator | Not Listed | Species of Concern | | |
| Insects | Benderman's cave beetle | Pseudanophthalmus bendermani | Not Listed | Species of Concern | | TN |
| Birds | Bendire's Thrasher | Toxostoma bendirei | Not Listed | Species of Concern | | AZ, CA, CO, NM, NV, UT |
| Flowering Plants | Ben Franklin's Beardtongue | Penstemon franklinii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Ben Lomond spineflower | Chorizanthe pungens var. hartwegiana | Listed | Endangered | | CA |
| Flowering Plants | Ben Lomond wallflower | Erysimum teretifolium | Listed | Endangered | | CA |
| Crustaceans | Bennets Mill Cave water slater | Caecidotea carolinensis | Not Listed | Species of Concern | | NC |
| Flowering Plants | Bensoniella | Bensoniella oregona | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Bent avens | Geum geniculatum | Not Listed | Species of Concern | | NC |
| Crustaceans | Benton County cave crayfish | Cambarus aculabrum | Listed | Endangered | | AR, MO |
| Fishes | Benton Valley speckled dace | Rhinichthys osculus ssp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Berenghenas halomtano | Solanum guamense | Listed | Endangered | | GU, MP |
| Fishes | Bering Cisco | Coregonus laurettae | | Not Listed | | |
| Insects | Berkeley Ground cricket | Neonemobius eurynotus | Not Listed | Resolved Taxon | | |
| Mammals | Berkeley kangaroo rat | Dipodomys heermanni berkleyensis | Not Listed | Species of Concern | | CA |
| Birds | Bermuda petrel | Pterodroma cahow | Listed | Endangered | | FL, MA, NC, SC, VA |
| Insects | Berner's two-winged mayfly | Heterocleon berneri | Not Listed | Species of Concern | | GA |
| Amphibians | Berry Cave salamander | Gyrinophilus gulolineatus | Not Listed | Resolved Taxon | | TN |
| Snails | Berry's mountainsnail | Oreohelix strigosa berryi | Not Listed | Species of Concern | | MT, WY |
| Insects | Bethany Beach firefly | Photuris bethaniensis | Proposed for Listing | Proposed Threatened | | DE, NJ, VA |
| Reptiles | Bezy's night lizard | Xantusia bezyi | Not Listed | Resolved Taxon | | AZ |
| Birds | Bicknell's thrush | Catharus bicknelli | Not Listed | Resolved Taxon | | MA, ME, NH, NY, VT |
| Snails | Bicolored cactus snail | Xerarionta tryoni | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Biddle's lupine | Lupinus oreganus var. oreganus | Not Listed | Species of Concern | | OR |
| Insects | Bidecoratus sphecid wasp | Ectemnius bidecoratus | Not Listed | Species of Concern | | HI |
| Insects | Bidens long-horned beetle | Plagithmysus bidensae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Bidwell's knotweed | Polygonum bidwelliae | Not Listed | Resolved Taxon | | CA |
| Snails | Bifid duct pyrg | Pyrgulopsis peculiaris | Not Listed | Resolved Taxon | | NV, UT |
| Crustaceans | Bifurcated cave amphipod | Stygobromus bifurcatus | Not Listed | Species of Concern | | TX |
| Snails | Big Bar hesperian | Vespericola pressleyi | Petitioned for Listing, Under Review | Under Review | | CA |
| Flowering Plants | Big Bear milk-vetch | Astragalus lentiginosus sierrae | Not Listed | Species of Concern | | CA |
| Flowering Plants | Big Bend bluegrass | Poa strictiramea | Not Listed | Resolved Taxon | | TX |
| Fishes | Big Bend gambusia | Gambusia gaigei | Listed | Endangered | | TX |
| Flowering Plants | Big Bend hop hornbeam | Ostrya chisosensis | Not Listed | Species of Concern | | TX |
| Reptiles | Big Bend mud turtle | Kinosternon hirtipes murrayi | Not Listed | Species of Concern | | TX |
| Flowering Plants | Big Bend prickly pear | Grusonia densispina | | Not Listed | | |
| Reptiles | Big Bend slider | Pseudemys scripta gaigeae | Not Listed | Resolved Taxon | | TX |
| Snails | Big Black Rocksnail | Lithasia hubrichti | | Not Listed | | |
| Crustaceans | Big Blue Springs Cave crayfish | Procambarus horsti | Not Listed | Resolved Taxon | | |
| Flowering Plants | Big Bluestem | Andropogon gerardii | | Not Listed | | |
| Mammals | Big brown bat | eptesicus fuscus | Not Listed | Species of Concern | | |
| Insects | Big Cedar grasshopper | Eximacris phenax | Not Listed | Species of Concern | | OK |
| Crustaceans | Bigcheek Cave crayfish | Procambarus delicatus | Petitioned for Listing, Under Review | Under Review | | FL |
| Crustaceans | Big Creek Crayfish | Faxonius peruncus | Listed | Threatened | | MO |
| Flowering Plants | Big cypress epidendrum | Epidendrum strobiliferum | Not Listed | Resolved Taxon | | |
| Mammals | Big Cypress fox squirrel | Sciurus niger avicennia | Not Listed | Resolved Taxon | | |
| Insects | Big Dune aphodius scarab | Aphodius sp. | Not Listed | Species of Concern | | NV |
| Mammals | Big-eared kangaroo rat | Dipodomys elephantinus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Bigelow tansyaster | Dieteria bigelovii var. mucronata | Not Listed | Resolved Taxon | | AZ |
| Fishes | Bigeye Chub | Hybopsis amblops | | Not Listed | | |
| Fishes | Bigeye Shiner | Notropis boops | | Not Listed | | |
| Mammals | Big free-tailed bat | Nyctinomops macrotis | Not Listed | Species of Concern | | CO |
| Crustaceans | Bigger's amphipod | Stygobromus biggersi | Not Listed | Species of Concern | | VA |
| Flatworms and Roundworms | Bigger's groundwater planarian | Sphalloplana subtilis | Not Listed | Resolved Taxon | | VA |
| Snails | big hatchet woodlandsnail | Ashmunella mearnsii | Not Listed | Resolved Taxon | | |
| Mammals | Bighorn sheep | Ovis canadensis | Not Listed | Species of Concern | | |
| Flowering Plants | Bigleaf scurf-pea | Orbexilum macrophyllum | Not Listed | Species of Concern | | NC |
| Flowering Plants | Big-leaved crownbeard | Verbesina dissita | Listed | Threatened | | CA |
| Fishes | Bigmouth Buffalo | Ictiobus cyprinellus | | Not Listed | | |
| Snails | Bigmouth rocksnail | Leptoxis occultata | Not Listed | Resolved Taxon | | AL |
| Fishes | Bigmouth Shiner | Hybopsis dorsalis | | Not Listed | | |
| Fishes | Bigmouth Sleeper | Gobiomorus dormitor | | Not Listed | | |
| Insects | Big Pine Key ataenius dung beetle | Ataenius superficialis | Not Listed | Species of Concern | | |
| Insects | Big Pine Key conehead katydid | Belocephalus micanopy | Not Listed | Species of Concern | | |
| Flowering Plants | Big Pine lomatium | Lomatium rigidum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Big Pine partridge pea | Chamaecrista lineata keyensis | Listed | Endangered | | FL |
| Flowering Plants | Bigpod bonamia | Bonamia ovalifolia | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Big red sage | Salvia pentstemonoides | Proposed for Listing | Proposed Endangered | | TX |
| Crustaceans | Big Sandy crayfish | Cambarus callainus | Listed | Threatened | | KY, VA, WV |
| Flowering Plants | Big scale balsamroot | balsamorhiza macrolepis var. macrolepis | Not Listed | Species of Concern | | |
| Fishes | Bigscale Logperch | Percina macrolepida | | Not Listed | | |
| Fishes | Big Smoky Valley tui chub | Siphateles bicolor ssp. 8 | Not Listed | Species of Concern | | NV |
| Crustaceans | Big South Fork crayfish | Cambarus bouchardi | Not Listed | Status Undefined | | KY, TN |
| Crustaceans | Big Springs isopod | Bowmanasellus sequoiae | Not Listed | Status Undefined | | CA |
| Fishes | Big Spring spinedace | Lepidomeda mollispinis pratensis | Listed | Threatened | | NV, UT |
| Mammals | Big Thicket hog-nosed skunk | Conepatus mesoleucus telmalestes | Not Listed | Species of Concern | | TX |
| Snails | Big-tooth covert snail | Fumonelix jonesiana | Not Listed | Resolved Taxon | | NC, TN |
| Snails | Big Warm Spring pyrg | Pyrgulopsis papillata | Not Listed | Resolved Taxon | | NV |
| Insects | Bilobed rhyacophilan caddisfly | Rhyacophila mosana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Biltmore sedge | Carex biltmoreana | Not Listed | Resolved Taxon | | GA, NC, SC |
| Flowering Plants | Bird's-eye primrose | Primula mistassinica | Not Listed | Resolved Taxon | | IA, IL, ME, MI, MN, NY, VT, WI |
| Clams | Birdwing pearlymussel | Lemiox rimosus | Listed | Endangered | | KY, TN, VA |
| Clams | Birdwing pearlymussel | Lemiox rimosus | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Birdwing pearlymussel | Lemiox rimosus | Listed | Experimental Population, Non-Essential | | AL |
| Snails | Bishop Cap Tubesnail | Coelostemma pyrgonasta | Not Listed | Resolved Taxon | | |
| Birds | Bishop's `o`o | Moho bishopi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Bisti Fleabane | Erigeron bistiensis | | Not Listed | | |
| Snails | Bitterroot Mountainsnail | Oreohelix amariradix | Not Listed | Resolved Taxon | | |
| Snails | Black Abalone | Haliotis cracherodii | Listed | Endangered | | |
| Birds | Black-backed tanager | Tangara peruviana | Candidate for Listing | Candidate | | |
| Birds | Black-backed woodpecker | picoides arcticus | Not Listed | Resolved Taxon | | CA, OR, SD |
| Fishes | Black-Banded Sunfish | Enneacanthus chaetodon | | Not Listed | | |
| Birds | Black barbthroat | Threnetes grzimeki | Not Listed | Resolved Taxon | | |
| Crustaceans | Blackbarred crayfish | Cambarus unestami | | Not Listed | | AL, GA |
| Mammals | Blackbeard Island white-tailed deer | Odocoileus virginianus nigribarbis | Not Listed | Species of Concern | | GA |
| Amphibians | Black-bellied slender salamander | batrachoseps nigriventris | Not Listed | Species of Concern | | |
| Birds | Black-billed Cuckoo | Coccyzus erythropthalmus | Not Listed | Species of Concern | | |
| Birds | Black billed Magpie | Pica hudsonia | Not Listed | Species of Concern | | |
| Flowering Plants | Blackbract pipewort | Eriocaulon nigrobracteatum | Petitioned for Listing, Under Review | Under Review | | FL |
| Birds | black-breasted puffleg | Eriocnemis nigrivestis | Listed | Endangered | | |
| Fishes | Black Buffalo | Ictiobus niger | | Not Listed | | |
| Fishes | Black Bullhead | Ameiurus melas | | Not Listed | | |
| Insects | Blackburn's pentarthrum weevil | Pentarthrum blackburni | Not Listed | Species of Concern | | HI |
| Insects | Blackburn's rhyncogonus weevil | Rhyncogonus blackburni | Not Listed | Species of Concern | | HI |
| Insects | Blackburn's sphinx moth | Manduca blackburni | Listed | Endangered | | HI |
| Insects | Blackburn's yellow-faced bee | Hylaeus blackburni | Not Listed | Resolved Taxon | | HI |
| Reptiles | Black caiman | Melanosuchus niger | Listed | Endangered | | |
| Snails | Black Canyon Pyrg | Pyrgulopsis plicata | Not Listed | Resolved Taxon | | |
| Birds | Black-capped Chickadee | Poecile atricapillus | Not Listed | Species of Concern | | |
| Birds | Black-capped Chickadee | Poecile atricapillus practicus | Not Listed | Species of Concern | | |
| Birds | Black-capped Petrel | Pterodroma hasitata | Listed | Endangered | | FL, LA, PR, VI |
| Birds | Black-capped Vireo | Vireo atricapilla | Delisted | Recovery | | OK, TX |
| Fishes | Blackchin guitarfish | Rhinobatos cemiculus | Listed | Threatened | | |
| Birds | Black-chinned Sparrow | Spizella atrogularis | Not Listed | Species of Concern | | |
| Fishes | Blackchin Shiner | Notropis heterodon | | Not Listed | | |
| Clams | Black clubshell | Pleurobema curtum | Listed | Endangered | | MS |
| Mammals | Black colobus monkey | Colobus satanas | Listed | Endangered | | |
| Fishes | Black Crappie | Pomoxis nigromaculatus | | Not Listed | | |
| Crustaceans | Black Creek crayfish | Procambarus pictus | Proposed for Listing | Proposed Endangered | | FL |
| Snails | Black-crest elima | Elimia albanyensis | Not Listed | Species of Concern | | AL, GA |
| Birds | Black-crowned Night-Heron | Nycticorax nycticorax | Not Listed | Species of Concern | | |
| Fishes | Black Drum | Pogonias cromis | | Not Listed | | |
| Mammals | Black-faced impala | Aepyceros melampus petersi | Listed | Endangered | | |
| Fishes | Blackfin cisco | Coregonus nigripinnis nigripinnis | Not Listed | Resolved Taxon | | IL, IN, MI, WI |
| Fishes | Blackfin sucker | Thoburnia atripinnis | Not Listed | Resolved Taxon | | KY, TN |
| Flowering Plants | Black-flowered figwort | Scrophularia atrata | Not Listed | Species of Concern | | CA |
| Birds | Black-footed Albatross | Phoebastria nigripes | Not Listed | Resolved Taxon | | |
| Mammals | Black-footed cat | Felis nigripes | Listed | Endangered | | |
| Mammals | Black-footed ferret | Mustela nigripes | Listed | Experimental Population, Non-Essential | | |
| Mammals | Black-footed ferret | Mustela nigripes | Listed | Experimental Population, Non-Essential | | AZ, CO, MT, SD, UT, WY |
| Mammals | Black-footed ferret | Mustela nigripes | Listed | Endangered | | CO, KS, MT, NM, SD |
| Mammals | Black-footed ferret | Mustela nigripes | Listed | Experimental Population, Non-Essential | | |
| Mammals | Black-footed ferret | Mustela nigripes | Listed | Experimental Population, Non-Essential | | |
| Birds | Black-fronted piping-guan | Pipile jacutinga | Listed | Endangered | | |
| Birds | Black Guillemot | Cepphus grylle | Not Listed | Species of Concern | | |
| Reptiles | Black Hills redbelly snake | Storeria occipitomaculata pahasapae | Not Listed | Species of Concern | | SD, WY |
| Birds | Black hooded (black-headed) antwren | Formicivora erythronotos | Listed | Endangered | | |
| Mammals | Black howler monkey | Alouatta pigra | Listed | Threatened | | |
| Reptiles | Black-knobbed map turtle | Graptemys nigrinoda | Petitioned for Listing, Under Review | Under Review | | AL, MS |
| Flowering Plants | Black lace cactus | Echinocereus reichenbachii var. albertii | Listed | Endangered | | TX |
| Birds | Black-legged Kittiwake | Rissa tridactyla | Not Listed | Species of Concern | | |
| Reptiles | Black legless lizard | Anniella pulchra nigra | Not Listed | Resolved Taxon | | CA |
| Insects | Blackline Hawaiian damselfly | Megalagrion nigrohamatum nigrolineatum | Listed | Endangered | | HI |
| Insects | Black lordithon rove beetle | Lordithon niger | Not Listed | Species of Concern | | AR, CT, DC, GA, IL, KY, MI, MO, NC, NY, OH, PA, TX, VA, WV |
| Snails | Black Mesa Talussnail | Sonorella russelli | Not Listed | Resolved Taxon | | |
| Mammals | Black Mountain cactus mouse | Peromyscus eremicus pullus | Not Listed | Species of Concern | | AZ |
| Mammals | Black Mountain pocket mouse | Perognathus intermedius nigrimontis | Not Listed | Species of Concern | | AZ |
| Snails | Black Mountain Talussnail | Sonorella papagorum | Not Listed | Resolved Taxon | | |
| Fishes | Blackmouth shiner | Notropis melanostomus | Not Listed | Species of Concern | | |
| Snails | Black mudalia | Elimia melanoides | Petitioned for Listing, Under Review | Under Review | | AL |
| Snails | Black mudalia | Leptoxis melanoides | Not Listed | Species of Concern | | AL |
| Birds | Black-necked Crane | Grus nigricollis | Listed | Endangered | | |
| Birds | Black Noddy | Anous minutus melanogenys | Not Listed | Species of Concern | | |
| Fishes | Blacknose Dace | Rhinichthys atratulus | | Not Listed | | |
| Fishes | Blacknose Shiner | Notropis heterolepis | | Not Listed | | |
| Birds | Black Oystercatcher | Haematopus bachmani | Not Listed | Species of Concern | | |
| Reptiles | Black pinesnake | Pituophis melanoleucus lodingi | Listed | Threatened | | AL, MS |
| Birds | Black Rail | Laterallus jamaicensis | Not Listed | Species of Concern | | GA, NC, VA |
| Fishes | Black redhorse | Moxostoma duquesnii | Not Listed | Status Undefined | | |
| Mammals | Black rhinoceros | Diceros bicornis | Listed | Endangered | | |
| Insects | Black rhyncogonus weevil | Rhyncogonus stygius | Not Listed | Species of Concern | | HI |
| Flowering Plants | Black Rock Ground-daisy | Townsendia smithii | Not Listed | Resolved Taxon | | |
| Birds | Black Rosy-Finch | Leucosticte atrata | Not Listed | Species of Concern | | |
| Amphibians | Black Salamander | Aneides flavipunctatus | | Not Listed | | |
| Clams | Black Sandshell | Ligumia recta | | Not Listed | | |
| Birds | Black Scoter | Melanitta nigra | Not Listed | Species of Concern | | |
| Fishes | Black Sea Bass | Centropristis striata | | Not Listed | | |
| Fishes | Blackside dace | Phoxinus cumberlandensis | Listed | Threatened | | KY, TN, VA |
| Fishes | Blackside darter | Percina maculata | Not Listed | Status Undefined | | |
| Birds | Black Skimmer | Rynchops niger | Not Listed | Species of Concern | | |
| Fishes | Black Skipjack | Euthynnus lineatus | | Not Listed | | |
| Reptiles | Black softshell turtle | Trionyx nigricans | Listed | Endangered | | |
| Ferns and Allies | Black spored quillwort | Isoetes melanospora | Listed | Endangered | | GA |
| Amphibians | Black-spotted newt | Notophthalmus meridionalis | Petitioned for Listing, Under Review | Under Review | | TX |
| Birds | Black Stilt | Himantopus novaezelandiae | Listed | Endangered | | |
| Birds | Black Storm-Petrel | Hydrobates melania | Not Listed | Species of Concern | | |
| Fishes | Blackstripe Topminnow | Fundulus notatus | | Not Listed | | |
| Birds | Black Swift | Cypseloides niger | Not Listed | Species of Concern | | |
| Birds | Black-tailed gnatcatcher | Polioptila melanura californica | Not Listed | Status Undefined | | |
| Mammals | Black-tailed prairie dog | Cynomys ludovicianus | Not Listed | Resolved Taxon | | CO |
| Fishes | Blacktail Redhorse | Moxostoma poecilurum | | Not Listed | | |
| Fishes | Blacktail Shiner | Cyprinella venusta | | Not Listed | | |
| Birds | Black Tern | Chlidonias niger surinamenisis | Not Listed | Species of Concern | | CA, CO, IA, ID, IL, IN, KS, ME, MI, MN, MO, MT, ND, NE, NV, NY, OH, OR, SD, UT, WA, WI, WY |
| Birds | Black-throated Gray Warbler | Setophaga nigrescens | Not Listed | Species of Concern | | |
| Birds | Black-throated Green Warbler | Dendroica virens | Not Listed | Species of Concern | | |
| Birds | Black-throated Green Warbler | Dendroica virens waynei | Not Listed | Species of Concern | | |
| Birds | Black throated Sparrow | Amphispiza bilineata | Not Listed | Species of Concern | | |
| Birds | Black-throated Sparrow | Amphispiza bilineata bilineata | Not Listed | Species of Concern | | |
| Birds | Black-throated Sparrow | Amphispiza bilineata deserticola | Not Listed | Species of Concern | | |
| Birds | Black-throated Sparrow | Amphispiza bilineata opuntia | Not Listed | Species of Concern | | |
| Amphibians | Black toad | Bufo exsul | Not Listed | Species of Concern | | CA |
| Amphibians | Black Toad | Anaxyrus exsul | | Not Listed | | |
| Birds | Black Turnstone | Arenaria melanocephala | Not Listed | Species of Concern | | |
| Insects | Black-veined agrotis noctuid moth | Agrotis melanoneura | Not Listed | Species of Concern | | HI |
| Birds | Black-vented Shearwater | Puffinus opisthomelas | Not Listed | Species of Concern | | |
| Amphibians | Black warrior (=Sipsey Fork) Waterdog | Necturus alabamensis | Listed | Endangered | | AL |
| Insects | Blackwater sandfiltering mayfly | Homoeoneuria dolani | Not Listed | Species of Concern | | |
| Birds | Black-whiskered Vireo | Vireo altiloquus | Not Listed | Species of Concern | | |
| Birds | Black-winged kite | Elanus caeruleus | Not Listed | Species of Concern | | |
| Insects | Black-winged odynerus vespid wasp | Odynerus nigripennis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Black wooly-pod | Astragalus funereus | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Bladen buttercup | Ranunculus laxicaulis | Not Listed | Resolved Taxon | | NC |
| Flowering Plants | Blaine's fishhook cactus | Sclerocactus blainei | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Blair's munzothamnus | Stephanomeria blairii | Not Listed | Species of Concern | | CA |
| Insects | Blaisdell trigonoscuta weevil | Trigonoscuta blaisdelli | Not Listed | Species of Concern | | CA |
| Flowering Plants | Blakley's spineflower | Chorizanthe blakleyi | Not Listed | Resolved Taxon | | CA |
| Amphibians | Blanchard's Cricket Frog | Acris blanchardi | | Not Listed | | |
| Insects | Blanchards' sphinx moth | Adhemarius blanchardorum | Not Listed | Resolved Taxon | | TX |
| Amphibians | Blanco blind salamander | Eurycea robusta | Not Listed | Resolved Taxon | | TX |
| Reptiles | Blanding's turtle | Emydoidea blandingii | Petitioned for Listing, Under Review | Under Review | | IA, IL, IN, MI, MN, NE, NY, OH, PA, SD, WI, WY |
| Mammals | Blarina carolinensis ssp. shermani | Blarina brevicauda shermani | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Blasdale's bentgrass | Agrostis blasdalei blasdalei | Not Listed | Species of Concern | | CA |
| Insects | bleached sandhill skipper | Polites sabuleti sinemaculata | Proposed for Listing | Proposed Endangered | | NV |
| Clams | Bleedingtooth Mussel | Venustaconcha pleasii | | Not Listed | | |
| Clams | Bleufer | Potamilus purpuratus | | Not Listed | | |
| Insects | Blind cave leiodid | Glacicavicola bathysciodes | Not Listed | Species of Concern | | ID |
| Snails | Blind glyph | Glyphyalinia pecki | Not Listed | Species of Concern | | AL |
| Crustaceans | Blinn's Amphipod | Stygobromus blinni | Not Listed | Resolved Taxon | | |
| Snails | Bliss Rapids snail | Taylorconcha serpenticola | Listed | Threatened | | ID |
| Fishes | Bloater | Coregonus hoyi | | Not Listed | | |
| Mammals | Block Island meadow vole | Microtus pennsylvanicus provectus | Not Listed | Species of Concern | | RI |
| Flowering Plants | Blockman's leafy-daisy | Erigeron foliosus blochmaniae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Blodgett's sage | Salvia micrantha var. blodgettii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Blodgett's silverbush | Argythamnia blodgettii | Listed | Threatened | | FL |
| Crustaceans | Blood River crayfish | Orconectes burri | Not Listed | Resolved Taxon | | KY, TN |
| Fishes | Blotched gambusia | Gambusia senilis | Not Listed | Species of Concern | | TX |
| Fishes | Blotchside Logperch | Percina burtoni | Not Listed | Species of Concern | | NC |
| Insects | Blowing cave beetle | Pseudanophthalmus ventus | Not Listed | Species of Concern | | TN |
| Flowering Plants | Blowout penstemon | Penstemon haydenii | Listed | Endangered | | NE, WY |
| Fishes | Blueback herring | Alosa aestivalis | Not Listed | Status Undefined | | |
| Fishes | Bluebarred pygmy sunfish | Elassoma okatie | Not Listed | Resolved Taxon | | SC |
| Birds | Blue-billed curassow | Crax alberti | Listed | Endangered | | |
| Insects | Blueblack silverspot butterfly | Speyeria nokomis nigrocaerulea | Not Listed | Resolved Taxon | | AZ, NM |
| Fishes | Bluebreast Darter | Nothonotus camurus | | Not Listed | | |
| Insects | Blue Calamintha Bee | Osmia calaminthae | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Blue Catfish | Ictalurus furcatus | | Not Listed | | |
| Fishes | Blue Chub | Gila coerulea | | Not Listed | | |
| Crustaceans | Blue Crab | Callinectes sapidus | | Not Listed | | |
| Crustaceans | Blue Crawfish | Cambarus monongalensis | | Not Listed | | |
| Flowering Plants | Blue Diamond cholla | Opuntia X multigeniculata | Not Listed | Resolved Taxon | | NV |
| Fishes | Bluefin Trevally, Omilu | Caranx melampygus | | Not Listed | | |
| Fishes | Bluefish | Pomatomus saltatrix | | Not Listed | | |
| Fishes | Bluegill | Lepomis macrochirus | | Not Listed | | |
| Insects | Blue glyphodes moth | Glyphodes cyanomichla | Not Listed | Species of Concern | | HI |
| Birds | Blue gray Gnatcatcher | Polioptila caerulea | Not Listed | Species of Concern | | |
| Birds | Blue-gray Noddy | Anous ceruleas | Not Listed | Species of Concern | | |
| Snails | Blue-gray taildropper | prophysaon coeruleum | Not Listed | Species of Concern | | |
| Birds | Blue Grosbeak | Passerina caerulea | Not Listed | Species of Concern | | |
| Fishes | Bluehead Chub | Nocomis leptocephalus | | Not Listed | | |
| Birds | Blue-headed macaw | Primolius couloni | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Bluehead shiner | Pteronotropis hubbsi | | Not Listed | | AR, LA, OK, TX |
| Fishes | bluemask darter | Etheostoma akatulo | Listed | Endangered | | TN |
| Flowering Plants | Blue Mountain onion | Allium dictuon | Not Listed | Species of Concern | | WA |
| Insects | Blue Mountains cryptochian caddisfly | Cryptochia neosa | Not Listed | Species of Concern | | CA, NV, OR |
| Snails | Blue Mountain Woodlandsnail | Ashmunella pilsbryana | Not Listed | Resolved Taxon | | |
| Fishes | Bluenose Shiner | Pteronotropis welaka | | Not Listed | | |
| Flowering Plants | Blue oak | Quercus douglasii | Not Listed | Resolved Taxon | | |
| Fishes | Blue pike | Stizostedion vitreum glaucum | Delisted | Extinction | | MI, NY, OH, PA |
| Snails | Blue Point pyrg | Pyrgulopsis coloradensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Blue Ridge catchfly | Silene ovata | Not Listed | Species of Concern | | NC |
| Flowering Plants | Blue Ridge goldenrod | Solidago spithamaea | Listed | Threatened | | NC, TN |
| Amphibians | Blue Ridge gray-cheeked salamander | Plethodon amplus | Not Listed | Resolved Taxon | | NC |
| Insects | Blueridge springfly | Remenus kirchneri | Petitioned for Listing, Under Review | Under Review | | VA |
| Fishes | Blue shiner | Cyprinella caerulea | Listed | Threatened | | AL, GA, TN |
| Insects | Blue silverspot | Speyeria nokomis caerulescens | Not Listed | Species of Concern | | AZ |
| Snails | Blue Spring hydrobe | Aphaostracon asthenes | Not Listed | Status Undefined | | |
| Fishes | Bluestone sculpin | Cottus sp. | Not Listed | Species of Concern | | MO |
| Fishes | Bluestripe darter | Percina cymatotaenia | Petitioned for Listing, Under Review | Under Review | | MO |
| Fishes | Bluestripe shiner | Cyprinella callitaenia | Not Listed | Status Undefined | | |
| Fishes | Blue sucker | Cycleptus elongatus | Not Listed | Species of Concern | | NM |
| Reptiles | Blue-tailed ground lizard | Ameiva wetmorei | Not Listed | Species of Concern | | PR, VI |
| Reptiles | blue-tailed mole skink | Eumeces egregius lividus | Listed | Threatened | | FL |
| Snails | Blue Talussnail | Sonorella caerulifluminis | Not Listed | Resolved Taxon | | |
| Birds | Blue-throated Hummingbird | Lampornis clemenciae | Not Listed | Species of Concern | | |
| Birds | Blue-throated macaw | Ara glaucogularis | Listed | Endangered | | |
| Birds | Blue-throated (=ochre-marked) parakeet | Pyrrhura cruentata | Listed | Endangered | | |
| Reptiles | blue tree monitor lizard | Varanus macraei | Listed | Emergency Listing, Endangered | | |
| Mammals | Blue whale | Balaenoptera musculus | Listed | Endangered | | |
| Birds | Blue-winged Warbler | Vermivora cyanoptera | Not Listed | Species of Concern | | |
| Insects | Bluewing yellow-faced bee | Hylaeus caeruleipennis | Not Listed | Species of Concern | | HI |
| Lichens | Bluff Mountain Reindeer Lichen | Cladonia psoromica | Not Listed | Species of Concern | | NC |
| Flowering Plants | blumberg rosita | centaurium blumbergianum | Not Listed | Resolved Taxon | | |
| Reptiles | Blunt-nosed leopard lizard | Gambelia silus | Listed | Endangered | | CA |
| Fishes | Bluntnose Shiner | Notropis simus | | Not Listed | | |
| Birds | Blyth's tragopan pheasant | Tragopan blythii | Listed | Endangered | | |
| Flowering Plants | Boat-shaped Bugseed | Corispermum navicula | Not Listed | Resolved Taxon | | |
| Mammals | Bobcat | Lynx rufus | Not Listed | Resolved Taxon | | |
| Birds | Bobolink | Dolichonyx oryzivorus | Not Listed | Species of Concern | | |
| Fishes | Bocaccio | Sebastes paucispinis | Listed | Endangered | | |
| Flowering Plants | Bodie Hills draba | Cusickiella quadricostata | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Bodie Hills rock-cress | Arabis bodiensis | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Bog Asphodel | Narthecium americanum | Not Listed | Resolved Taxon | | NJ, SC |
| Flowering Plants | Bog, Barnstable rush | Juncus pervetus | Not Listed | Resolved Taxon | | MA |
| Flowering Plants | Bog bluegrass | Poa paludigena | Not Listed | Species of Concern | | NC |
| Insects | bog buck moth | Hemileuca maia menyanthevora (=H. iroquois) | Listed | Endangered | | NY |
| Flowering Plants | Bog coneflower | Rudbeckia scabrifolia | Not Listed | Species of Concern | | LA, TX |
| Insects | Bog elfin butterfly | Incisalia lanoraieensis | Not Listed | Resolved Taxon | | ME, NH, NY |
| Flowering Plants | Bogg's Lake dodder | Cuscuta howelliana | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Boggs Lake hedge-hyssop | Gratiola heterosepala | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Bog idol leaf beetle | Donacia idola | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | Bog labordia | Labordia hedyosmifolia | Not Listed | Resolved Taxon | | HI |
| Birds | Bogota rail | Rallus semiplumbeus | Candidate for Listing | Candidate | | |
| Flowering Plants | Bog spicebush | Lindera subcoriacea | Not Listed | Resolved Taxon | | GA, NC, SC |
| Reptiles | bog turtle | Glyptemys muhlenbergii | Listed | Threatened | | CT, DC, DE, MA, MD, NJ, NY, PA, VA |
| Reptiles | bog turtle | Glyptemys muhlenbergii | Listed | Similarity of Appearance (Threatened) | | NC, SC, TN |
| Insects | Boharts' blue | Philotiella speciosa bohartorum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Boke's button cactus | Epithelantha bokei | Not Listed | Resolved Taxon | | TX |
| Conifers and Cycads | Bolander's beach pine | Pinus contorta bolanderi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Bolander's horkelia | Horkelia bolanderi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Bolander's lily | Lilium bolanderi | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Bolander's sagebrush | Artemisia cana bolanderi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Bolander water-hemlock | Cicuta bolanderi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Bolinas ceanothus | Ceanothus masonii | Not Listed | Species of Concern | | CA |
| Mammals | Bolivian short-tailed chinchilla | Chinchilla chinchilla boliviana | Listed | Endangered | | |
| Reptiles | Bolson tortoise | Gopherus flavomarginatus | Listed | Endangered | | |
| Birds | Bonaparte's Gull | Chroicocephalus philadelphia | Not Listed | Species of Concern | | |
| Arachnids | Bone Cave harvestman | Texella reyesi | Listed | Endangered | | TX |
| Mammals | Bonin Flying Fox Bat | Pteropus pselaphon | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Bonin Petrel | Pterodroma hypoleuca | Not Listed | Species of Concern | | |
| Insects | Bonita diving beetle | Deronectes neomexicana | Not Listed | Species of Concern | | NM, TX |
| Fishes | Bonnethead | Sphyrna tiburo | | Not Listed | | |
| Fishes | Bonneville Cisco | Prosopium gemmifer | Not Listed | Resolved Taxon | | |
| Fishes | Bonneville cutthroat trout | Oncorhynchus clarkii utah | Not Listed | Resolved Taxon | | ID, NV, UT, WY |
| Mammals | Bonneville southern pocket gopher | Thomomys umbrinus bonnevillei | Not Listed | Species of Concern | | UT |
| Fishes | Bonneville Whitefish | Prosopium spilonotus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Bonny Doon manzanita | Arctostaphylos silvicola | Not Listed | Species of Concern | | CA |
| Mammals | Bontebok | Damaliscus pygarus (=dorcas) dorcas | Listed | Endangered | | |
| Fishes | Bonytail | Gila elegans | Listed | Endangered | | AZ, CA, CO, NV, UT |
| Flowering Plants | Boott's rattlesnake root | Prenanthes boottii | Not Listed | Species of Concern | | ME, NH, NY, VT |
| Fishes | Borax Lake chub | Gila boraxobius | Delisted | Recovery | | OR |
| Crustaceans | Border Cave Amphipod | Stygobromus limbus | Not Listed | Resolved Taxon | | |
| Amphibians | Boreal toad | Anaxyrus boreas boreas | Not Listed | Resolved Taxon | | |
| Amphibians | Boreal toad | Anaxyrus boreas boreas | Not Listed | Resolved Taxon | | CO, WY |
| Reptiles | Borneo earless monitor | Lanthanotus borneensis | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Borrego aster | Xylorhiza orcuttii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Borrego bedstraw | Galium angustifolium borregoense | Not Listed | Species of Concern | | CA |
| Flowering Plants | Borrego Valley peppergrass | Lepidium flavum felipense | Not Listed | Species of Concern | | CA |
| Birds | Botteri's Sparrow | Aimophila botterii | Not Listed | Species of Concern | | |
| Fishes | Boulder darter | Etheostoma wapiti | Listed | Experimental Population, Non-Essential | | AL, TN |
| Fishes | Boulder darter | Etheostoma wapiti | Listed | Endangered | | AL, TN |
| Snails | Boulder pile mountainsnail | Oreohelix jugalis | Not Listed | Species of Concern | | ID |
| Snails | Boulder Slide Threeband | Humboldtiana edithae | Not Listed | Resolved Taxon | | |
| Snails | Boulder snail | Leptoxis crassa | Not Listed | Species of Concern | | AL, GA, TN |
| Corals | Boulder star coral | Orbicella franksi | Listed | Threatened | | |
| Crustaceans | Boulton's Amphipod | Stygobromus boultoni | Not Listed | Resolved Taxon | | |
| Flowering Plants | Boundary Peak rock-cress | Boechera pinzliae | Not Listed | Species of Concern | | CA, NV |
| Crustaceans | Bousfield's amphipod | Gammarus bousfieldi | Not Listed | Species of Concern | | KY |
| Fishes | Bowfin | Amia calva | | Not Listed | | |
| Mammals | Bowhead whale | Balaena mysticetus | Listed | Endangered | | |
| Crustaceans | Bowman's cave amphipod | Stygobromus bowmani | Not Listed | Resolved Taxon | | OK |
| Crustaceans | bowman's fairy shrimp | streptocephalus thomasbowmani | Not Listed | Resolved Taxon | | |
| Flowering Plants | Boxfruit alani | Melicope peduncularis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Box huckleberry | Gaylussacia brachycera | Not Listed | Resolved Taxon | | DE, KY, MD, PA, TN, VA, WV |
| Flowering Plants | Boykin's lobelia | Lobelia boykinii | Petitioned for Listing, Under Review | Under Review | | GA, SC |
| Flowering Plants | Boynton's oak | Quercus boyntonii | Not Listed | Resolved Taxon | | AL, TX |
| Flowering Plants | Bracted twistflower | Streptanthus bracteatus | Listed | Threatened | | TX |
| Flowering Plants | Bradshaw''s lomatium | Lomatium bradshawii | Delisted | Recovery | | OR, WA |
| Snails | Bradshaw Talussnai | Sonorella bradshaveana | Not Listed | Resolved Taxon | | |
| Insects | (Bradycellus fenderi) ground beetle | bradycellus fenderi | Not Listed | Species of Concern | | |
| Flowering Plants | Brady pincushion cactus | Pediocactus bradyi | Listed | Endangered | | AZ |
| Arachnids | Braken Bat Cave meshweaver | Cicurina venii | Delisted | Original Data in Error - Not a listable entity | | TX |
| Flowering Plants | Branched draba | Draba stenoloba ramosa | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Branched fleabane | Erigeron allocotus | Not Listed | Resolved Taxon | | MT, WY |
| Flowering Plants | Brandegee eriastrum | Eriastrum brandegeeae | Not Listed | Species of Concern | | CA |
| Flowering Plants | Brandegee's Buckwheat | Eriogonum brandegeei | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Brandegee's sage | Salvia brandegeei | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Brand's phacelia | Phacelia stellaris | Not Listed | Resolved Taxon | | CA |
| Birds | Brandt's Cormorant | Urile penicillatus | Not Listed | Species of Concern | | |
| Birds | Brasilia tapaculo | Scytalopus novacapitalis | Candidate for Listing | Candidate | | |
| Fishes | Brassy Minnow | Hybognathus hankinsoni | | Not Listed | | |
| Flowering Plants | Braun mato | Caesalpinia portoricensis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Braun's rock-cress | Arabis perstellata | Listed | Endangered | | KY, TN |
| Flowering Plants | Braunton's milk-vetch | Astragalus brauntonii | Listed | Endangered | | CA |
| Crustaceans | Brawleys Fork crayfish | Cambarus williami | Proposed for Listing | Proposed Threatened | | TN |
| Fishes | Brazilian guitarfish | Rhinobatos horkelii | Listed | Endangered | | |
| Reptiles | Brazilian sideneck turtle | Phrynops hogei | Listed | Endangered | | |
| Mammals | Brazilian three-toed sloth | Bradypus torquatus | Listed | Endangered | | |
| Birds | Brazillian merganser | Mergus octosetaceus | Listed | Endangered | | |
| Crustaceans | Brazoria Crayfish | Procambarus brazoriensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Brazos River Yucca | Yucca necopina | Not Listed | Resolved Taxon | | |
| Reptiles | Brazos water snake | Nerodia harteri harteri | Not Listed | Resolved Taxon | | TX |
| Amphibians | Breckenridge Mountain slender salamander | Batrachoseps sp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Brewer's dwarf-flax | Hesperolinon breweri | Not Listed | Species of Concern | | CA |
| Birds | Brewer's Sparrow | Spizella breweri | Not Listed | Species of Concern | | |
| Flowering Plants | Brewer's spineflower | Chorizanthe breweri | Not Listed | Resolved Taxon | | CA |
| Snails | Brian Head Mountainsnail | Oreohelix parawanensis | Not Listed | Resolved Taxon | | |
| Snails | Briarton Pleistocene snail | Vertigo briarensis | Not Listed | Species of Concern | | IA, MN, WI |
| Insects | Bridewell's nesosydne planthopper | Nesosydne bridwelli | Not Listed | Species of Concern | | HI |
| Fishes | Bridgelip sucker | Catostomus columbianus | Not Listed | Status Undefined | | |
| Snails | Bridges' Coast Range shoulderband | Helminthoglypta nickliniana bridgesi | Not Listed | Species of Concern | | CA |
| Fishes | Bridled darter | Percina kusha | Not Listed | Status Undefined | | GA, TN |
| Birds | Bridled Quail-Dove | Geotrygon mystacea | Not Listed | Species of Concern | | |
| Birds | Bridled Tern | Onychoprion anaethetus | Not Listed | Species of Concern | | |
| Birds | Bridled Tern | Onychoprion anaethetus recongnitus | Not Listed | Species of Concern | | |
| Birds | Bridled white-eye | Zosterops conspicillatus conspicillatus | Delisted | Extinction | | |
| Birds | Bridled White-eye | Zosterops conspicillatus saypani | Not Listed | Species of Concern | | |
| Fishes | Bridle Shiner | Notropis bifrenatus | | Not Listed | | |
| Insects | Bridwell's long-horned beetle | Plagithmysus bridwelli | Not Listed | Species of Concern | | HI |
| Flowering Plants | Brikellbush aster | Eucephalus tomentellus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Snails | Briley Creek pyrg | Pyrgulopsis sp. | Not Listed | Species of Concern | | AL |
| Fishes | Brindled Madtom | Noturus miurus | | Not Listed | | |
| Mammals | Brindled nail-tailed wallaby | Onychogalea fraenata | Listed | Endangered | | |
| Flowering Plants | Bristlecone catseye | Cryptantha roosiorum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Bristle-flowered collomia | Collomia macrocalyx | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Bristlefront yellow-faced bee | Nesoprosopis setosifrons | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Bristle Nailwort | Paronychia lundelliorum | Not Listed | Resolved Taxon | | |
| Birds | Bristle-thighed Curlew | Numenius tahitiensis | Not Listed | Species of Concern | | AS |
| Flowering Plants | Brittlescale | Atriplex depressa | Not Listed | Status Undefined | | |
| Flowering Plants | Britton's beargrass | Nolina brittoniana | Listed | Endangered | | FL |
| Insects | Broadhead yellow-faced bee | Hylaeus laticeps | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Broad-leaf Ground-cherry | Physalis latiphysa | Not Listed | Resolved Taxon | | |
| Flowering Plants | Broad-pod rushpea | Caesalpinia brachycarpa | Not Listed | Species of Concern | | TX |
| Crustaceans | Broad River Burrowing crayfish | Distocambarus devexus | Not Listed | Status Undefined | | GA |
| Reptiles | Broad-snouted caiman | Caiman latirostris | Listed | Endangered | | |
| Reptiles | Broad-snouted caiman | Caiman latirostris | Listed | Threatened | | |
| Fishes | Broadstripe shiner | Pteronotropis euryzonus | Not Listed | Status Undefined | | AL, GA |
| Birds | Broad-tailed Hummingbird | Selasphorus platycercus | Not Listed | Species of Concern | | |
| Fishes | Broad Whitefish | Coregonus nasus | | Not Listed | | |
| Snails | Broken hornsnail | Pleurocera postelli | Not Listed | Species of Concern | | AL |
| Insects | Bronze clubtail | Stylurus townesi | Not Listed | Species of Concern | | |
| Fishes | Bronze darter | Percina palmaris | Not Listed | Resolved Taxon | | AL, GA, TN |
| Snails | Brook elimia | Elimia strigosa | Not Listed | Species of Concern | | TN |
| Clams | Brook floater | Alasmidonta varicosa | Not Listed | Resolved Taxon | | GA, NC, SC, VA |
| Flowering Plants | Brooksville bellflower | Campanula robinsiae | Listed | Endangered | | FL |
| Fishes | brook trout | Salvelinus fontinalis | Not Listed | Status Undefined | | |
| Fishes | brook trout | Salvelinus fontinalis | Not Listed | Resolved Taxon | | CT, DE, GA, IN, MA, MD, ME, MI, MN, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VT, WI, WV |
| Reptiles | Brother's Island tuatara | Sphenodon guntheri | Listed | Endangered | | |
| Clams | Brother spike | Elliptio fraterna | Not Listed | Status Undefined | | AL, GA, SC |
| Birds | Brown-banded antpitta | Grallaria milleri | Listed | Endangered | | |
| Mammals | Brown bear | Ursus arctos arctos | Listed | Endangered | | |
| Mammals | Brown bear | Ursus arctos pruinosus | Listed | Endangered | | |
| Birds | Brown Booby | Sula leucogaster | Not Listed | Species of Concern | | |
| Fishes | Brown Bullhead | Ameiurus nebulosus | | Not Listed | | |
| Reptiles | Brown Caiman | Caiman crocodilus fuscus (includes Caiman crocodilus chiapasius) | Listed | Similarity of Appearance (Threatened) | | |
| Birds | Brown-capped Rosy-Finch | Leucosticte australis | Not Listed | Species of Concern | | |
| Birds | Brown creeper | certhia americana | Not Listed | Species of Concern | | |
| Birds | Brown-crested flycatcher | myiarchus tyrannulus | Not Listed | Species of Concern | | |
| Insects | Brown cross ectemnius sphecid wasp | Ectemnius fulvicrus | Not Listed | Species of Concern | | HI |
| Fishes | Brown Darter | Etheostoma edwini | | Not Listed | | |
| Birds | Brown eared pheasant | Crossoptilon mantchuricum | Listed | Endangered | | |
| Birds | Brown-headed Nuthatch | Sitta pusilla | Not Listed | Species of Concern | | |
| Mammals | Brown Hyena | Parahyaena (=Hyaena) brunnea | Listed | Endangered | | |
| Insects | Brownish dubiraphian riffle beetle | Dubiraphia brunnescens | Not Listed | Species of Concern | | CA |
| Insects | Brown merycomyian tabanid fly | Merycomyia brunnea | Not Listed | Species of Concern | | |
| Birds | Brown Pelican | Pelecanus occidentalis | Not Listed | Resolved Taxon | | |
| Birds | Brown Pelican | Pelecanus occidentalis | Delisted | Recovery | | AZ, CA, LA, TX, WA |
| Birds | Brown Pelican | Pelecanus occidentalis | Delisted | Recovery | | |
| Birds | Brown Pelican | Pelecanus occidentalis | Not Listed | Resolved Taxon | | |
| Fishes | Brown Rockfish | Sebastes auriculatus | | Not Listed | | |
| Insects | Brown's microcylloepus riffle beetle | Microcylloepus browni | Not Listed | Resolved Taxon | | MT |
| Insects | Brown's optioservus riffle beetle | Optioservus browni | Not Listed | Species of Concern | | AR |
| Snails | Brown springsnail | Pyrgulopsis sola | Not Listed | Resolved Taxon | | AZ |
| Birds | Brownsville common yellowthroat | Geothlypis trichas insperata | Not Listed | Species of Concern | | TX |
| Birds | Brownsville Curve-billed Thrasher | Toxostoma curvirostre oberholseri | Not Listed | Species of Concern | | |
| Insects | Brown-tassel trigonoscuta weevil | Trigonoscuta brunneotesselata | Not Listed | Species of Concern | | CA |
| Birds | Brown Thrasher | Toxostoma rufum | Not Listed | Species of Concern | | |
| Fishes | Brown Trout | Salmo trutta | | Not Listed | | |
| Fishes | Brown Trout | Salmo trutta | Not Listed | Status Undefined | | |
| Snails | Bruneau Hot springsnail | Pyrgulopsis bruneauensis | Listed | Endangered | | ID, NV |
| Snails | Brune's tryonia | Tryonia brunei | Not Listed | Resolved Taxon | | TX |
| Snails | Brunson Mountain snail | Oreohelix speciesfive | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Brush Prairie pocket gopher | Thomomys mazama douglasii | Not Listed | Resolved Taxon | | WA |
| Mammals | brush rabbit | Sylvilagus bachmani | Not Listed | Species of Concern | | |
| Mammals | Brush-tailed rat-kangaroo | Bettongia penicillata | Listed | Endangered | | |
| Flowering Plants | Bryan's nehe | Lipochaeta bryanii | Not Listed | Resolved Taxon | | HI |
| Insects | Bryan's oceanides seed bug | Oceanides bryani | Not Listed | Species of Concern | | HI |
| Flowering Plants | Bryce bladder-pod | Lesquerella rubicundula | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Bryson's sedge | Carex brysonii | Not Listed | Status Undefined | | AL |
| Insects | Buchholz' dart moth | Agrotis buchholzi | Not Listed | Species of Concern | | DE, NC, NJ |
| Flowering Plants | Buck Creek serpentine barren aster | Symphyotrichum rhiannon | Not Listed | Species of Concern | | NC |
| Fishes | Buck Darter | Etheostoma nebra | Not Listed | Species of Concern | | |
| Mammals | Buena Vista Lake ornate Shrew | Sorex ornatus relictus | Listed | Endangered | | CA |
| Insects | Buffalo Springs caddisfly | Ceratopsyche etnieri | Not Listed | Species of Concern | | TN |
| Birds | Buff-banded Rail | Gallirallus philippensis goodsoni | Not Listed | Species of Concern | | |
| Birds | Buff-bellied Hummingbird | Amazilia yucatanensis | Not Listed | Species of Concern | | |
| Birds | Buff-breasted flycatcher | Empidonax fulvifrons pygmaeus | Not Listed | Resolved Taxon | | AZ, NM |
| Birds | Buff-breasted Flycatcher | Empidonax fulvifrons | Not Listed | Species of Concern | | |
| Birds | Buff-breasted Sandpiper | Calidris subruficollis | Not Listed | Species of Concern | | |
| Mammals | Buff-headed marmoset | Callithrix flaviceps | Listed | Endangered | | |
| Birds | Buller's Shearwater | Ardenna bulleri | Not Listed | Species of Concern | | |
| Flowering Plants | Bullfrog Mountain wild pea | Lathyrus hitchcockianus | Not Listed | Resolved Taxon | | NV |
| Birds | Bullock's Oriole | Icterus bullockii | Not Listed | Species of Concern | | |
| Mammals | Bulls Island white-tailed deer | Odocoileus virginianus taurinsulae | Not Listed | Species of Concern | | SC |
| Fishes | Bull Trout | Salvelinus confluentus | Listed | Threatened | | ID, MT, NV, OR, WA |
| Fishes | Bull Trout | Salvelinus confluentus | Listed | Experimental Population, Non-Essential | | |
| Mammals | Bulmer's fruit bat (=flying fox) | Aproteles bulmerae | Listed | Endangered | | |
| Birds | Bulwer's Petrel | Bulweria bulwerii | Not Listed | Species of Concern | | |
| Mammals | Bumblebee bat | Craseonycteris thonglongyai | Listed | Endangered | | |
| Insects | Bumblebee scarab | Lichnanthe ursina | Not Listed | Species of Concern | | CA |
| Flowering Plants | Bunched arrowhead | Sagittaria fasciculata | Listed | Endangered | | NC, SC |
| Flowering Plants | Bunched cory cactus | Coryphantha ramillosa | Listed | Threatened | | TX |
| Fishes | Burbot | Lota lota | Not Listed | Resolved Taxon | | |
| Flowering Plants | Burke's goldfields | Lasthenia burkei | Listed | Endangered | | CA |
| Reptiles | Burmese peacock turtle | Morenia ocellata | Listed | Endangered | | |
| Insects | Burnell's false water penny | Acneus burnelli | Not Listed | Species of Concern | | OR |
| Crustaceans | Burnsville Cove cave amphipod | Stygobromus conradi | Not Listed | Species of Concern | | VA |
| Fishes | Burrhead Chub | Macrhybopsis marconis | | Not Listed | | |
| Fishes | Burrhead shiner | Notropis asperifrons | Not Listed | Resolved Taxon | | AL, GA, TN |
| Snails | Burrington jumping-slug | Hemphillia burringtoni | Not Listed | Resolved Taxon | | OR, WA |
| Fishes | Burro Grunt | Pomadasys crocro | | Not Listed | | |
| Crustaceans | Burrowing bog crayfish | Fallicambarus burrisi | | Not Listed | | AL, MS |
| Insects | Burrowing mayfly | Hexagenia sp | Not Listed | Resolved Taxon | | |
| Birds | Burrowing Owl | Athene cunicularia | Not Listed | Species of Concern | | |
| Insects | Busck's gall moth | Carolella busckana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Bushy rush-rose | Helianthemum dumosum | Not Listed | Species of Concern | | CT, MA, NY, RI |
| Flowering Plants | Bushy whitlow-wort | Paronychia congesta | Proposed for Listing | Proposed Endangered | | TX |
| Flowering Plants | Bushy wild-buckwheat | Eriogonum suffruticosum | Not Listed | Species of Concern | | TX |
| Flowering Plants | Butte County catchfly | Silene occidentalis longistipitata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Butte County meadowfoam | Limnanthes floccosa ssp. californica | Listed | Endangered | | CA |
| Flowering Plants | Butte County morning-glory | Calystegia atriplicifolia buttensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Butte County sidalcea | Sidalcea robusta | Not Listed | Species of Concern | | CA |
| Flowering Plants | Butte fritillary | Fritillaria eastwoodiae | Not Listed | Species of Concern | | CA |
| Flowering Plants | buttercup phacelia | Phacelia covillei | Not Listed | Species of Concern | | |
| Snails | Butterfield pyrg | Pyrgulopsis lata | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Butterfly, Gaut's cactus | Turbinicarpus gautii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | butterfly milkweed | Asclepias tuberosa | | Not Listed | | |
| Clams | Butterfly Mussel | Ellipsaria lineolata | | Not Listed | | |
| Flowering Plants | Butternut | Juglans cinerea | Not Listed | Species of Concern | | NC |
| Flowering Plants | Butterworth's buckwheat | Eriogonum butterworthianum | Not Listed | Species of Concern | | CA |
| Snails | Button's Sierra sideband | Monadenia mormonum buttoni | Not Listed | Species of Concern | | CA |
| Snails | Bylas springsnail | Pyrgulopsis arizonae | Petitioned for Listing, Under Review | Under Review | | AZ |
| Snails | Byrne Resort mountainsnail | Oreohelix spthirtyone | Not Listed | Resolved Taxon | | MT |
| Birds | Cabot's tragopan pheasant | Tragopan caboti | Listed | Endangered | | |
| Mammals | Cabrera's hutia | Capromys angelcabrerai | Listed | Endangered | | |
| Flowering Plants | Cache beardtongue | Penstemon compactus | Not Listed | Species of Concern | | ID, UT |
| Flowering Plants | Cache Peak buckwheat | Eriogonum kennedyi pinicola | Not Listed | Species of Concern | | CA |
| Birds | Cactus ferruginous pygmy-owl | Glaucidium brasilianum cactorum | Listed | Threatened | | AZ, TX |
| Birds | Cactus Wren | Campylorhynchus brunneicapillus guttatus | Not Listed | Species of Concern | | |
| Insects | Caddisfly | Apatania arizona | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Chimarra primula | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Culoptila kimminsi | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Culoptila moselyi | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Hydroptila protera | Petitioned for Listing, Under Review | Under Review | | |
| Insects | Caddisfly | Lepidostoma ozarkense | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Neotrichia mobilensis | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Ochrotrichia guadalupensis | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Ochrotrichia weddleae | Not Listed | Resolved Taxon | | |
| Insects | Caddisfly | Phylocentropus harrisi | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Caddo madtom | Noturus taylori | | Not Listed | | AR |
| Amphibians | Caddo Mountain salamander | Plethodon caddoensis | Not Listed | Resolved Taxon | | AR |
| Flowering Plants | Caddo purple false-foxglove | Tomanthera caddoensis | Not Listed | Species of Concern | | LA |
| Crustaceans | (Caecidotea reddelli) isopod | caecidotea reddelli | Not Listed | Species of Concern | | |
| Birds | Caerulean Paradise flycatcher | Eutrichomyias rowleyi | Listed | Endangered | | |
| Reptiles | Cagle's map turtle | Graptemys caglei | Not Listed | Resolved Taxon | | TX |
| Snails | Cahaba elimia | Elimia cahawbensis | Not Listed | Resolved Taxon | | AL |
| Snails | Cahaba pebblesnail | Clappia cahabensis | Not Listed | Resolved Taxon | | AL |
| Snails | Cahaba pebblesnail | Clappia umbilicata | Not Listed | Resolved Taxon | | AL |
| Insects | Cahaba saddle-case caddisfly | Protoptila cahabensis | Not Listed | Species of Concern | | AL |
| Insects | Cahaba sandfiltering mayfly | Homoeoneuria cahabensis | Not Listed | Species of Concern | | AL, MS |
| Fishes | Cahaba shiner | Notropis cahabae | Listed | Endangered | | AL |
| Flowering Plants | Cain's reedgrass | Calamagrostis cainii | Not Listed | Species of Concern | | NC |
| Mammals | Calamianes (=Philippine) deer | Axis porcinus calamianensis | Listed | Endangered | | |
| Crustaceans | Calcasieu crayfish | Orconectes blacki | Petitioned for Listing, Under Review | Under Review | | LA |
| Flowering Plants | Calico monkeyflower | Mimulus pictus | Not Listed | Resolved Taxon | | CA |
| Snails | Calico Rock oval | Patera clenchi | Not Listed | Species of Concern | | AR |
| Flowering Plants | Caliente clarkia | Clarkia tembloriensis ssp. calientensis | Not Listed | Species of Concern | | CA |
| Ferns and Allies | California adder's-tongue | Ophioglossum lusitanicum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | California adolphia | Adolphia californica | Not Listed | Species of Concern | | |
| Fishes | California Bay Shrimp | Crangon franciscorum | | Not Listed | | |
| Flowering Plants | California beaked-rush | Rhynchospora californica | Not Listed | Species of Concern | | CA |
| Flowering Plants | California black oak | Quercus kelloggii | Not Listed | Resolved Taxon | | |
| Birds | California black rail | laterallus jamaicensis ssp. coturniculus | Not Listed | Species of Concern | | |
| Flowering Plants | California bottlebrush grass | Elymus californicus | Not Listed | Resolved Taxon | | CA |
| Birds | California condor | Gymnogyps californianus | Listed | Experimental Population, Non-Essential | | CA, ID, NV, OR, WA |
| Birds | California condor | Gymnogyps californianus | Listed | Endangered | | AZ, CA, NV, UT |
| Birds | California condor | Gymnogyps californianus | Listed | Experimental Population, Non-Essential | | AZ, NV, UT |
| Flowering Plants | California dichondra | Dichondra donnelliana | Not Listed | Resolved Taxon | | CA |
| Insects | California diplectronan caddisfly | Diplectrona californica | Not Listed | Species of Concern | | CA |
| Flowering Plants | California dissanthelium | Dissanthelium californicum | Not Listed | Species of Concern | | CA |
| Flowering Plants | California ditaxis | Ditaxis serrata | Not Listed | Species of Concern | | CA |
| Clams | California floater | Anodonta californiensis | Not Listed | Resolved Taxon | | AZ, CA, ID, NV, OR, UT, WA |
| Crustaceans | California freshwater shrimp | Syncaris pacifica | Listed | Endangered | | CA |
| Amphibians | California giant salamander | Dicamptodon ensatus | Not Listed | Resolved Taxon | | CA |
| Fishes | California golden trout | Oncorhynchus aguabonita | Not Listed | Resolved Taxon | | CA |
| Birds | California Gull | Larus californicus | | Not Listed | | |
| Flowering Plants | California hibiscus | Hibiscus californicus | Not Listed | Resolved Taxon | | CA |
| Birds | California horned lark | Eremophila alpestris actia | Not Listed | Resolved Taxon | | CA |
| Reptiles | California horned lizard | Phrynosoma coronatum frontale | Not Listed | Species of Concern | | CA |
| Flowering Plants | California jewelflower | Caulanthus californicus | Listed | Endangered | | CA |
| Reptiles | California king snake | lampropeltis getula ssp. californiae | Not Listed | Species of Concern | | |
| Flowering Plants | California lady's-slipper | Cypripedium californicum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Mammals | California leaf-nosed bat | Macrotus californicus | Not Listed | Species of Concern | | AZ, CA |
| Birds | California least tern | Sternula antillarum browni | Listed | Endangered | | AZ, CA, NV |
| Crustaceans | California linderiella | Linderiella occidentalis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | California marina | Marina orcuttii orcuttii | Not Listed | Species of Concern | | CA |
| Snails | California McCoy snail islandsnail | Micrarionta rowelli mccoiana | Not Listed | Species of Concern | | CA |
| Mammals | California mountain lion | Felis concolor californica | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | California muhly | Muhlenbergia californica | Not Listed | Species of Concern | | |
| Mammals | California myotis | myotis californicus | Not Listed | Species of Concern | | |
| Flowering Plants | California Orcutt grass | Orcuttia californica | Listed | Endangered | | CA |
| Flowering Plants | California penstemon | Penstemon californicus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | California pine-foot | Pityopus californicus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | California pitcherplant | Darlingtonia californica | Not Listed | Resolved Taxon | | CA, NV, OR |
| Amphibians | California red-legged frog | Rana draytonii | Listed | Threatened | | CA |
| Mammals | California red tree vole | Arborimus pomo | Not Listed | Species of Concern | | CA, OR |
| Birds | California Ridgway's rail | Rallus obsoletus obsoletus | Listed | Endangered | | CA |
| Fishes | California Roach | Hesperoleucus symmetricus | | Not Listed | | |
| Flowering Plants | California seablite | Suaeda californica | Listed | Endangered | | CA |
| Birds | California Spotted Owl | Strix occidentalis occidentalis | Proposed for Listing | Proposed Endangered | | CA |
| Birds | California Spotted Owl | Strix occidentalis occidentalis | Proposed for Listing | Proposed Threatened | | CA, NV |
| Flowering Plants | California taraxacum | Taraxacum californicum | Listed | Endangered | | CA |
| Birds | California Thrasher | Toxostoma redivivum | Not Listed | Species of Concern | | |
| Amphibians | California tiger Salamander | Ambystoma californiense | Listed | Endangered | | CA |
| Amphibians | California tiger Salamander | Ambystoma californiense | Listed | Threatened | | CA |
| Amphibians | California tiger Salamander | Ambystoma californiense | Listed | Endangered | | CA |
| Flowering Plants | California walnut | Juglans californica var. californica | Not Listed | Species of Concern | | |
| Mammals | California wolverine | Gulo gulo luteus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Calistoga allocarya | Plagiobothrys strictus | Listed | Endangered | | CA |
| Flowering Plants | Calistoga ceanothus | Ceanothus divergens | Not Listed | Species of Concern | | CA |
| Birds | Calliope Hummingbird | Selasphorus calliope | Not Listed | Species of Concern | | |
| Insects | Callippe silverspot butterfly | Speyeria callippe callippe | Listed | Endangered | | CA |
| Flowering Plants | Calloway milk-vetch | Astragalus callithrix | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | Call's angelica | Angelica callii | Not Listed | Resolved Taxon | | CA |
| Snails | Callused vertigo | Vertigo arthuri | Not Listed | Species of Concern | | MN, ND, SD, WY |
| Insects | Calvert's emerald | Somatochlora calverti | Petitioned for Listing, Under Review | Under Review | | FL, SC |
| Flowering Plants | Cambria morning-glory | Calystegia subacaulis episcopalis | Not Listed | Species of Concern | | CA |
| Mammals | Cameroon clawless otter | Aonyx congicus (=congica) microdon | Listed | Endangered | | |
| Amphibians | Cameroon toad | Bufo superciliaris | Listed | Endangered | | |
| Birds | Campbell Island flightless teal | Anas aucklandica nesiotis | Listed | Endangered | | |
| Crustaceans | Camp Shelby burrowing crayfish | Fallicambarus gordoni | Not Listed | Resolved Taxon | | MS |
| Snails | Camp Valley pyrg | Pyrgulopsis montana | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Campylotheca bidens | Bidens campylotheca campylotheca | Not Listed | Resolved Taxon | | HI |
| Birds | Canada goose | Branta canadensis | Not Listed | Status Undefined | | |
| Mammals | Canada Lynx | Lynx canadensis | Listed | Threatened | | CA, CO, ID, ME, MI, MN, MT, NH, NM, UT, VT, WA, WI, WY |
| Birds | Canada Warbler | Cardellina canadensis | Not Listed | Species of Concern | | |
| Flowering Plants | Canadian, columbine | Aquilegia canadensis australis | Not Listed | Species of Concern | | |
| Amphibians | Canadian Toad | Anaxyrus hemiophrys | | Not Listed | | |
| Birds | Canarian black oystercatcher | Haematopus meadewaldoi | Listed | Endangered | | |
| Snails | Canary duskysnail | Lyogyrus spc | Not Listed | Resolved Taxon | | CA |
| Fishes | canary rockfish | Sebastes pinniger | Listed | Threatened | | |
| Flowering Plants | Canby's dropwort | Oxypolis canbyi | Listed | Endangered | | DE, GA, MD, NC, SC |
| Flowering Plants | Candleholder dudleya | Dudleya candelabrum | Not Listed | Species of Concern | | CA |
| Fishes | Candy darter | Etheostoma osburni | Listed | Endangered | | VA, WV |
| Insects | Cane Creek cave beetle | Pseudanophthalmus occidentalis | Not Listed | Species of Concern | | TN |
| Flowering Plants | Canelo Hills ladies'-tresses | Spiranthes delitescens | Listed | Endangered | | AZ |
| Flowering Plants | Canescent bluebells | Mertensia viridis cana | Not Listed | Resolved Taxon | | CO, UT |
| Fishes | Caney Mountain Cave Crayfish | Faxonius stygocaneyi | | Not Listed | | |
| Crustaceans | cannulate cave isopod | Caecidotea cannulus | Not Listed | Species of Concern | | MD, WV |
| Crustaceans | cannulate cave isopod | Pseudobaicalasellus cannula | Not Listed | Resolved Taxon | | WV |
| Clams | Canoe Creek Clubshell | Pleurobema athearni | Listed | Endangered | | AL |
| Birds | Cantabrian capercaillie | Tetrao urogallus cantabricus | Listed | Endangered | | |
| Flowering Plants | Cantelow's lewisia | Lewisia cantelowii | Not Listed | Resolved Taxon | | CA |
| Mammals | Canyon bat | Parastrellus hesperus | Not Listed | Species of Concern | | |
| Flowering Plants | Canyon Creek stonecrop | Sedum paradisum | Not Listed | Species of Concern | | CA |
| Ferns and Allies | Canyon lip fern | Cheilanthes arizonica californicum | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Canyon mock orange | Philadelphus ernestii | Not Listed | Species of Concern | | TX |
| Reptiles | Canyon spotted whiptail | Cnemidophorus burti | Not Listed | Species of Concern | | AZ, NM |
| Birds | Canyon Towhee | Pipilo fuscus | Not Listed | Species of Concern | | |
| Flowering Plants | Capa rosa | Callicarpa ampla | Listed | Endangered | | PR |
| Fishes | Cape Fear shiner | Notropis mekistocholas | Listed | Endangered | | NC |
| Clams | Cape Fear spike | Elliptio marsupiobesa | Not Listed | Resolved Taxon | | NC |
| Snails | Cape Fear threetooth | Triodopsis soelneri | Not Listed | Species of Concern | | NC |
| Birds | Cape May Warbler | Setophaga tigrina | Not Listed | Species of Concern | | |
| Snails | Cape Mendocino snail | Helminthoglypta arrosa mattolensis | Not Listed | Resolved Taxon | | CA |
| Mammals | Cape Mountain zebra | Equus zebra ssp. zebra | Listed | Endangered | | |
| Snails | Caper elimia | Elimia olivula | | Not Listed | | AL |
| Flowering Plants | Caper-fruited tropidocarpum | Tropidocarpum capparideum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Cape Sable orchid | Trichocentrum undulatum | Not Listed | Resolved Taxon | | |
| Birds | Cape Sable seaside sparrow | Ammospiza maritima mirabilis | Listed | Endangered | | FL |
| Flowering Plants | Cape Sable Thoroughwort | Chromolaena frustrata | Listed | Endangered | | FL |
| Snails | Capitan Woodlandsnail | Ashmunella pseudodonta | Not Listed | Resolved Taxon | | |
| Snails | Capote Threeband | Humboldtiana fullingtoni | Not Listed | Resolved Taxon | | |
| Mammals | Capped Langur | Trachypithecus (=Presbytis) pileatus | Listed | Endangered | | |
| Insects | Caracara commensal scarab | Trox howelli | Not Listed | Species of Concern | | |
| Birds | Cardinal honey-eater | Myzomela cardinalis saffordi | Not Listed | Resolved Taxon | | GA |
| Lichens | Cardot's campylium moss | Campylium cardotii | Not Listed | Resolved Taxon | | |
| Birds | Caribbean coot | Fulica caribaea | Not Listed | Species of Concern | | PR, VI |
| Mammals | Caribbean monk seal | Monachus tropicalis | Delisted | Extinction | | |
| Crustaceans | Caribbean Spiny Lobster | Panulirus argus | | Not Listed | | |
| Snails | Carinated rocky mountainsnail | Oreohelix strigosa goniogyra | Not Listed | Species of Concern | | ID |
| Snails | Carinate Glenwood Pyrg | Pyrgulopsis inopinata | Not Listed | Resolved Taxon | | |
| Snails | Carinate Mountainsnail | Oreohelix elrodi | Not Listed | Resolved Taxon | | |
| Snails | Carinate pillsnail | Euchemotrema hubrichti | Not Listed | Species of Concern | | IL |
| Flowering Plants | Carite babyboot orchid | Lepanthes caritensis | Not Listed | Status Undefined | | PR |
| Arachnids | Carlow's Cave pseudoscorpion | Aphrastochthonius similis | Not Listed | Species of Concern | | CA |
| Insects | Carlson's polycentropus caddisfly | Polycentropus carlsoni | Not Listed | Species of Concern | | SC |
| Flowering Plants | Carmel Valley bush-mallow | Malacothamnus palmeri involucratus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Carmel Valley malacothrix | Malacothrix saxatilis arachnoidea | Not Listed | Species of Concern | | CA |
| Fishes | Carmine Shiner | Notropis percobromus | | Not Listed | | |
| Insects | Carole's silverspot | Speyeria zerene carolae | Not Listed | Species of Concern | | NV |
| Flowering Plants | Carolina birds-in-a-nest | Macbridea caroliniana | | Not Listed | | GA, SC |
| Flowering Plants | Carolina bishopweed | Ptilimnium ahlesii | Not Listed | Status Undefined | | GA, NC, SC |
| Amphibians | Carolina crawfish frog | Rana areolata capito | Not Listed | Species of Concern | | GA, NC, SC |
| Clams | Carolina creekshell | Villosa vaughaniana | Not Listed | Species of Concern | | |
| Fishes | Carolina Darter | Etheostoma collis | Not Listed | Species of Concern | | |
| Clams | Carolina elktoe | Alasmidonta robusta | Not Listed | Resolved Taxon | | NC |
| Flowering Plants | Carolina goldenrod | Solidago pulchra | Not Listed | Species of Concern | | NC |
| Flowering Plants | Carolina grass-of-parnassus | Parnassia caroliniana | Not Listed | Species of Concern | | |
| Clams | Carolina heelsplitter | Lasmigona decorata | Listed | Endangered | | NC, SC |
| Conifers and Cycads | Carolina hemlock | Tsuga caroliniana | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC, TN, VA |
| Flowering Plants | Carolina lead-plant | Amorpha georgiana confusa | Petitioned for Listing, Under Review | Under Review | | NC |
| Flowering Plants | Carolina Least Trillium | Trillium pusillum var. pusillum | Not Listed | Species of Concern | | AL, KY, MS, NC, SC, TN |
| Fishes | Carolina madtom | Noturus furiosus | Listed | Endangered | | NC |
| Flowering Plants | Carolina mnium | Plagiomnium carolinianum | Not Listed | Species of Concern | | NC |
| Mammals | Carolina northern flying squirrel | Glaucomys sabrinus coloratus | Listed | Endangered | | NC, TN, VA |
| Flowering Plants | Carolina oatgrass | Danthonia epilis | Not Listed | Species of Concern | | |
| Fishes | Carolina pygmy sunfish | Elassoma boehlkei | Not Listed | Status Undefined | | NC, SC |
| Crustaceans | Carolina skistodiaptomus | Skistodiaptomus carolinensis | Not Listed | Species of Concern | | NC |
| Clams | Carolina Slabshell | Elliptio congaraea | | Not Listed | | |
| Sponges | Carolina sponge | Corvomeyenia carolinensis | Not Listed | Species of Concern | | SC |
| Crustaceans | Carolina well diacyclops | Diacyclops jeanneli putei | Not Listed | Species of Concern | | NC |
| Birds | Carribean Brown Pelican | pelecanus occidentalis ssp. occidentalis | Not Listed | Species of Concern | | |
| Mammals | Carrizo Springs Texas pocket gopher | Geomys personatus streckeri | Not Listed | Species of Concern | | TX |
| Crustaceans | Carrollton crayfish | Procambarus connus | Not Listed | Species of Concern | | MS |
| Flowering Plants | Carson Valley monkeyflower | Erythranthe carsonensis | Petitioned for Listing, Under Review | Under Review | | CA, NV |
| Insects | Carson Valley silverspot | Speyeria nokomis carsonensis | Not Listed | Resolved Taxon | | CA, NV |
| Insects | Carson Valley wood nymph | Cercyonis pegala carsonensis | Not Listed | Resolved Taxon | | CA, NV |
| Insects | Carson wandering skipper | Pseudocopaeodes eunus obscurus | Listed | Endangered | | CA, NV |
| Flowering Plants | Carter's mustard | Warea carteri | Listed | Endangered | | FL |
| Insects | Carter's noctuid moth | Spartiniphaga carterae | Not Listed | Species of Concern | | DE, NC, NJ |
| Flowering Plants | Carter's panicgrass | Panicum fauriei var. carteri | Listed | Endangered | | HI |
| Flowering Plants | Carter's small-flowered flax | Linum carteri carteri | Listed | Endangered | | FL |
| Flowering Plants | Cary beardtongue | Penstemon caryi | Not Listed | Species of Concern | | MT, WY |
| Crustaceans | Cascade Cave amphipod | Stygobromus dejectus | Not Listed | Resolved Taxon | | TX |
| Amphibians | Cascade Caverns salamander | Eurycea latitans | Petitioned for Listing, Under Review | Under Review | | TX |
| Flowering Plants | Cascade head catchfly | Silene douglasii oraria | Not Listed | Species of Concern | | CA, NV, OR |
| Mammals | Cascade red fox | Vulpes vulpes cascadensis | Not Listed | Status Undefined | | WA |
| Insects | Cascades apatanian caddisfly | Apatania tavala | Not Listed | Species of Concern | | OR |
| Amphibians | Cascades frog | Rana cascadae | Not Listed | Resolved Taxon | | CA, OR, WA |
| Amphibians | Cascade torrent salamander | Rhyacotriton cascadae | Petitioned for Listing, Under Review | Under Review | | |
| Insects | Casey's June Beetle | Dinacoma caseyi | Listed | Endangered | | CA |
| Birds | Caspian Tern | Hydroprogne caspia | Not Listed | Species of Concern | | |
| Birds | Cassia Crossbill | Loxia sinesciuris | Not Listed | Species of Concern | | |
| Birds | Cassin's Auklet | Ptychoramphus aleuticus | Not Listed | Species of Concern | | |
| Birds | Cassin's Finch | Haemorhous cassinii | Not Listed | Species of Concern | | |
| Birds | Cassin's Sparrow | Peucaea cassinii | Not Listed | Species of Concern | | |
| Insects | Cassius Blue Butterfly | Leptotes cassius theonus | Listed | Similarity of Appearance (Threatened) | | |
| Flowering Plants | Castetter milk-vetch | Astragalus castetteri | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | Castle Crags campanula | Campanula shetleri | Not Listed | Resolved Taxon | | CA |
| Insects | Castle Crags rhyacophilan caddisfly | Rhyacophila lineata | Not Listed | Species of Concern | | CA |
| Insects | Castle Lake rhyacophilan caddisfly | Rhyacophila amabilis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Cataiina beardtongue | Penstemon discolor | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Catalina crossosoma | Crossosoma californicum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Catalina ironwood | Lyonothamnus floribundus floribundus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Catalina Island mountain-mahogany | Cercocarpus traskiae | Listed | Endangered | | CA |
| Flowering Plants | Catalina mariposa lily | calochortus catalinae | Not Listed | Species of Concern | | |
| Snails | Catalina mountainsnail | Radiocentrum avalonense | Not Listed | Species of Concern | | CA |
| Insects | Catalina orange tip butterfly | Anthocharis cethura catalina | Not Listed | Resolved Taxon | | CA |
| Fishes | Catfish | Pangasius sanitwongsei | Listed | Endangered | | |
| Snails | Cathedral snail | Micrarionta indioensis cathedralis | Not Listed | Resolved Taxon | | CA |
| Insects | Catherine's cave beetle | Pseudanophthalmus catherinae | Not Listed | Species of Concern | | TN |
| Reptiles | Cat Island turtle | Trachemys terrapen | Listed | Endangered | | |
| Fishes | Catlow tui chub | Gila bicolor ssp. | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Catlow Valley redband trout | Oncorhynchus mykiss ssp. | Not Listed | Species of Concern | | CA, NV, OR |
| Birds | Cauca guan | Penelope perspicax | Listed | Endangered | | |
| Snails | Cave Creek Woodlandsnail | Ashmunella chiricahuana | Not Listed | Resolved Taxon | | |
| Mammals | Cave myotis | Myotis velifer | Not Listed | Species of Concern | | AZ, CA, NE, NM, NV, TX |
| Crustaceans | Cave Obligate Isopod | Amerigoniscus centralis | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Cave physa | Physella spelunca | Not Listed | Resolved Taxon | | WY |
| Arachnids | Cavern sheet-web spider | Islandiana speophila | Not Listed | Species of Concern | | WV |
| Amphibians | Cave Salamander | Eurycea lucifuga | | Not Listed | | |
| Arachnids | Cave Spring Cave spider | Nesticus jonesi | Not Listed | Species of Concern | | AL |
| Reptiles | Cayman Brac ground iguana | Cyclura nubila caymanensis | Listed | Threatened | | |
| Insects | Cazier's tiger beetle | Cicindela cazieri | Not Listed | Species of Concern | | TX |
| Flowering Plants | Cebello halumtano | Bulbophyllum guamense | Listed | Threatened | | GU, MP |
| Mammals | Cebolleta southern pocket gopher | Thomomys umbrinus paguatae | Not Listed | Species of Concern | | NM |
| Birds | Cebu black shama (thrush) | Copsychus niger cebuensis | Listed | Endangered | | |
| Flowering Plants | Cedar Breaks biscuitroot | Cymopterus minimus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Cedar Crest allocarya | Plagiobothrys glyptocarpus modestus | Not Listed | Species of Concern | | CA |
| Reptiles | Cedar Key mole skink | Plestiodon egregius insularis | Proposed for Listing | Proposed Endangered | | FL |
| Mammals | Cedros Island mule Deer | Odocoileus hemionus cerrosensis | Listed | Endangered | | |
| Flowering Plants | Centerville brazos-mint | Brazoria pulcherrima | Not Listed | Resolved Taxon | | TX |
| Reptiles | Central American river turtle | Dermatemys mawii | Listed | Endangered | | |
| Mammals | Central American tapir | Tapirus bairdii | Listed | Endangered | | |
| Crustaceans | Central Kentucky cave amphipod | Stygobromus exilis | Not Listed | Resolved Taxon | | AL, KY, TN |
| Crustaceans | Central Missouri cave amphipod | Allocrangonyx hubrichti | Not Listed | Species of Concern | | MO |
| Fishes | Central Mudminnow | Umbra limi | | Not Listed | | |
| Fishes | Central Stoneroller | Campostoma anomalum | | Not Listed | | |
| Insects | Central Valley grasshopper | Conozoa hyalina | Not Listed | Resolved Taxon | | |
| Insects | Ceraunus Blue Butterfly | Hemiargus ceraunus antibubastus | Listed | Similarity of Appearance (Threatened) | | |
| Birds | Cerulean Warbler | Setophaga cerulea | Not Listed | Resolved Taxon | | AL, AR, CT, DE, IA, IL, IN, KS, KY, LA, MA, MD, MI, MN, MO, MS, NC, NE, NH, NJ, NY, OH, OK, PA, RI, TN, TX, VA, VT, WI, WV |
| Reptiles | Ceylon mugger crocodile | Crocodylus palustris kimbula | Listed | Endangered | | |
| Mammals | Chadwick Beach cotton mouse | Peromyscus gossypinus restrictus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Chaffey's cory cactus | Coryphantha chaffeyi | Not Listed | Species of Concern | | TX |
| Fishes | Chain Pickerel | Esox niger | | Not Listed | | |
| Snails | Chambered nautilus | Nautilus pompilius | Listed | Threatened | | |
| Amphibians | Chamberlain's Dwarf salamander | Eurycea chamberlaini | Petitioned for Listing, Under Review | Under Review | | SC |
| Fishes | Channel Catfish | Ictalurus punctatus | | Not Listed | | |
| Fishes | Channel Darter | Percina copelandi | | Not Listed | | |
| Snails | Channeled pebblesnail | Somatogyrus wheeleri | Not Listed | Species of Concern | | AR |
| Insects | Channel Islands dune beetle | Coelus pacificus | Not Listed | Species of Concern | | CA |
| Amphibians | Channel Islands slender salamander | Batrachoseps pacificus pacificus | Not Listed | Species of Concern | | CA |
| Mammals | Channel Islands spotted skunk | Spilogale putorius amphiala | Not Listed | Species of Concern | | CA |
| Flowering Plants | Channel Island tree poppy | Dendromecon rigida ssp. harfordii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Chaparral harebell | campanula exigua | Not Listed | Species of Concern | | |
| Flowering Plants | Chapin Mesa milkvetch | Astragalus schmolliae | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Chapman rhododendron | Rhododendron chapmanii | Listed | Endangered | | FL |
| Flowering Plants | Chapman's aster | Symphyotrichum chapmanii | Not Listed | Species of Concern | | |
| Flowering Plants | Chapman's butterwort | Pinguicula planifolia | Not Listed | Species of Concern | | |
| Flowering Plants | Chapman's crownbeard | Verbesina chapmanii | Not Listed | Species of Concern | | |
| Flowering Plants | Chapman's sedge | Carex chapmanii | Not Listed | Species of Concern | | |
| Insects | Charleston Ant | Lasius nevadensis | Not Listed | Status Undefined | | |
| Flowering Plants | Charleston beardtongue | penstemon leiophyllus var. keckii | Not Listed | Species of Concern | | |
| Flowering Plants | Charlotte's phacelia | Phacelia nashiana | Not Listed | Species of Concern | | CA |
| Lichens | Charred volcanoes | Mycoporum biseptatum | Not Listed | Species of Concern | | |
| Birds | Chatham Island oystercatcher | Haematopus chathamensis | Candidate for Listing | Candidate | | |
| Birds | Chatham Island petrel | Pterodroma axillaris | Listed | Endangered | | |
| Birds | Chatham Island pigeon | Hemiphaga novaeseelandiae chathamensis | Listed | Endangered | | |
| Birds | Chatham Island robin | Petroica traversi | Listed | Endangered | | |
| Fishes | Chattahoochee Bass | Micropterus chattahoochae | | Not Listed | | |
| Crustaceans | Chattahoochee Crayfish | Cambarus howardi | | Not Listed | | |
| Crustaceans | Chattooga River crayfish | Cambarus scotti | | Not Listed | | AL, GA |
| Crustaceans | Chauga crayfish | Cambarus chaugaensis | Not Listed | Status Undefined | | GA, NC, SC |
| Insects | Cheaha beloneurian stonefly | Beloneuria jamesae | Not Listed | Species of Concern | | AL |
| Fishes | Cheat minnow | Pararhinichthys bowersi | Not Listed | Species of Concern | | MD, PA, WV |
| Amphibians | Cheat Mountain salamander | Plethodon nettingi | Listed | Threatened | | WV |
| Reptiles | Checkered whiptail | Aspidoscelis tesselatus | Not Listed | Resolved Taxon | | CO |
| Birds | Cheer pheasant | Catreus wallichii | Listed | Endangered | | |
| Insects | Cheese-weed moth lacewing | Oliarces clara | Not Listed | Species of Concern | | AZ, CA |
| Mammals | Cheetah | Acinonyx jubatus | Listed | Endangered | | |
| Snails | Chelan mountainsnail | Oreohelix sp | | Not Listed | | |
| Flowering Plants | Chelan rockmat | Petrophytum cinerascens | Not Listed | Species of Concern | | WA |
| Amphibians | Cheoah Bald salamander | Plethodon cheoah | Not Listed | Resolved Taxon | | NC |
| Insects | Chermock's mulberry wing skipper | Poanes massasoit chermocki | Not Listed | Species of Concern | | MD |
| Insects | Cherokee clubtail | Gomphus consanguis | Petitioned for Listing, Under Review | Under Review | | GA, VA |
| Fishes | Cherokee darter | Etheostoma scotti | Listed | Threatened | | GA |
| Snails | Cherrystone Drop | Hendersonia occulta | | Not Listed | | |
| Birds | Cherry-throated tanager | Nemosia rourei | Listed | Endangered | | |
| Fishes | Chesapeake logperch | Percina bimaculata | Petitioned for Listing, Under Review | Under Review | | DC, MD, PA, VA |
| Birds | Chestnut-backed Chickadee | Poecile rufescens rufescens | Not Listed | Species of Concern | | |
| Insects | Chestnut casebearer moth | Coleophora leucochrysella | Not Listed | Species of Concern | | CT, PA |
| Insects | Chestnut clearwing moth | Synanthedon castaneae | Not Listed | Resolved Taxon | | |
| Birds | Chestnut-collared Longspur | Calcarius ornatus | Not Listed | Species of Concern | | |
| Insects | Chestnut ermine moth | Argyresthia castaneela | Not Listed | Species of Concern | | NH, VT |
| Fishes | Chestnut Lamprey | Ichthyomyzon castaneus | | Not Listed | | |
| Insects | Chestnut leaf miner | Tischeria perplexa | Not Listed | Species of Concern | | VA |
| Flowering Plants | Chickahominy water-hyssop | Bacopa rotundifolia | Not Listed | Resolved Taxon | | VA |
| Crustaceans | Chickamauga crayfish | Cambarus extraneus | Not Listed | Status Undefined | | GA, TN |
| Flowering Plants | Chickweed | Stellaria irrigua | Not Listed | Resolved Taxon | | CO, NM |
| Flowering Plants | chickweed oxytheca | Oxytheca caryophylloides | Not Listed | Species of Concern | | |
| Flowering Plants | Chico Creek rock-cress | Arabis breweri austinae | Not Listed | Resolved Taxon | | CA |
| Fishes | Chihuahua catfish | Ictalurus sp. | Not Listed | Resolved Taxon | | NM, TX |
| Fishes | Chihuahua chub | Gila nigrescens | Listed | Threatened | | NM |
| Birds | Chihuahuan Raven | Corvus cryptoleucus | Not Listed | Species of Concern | | |
| Flowering Plants | Chihuahua scurfpea | Pediomelum pentaphyllum | Not Listed | Resolved Taxon | | AZ, NM |
| Fishes | Chihuahua shiner | Notropis chihuahua | Not Listed | Species of Concern | | TX |
| Conifers and Cycads | Chilean false larch | Fitzroya cupressoides | Listed | Threatened | | |
| Birds | Chilean woodstar | Eulidia yarrellii | Listed | Endangered | | |
| Mammals | Chiltan (=wild goat) markhor | Capra falconeri (=aegragrus) chiltanensis | Listed | Endangered | | |
| Birds | Chimney Swift | Chaetura pelagica | Not Listed | Species of Concern | | |
| Mammals | Chimpanzee | Pan troglodytes | Listed | Endangered | | |
| Reptiles | Chinese alligator | Alligator sinensis | Listed | Endangered | | |
| Flowering Plants | Chinese Camp brodiaea | Brodiaea pallida | Listed | Threatened | | CA |
| Birds | Chinese egret | Egretta eulophotes | Listed | Endangered | | |
| Amphibians | Chinese giant salamander | Andrias davidianus (=davidianus d.) | Listed | Endangered | | |
| Birds | Chinese monal pheasant | Lophophorus lhuysii | Listed | Endangered | | |
| Mammals | Chinese pangolin | Manis pentadactyla | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Chinese River Dolphin | Lipotes vexillifer | Listed | Endangered | | |
| Fishes | Chinese sturgeon | Acipenser sinensis | Listed | Endangered | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Threatened | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Endangered | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Threatened | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Threatened | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Experimental Population, Non-Essential | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Threatened | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Threatened | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Experimental Population, Non-Essential | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Experimental Population, Non-Essential | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Endangered | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Threatened | | |
| Fishes | Chinook salmon | Oncorhynchus (=Salmo) tshawytscha | Listed | Threatened | | |
| Clams | Chipola slabshell | Elliptio chipolaensis | Listed | Threatened | Proposed Delisting | AL, FL |
| Birds | Chipping Sparrow | Spizella passerina | Not Listed | Species of Concern | | |
| Flowering Plants | Chiricahua dock | Rumex orthoneurus | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | Chiricahua fleabane | Erigeron kuschei | Not Listed | Resolved Taxon | | AZ |
| Amphibians | Chiricahua leopard frog | Rana chiricahuensis | Listed | Threatened | | AZ, NM |
| Flowering Plants | Chiricahua mudwort | Limosella pubiflora | Not Listed | Species of Concern | | AZ |
| Mammals | Chiricahua Nayarit squirrel | Sciurus nayaritensis chiricahuae | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Chiricahua rock-daisy | Perityle cochisensis | Not Listed | Resolved Taxon | | AZ |
| Insects | Chiricahua water scavenger beetle | Cymbiodyta arizonica | Not Listed | Species of Concern | | AZ |
| Mammals | Chiricahua western harvest mouse | Reithrodontomys megalotis arizonensis | Not Listed | Species of Concern | | AZ |
| Fishes | Chiselmouth | Acrocheilus alutaceus | | Not Listed | | |
| Flowering Plants | Chisos agave | Agave glomeruliflora | Not Listed | Species of Concern | | TX |
| Snails | Chisos Foxsnail | Pseudosubulina cheatumi | Not Listed | Resolved Taxon | | |
| Insects | chisos metalmark | apodemia chisosensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Chisos Mountain crested coralroot | Bletia revoluta | Petitioned for Listing, Under Review | Under Review | | TX |
| Flowering Plants | Chisos Mountain hedgehog Cactus | Echinocereus chisoensis var. chisoensis | Listed | Threatened | | TX |
| Flowering Plants | Chisos Mountains oak | Quercus tardifolia | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Chisos pinweed | Lechea mensalis | Not Listed | Resolved Taxon | | TX |
| Snails | Chisos Threeband | Humboldtiana chisosensis | Not Listed | Resolved Taxon | | |
| Snails | Chittenango ovate amber snail | Novisuccinea chittenangoensis | Listed | Threatened | | NY |
| Insects | Chlorostictan yellow-faced bee | Hylaeus chlorosticata | Not Listed | Species of Concern | | HI |
| Clams | Choctaw bean | Obovaria choctawensis | Listed | Endangered | | AL, FL |
| Mammals | Choctawhatchee beach mouse | Peromyscus polionotus allophrys | Listed | Endangered | | FL |
| Flowering Plants | Chorro Creek bog thistle | Cirsium fontinale var. obispoense | Listed | Endangered | | CA |
| Snails | Chorro shoulderband snail | Helminthoglypta morroensis | Not Listed | Resolved Taxon | | |
| Crustaceans | Chowanoke crayfish | Faxonius virginiensis | Not Listed | Resolved Taxon | | NC, VA |
| Birds | Christmas Island goshawk | Accipiter fasciatus natalis | Listed | Endangered | | |
| Mammals | Christmas Island Pipistrelle Bat | Pipistrellus murrayi | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Christmas Shearwater | Puffinus nativitatis | Not Listed | Species of Concern | | |
| Flowering Plants | Christ's paintbrush | Castilleja christii | Not Listed | Resolved Taxon | | ID |
| Insects | Chryxus arctic butterfly | Oeneis chryxus valerata | Not Listed | Resolved Taxon | | WA |
| Reptiles | Chuckwalla | Sauromalus ater | Not Listed | Species of Concern | | AZ, CA, NV, UT |
| Birds | Chuck-will's-widow | Antrostomus carolinensis | Not Listed | Species of Concern | | |
| Fishes | Chucky Madtom | Noturus crypticus | Listed | Endangered | | TN |
| Insects | Chukcho stonefly | Haploperla chukcho | Not Listed | Species of Concern | | MS |
| Fishes | Chum salmon | Oncorhynchus keta | Listed | Threatened | | |
| Fishes | Chum salmon | Oncorhynchus keta | Listed | Threatened | | |
| Flowering Plants | Chupacallos | Pleodendron macranthum | Listed | Endangered | | PR |
| Snails | Chupadera springsnail | Pyrgulopsis chupaderae | Listed | Endangered | | NM |
| Flowering Plants | Churchill Narrows buckwheat | Eriogonum diatomaceum | Not Listed | Resolved Taxon | | NV |
| Fishes | Cicek (minnow) | Acanthorutilus handlirschi | Listed | Endangered | | |
| Flowering Plants | Cienega Seca oxytheca | Oxytheca parishii ciengensis | Not Listed | Species of Concern | | CA |
| Insects | Ciervo aegialian scarab | Aegialia concinna | Not Listed | Species of Concern | | CA |
| Flowering Plants | Ciliate-leaf tickseed | Coreopsis integrifolia | Petitioned for Listing, Under Review | Under Review | | GA, SC |
| Flowering Plants | Cima rattleweed | Astragalus cimae cimae | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Cimarron wild-buckwheat | Eriogonum aliquantum | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | Cinder phacelia | Phacelia serrata | Not Listed | Species of Concern | | AZ, NM |
| Snails | Cinnamon juga | Juga canella | Not Listed | Resolved Taxon | | CA, OR |
| Mammals | Cinnamon pika | Ochotona princeps cinnamomea | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Cisco] milkvetch | Astragalus sabulosus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Clackamas iris | Iris tenuis | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Clam-shell orchid | Encyclia cochleata var. triandra | Not Listed | Resolved Taxon | | |
| Crustaceans | Clanton's cave amphipod | Stygobromus clantoni | Not Listed | Species of Concern | | KS, MO |
| Birds | Clapper rail | Rallus longirostris | Not Listed | Species of Concern | | |
| Birds | Clapper Rail | Rallus crepitans | Not Listed | Species of Concern | | |
| Flowering Plants | Clara Hunt's milk-vetch | Astragalus clarianus | Listed | Endangered | | CA |
| Birds | Clarke's weaver | Ploceus golandi | Listed | Endangered | | |
| Flowering Plants | Clark Mountain buckwheat | Eriogonum heermannii floccosum | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Clark Mountains agave | Agave utahensis nevadensis | Not Listed | Resolved Taxon | | CA, NV |
| Snails | Clark Peak talussnail | Sonorella christenseni | Not Listed | Resolved Taxon | | AZ |
| Mammals | Clark's gazelle | Ammodorcas clarkei | Listed | Endangered | | |
| Birds | Clark's Grebe | Aechmophorus clarkii | Not Listed | Species of Concern | | |
| Birds | Clark's Nutcracker | Nucifraga columbiana | Not Listed | Species of Concern | | |
| Insects | Clatsop philocascan caddisfly | Philocasca oron | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Clausen's Violet | Viola clauseniana | Not Listed | Resolved Taxon | | |
| Flowering Plants | Clay bindweed | convolvulus equitans | Not Listed | Species of Concern | | |
| Flowering Plants | Clay blazing-star | Mentzelia argillosa | Not Listed | Species of Concern | | CO, UT |
| Flowering Plants | Clay-Loving wild buckwheat | Eriogonum pelinophilum | Listed | Endangered | | CO |
| Flowering Plants | Clay phacelia | Phacelia argillacea | Listed | Endangered | | UT |
| Flowering Plants | Clay reed-mustard | Schoenocrambe argillacea | Listed | Threatened | | UT |
| Flowering Plants | Clay's hibiscus | Hibiscus clayi | Listed | Endangered | | HI |
| Insects | Clayton's copper | Lycaena dorcas claytoni | Not Listed | Species of Concern | | ME |
| Crustaceans | Clear Creek Amphipod | Hyalella texana | Not Listed | Resolved Taxon | | |
| Flowering Plants | Clear Creek fleabane | Erigeron religiosus | Not Listed | Resolved Taxon | | UT |
| Fishes | Clear Creek gambusia | Gambusia heterochir | Listed | Endangered | | TX |
| Fishes | Clear Lake Hitch | Lavinia exilicauda chi | Proposed for Listing | Proposed Threatened | Proposed Listing | CA |
| Mammals | Clear Lake pocket gopher | Thomomys umbrinus convexus | Not Listed | Species of Concern | | UT |
| Fishes | Clear Lake splittail | Pogonichthys ciscoides | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Clearwater phlox | Phlox idahonis | Not Listed | Species of Concern | | ID |
| Flowering Plants | Cleft, phlox | Phlox bifida stellaria | Not Listed | Species of Concern | | AR, IL, IN, KY, MO, TN |
| Insects | Clemence's fritillary butterfly | Speyeria adiaste clemencei | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Cleveland's bush monkeyflower | Diplacus clevelandii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Cliff bedstraw | Galium correllii | Not Listed | Species of Concern | | TX |
| Flowering Plants | cliff cinquefoil | Potentilla rimicola | Not Listed | Species of Concern | | |
| Flowering Plants | Cliff daisy | Erigeron proselyticus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Cliffdweller's candlestick catseye | Cryptantha elata | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | Cliff milk-vetch | Astragalus cremnophylax myriorrhaphis | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Cliff-palace milk-vetch | Astragalus deterior | Not Listed | Species of Concern | | CO |
| Flowering Plants | Cliff spurge | euphorbia misera | Not Listed | Species of Concern | | CA |
| Insects | Clifton Cave beetle | Pseudanophthalmus caecus | Not Listed | Resolved Taxon | | KY |
| Crustaceans | Clifton Cave isopod | Caecidotea barri | Not Listed | Species of Concern | | KY |
| Snails | Clifton Spring Hydrobe snail | Aphaostracon theiocrenetum | Not Listed | Status Undefined | | |
| Flowering Plants | Climbing dayflower | Commelina gigas | Not Listed | Resolved Taxon | | |
| Fishes | Clinch dace | Chrosomus sp. cf. saylori | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Clingman covert | Mesodon clingmanicus | Not Listed | Species of Concern | | NC, TN |
| Flowering Plants | Clokey greasebush | glossopetalon clokeyi | Not Listed | Species of Concern | | |
| Flowering Plants | Clokey paintbrush | Castilleja applegatei ssp. martinii | Not Listed | Species of Concern | | |
| Flowering Plants | Clokey's egg-vetch | Astragalus oophorus clokeyanus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Clokey's forsellesia | Glossopetalon clokeyi | Not Listed | Species of Concern | | NV |
| Flowering Plants | Clokey's thistle | Cirsium clokeyi | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Closed-lip beardtongue | Penstemon personatus | Not Listed | Species of Concern | | CA |
| Mammals | Clouded leopard | Neofelis nebulosa | Listed | Endangered | | |
| Amphibians | Clouded Salamander | Aneides ferreus | | Not Listed | | |
| Insects | Clouded tailed copper butterfly | Lycaena arota nubila | Not Listed | Resolved Taxon | | CA |
| Birds | Cloven-feathered dove | Drepanoptila holosericea | Listed | Endangered | | |
| Flowering Plants | Clover's cactus | Sclerocactus cloverae | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Clover (Tidestrom''s) lupine | Lupinus tidestromii | Listed | Endangered | | CA |
| Fishes | Clover Valley speckled dace | Rhinichthys osculus oligoporus | Listed | Endangered | | NV |
| Clams | Clubshell | Pleurobema clava | Listed | Endangered | | IL, IN, KY, MI, MS, NY, OH, PA, TN, WV |
| Clams | Clubshell | Pleurobema clava | Listed | Experimental Population, Non-Essential | | AL |
| Flowering Plants | Clustered lady's-slipper | Cypripedium fasciculatum | Not Listed | Species of Concern | | WA |
| Insects | Coachella giant sand treader cricket | Macrobaenetes valgum | Not Listed | Species of Concern | | CA |
| Reptiles | Coachella Valley fringe-toed lizard | Uma inornata | Listed | Threatened | | CA |
| Insects | Coachella Valley jerusalem cricket | Stenopelmatus cahuilaensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Coachella Valley milk-vetch | Astragalus lentiginosus var. coachellae | Listed | Endangered | | CA |
| Fishes | Coal darter | Percina brevicauda | Proposed for Listing | Proposed Threatened | | AL |
| Snails | Coal elimia | Elimia aterina | Not Listed | Species of Concern | | TN |
| Crustaceans | Coal Fields Crayfish | Cambarus theepiensis | | Not Listed | | |
| Flowering Plants | Coaltown sagebrush | Artemisia argilosa | Not Listed | Resolved Taxon | | CO |
| Snails | Coalville mountainsnail | Oreohelix peripherica weberiana | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Coastal bluff bentgrass | Agrostis clivicola clivicola | Not Listed | Resolved Taxon | | CA |
| Birds | Coastal California gnatcatcher | Polioptila californica californica | Listed | Threatened | | CA |
| Fishes | Coastal cutthroat Trout | Oncorhynchus clarkii clarkii | Not Listed | Resolved Taxon | | WA |
| Fishes | Coastal cutthroat Trout | Oncorhynchus clarkii clarkii | Not Listed | Status Undefined | | |
| Fishes | Coastal cutthroat Trout | Oncorhynchus clarkii clarkii | Delisted | Original Data in Error - Taxonomic Revision | Original Data in Error - Taxonomic Revision | CA, NV, OR |
| Flowering Plants | Coastal dunes milk-vetch | Astragalus tener var. titi | Listed | Endangered | | CA |
| Crustaceans | Coastal Flatwoods crayfish | Procambarus apalachicolae | Petitioned for Listing, Under Review | Under Review | | FL |
| Crustaceans | Coastal Lowland Cave crayfish | Procambarus leitheuseri | Petitioned for Listing, Under Review | Under Review | | FL |
| Fishes | Coastal rainbow trout | oncorhynchus mykiss ssp. irideus | Not Listed | Species of Concern | | |
| Fishes | Coastal Roach | Hesperoleucus venustus | | Not Listed | | |
| Reptiles | Coastal rosy boa | Charina trivirgata roseofusca | Not Listed | Species of Concern | | CA |
| Birds | Coastal (WayneÂ’s) Black-throated Green Warbler | Setophaga virens waynei | Not Listed | Species of Concern | | NC, SC, VA |
| Reptiles | Coastal western whiptail | Cnemidophorus tigris multiscutatus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Coast barrel cactus | Ferocactus viridescens | Not Listed | Species of Concern | | CA |
| Flowering Plants | Coast lily | Lilium maritimum | Not Listed | Species of Concern | | CA |
| Reptiles | Coast patch-nosed snake | Salvadora hexalepis virgultea | Not Listed | Species of Concern | | CA |
| Amphibians | Coast range newt | taricha torosa ssp. torosa | Not Listed | Species of Concern | | |
| Fishes | Coastrange Sculpin | Cottus aleuticus | | Not Listed | | |
| Flowering Plants | Coast rock-cress | Arabis blepharophylla | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Coast wallflower | Erysimum ammophilum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Cobana negra | Stahlia monosperma | Listed | Threatened | | PR |
| Snails | Cobble elimia | Elimia vanuxemiana | | Not Listed | | AL |
| Insects | Cobblestone tiger beetle | Cicindela marginipennis | Not Listed | Resolved Taxon | | AL, CT, DE, IN, KY, MA, ME, NH, NJ, NY, OH, PA, RI, VT, WV |
| Flowering Plants | Cobb Mountain lupine | Lupinus sericatus | Not Listed | Resolved Taxon | | CA |
| Fishes | Cobia | Rachycentron canadum | | Not Listed | | |
| Flowering Plants | Cobweb hymenopappus | Hymenopappus filifolius tomentosus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Cochise pincushion cactus | Coryphantha robbinsorum | Listed | Threatened | | AZ, NM |
| Mammals | Cochito | Phocoena sinus | Listed | Endangered | | |
| Snails | Cockerell Holospira | Holospira cockerelli | Not Listed | Resolved Taxon | | |
| Snails | Cockerell's striate disc | Discus shemeki cockerelli | Not Listed | Species of Concern | | AZ, CA, CO, MT, NM, NV, OR, SD, UT, WY |
| Snails | Cockle elimia | Elimia cochliaris | Petitioned for Listing, Under Review | Under Review | | AL |
| Mammals | Coconino Arizona pocket mouse | Perognathus amplus ammodytes | Not Listed | Species of Concern | | AZ |
| Birds | Codfish Island fernbird | Bowdleria punctata wilsoni | Petitioned for Listing, Under Review | Under Review | | |
| Amphibians | Coeur d'Alene salamander | Plethodon idahoensis | Not Listed | Resolved Taxon | | ID, MT |
| Insects | Coffin Cave mold beetle | Batrisodes texanus | Listed | Endangered | | TX |
| Insects | Cognatus eopenthes click beetle | Eopenthes cognatus | Not Listed | Species of Concern | | HI |
| Fishes | Coho salmon | Oncorhynchus (=Salmo) kisutch | Listed | Endangered | | |
| Fishes | Coho salmon | Oncorhynchus (=Salmo) kisutch | Listed | Threatened | | |
| Fishes | Coho salmon | Oncorhynchus (=Salmo) kisutch | Listed | Threatened | | |
| Fishes | Coho salmon | Oncorhynchus (=Salmo) kisutch | Listed | Threatened | | |
| Arachnids | Cokendolpher Cave Harvestman | Texella cokendolpheri | Listed | Endangered | | TX |
| Insects | Cold Spring caddisfly | Lepidostoma ermanae | Not Listed | Species of Concern | | CA |
| Crustaceans | Coldwater crayfish | Faxonius eupunctus | Not Listed | Resolved Taxon | | AR, MO |
| Fishes | Coldwater darter | Etheostoma ditrema | Not Listed | Species of Concern | | AL, GA, TN |
| Snails | Coldwater elimia | Elimia gerhardti | Not Listed | Resolved Taxon | | AL, GA |
| Insects | Coleman Cave beetle | Pseudanophthalmus colemanensis | Petitioned for Listing, Under Review | Under Review | | TN |
| Flowering Plants | Colemans coralroot | Hexalectris colemanii | Not Listed | Resolved Taxon | | AZ |
| Birds | Colima Warbler | Leiothlypis crissalis | Not Listed | Resolved Taxon | | TX |
| Mammals | Colonial pocket gopher | Geomys colonus | Not Listed | Resolved Taxon | | GA |
| Insects | Colorado burrowing mayfly | Ephemera compar | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Colorado Buttercup | Ranunculus coloradensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Colorado Butterfly plant | Gaura neomexicana var. coloradensis | Delisted | Recovery | | CO, NE, WY |
| Clams | Colorado delta clam | Mulinia coloradoensis | Candidate for Listing | Candidate | | |
| Reptiles | Colorado Desert fringed-toed lizard | Uma notata | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Colorado Groundwater Amphipod | Stygobromus coloradensis | Not Listed | Resolved Taxon | | |
| Mammals | Colorado hog-nosed skunk | Conepatus mesoleucus figginsi | Not Listed | Species of Concern | | CO |
| Flowering Plants | Colorado hookless Cactus | Sclerocactus glaucus | Delisted | Recovery | | CO |
| Fishes | Colorado pikeminnow | Ptychocheilus lucius | Listed | Experimental Population, Non-Essential | | |
| Fishes | Colorado pikeminnow | Ptychocheilus lucius | Listed | Endangered | | AZ, CO, NM, UT |
| Mammals | Colorado River cotton rat | Sigmodon arizonae plenus | Not Listed | Species of Concern | | CA |
| Fishes | Colorado River cutthroat trout | Oncorhynchus clarkii pleuriticus | Not Listed | Resolved Taxon | | CO, UT, WY |
| Amphibians | Colorado River toad | bufo alvarius | Not Listed | Species of Concern | | |
| Insects | Colton Sand Dune Jerusalem cricket | Stenopelmatus spp | Not Listed | Resolved Taxon | | |
| Snails | Columbia Duskysnail | Lyogyrus sp | Not Listed | Resolved Taxon | | |
| Insects | Columbia Gorge neothremman caddisfly | Neothremma andersoni | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Columbia milk-vetch | Astragalus columbianus | Not Listed | Species of Concern | | WA |
| Birds | Columbian sharp-tailed grouse | Tympanuchus phasianellus columbianus | Not Listed | Resolved Taxon | | CA, CO, ID, MT, NV, OR, UT, WA, WY |
| Mammals | Columbian white-tailed deer | Odocoileus virginianus leucurus | Delisted | Recovery | | |
| Mammals | Columbian white-tailed deer | Odocoileus virginianus leucurus | Listed | Threatened | | OR, WA |
| Flowering Plants | Columbian whitetop aster | Sericocarpus rigidus | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Snails | Columbia Oregonian | Cryptomastix hendersoni | Not Listed | Resolved Taxon | | OR, WA |
| Snails | Columbia pebblesnail | Fluminicola columbiana | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Fishes | Columbia River Redband | Oncorhynchus mykiss gairdnerii | Not Listed | Resolved Taxon | | |
| Fishes | Columbia River smelt | Thaleichthys pacificus | Not Listed | Resolved Taxon | | |
| Insects | Columbia River tiger beetle | Cicindela columbica | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Amphibians | Columbia spotted frog | Rana luteiventris | Not Listed | Resolved Taxon | | ID, NV, OR |
| Amphibians | Columbia spotted frog | Rana luteiventris | Not Listed | Resolved Taxon | | ID, OR |
| Snails | Columbia springsnail | Pyrgulopsis | Not Listed | Resolved Taxon | | |
| Amphibians | Columbia torrent salamander | Rhyacotriton kezeri | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Columbia yellowcress | Rorippa columbiae | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | Colusa grass | Neostapfia colusana | Listed | Threatened | | CA |
| Amphibians | Comal blind salamander | Eurycea tridentifera | | Not Listed | | TX |
| Clams | comal siltsnail | marstonia comalensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Comal snakewood | Colubrina stricta | Not Listed | Species of Concern | | TX |
| Insects | Comal Springs Diving Beetle | Comaldessus stygius | Not Listed | Resolved Taxon | | |
| Insects | Comal Springs dryopid beetle | Stygoparnus comalensis | Listed | Endangered | | TX |
| Insects | Comal Springs riffle beetle | Heterelmis comalensis | Listed | Endangered | | TX |
| Amphibians | Comal Springs salamander | Eurycea species | | Not Listed | | |
| Amphibians | Comal Springs salamander | Eurycea species | Not Listed | Resolved Taxon | | |
| Amphibians | Comal Springs Salamander | Eurycea sp. | | Not Listed | | |
| Flowering Plants | Comanche layia | Layia leucopappa | Not Listed | Species of Concern | | CA |
| Flowering Plants | Comanche-peak prairie-clover | Dalea reverchonii | Not Listed | Species of Concern | | TX |
| Fishes | Comanche Springs pupfish | Cyprinodon elegans | Listed | Endangered | | TX |
| Flowering Plants | Combleaf | Polyctenium williamsiae | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Comb Wash wild-buckwheat | Eriogonum clavellatum | Not Listed | Resolved Taxon | | CO, UT |
| Insects | Comes yellow-faced bee | Hylaeus communis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Common Arrowhead | Sagittaria latifolia | | Not Listed | | |
| Birds | Common Black-Hawk | Buteogallus anthracinus | Not Listed | Species of Concern | | |
| Reptiles | Common caiman | Caiman crocodilus crocodilus | Listed | Similarity of Appearance (Threatened) | | |
| Flowering Plants | Common eelgrass | Zostera marina | | Not Listed | | |
| Birds | Common Eider | Somateria mollissima | Not Listed | Species of Concern | | |
| Insects | Common eopenthes click beetle | Eopenthes plebeius | Not Listed | Species of Concern | | HI |
| Birds | Common Ground-Dove | Columbina passerina exigua | Not Listed | Species of Concern | | |
| Fishes | Common Guitarfish | Rhinobatos rhinobatos | Listed | Threatened | | |
| Mammals | Common Hippopotamus | Hippopotamus amphibius | | Not Listed | | |
| Birds | Common loon | gavia immer | Not Listed | Species of Concern | | |
| Birds | Common Murre | Uria aalge | Not Listed | Species of Concern | | |
| Birds | Common Nighthawk | Chordeiles minor | Not Listed | Species of Concern | | |
| Birds | Common Poorwill | Phalaenoptilus nuttallii | Not Listed | Species of Concern | | |
| Fishes | Common Shiner | Luxilus cornutus | | Not Listed | | |
| Fishes | Common Snook | Centropomus undecimalis | | Not Listed | | |
| Birds | Common Tern | Sterna hirundo | Not Listed | Species of Concern | | IL, IN, MI, MN, NY, OH, PA, WI |
| Flowering Plants | Common Wallowa paintbrush | Castilleja chrysantha | Not Listed | Resolved Taxon | | CA, NV, OR |
| Birds | Common Yellowthroat | Geothlypis trichas sinuosa | Not Listed | Species of Concern | | CA |
| Flowering Plants | Compact catseye | Cryptantha compacta | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Compact cobweb thistle | Cirsium occidentale compactum | Not Listed | Species of Concern | | CA |
| Snails | Compact elimia | Elimia showalteri | | Not Listed | | AL |
| Insects | Comstock's blue butterfly | Euphilotes battoides comstocki | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Conasauga Blue burrower | Cambarus cymatilis | Not Listed | Status Undefined | | GA, TN |
| Fishes | Conasauga logperch | Percina jenkinsi | Listed | Endangered | | GA, TN |
| Crustaceans | Conchas crayfish | Orconectes deanae | Not Listed | Resolved Taxon | | NM |
| Fishes | Conchos pupfish | Cyprinodon eximius | Not Listed | Species of Concern | | TX |
| Reptiles | Concho water snake | Nerodia paucimaculata | Delisted | Recovery | | TX |
| Insects | Conehead yellow-faced bee | Hylaeus coniceps | Not Listed | Species of Concern | | HI |
| Flowering Plants | Conejo buckwheat | Eriogonum crocatum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Conejo dudleya | Dudleya abramsii ssp. parva | Listed | Threatened | | CA |
| Flowering Plants | Cone Peak bedstraw | Galium californicum luciense | Not Listed | Species of Concern | | CA |
| Insects | Confused helicoverpan noctuid moth | Helicoverpa confusa | Not Listed | Resolved Taxon | | HI |
| Insects | Confusion caddisfly | Cryptochia shasta | Not Listed | Species of Concern | | CA |
| Flowering Plants | Congdon's buckwheat | Eriogonum congdonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Congdon's lewisia | Lewisia congdonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Congdon's lomatium | Lomatium congdonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Congdon's wooly-sunflower | Eriophyllum congdonii | Not Listed | Resolved Taxon | | CA |
| Reptiles | Congo dwarf crocodile | Osteolaemus tetraspis osborni | Listed | Endangered | | |
| Crustaceans | Conhaway Crayfish | Cambarus appalachiensis | | Not Listed | | |
| Insects | Connected yellow-faced bee | Hylaeus connectens | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Connecticut clam shrimp | Eulimnadia stoningtonensis | Not Listed | Species of Concern | | CT |
| Birds | Connecticut Warbler | Oporornis agilis | Not Listed | Species of Concern | | |
| Crustaceans | Conservancy fairy shrimp | Branchinecta conservatio | Listed | Endangered | | CA |
| Flowering Plants | Constance's bittercress | Cardamine constancei | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | Constance's rock-cress | Arabis constancei | Not Listed | Resolved Taxon | | CA |
| Snails | Constricted elimia | Elimia impressa | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | Contact Mine streptanthus | Streptanthus brachiatus brachiatus | Not Listed | Species of Concern | | CA |
| Insects | Contorted ochrotrichian micro caddisfly | Ochrotrichia contorta | Not Listed | Species of Concern | | AR, MO |
| Flowering Plants | Contra Costa buckwheat | Eriogonum truncatum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Contra Costa goldfields | Lasthenia conjugens | Listed | Endangered | | CA |
| Flowering Plants | Contra Costa wallflower | Erysimum capitatum var. angustatum | Listed | Endangered | | CA |
| Insects | Cookes' brown lacewing | Micromus cookeorum | Not Listed | Species of Concern | | HI |
| Snails | Cooke's Peak woodlandsnail | Ashmunella macromphala | Petitioned for Listing, Under Review | Under Review | | NM |
| Flowering Plants | Cooke's phacelia | Phacelia cookei | Not Listed | Species of Concern | | CA |
| Reptiles | Cook's anole | Ctenonotus cooki | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Cook's holly | Ilex cookii | Listed | Endangered | | PR |
| Flowering Plants | Cook's lomatium | Lomatium cookii | Listed | Endangered | | OR |
| Birds | Cook's petrel | Pterodroma cookii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Cooley's meadowrue | Thalictrum cooleyi | Listed | Endangered | | FL, GA, NC |
| Flowering Plants | Cooley's water-willow | Justicia cooleyi | Listed | Endangered | | FL |
| Crustaceans | Cooper's cave amphipod | Stygobromus cooperi | Not Listed | Resolved Taxon | | WV |
| Birds | Cooper's hawk | Accipiter cooperii | Not Listed | Species of Concern | | CA |
| Snails | Cooper's rocky mountainsnail | Oreohelix strigosa cooperi | Not Listed | Resolved Taxon | | SD, WY |
| Clams | Coosa creekshell | Villosa umbrans | Petitioned for Listing, Under Review | Under Review | | AL, GA, TN |
| Clams | Coosa elktoe | Alasmidonta mccordi | Not Listed | Resolved Taxon | | AL |
| Clams | Coosa moccasinshell | Medionidus parvulus | Listed | Endangered | | AL, GA, TN |
| Snails | Coosa pebblesnail | Somatogyrus coosaensis | Not Listed | Species of Concern | | AL |
| Snails | Coosa rocksnail | Leptoxis showalterii | Not Listed | Resolved Taxon | | AL |
| Crustaceans | Coosawattae crayfish | Cambarus coosawattae | Not Listed | Status Undefined | | GA |
| Flowering Plants | Coot Bay dancing-lady | Oncidium carthagenense | Not Listed | Resolved Taxon | | |
| Flowering Plants | Copeland's speedwell | Veronica copelandii | Not Listed | Resolved Taxon | | CA |
| Mammals | Copenhagen Basin pika | Ochotona princeps clamosa | Not Listed | Resolved Taxon | | ID |
| Crustaceans | Copepod | Acanthocyclops columbiensis | Not Listed | Resolved Taxon | | |
| Reptiles | Copperbelly water snake | Nerodia erythrogaster neglecta | Listed | Threatened | | IN, MI, OH |
| Fishes | Coppercheek darter | Etheostoma aquali | Not Listed | Species of Concern | | TN |
| Flowering Plants | Coppermine milk-vetch | Astragalus cobrensis maguirei | Not Listed | Species of Concern | | AZ |
| Insects | Copris tortoise commensal scarab | Copris gopheri | Not Listed | Species of Concern | | |
| Insects | Coral Beach Sand Dune weevil | Trigonoscuta dorothea corallana | Not Listed | Status Undefined | | |
| Insects | Coral Pink Sand Dunes tiger beetle | Cicindela albissima | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | coral seeded popcornflower | Plagiobothrys figuratus ssp. corallicarpus | Not Listed | Species of Concern | | CA, NV, OR |
| Birds | Cordilleran Flycatcher | Empidonax occidentalis | Not Listed | Species of Concern | | |
| Flowering Plants | Corkwood | Leitneria floridana | Not Listed | Species of Concern | | |
| Snails | Corn Creek pyrg | Pyrgulopsis fausta | Not Listed | Resolved Taxon | | NV |
| Reptiles | Coronado skink | Eumeces skiltonianus interparietalis | Not Listed | Species of Concern | | CA |
| Snails | Corpulent hornsnail | Pleurocera corpulenta | Petitioned for Listing, Under Review | Under Review | | AL, TN |
| Snails | Corpulent Rams Horn | Planorbella corpulenta | | Not Listed | | |
| Flowering Plants | Correll's Bluet | Houstonia correllii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Correll''s false dragonhead | Physostegia correllii | Petitioned for Listing, Under Review | Under Review | | LA, TX |
| Flowering Plants | Correll's green pitaya | Echinocereus viridiflorus correllii | Not Listed | Resolved Taxon | | TX |
| Mammals | Corsican red deer | Cervus elaphus corsicanus | Listed | Endangered | | |
| Insects | Corsican swallowtail butterfly | Papilio hospiton | Listed | Endangered | | |
| Flowering Plants | Corymbed, Davidse wild-buckwheat | Eriogonum corymbosum davidsei | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Corymbed, Reveal wild-buckwheat | Eriogonum corymbosum revealianum | Not Listed | Resolved Taxon | | UT |
| Birds | Cory's Shearwater | Calonectris diomedea | Not Listed | Species of Concern | | |
| Flowering Plants | Cossatot leaf-cup | Polymnia cossatotensis | Not Listed | Species of Concern | | AR |
| Flowering Plants | Costa Rican jatropha | Jatropha costaricensis | Listed | Endangered | | |
| Mammals | Costa Rican puma | Puma (=Felis) concolor costaricensis | Listed | Endangered | | |
| Birds | Costa's Hummingbird | Calypte costae | Not Listed | Species of Concern | | |
| Flowering Plants | Cotorrilla | Heliotropium guanicense | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Cottam milk-vetch | Astragalus cottamii | Not Listed | Resolved Taxon | | AZ, NM, UT |
| Fishes | Cottonball Marsh Pupfish | Cyprinodon salinus milleri | | Not Listed | | |
| Flowering Plants | Cotton's milk-vetch | Astragalus cottonii | Not Listed | Species of Concern | | WA |
| Mammals | Cotton-top tamarin | Saguinus oedipus | Listed | Endangered | | |
| Flowering Plants | Cottonwood Spring suncup | Camissonia exilis | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Cottony buckwheat | Eriogonum gossypinum | Not Listed | Resolved Taxon | | CA |
| Amphibians | Couch's spadefoot toad | scaphiopus couchii | Not Listed | Species of Concern | | |
| Mammals | Coues' rice rat | Oryzomys couesi aquaticus | Not Listed | Species of Concern | | TX |
| Flowering Plants | Coulter biscuitroot | Cymopterus coulteri | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Coulter's matilija poppy | romneya coulteri | Not Listed | Species of Concern | | |
| Flowering Plants | Coulter's saltbush | Atriplex coulteri | Not Listed | Species of Concern | | |
| Crustaceans | Cowan'S Amphipod | Stygobromus cowani | | Not Listed | | |
| Fishes | Cow Head tui chub | Siphateles bicolor vaccaceps | Not Listed | Resolved Taxon | | CA |
| Amphibians | Cow Knob salamander | Plethodon punctatus | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | Cow-tongue prickly-pear | Opuntia lindheimeri linguiformis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Cox's dalea | Dalea bartonii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Cox's mariposa lily | Calochortus coxii | Not Listed | Species of Concern | | CA, NV, OR |
| Mammals | coyote | canis latrans | Not Listed | Species of Concern | | AK, AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY |
| Flowering Plants | Coyote ceanothus | Ceanothus ferrisae | Listed | Endangered | | CA |
| Flowering Plants | Coyote-thistle aster | Eurybia eryngiifolia | Not Listed | Species of Concern | | |
| Insects | Crabronoid yellow-faced bee | Hylaeus crabronoides | Not Listed | Species of Concern | | HI |
| Clams | Cracking pearlymussel | Hemistena lata | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Cracking pearlymussel | Hemistena lata | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Cracking pearlymussel | Hemistena lata | Listed | Endangered | | AL, TN, VA |
| Flowering Plants | Craighead's nodding-caps | Triphora craigheadii | Not Listed | Species of Concern | | |
| Flowering Plants | Crater Lake collomia | Collomia mazama | Not Listed | Species of Concern | | OR |
| Ferns and Allies | Crater Lake grap fern | Botrychium pumicola nealleyi | Not Listed | Species of Concern | | CA, OR |
| Snails | Crater Lake tightcoil | Pristiloma arcticum ssp. crateris | Not Listed | Resolved Taxon | | OR |
| Birds | Craveri's Murrelet | Synthliboramphus craveri | Not Listed | Species of Concern | | |
| Crustaceans | Crayfish | Cambarus smilax | | Not Listed | | |
| Flowering Plants | Creamy tick-trefoil | Desmodium ochroleucum | Not Listed | Status Undefined | | NC |
| Fishes | Creek Chub | Semotilus atromaculatus | | Not Listed | | |
| Fishes | Creek Chubsucker | Erimyzon oblongus | | Not Listed | | |
| Fishes | Creek Heelsplitter | Lasmigona compressa | | Not Listed | | |
| Clams | Creeper | Strophitus undulatus | | Not Listed | | |
| Insects | Cremata agrotis noctuid moth | Agrotis cremata | Not Listed | Species of Concern | | HI |
| Flowering Plants | Crenulate lead-plant | Amorpha crenulata | Listed | Endangered | | FL |
| Insects | Crescent Dune aegialian scarab | Aegialia crescenta | Not Listed | Resolved Taxon | | NV |
| Insects | Crescent Dune aphodius scarab | Aphodius sp. | Not Listed | Species of Concern | | NV |
| Insects | Crescent Dunes serican scarab | Serica ammomensico | Not Listed | Resolved Taxon | | NV |
| Mammals | Crescent nail-tailed wallaby | Onychogalea lunata | Listed | Endangered | | |
| Fishes | Crescent Shiner | Luxilus cerasinus | | Not Listed | | |
| Birds | Crested auklet | Aethia cristatella | | Not Listed | | |
| Birds | Crested caracara (Audubon's) [FL DPS] | Caracara plancus audubonii | Listed | Threatened | | FL |
| Crustaceans | Crested Riverlet crayfish | Hobbseus cristatus | Petitioned for Listing, Under Review | Under Review | | MS |
| Insects | Crimson Hawaiian damselfly | Megalagrion leptodemas | Listed | Endangered | | HI |
| Birds | Crimson shining parrot | Prosopeia splendens | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Crisp monardella | Monardella crispa | Not Listed | Species of Concern | | CA |
| Birds | Crissal thrasher | toxostoma crissale | Not Listed | Species of Concern | | |
| Crustaceans | Croatan crayfish | Procambarus plumimanus | Not Listed | Species of Concern | | NC |
| Flowering Plants | Crocker's draba | Draba douglasii crockeri | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Cronquist daisy | Erigeron cronquistii | Not Listed | Species of Concern | | ID, UT |
| Flowering Plants | Cronquist milk-vetch | Astragalus cronquistii | Not Listed | Species of Concern | | CO, UT |
| Flowering Plants | Cronquist's stickseed | Hackelia cronquistii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Cronquist wild-buckwheat | Eriogonum cronquistii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Crosby's buckwheat | Eriogonum crosbyae | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Crossroads cave beetle | Pseudanophthalmus intersectus | | Not Listed | | VA |
| Insects | Crotch bumble bee | Bombus crotchii | | Not Listed | | |
| Fishes | Crown darter | Etheostoma corona | Not Listed | Species of Concern | | AL, TN |
| Flowering Plants | Crowned muilla | Muilla coronata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Cruise's golden aster | Chrysopsis gossypina cruiseana | Not Listed | Species of Concern | | |
| Arachnids | Crystal Caverns cave spider | Nesticus furtivus | Not Listed | Species of Concern | | TN |
| Fishes | Crystal darter | Crystallaria asprella | Not Listed | Resolved Taxon | | |
| Snails | Crystal siltsnail | Cincinnatia helicogyra | Not Listed | Species of Concern | | |
| Snails | Crystal springsnail | Pyrgulopsis crystalis | Not Listed | Resolved Taxon | | NV |
| Reptiles | Cuatro Cienegas softshell turtle | Trionyx ater | Listed | Endangered | | |
| Birds | Cuba hook-billed kite | Chondrohierax uncinatus wilsonii | Listed | Endangered | | |
| Reptiles | Cuban crocodile | Crocodylus rhombifer | Listed | Endangered | | |
| Mammals | Cuban Greater Funnel-Eared Bat | Natalus primus | Petitioned for Listing, Under Review | Under Review | | |
| Reptiles | Cuban ground iguana | Cyclura nubila nubila | Listed | Threatened | | |
| Mammals | Cuban solenodon | Solenodon cubanus | Listed | Endangered | | |
| Birds | Cuba sandhill crane | Grus canadensis nesiotes | Listed | Endangered | | |
| Insects | Cudjo's cave beetle | Pseudanophthalmus hirsutus | | Not Listed | | VA |
| Flowering Plants | Cuero de sapo | Maytenus elongata | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Cuero de sapo | Maytenus ponceana | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Cuesta Pass sidalcea | Sidalcea hickmanii anomala | Not Listed | Species of Concern | | CA |
| Fishes | Cui-ui | Chasmistes cujus | Listed | Endangered | | CA, NV |
| Flowering Plants | Culbertson's paintbrush | Castilleja lemmonii | Not Listed | Resolved Taxon | | CA |
| Reptiles | Culebra garden snake | Arrhyton exiguum exiguum | Not Listed | Species of Concern | | PR, VI |
| Reptiles | Culebra Island giant anole | Anolis roosevelti | Listed | Endangered | | PR |
| Reptiles | Culebra Skink | Spondylurus culebrae | Proposed for Listing | Proposed Threatened | | PR, VI |
| Crustaceans | Culver's cave amphipod | Stygobromus culveri | Not Listed | Species of Concern | | WV |
| Flatworms and Roundworms | Culver's planarian | Sphalloplana culveri | Not Listed | Species of Concern | | WV |
| Fishes | Cumberland arrow darter | Etheostoma sagitta | Not Listed | Resolved Taxon | | KY, TN, VA |
| Clams | Cumberland bean (pearlymussel) | Villosa trabalis | Listed | Endangered | | KY, TN |
| Clams | Cumberland bean (pearlymussel) | Villosa trabalis | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Cumberland bean (pearlymussel) | Villosa trabalis | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Cumberland darter | Etheostoma susanae | Listed | Endangered | | KY, TN |
| Amphibians | Cumberland Dusky salamander | Desmognathus abditus | Petitioned for Listing, Under Review | Under Review | | TN |
| Clams | Cumberland elktoe | Alasmidonta atropurpurea | Listed | Endangered | | KY, TN |
| Clams | Cumberlandian combshell | Epioblasma brevidens | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Cumberlandian combshell | Epioblasma brevidens | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Cumberlandian combshell | Epioblasma brevidens | Listed | Endangered | | AL, KY, MS, TN, VA |
| Clams | Cumberland leafshell | Epioblasma stewardsonii | Not Listed | Resolved Taxon | | AL, TN |
| Clams | Cumberland moccasinshell | Medionidus conradicus | Proposed for Listing | Proposed Endangered | | AL, GA, KY, MS, NC, TN, VA |
| Clams | Cumberland monkeyface (pearlymussel) | Theliderma intermedia | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Cumberland monkeyface (pearlymussel) | Theliderma intermedia | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Cumberland monkeyface (pearlymussel) | Theliderma intermedia | Listed | Endangered | | KY, TN, VA |
| Clams | Cumberland papershell | Anodontoides denigrata | Not Listed | Species of Concern | | KY, TN |
| Clams | Cumberland pigtoe | Pleuronaia gibber | Listed | Endangered | | TN |
| Mammals | Cumberland pocket gopher | Geomys cumberlandius | Not Listed | Species of Concern | | GA |
| Flowering Plants | Cumberland rosemary | Conradina verticillata | Listed | Threatened | | KY, TN |
| Flowering Plants | Cumberland sandreed | Calamovilfa arcuata | Not Listed | Status Undefined | | AR, OK, TN |
| Flowering Plants | Cumberland sandwort | Arenaria cumberlandensis | Delisted | Recovery | | KY, TN |
| Flowering Plants | Cuneate bidens | Bidens cuneata | Delisted | Original Data in Error - Taxonomic Revision | | HI |
| Flowering Plants | Cup Lake draba | Draba asterophora macrocarpa | Not Listed | Species of Concern | | CA |
| Ferns and Allies | Curly-grass fern | Actinostachys pennula | Not Listed | Resolved Taxon | | |
| Ferns and Allies | Curly-grass fern | Schizaea pusilla | Not Listed | Resolved Taxon | | DE, NJ, NY |
| Crustaceans | Curro's Amphipod | Stygobromus curroae | Not Listed | Resolved Taxon | | |
| Clams | Curtis Pearlymussel | Epioblasma curtisii | Listed | Endangered | | AR, MO |
| Flowering Plants | Curtiss' loosestrife | Lythrum curtissii | Petitioned for Listing, Under Review | Under Review | | GA |
| Birds | Curve-billed Thrasher | Toxostoma curvirostre | Not Listed | Species of Concern | | |
| Insects | Curved-foot hygrotus diving beetle | Hygrotus curvipes | Not Listed | Species of Concern | | CA |
| Flowering Plants | Curve-podded Mojave milk-vetch | Astragalus mohavensis hemigyrus | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Cushenbury buckwheat | Eriogonum ovalifolium var. vineum | Listed | Endangered | | CA |
| Flowering Plants | Cushenbury milk-vetch | Astragalus albens | Listed | Endangered | | CA |
| Flowering Plants | Cushenbury oxytheca | Oxytheca parishii var. goodmaniana | Listed | Endangered | | CA |
| Flowering Plants | Cushion Bladderpod | Physaria pulvinata | Not Listed | Resolved Taxon | | |
| Flowering Plants | Cusick's buckwheat | Eriogonum cusickii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Cusick's lupine | Lupinus cusickii | Not Listed | Species of Concern | | WA |
| Flowering Plants | Cuthbert's turtlehead | chelone cuthbertii | Not Listed | Species of Concern | | |
| Flowering Plants | Cutler milkweed | Asclepias cutleri | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Cutler's spurred lupine | Lupinus caudatus ssp. cutleri | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Cutler's twistflower | Streptanthus cutleri | Not Listed | Species of Concern | | TX |
| Flowering Plants | Cutthroat grass | Panicum abscissum | Not Listed | Species of Concern | | |
| Conifers and Cycads | Cuyamaca cypress | Callitropsis stephensonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Cuyamaca gumplant | Grindelia hirsutula | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Cuyamaca larkspur | Delphinium hesperium cuyamacae | Not Listed | Species of Concern | | CA |
| Flowering Plants | Cuyamaca raspberry | Rubus glaucifolius ganderi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Cuyamac Lake downingia | Downingia concolor brevior | Not Listed | Resolved Taxon | | CA |
| Snails | Cylinder elimia | Elimia cylindracea | Not Listed | Status Undefined | | AL, MS |
| Flowering Plants | Cylinder spikerush | Eleocharis cylindrica | Not Listed | Resolved Taxon | | TX |
| Snails | Cylindrical lioplax (snail) | Lioplax cyclostomaformis | Listed | Endangered | | AL |
| Clams | Cylindrical Papershell | Anodontoides ferussacianus | | Not Listed | | |
| Snails | Cylindrical Vertigo | Vertigo binneyana | Not Listed | Resolved Taxon | | |
| Crustaceans | Cypress crayfish | Cambarellus blacki | Petitioned for Listing, Under Review | Under Review | | FL |
| Fishes | Cypress Darter | Etheostoma proeliare | | Not Listed | | |
| Fishes | Cypress Minnow | Hybognathus hayi | | Not Listed | | |
| Flowering Plants | Dacite manzanita | Arctostaphylos tomentosa daciticola | Not Listed | Species of Concern | | CA |
| Insects | Daecke's pyralid moth | Crambus daeckeellus | Not Listed | Species of Concern | | DE, NJ |
| Algae | Daggernose Shark | Isogomphodon oxyrhynchus | Listed | Endangered | | |
| Flowering Plants | Daggett, rock-cress | Arabis demissa languida | Not Listed | Resolved Taxon | | UT, WY |
| Flowering Plants | Daggett, rock-cress | Arabis demissa russeola | Not Listed | Resolved Taxon | | CO, UT, WY |
| Insects | Dakota Skipper | Hesperia dacotae | Listed | Threatened | | MN, ND, SD |
| Snails | Dalles sideband | Monadenia fidelis minor | Not Listed | Resolved Taxon | | OR, WA |
| Mammals | Dama gazelle | Gazella dama | Listed | Endangered | | |
| Birds | Dappled mountain robin | Arcanator orostruthus | Listed | Threatened | | |
| Insects | Dark blue | Euphilotes enoptes ssp. | Not Listed | Species of Concern | | NV |
| Clams | Dark pigtoe | Pleurobema furvum | Listed | Endangered | | AL |
| Amphibians | Dark-sided salamander | Eurycea aquatica | Not Listed | Species of Concern | | AL, TN |
| Insects | Darkwing yellow-faced bee | Hylaeus fuscipennis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Darlington's spurge | Euphorbia purpurea | Not Listed | Species of Concern | | NC |
| Flowering Plants | Darrov's wild-buckwheat | Eriogonum darrovii | Not Listed | Resolved Taxon | | AZ, NV |
| Flowering Plants | Davidson's bush-mallow | Malacothamnus davidsonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Davidson's saltscale | atriplex serenana var. davidsonii | Not Listed | Species of Concern | | |
| Flowering Plants | Davidson's stonecrop | Sedum niveum | Not Listed | Resolved Taxon | | CA |
| Snails | Davis County springsnail | Fontelicella davisi | Not Listed | Species of Concern | | TX |
| Flowering Plants | Davis' green pitaya | Echinocereus viridiflorus var. davisii | Listed | Endangered | | TX |
| Mammals | Davis Mountains cottontail rabbit | Sylvilagus floridanus robustus | Not Listed | Species of Concern | | TX |
| Flowering Plants | Davis' pepper cress | Lepidium davisii | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Flowering Plants | Davis' stickseed | Hackelia davisii | Not Listed | Resolved Taxon | | ID |
| Reptiles | Day gecko | Phelsuma edwardnewtoni | Listed | Endangered | | |
| Flowering Plants | Day Valley desert-parsley | Lomatium minus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Deane's milk-vetch | Astragalus deanei | Not Listed | Species of Concern | | CA |
| Crustaceans | Dearolf's cave amphipod | Crangonyx dearolfi | Not Listed | Species of Concern | | MD, PA |
| Insects | Death eopenthes click beetle | Eopenthes funebris | Not Listed | Species of Concern | | HI |
| Insects | Death Valley agabus diving beetle | Agabus rumppi | Not Listed | Resolved Taxon | | CA, NV |
| Crustaceans | Death Valley Amphipod | Hyalella sandra | | Not Listed | | |
| Insects | Death Valley june beetle | Polyphylla erratica | Not Listed | Species of Concern | | CA |
| Flowering Plants | Death Valley monkeyflower | Mimulus rupicola | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Death Valley sage | Salvia funerea | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Death Valley sandpaperplant | Petalonyx thurberi gilmanii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Debeque milk-vetch | Astragalus debequaeus | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | DeBeque phacelia | Phacelia submutica | Listed | Threatened | | CO |
| Flowering Plants | Debris milk-vetch | Astragalus detritalis | Not Listed | Resolved Taxon | | CO, UT |
| Insects | Deceptive cave beetle | Pseudanophthalmus deceptivus | Not Listed | Species of Concern | | VA |
| Insects | Deceptive eopenthes click beetle | Eopenthes deceptor | Not Listed | Species of Concern | | HI |
| Insects | Decodon borer moth | Papaipema sulphurata | Not Listed | Species of Concern | | MA |
| Flowering Plants | Decurrent false aster | Boltonia decurrens | Listed | Threatened | | IL, MO |
| Flowering Plants | DeDecker's clover | Trifolium dedeckerae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | DeDecker's lupine | Lupinus padre-crowleyi | Not Listed | Species of Concern | | CA |
| Insects | Deep Burrowing Mayfly | Hexagenia bilineata | | Not Listed | | |
| Fishes | Deepwater cisco | Coregonus johannae | Not Listed | Resolved Taxon | | IL, IN, MI, MN, WI |
| Fishes | Deepwater Sculpin | Myoxocephalus thompsonii | | Not Listed | | |
| Clams | Deertoe | Truncilla truncata | | Not Listed | | |
| Flowering Plants | Degener beardtongue | Penstemon degeneri | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Dehesa beargrass | Nolina interrata | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Delaware County Cave Crayfish | Cambarus subterraneus | Petitioned for Listing, Under Review | Under Review | | |
| Insects | Delhi Sands flower-loving fly | Rhaphiomidas terminatus abdominalis | Listed | Endangered | | CA |
| Clams | Delicate spike | Elliptio arctata | Petitioned for Listing, Under Review | Under Review | | GA |
| Snails | Delicate Vertigo | Vertigo bollesiana | | Not Listed | | |
| Flowering Plants | Del Mar manzanita | Arctostaphylos glandulosa ssp. crassifolia | Listed | Endangered | | CA |
| Flowering Plants | Del Mar sand aster | Corethrogyne filaginifolia linifolia | Not Listed | Resolved Taxon | | CA |
| Mammals | Delmarva Peninsula fox squirrel | Sciurus niger cinereus | Delisted | Recovery | | DE, MD, VA |
| Mammals | Delmarva Peninsula fox squirrel | Sciurus niger cinereus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Del Norte checkermallow | Sidalcea malviflora elegans | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Del Norte fleabane | Erigeron cervinus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Del Norte manzanita | Arctostaphylos nortensis | Not Listed | Species of Concern | | CA |
| Amphibians | Del Norte salamander | Plethodon elongatus | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Delong's mixogaster flower fly | Mixogaster delongi | Not Listed | Species of Concern | | |
| Flowering Plants | Delta coyote-thistle | Eryngium racemosum | Not Listed | Species of Concern | | CA |
| Insects | Delta green ground beetle | Elaphrus viridis | Listed | Threatened | | CA |
| Snails | Delta Hydrobe | Probythinella emarginata | | Not Listed | | |
| Insects | Delta june beetle | Polyphylla stellata | Not Listed | Species of Concern | | CA |
| Fishes | Delta smelt | Hypomesus transpacificus | Listed | Threatened | | CA |
| Flowering Plants | Delta tule-pea | Lathyrus jepsonii jepsonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Deltoid spurge | Chamaesyce deltoidea ssp. deltoidea | Listed | Endangered | | FL |
| Insects | Denning's agapetus caddisfly | Agapetus denningi | Not Listed | Species of Concern | | OR |
| Insects | Denning's cryptic caddisfly | Cryptochia denningi | Not Listed | Species of Concern | | CA |
| Snails | Dense hydrobe | Aphaostracon pycnum | Not Listed | Status Undefined | | |
| Flowering Plants | Dense reedgrass | Calamagrostis koelerioides | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Dense twinpod | Physaria condensata | Not Listed | Resolved Taxon | | WY |
| Snails | Dented Peninsula snail | Helminthoglypta arrosa miwoka | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Depauperate daisy | Erigeron mancus | Not Listed | Species of Concern | | UT |
| Flowering Plants | Descanso milk-vetch | Astragalus oocarpus | Not Listed | Species of Concern | | CA |
| Insects | Deschutes ochrotrichian micro caddisfly | Ochrotrichia phenosa | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Deseret milkvetch | Astragalus desereticus | Delisted | Recovery | | UT |
| Mammals | Desert bandicoot | Perameles eremiana | Listed | Endangered | | |
| Flowering Plants | Desert beauty | Linanthus bellus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Desert birds-beak | Cordylanthus eremicus eremicus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Desert christmas tree | Pholisma arenarium | Not Listed | Resolved Taxon | | AZ, CA |
| Flowering Plants | Desert cymopterus | Cymopterus deserticola | Not Listed | Resolved Taxon | | CA |
| Fishes | Desert dace | Eremichthys acros | Listed | Threatened | | NV |
| Reptiles | Desert iguana | dipsosaurus dorsalis | Not Listed | Species of Concern | | |
| Reptiles | Desert king snake | Lampropeltis getula splendida | Not Listed | Resolved Taxon | | AZ, NM, OK, TX |
| Reptiles | Desert massasauga | Sistrurus catenatus ssp. edwardsii | | Not Listed | | CO |
| Reptiles | Desert monitor | Varanus griseus | Listed | Endangered | | |
| Insects | Desert monkey grasshopper | Psychomastix deserticola | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Desert night-blooming cereus | Peniocereus greggii greggii | Not Listed | Species of Concern | | NM, TX |
| Mammals | Desert (=plain) rat-kangaroo | Caloprymnus campestris | Listed | Endangered | | |
| Mammals | Desert pocket gopher | Geomys bursarius arenarius | Not Listed | Species of Concern | | NM, TX |
| Fishes | Desert pupfish | Cyprinodon macularius | Listed | Endangered | | AZ, CA, NM, NV |
| Flowering Plants | Desert sage | Salvia eremostachya | Not Listed | Resolved Taxon | | CA |
| Amphibians | Desert slender salamander | Batrachoseps aridus | Listed | Endangered | | CA |
| Snails | Desert springsnail snail | Pyrgulopsis deserta | Not Listed | Resolved Taxon | | AZ, UT |
| Fishes | Desert sucker | Pantosteus clarkii | Not Listed | Species of Concern | | AZ, NM, NV, UT |
| Flowering Plants | Desert tansyaster | Arida arizonica | Not Listed | Resolved Taxon | | CA, NV |
| Reptiles | Desert tortoise | Gopherus agassizii | Listed | Threatened | | AZ, CA, NV, UT |
| Reptiles | Desert tortoise | Gopherus agassizii | Listed | Similarity of Appearance (Threatened) | | AZ |
| Mammals | Desert Valley kangaroo mouse | Microdipodops megacephalus albiventer | Not Listed | Species of Concern | | NV |
| Flowering Plants | Desert wild-buckwheat | Eriogonum deserticola | Not Listed | Resolved Taxon | | AZ, CA |
| Flowering Plants | Desert yellowhead | Yermo xanthocephalus | Listed | Threatened | | WY |
| Mammals | Desmarest's fig-eating bat | Stenoderma rufum | Not Listed | Species of Concern | | PR, VI |
| Mammals | Destruction Island shrew | Sorex trowbridgii destructioni | Not Listed | Species of Concern | | WA |
| Fishes | Devils Hole pupfish | Cyprinodon diabolis | Listed | Endangered | | CA, NV |
| Insects | Devil's Hole warm spring riffle beetle | Stenelmis calida calida | Not Listed | Resolved Taxon | | NV |
| Fishes | Devils River minnow | Dionda diaboli | Listed | Threatened | | TX |
| Crustaceans | Devil's Sinkhole amphipod | Stygobromus hadenoecus | Not Listed | Resolved Taxon | | TX |
| Snails | devil tryonia | Tryonia diaboli | Not Listed | Resolved Taxon | | |
| Mammals | Dhole | Cuon alpinus | Listed | Endangered | | |
| Snails | Diablo Mountainsnail | Oreohelix houghi | Not Listed | Resolved Taxon | | |
| Flowering Plants | Diablo rock-rose | Helianthella castanea | Not Listed | Species of Concern | | CA |
| Reptiles | Diamondback terrapin | Malaclemys terrapin | Not Listed | Status Undefined | | AL, CT, DE, FL, GA, LA, MA, MD, MS, NC, NJ, NY, RI, SC, TX, VA |
| Fishes | diamond Darter | Crystallaria cincotta | Listed | Endangered | | WV |
| Insects | Diamond Head nesosydne planthopper | Nesosydne leahi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Diamond Head schiedea | Schiedea adamantis | Listed | Endangered | | HI |
| Flowering Plants | Diamond Lake mission-bells | Fritillaria atropurpurea | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Diamond-petaled poppy | Eschscholzia rhombipetala | Not Listed | Species of Concern | | CA |
| Snails | Diamond Tryonia | Pseudotryonia adamantina | Listed | Endangered | | TX |
| Fishes | Diamond Valley speckled dace | Rhinichthys osculus ssp. | Not Listed | Species of Concern | | NV |
| Flowering Plants | Diamond Valley suncup | Camissonia gouldii | Not Listed | Resolved Taxon | | AZ, UT |
| Snails | Diamond-Y pond snail | Physella bottimeri | Not Listed | Resolved Taxon | | TX |
| Insects | Diana fritillary | Speyeria diana | Not Listed | Species of Concern | | AR, GA, IL, IN, LA, MD, MO, MS, NC, OH, PA, SC, TN, VA, WV |
| Mammals | Diana monkey | Cercopithecus diana | Listed | Endangered | | |
| Mammals | Dibbler | Antechinus apicalis | Listed | Endangered | | |
| Birds | Dickcissel | Spiza americana | Not Listed | Species of Concern | | |
| Lichens | Dicranoweisia moss | dicranoweisia crispula | Not Listed | Species of Concern | | |
| Insects | Difficult yellow-faced bee | Hylaeus difficilis | Not Listed | Species of Concern | | HI |
| Insects | Dimidiatan yellow-faced bee | Hylaeus dimidiatus | Not Listed | Species of Concern | | HI |
| Snails | Diminuitive Pebblesnail | Fluminicola sp | Not Listed | Resolved Taxon | | OR |
| Crustaceans | Diminutive Amphipod | Gammarus hyalleloides | Listed | Endangered | | TX |
| Flowering Plants | Dimmit sunflower | Helianthus praecox hirtus | Not Listed | Species of Concern | | TX |
| Flowering Plants | Dimorphic snapdragon | Sairocarpus subcordatus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Dinosaur milk-vetch | Astragalus saurinus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Dinosaur wild-buckwheat | Eriogonum lonchophyllum saurinum | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | disciplina | lycopodium phlegmaria var. | Not Listed | Species of Concern | | |
| Insects | Disjunct crawling water beetle | Haliplus nitens | Not Listed | Species of Concern | | TX |
| Insects | Dismal Swamp chlorochroan bug | Chlorochroa dismalia | Not Listed | Species of Concern | | VA |
| Mammals | Dismal Swamp short-tailed shrew | Blarina brevicauda telmalestes | Not Listed | Resolved Taxon | | NC, VA |
| Mammals | Dismal Swamp southeastern shrew | Sorex longirostris fisheri | Delisted | Original Data in Error - New Information Discovered | | NC, VA |
| Mammals | Dismal Swamp (=southern bog) lemming | Synaptomys cooperi helaletes | Not Listed | Resolved Taxon | | NC, VA |
| Snails | Distal-gland springsnail | Pyrgulopsis nanus | Not Listed | Resolved Taxon | | NV |
| Insects | Diverse isonychian mayfly | Isonychia diversa | Not Listed | Resolved Taxon | | TN |
| Amphibians | Dixie Caverns salamander | Plethodon dixi | Not Listed | Status Undefined | | |
| Amphibians | Dixie Valley Toad | Anaxyrus williamsi | Listed | Endangered | | NV |
| Fishes | Dixie Valley tui chub | Siphateles bicolor ssp. 9 | Not Listed | Species of Concern | | NV |
| Birds | Djibouti francolin | Francolinus ochropectus | Listed | Endangered | | |
| Flowering Plants | Dog Valley ivesia | Ivesia aperta canina | Not Listed | Species of Concern | | CA |
| Insects | Dohrn's elegant eucnemid beetle | Paleoxenus dohrni | Not Listed | Species of Concern | | CA |
| Amphibians | dolan falls salamander | eurycea species | Not Listed | Resolved Taxon | | |
| Amphibians | Dolan Falls salamander | eurycea speciesten | Not Listed | Resolved Taxon | | |
| Flowering Plants | Dollar orchid | Encyclia boothiana erythronioides | Not Listed | Resolved Taxon | | |
| Arachnids | Dolloff Cave spider | Meta dollof | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Doll's daisy | Boltonia montana | Not Listed | Resolved Taxon | | DE, NJ, PA, VA |
| Insects | Doll's merolonche | Merolonche dolli | Not Listed | Species of Concern | | DE, MI, MN, NJ, NY, PA |
| Fishes | Dolly Varden | Salvelinus malma | Proposed for Listing | Proposed Similarity of Appearance (Threatened) | | WA |
| Flowering Plants | Dolomite draba | Draba crassifolia nevadensis | Not Listed | Species of Concern | | NV |
| Flowering Plants | Dolores desert pink | Lygodesmia doloresensis | Not Listed | Resolved Taxon | | CO, UT |
| Mammals | Dolphin and Union caribou | Rangifer tarandus ssp. groenlandicus x pearyi | Listed | Endangered | | |
| Mammals | Dolphin Island kangaroo rat | Dipodomys microps russeolus | Not Listed | Species of Concern | | UT |
| Mammals | Dolphin Island ord's kangaroo rat | Dipodomys ordii cineraceus | Not Listed | Species of Concern | | UT |
| Snails | Domed ancylid | Rhodacme elatior | Petitioned for Listing, Under Review | Under Review | | AL |
| Snails | Dona Ana talussnail | Sonorella todseni | Petitioned for Listing, Under Review | Under Review | | NM |
| Flowering Plants | Donner Pass buckwheat | Eriogonum umbellatum torreyanum | Not Listed | Species of Concern | | CA |
| Snails | Donner und Blitzen pebblesnail | Fluminicola insolitus | | Not Listed | | OR |
| Insects | Dorothy's El Segundo Dune weevil | Trigonoscuta dorothea dorothea | Not Listed | Species of Concern | | CA |
| Flowering Plants | Dorr's Cabin jewelflower | Streptanthus morrisonii hirtiflorus | Not Listed | Species of Concern | | CA |
| Birds | Double-crested Cormorant | phalacrocorax auritus | Not Listed | Species of Concern | | |
| Snails | Doubtful Canyon Talussnail | Sonorella waltoni | Not Listed | Resolved Taxon | | |
| Mammals | Douc langur | Pygathrix nemaeus | Listed | Endangered | | |
| Insects | Doudoroff's elfin butterfly | Incisalia mossi windi | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Dougherty Plain Cave crayfish | Cambarus cryptodytes | Not Listed | Status Undefined | | GA |
| Mammals | Douglas County pocket gopher | Thomomys talpoides macrotis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Douglas' draba | Draba douglasii douglasii | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Insects | Douglas stenelmis riffle beetle | Stenelmis douglasensis | Not Listed | Species of Concern | | IN, MI, WI |
| Birds | Dovekie | Alle alle | Not Listed | Resolved Taxon | | |
| Birds | Downy woodpecker | picoides pubescens | Not Listed | Species of Concern | | |
| Insects | Doyen's trigonoscuta dune weevil | Trigonoscuta sp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Drab phacelia | Phacelia indecora | Not Listed | Resolved Taxon | | UT |
| Snails | Dragoon Talussnail | Sonorella ferrissi | Not Listed | Resolved Taxon | | |
| Mammals | Drill | Mandrillus (=Papio) leucophaeus | Listed | Endangered | | |
| Clams | Dromedary pearlymussel | Dromus dromas | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Dromedary pearlymussel | Dromus dromas | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Dromedary pearlymussel | Dromus dromas | Listed | Endangered | | KY, TN, VA |
| Flowering Plants | Drummond bluebell | Mertensia drummondii | Not Listed | Species of Concern | | AK |
| Snails | Drummond mountainsnail | Oreohelix spfour | Not Listed | Resolved Taxon | | |
| Snails | Drummond mountain snail | Oreohelix speciesfour | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Drummond's yellow-eyed grass | Xyris drummondii | Not Listed | Species of Concern | | |
| Insects | Dry Creek cliff strider bug | Oravelia pege | Not Listed | Species of Concern | | CA |
| Insects | Dry Fork Valley cave beetle | Pseudanophthalmus montanus | Not Listed | Resolved Taxon | | WV |
| Arachnids | Dry Fork Valley cave pseudoscorpion | Apochthonius paucispinosus | Not Listed | Species of Concern | | WV |
| Flowering Plants | Drymaria dwarf-flax | Hesperolinon drymarioides | Not Listed | Species of Concern | | CA |
| Flowering Plants | Dubakella Mountain buckwheat | Eriogonum libertini | Not Listed | Resolved Taxon | | CA |
| Insects | Dubiraphian riffle beetle | Dubiraphia sp. | Not Listed | Resolved Taxon | | ME |
| Flowering Plants | Duchesne biscuitroot | Cymopterus duchesnensis | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | Duchesne milk-vetch | Astragalus duchesnensis | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | Duchesne River Twinpod | Physaria stylosa | Not Listed | Resolved Taxon | | |
| Flowering Plants | Duck River bladder-pod | Lesquerella densipila | Not Listed | Resolved Taxon | | AL, TN |
| Insects | Duck River cave beetle | Pseudanophthalmus tullahoma | Not Listed | Resolved Taxon | | TN |
| Clams | Duck River Dartersnapper | Epioblasma ahlstedti | | Not Listed | | |
| Amphibians | Duckwater frog | Rana | Not Listed | Resolved Taxon | | NV |
| Snails | Duckwater pyrg | Pyrgulopsis aloba | Not Listed | Resolved Taxon | | NV |
| Snails | Duckwater Warm Springs pyrg | Pyrgulopsis villacampae | Not Listed | Resolved Taxon | | |
| Flowering Plants | Dudley Bluffs bladderpod | Lesquerella congesta | Listed | Threatened | | CO |
| Flowering Plants | Dudley Bluffs twinpod | Physaria obcordata | Listed | Threatened | | CO |
| Flowering Plants | Dudley's brodiaea | Triteleia dudleyi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Dudley's lousewort | Pedicularis dudleyi | Not Listed | Species of Concern | | CA |
| Ferns and Allies | Dudley's swordfern | Polystichum dudleyi | Not Listed | Resolved Taxon | | CA |
| Mammals | Dugong | Dugong dugon | Listed | Endangered | | |
| Insects | Dukes' skipper | Euphyes dukesi calhouni | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Dulzura California pocket mouse | Perognathus californicus femoralis | Not Listed | Species of Concern | | CA |
| Mammals | Dulzura kangaroo rat | dipodomys simulans | Not Listed | Species of Concern | | |
| Flowering Plants | Duncan's cory cactus | Coryphantha duncanii | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Dune larkspur | Delphinium parryi blochmaniae | Not Listed | Species of Concern | | CA |
| Reptiles | Dunes sagebrush lizard | Sceloporus arenicolus | Listed | Endangered | | NM, TX |
| Flowering Plants | Dune tansy | Tanacetum camphoratum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Dune unicorn plant | Proboscidea sabulosa | Not Listed | Resolved Taxon | | NM, TX |
| Fishes | Dungeness Crab | Cancer magister | | Not Listed | | |
| Flowering Plants | Dunn's mariposa lily | Calochortus dunnii | Not Listed | Species of Concern | | CA |
| Amphibians | Dunn's salamander | plethodon dunni | Not Listed | Species of Concern | | |
| Insects | Dun skipper | Euphyes vestris harbisoni | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Duran's alumroot | Heuchera duranii | Not Listed | Resolved Taxon | | CA, NV |
| Amphibians | Dusky crawfish frog | Rana areolata sevosa | Not Listed | Species of Concern | | |
| Amphibians | dusky gopher frog | Rana sevosa | Listed | Endangered | | AL, MS |
| Snails | Dusky Mantleslug | Philomycus batchi | Not Listed | Resolved Taxon | | |
| Birds | Dusky seaside sparrow | Ammodramus maritimus nigrescens | Delisted | Extinction | | |
| Reptiles | Dusky sea snake | Aipysurus fuscus | Listed | Endangered | | |
| Fishes | Duskytail darter | Etheostoma percnurum | Listed | Endangered | | KY, TN, VA |
| Fishes | Duskytail darter | Etheostoma percnurum | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Duskytail darter | Etheostoma percnurum | Listed | Experimental Population, Non-Essential | | TN |
| Flowering Plants | Dwarf Bear-poppy | Arctomecon humilis | Listed | Endangered | | UT |
| Flowering Plants | Dwarf checkerbloom | Sidalcea malviflora ssp. virgata | Not Listed | Species of Concern | | |
| Flowering Plants | Dwarf downingia | Downingia pusilla | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Dwarf-flowered heartleaf | Hexastylis naniflora | Delisted | Recovery | | NC, SC |
| Flowering Plants | Dwarf goldenstar | Bloomeria humilis | Not Listed | Species of Concern | | CA |
| Mammals | Dwarf hutia | Capromys nana | Listed | Endangered | | |
| Flowering Plants | Dwarf iliau | Wilkesia hobdyi | Listed | Endangered | | HI |
| Flowering Plants | Dwarf lake iris | Iris lacustris | Listed | Threatened | | MI, WI |
| Flowering Plants | Dwarf meadowfoam | Limnanthes floccosa ssp. pumila | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Dwarf naupaka | Scaevola coriacea | Listed | Endangered | | HI |
| Snails | Dwarf pebblesnail | Somatogyrus nanus | Not Listed | Species of Concern | | AL |
| Ferns and Allies | Dwarf polypody | Grammitis nimbata | Not Listed | Species of Concern | | NC |
| Clams | Dwarf rainbow | Leaunio pataecus | | Not Listed | | |
| Fishes | Dwarf sawfish | Pristis clavata | Listed | Endangered | | |
| Fishes | Dwarf Seahorse | Hippocampus zosterae | | Not Listed | | |
| Fishes | Dwarf Sturgeon | Pseudoscaphirhynchus hermanni | Petitioned for Listing, Under Review | Under Review | | |
| Clams | Dwarf wedgemussel | Alasmidonta heterodon | Listed | Endangered | | CT, DE, MA, MD, NC, NH, NJ, NY, PA, VA, VT |
| Flowering Plants | Dwarf wild-buckwheat | Eriogonum nanum | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Dwarf witch-alder | Fothergilla gardenii | Not Listed | Resolved Taxon | | |
| Fishes | Eagle Lake rainbow Trout | Oncorhynchus mykiss aquilarum | Not Listed | Resolved Taxon | | CA |
| Birds | Eagle Mountain scrub jay | Aphelocoma coerulescens cana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Eared coneflower | Rudbeckia auriculata | Petitioned for Listing, Under Review | Under Review | | GA |
| Birds | Eared Grebe | Podiceps nigricollis | Not Listed | Species of Concern | | |
| Mammals | Earthquake Merriam's kangaroo rat | Dipodomys merriami collinus | Not Listed | Species of Concern | | CA |
| Flowering Plants | East Bay clarkia | Clarkia concinna automixa | Not Listed | Species of Concern | | CA |
| Insects | Eastern beard grass Skipper | Atrytone arogos arogos | Not Listed | Species of Concern | | |
| Birds | Eastern Bewick''s Wren | Thryomanes bewickii ssp. bewickii | Not Listed | Species of Concern | | |
| Birds | Eastern Black rail | Laterallus jamaicensis ssp. jamaicensis | Listed | Threatened | | AL, AR, CO, FL, GA, IN, LA, MS, NC, SC, TN, TX |
| Birds | Eastern Bluebird | Sialia sialis | | Not Listed | | |
| Reptiles | Eastern Box Turtle | Terrapene carolina carolina | | Not Listed | | |
| Mammals | Eastern cottontail rabbit | Sylvilagus floridanus mearnsi | Not Listed | Resolved Taxon | | |
| Clams | Eastern Creekshell | Villosa delumbis | | Not Listed | | |
| Reptiles | Eastern diamondback rattlesnake | Crotalus adamanteus | Petitioned for Listing, Under Review | Under Review | | AL, FL, GA, SC |
| Clams | Eastern Elliptio | Elliptio complanata | | Not Listed | | |
| Clams | Eastern Floater | Pyganodon cataracta | | Not Listed | | |
| Mammals | Eastern gray kangaroo | Macropus giganteus | Delisted | Recovery | | |
| Amphibians | Eastern Hellbender | Cryptobranchus alleganiensis alleganiensis | Listed | Endangered | | MO |
| Amphibians | Eastern Hellbender | Cryptobranchus alleganiensis alleganiensis | Proposed for Listing | Proposed Endangered | | AL, GA, IN, KY, MD, MS, NC, NY, OH, PA, TN, VA, WV |
| Reptiles | Eastern indigo snake | Drymarchon couperi | Listed | Threatened | | AL, FL, GA, MS |
| Mammals | Eastern jerboa marsupial | Antechinomys laniger | Listed | Endangered | | |
| Flowering Plants | Eastern Joshua tree | Yucca jaegeriana | | Not Listed | | AZ, CA, NV, UT |
| Birds | Eastern Kingbird | Tyrannus tyrannus | Not Listed | Species of Concern | | |
| Clams | Eastern Lampmussel | Lampsilis radiata | | Not Listed | | |
| Mammals | Eastern marten | Martes americana americana | Not Listed | Resolved Taxon | | MA, ME, MI, ND, NH, NY, OH, PA, VT, WI |
| Reptiles | Eastern Massasauga (=rattlesnake) | Sistrurus catenatus | Listed | Threatened | | IA, IL, IN, MI, MN, NY, OH, PA, WI |
| Birds | Eastern Meadowlark | Sturnella magna | Not Listed | Species of Concern | | |
| Fishes | Eastern Mosquitofish | Gambusia holbrooki | | Not Listed | | |
| Amphibians | Eastern narrowmouth toad | Gastrophryne carolinensis | | Not Listed | | |
| Mammals | Eastern native-cat | Dasyurus viverrinus | Listed | Endangered | | |
| Clams | Eastern Oyster | Crassostrea virginica | | Not Listed | | |
| Birds | Eastern painted bunting | Passerina ciris ciris | Not Listed | Species of Concern | | |
| Clams | Eastern Pearlshell | Margaritifera margaritifera | | Not Listed | | |
| Mammals | Eastern pipistrelle | Pipistrellus subflavus | Not Listed | Status Undefined | | VA |
| Clams | Eastern Pondmussel | Sagittunio nasutus | | Not Listed | | |
| Flowering Plants | Eastern prairie fringed orchid | Platanthera leucophaea | Listed | Threatened | | AR, IA, IL, IN, ME, MI, MO, OH, PA, VA, WI, WV |
| Mammals | Eastern puma (=cougar) | Puma (=Felis) concolor couguar | Delisted | Extinction | | |
| Insects | Eastern regal fritillary | Argynnis idalia idalia | Proposed for Listing | Proposed Endangered | | PA |
| Reptiles | Eastern Ribbon snake | Thamnophis sauritus | Not Listed | Status Undefined | | |
| Birds | eastern rockhopper penguin | Eudyptes chrysocome filholi | Not Listed | Resolved Taxon | | |
| Fishes | Eastern sand darter | Ammocrypta pellucida | Not Listed | Species of Concern | | IL, IN, KY, MI, NY, OH, PA, VT, WV |
| Reptiles | Eastern short-horned lizard | Phrynosoma douglassii brevirostra | Not Listed | Species of Concern | | CO |
| Reptiles | Eastern Spiny Softshell Turtle | Apalone spinifera spinifera | | Not Listed | | |
| Birds | Eastern Whip-poor-will | Antrostomus vociferus | Not Listed | Species of Concern | | |
| Birds | Eastern Whip-poor-will | Caprimulgus vociferus | Not Listed | Resolved Taxon | | |
| Birds | Eastern Wood Pewee | Contopus virens | Not Listed | Species of Concern | | |
| Flowering Plants | Eastwood's buckwheat | Eriogonum eastwoodianum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Eastwood's goldenweed | Ericameria fasciculata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Eastwood's milkweed | Asclepias eastwoodiana | Not Listed | Species of Concern | | NV |
| Insects | Easy yellow-faced bee | Hylaeus facilis | Listed | Endangered | | HI |
| Ferns and Allies | Eaton's quillwort | Isoetes eatonii | Not Listed | Resolved Taxon | | CT, DE, MA, NH, NJ, NY |
| Clams | Ebonyshell | Fusconaia ebena | | Not Listed | | |
| Flowering Plants | Edge Falls anemone | Anemone edwardsiana petraea | Not Listed | Species of Concern | | TX |
| Arachnids | Edgewood blind harvestman | Calcina minor | Not Listed | Species of Concern | | CA |
| Arachnids | Edgewood Park micro-blind harvestman | Microcina edgewoodensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Edison's ascyrum | Hypericum edisonianum | Not Listed | Resolved Taxon | | |
| Crustaceans | Edisto crayfish | Procambarus echinatus | Not Listed | Resolved Taxon | | SC |
| Insects | Edmund's snaketail | Ophiogomphus edmundo | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC |
| Insects | Edwards Aquifer diving beetle | Haideoporus texanus | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Edwards' brasil | Condalia hookeri edwardsiana | Not Listed | Species of Concern | | TX |
| Birds | Edward's pheasant | Lophura edwardsi | Listed | Endangered | | |
| Flowering Plants | Edwards' Plateau cornsalad | Valerianella texana | Not Listed | Species of Concern | | TX |
| Flowering Plants | Eggert's sunflower | Helianthus eggertii | Delisted | Recovery | | KY, TN |
| Flowering Plants | Egg Lake monkey-flower | Mimulus pygmaeus | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Egg-mimic darter | Etheostoma pseudovulatum | | Not Listed | | TN |
| Reptiles | Egyptian Tortoise | Testudo kleinmanni | Listed | Threatened | | |
| Birds | Eiao Marquesas reed-Warbler | Acrocephalus percernis aquilonis | Listed | Endangered | | |
| Flowering Plants | Eke silversword | Argyroxiphium caliginis | Not Listed | Species of Concern | | |
| Flowering Plants | El Dorado bedstraw | Galium californicum ssp. sierrae | Listed | Endangered | | CA |
| Flowering Plants | El Dorado mule-ears | Wyethia reticulata | Not Listed | Species of Concern | | CA |
| Mammals | Eld's brow-antlered Deer | Cervus eldi | Listed | Endangered | | |
| Snails | Elegant elimia | Elimia teres | Petitioned for Listing, Under Review | Under Review | | TN |
| Birds | Elegant Tern | Thalasseus elegans | Not Listed | Species of Concern | | CA |
| Birds | Elegant Trogon | Trogon elegans | Not Listed | Species of Concern | | |
| Clams | Elephant-Ear | Elliptio crassidens | | Not Listed | | |
| Crustaceans | Elevated Spring amphipod | Stygobromus elatus | Not Listed | Resolved Taxon | | AR |
| Crustaceans | Eleven Point River crayfish | Faxonius wagneri | Not Listed | Resolved Taxon | | |
| Ferns and Allies | Elfin tree fern | Cyathea dryopteroides | Listed | Endangered | | PR |
| Birds | Elfin-woods warbler | Setophaga angelae | Listed | Threatened | | PR |
| Birds | Elf owl | Micrathene whitneyi | Not Listed | Species of Concern | | |
| Mammals | Elk | Cervus elaphus | | Not Listed | | |
| Corals | Elkhorn coral | Acropora palmata | Listed | Threatened | | |
| Crustaceans | Elk River crayfish | Cambarus elkensis | Not Listed | Resolved Taxon | | WV |
| Millipedes | Ellett Valley millipede | Pseudotremia cavernarum | | Not Listed | | VA |
| Birds | Elliot's pheasant | Syrmaticus ellioti | Listed | Endangered | | |
| Flowering Plants | ElliottÂ’s croton | Croton elliottii | Not Listed | Resolved Taxon | | GA, SC |
| Clams | Ellipse Mussel | Venustaconcha ellipsiformis | | Not Listed | | |
| Corals | Elliptical Star Coral | Dichocoenia stokesi | Not Listed | Status Undefined | | |
| Snails | Elongate-gland Springsnail | Pyrgulopsis isolata | Petitioned for Listing, Under Review | Under Review | | NV |
| Snails | Elongate mud meadows Springsnail | Pyrgulopsis notidicola | Not Listed | Resolved Taxon | | NV |
| Insects | El Segundo blue butterfly | Euphilotes battoides allyni | Listed | Endangered | | CA |
| Insects | El Segundo flower-loving fly | Rhaphiomidas terminatus terminatus | Not Listed | Resolved Taxon | | CA |
| Insects | Elusive clubtail | Stylurus notatus | Not Listed | Species of Concern | | AL, GA, IA, IL, IN, KY, MD, MI, MN, NY, OH, PA, TN, WI, WV |
| Insects | Elusive hydroporus diving beetle | Hydroporus elusivus | Not Listed | Species of Concern | | NH |
| Fishes | Emerald Shiner | Notropis atherinoides | | Not Listed | | |
| Fishes | Emerald Sleeper | Erotelis smaragdus | | Not Listed | | |
| Snails | Emigrant pyrg | Pyrgulopsis gracilis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Emory acacia | Senegalia berlandieri | Not Listed | Resolved Taxon | | TX |
| Birds | emperor penguin | Aptenodytes forsteri | Listed | Threatened | | |
| Arachnids | Empire Cave pseudoscorpion | Microcreagris imperialis | Not Listed | Species of Concern | | CA |
| Snails | Empire Mountain Talussnail | Sonorella imperialis | Not Listed | Resolved Taxon | | |
| Flowering Plants | `Ena`ena | Pseudognaphalium sandwicensium var. molokaiense | Listed | Endangered | | HI |
| Flowering Plants | Encinitas baccharis | Baccharis vanessae | Listed | Threatened | | CA |
| Insects | Endless Caverns cave beetle | Pseudanophthalmus avernus | | Not Listed | | VA |
| Insects | Engelhardt's cave beetle | Pseudanophthalmus engelhardti | Not Listed | Species of Concern | | TN |
| Flowering Plants | Engelmann oak | quercus engelmannii | Not Listed | Species of Concern | | |
| Flowering Plants | Engelmann's goldenrod | Oonopsis engelmannii | Not Listed | Species of Concern | | CO, KS |
| Mammals | Englewood mole | Scalopus aquaticus bassi | Not Listed | Species of Concern | | |
| Fishes | English Sole | Parophrys vetulus | | Not Listed | | |
| Snails | Engraved covert | Fumonelix orestes | Not Listed | Resolved Taxon | | NC |
| Snails | Engraved elimia | Elimia perstriata | Petitioned for Listing, Under Review | Under Review | | AL |
| Flowering Plants | Enterprise clarkia | Clarkia mosquinii xerophila | Not Listed | Species of Concern | | CA |
| Snails | Enterprise siltsnail | Cincinnatia monroensis | Not Listed | Status Undefined | | |
| Flowering Plants | Entrada skeletonplant | Lygodesmia entrada | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Ephedra wild-buckwheat | Eriogonum ephedroides brevicaule | Not Listed | Resolved Taxon | | CO, UT |
| Crustaceans | Ephemeral cave amphipod | Stygobromus ephemerus | Not Listed | Resolved Taxon | | VA |
| Birds | erect-crested penguin | Eudyptes sclateri | Listed | Threatened | | |
| Lichens | Ernie''s mountain treasure | Rinodina brodoana | Not Listed | Species of Concern | | |
| Flowering Plants | Ertter's milk-vetch | Astragalus ertterae | Not Listed | Species of Concern | | CA |
| Flowering Plants | Ertter's ragwort | Senecio ertterae | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Erubia | Solanum drymophilum | Listed | Endangered | | PR |
| Insects | Erythrodeme yellow-faced bee | Hylaeus erythrodemas | Not Listed | Resolved Taxon | | HI |
| Snails | Escabrosa Talussnail | Sonorella bartschi | Not Listed | Resolved Taxon | | |
| Reptiles | Escambia Map turtle | Graptemys ernsti | Listed | Similarity of Appearance (Threatened) | | |
| Flowering Plants | Escarpment milk-vetch | Astragalus striatiflorus | Not Listed | Resolved Taxon | | AZ, UT |
| Birds | Eskimo curlew | Numenius borealis | Listed | Endangered | | AK, NE, TX |
| Birds | Esmeraldas woodstar | Chaetocercus berlepschi | Listed | Endangered | | |
| Insects | Esperanza swallowtail butterfly | Papilio esperanza | Not Listed | Resolved Taxon | | |
| Flowering Plants | Etonia rosemary | Conradina etonia | Listed | Endangered | | FL |
| Crustaceans | Etowah crayfish | Cambarus fasciatus | Not Listed | Status Undefined | | GA |
| Fishes | Etowah darter | Etheostoma etowahae | Listed | Endangered | | GA |
| Fishes | Eulachon | Thaleichthys pacificus | Listed | Threatened | | |
| Fishes | Eulachon | Thaleichthys pacificus | | Not Listed | | |
| Birds | Euler's flycatcher | Empidonax euleri johnstonei | Listed | Endangered | | |
| Flowering Plants | Eulophia | Pteroglossaspis ecristata | Not Listed | Species of Concern | | |
| Birds | Eurasian peregrine falcon | Falco peregrinus peregrinus | Listed | Endangered | | |
| Birds | Eurasian Siskin | Spinus spinus | Not Listed | Species of Concern | | |
| Flowering Plants | Eureka Dune grass | Swallenia alexandrae | Listed | Threatened | | CA |
| Snails | Eureka mountainsnail | Oreohelix eurekensis eurekensis | Not Listed | Species of Concern | | UT |
| Snails | Eureka Mountainsnail | Oreohelix eurekensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Eureka Valley evening-primrose | Oenothera avita ssp. eurekensis | Delisted | Recovery | | CA |
| Fishes | European sturgeon | Acipenser sturio | Listed | Endangered | | |
| Flowering Plants | Evalyn's jewelflower | Streptanthus farnsworthianus | Not Listed | Resolved Taxon | | CA |
| Lichens | Evelyn''s buttons | Buellia sharpiana | Not Listed | Species of Concern | | |
| Snails | Evening fieldslug | Deroceras hesperium | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Birds | Evening Grosbeak | Coccothraustes vespertinus | Not Listed | Species of Concern | | |
| Snails | Evening Talussnail | Sonorella vespertina | Not Listed | Resolved Taxon | | |
| Insects | Everglades brownwing firefly | Photuris brunnipennis floridana | Not Listed | Species of Concern | | |
| Flowering Plants | Everglades bully | Sideroxylon reclinatum ssp. austrofloridense | Listed | Threatened | | FL |
| Mammals | Everglades mink | Mustela vison evergladensis | Not Listed | Resolved Taxon | | |
| Birds | Everglade snail kite | Rostrhamus sociabilis plumbeus | Listed | Endangered | | FL |
| Flowering Plants | Evergreen everlasting | Antennaria suffrutescens | Not Listed | Resolved Taxon | | CA, NV, OR |
| Birds | Evermann's rock ptarmigan | Lagopus muta evermanni | Not Listed | Species of Concern | | AK |
| Flowering Plants | Ewan's paintbrush | Castilleja martinii ewanii | Not Listed | Resolved Taxon | | CA |
| Snails | Excised slitshell | Gyrotoma excisa | Not Listed | Resolved Taxon | | AL |
| Insects | Exiguous anomalan scarab | Anomala exigua | Not Listed | Species of Concern | | |
| Insects | Extra-striped snaketail | Ophiogomphus anomalus | Not Listed | Species of Concern | | DE, ME, NJ, NY, PA, WI |
| Reptiles | Exuma Island iguana | Cyclura cychlura figginsi | Listed | Threatened | | |
| Birds | Eyrean grasswren (flycatcher) | Amytornis goyderi | Listed | Endangered | | |
| Crustaceans | Ezell's Cave amphipod | Stygobromus flagellatus | Not Listed | Species of Concern | | TX |
| Insects | Fabulous green sphinx Moth | Tinostoma smaragditis | Not Listed | Resolved Taxon | | HI |
| Conifers and Cycads | Fadang | Cycas micronesica | Listed | Threatened | | GU, MP |
| Snails | Fairbanks springsnail | Pyrgulopsis fairbanksensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Fairchild's lily | Lilium fairchildii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Falfurrias anglepod | Matelea radiata | Not Listed | Species of Concern | | TX |
| Insects | Fallax megalagrion damselfly | Megalagrion amaurodytum fallax | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Fall-flowering ixia | Nemastylis floridana | Not Listed | Species of Concern | | |
| Insects | False ameletus mayfly | Ameletus falsus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | False dragon-head | Physostegia leptophylla | Not Listed | Resolved Taxon | | |
| Flowering Plants | False hellebore | Veratrum woodii | Not Listed | Resolved Taxon | | |
| Flowering Plants | False indian-mallow | Anoda abutiloides | Not Listed | Resolved Taxon | | AZ |
| Mammals | false killer whale | Pseudorca crassidens | Listed | Endangered | | |
| Reptiles | False map turtle | Graptemys pseudogeographica | Not Listed | Species of Concern | | IN, MN, MO, ND, WI |
| Clams | false spike | Fusconaia mitchelli | Listed | Endangered | | TX |
| Mammals | False water rat | Xeromys myoides | Listed | Endangered | | |
| Clams | Fanshell | Cyprogenia stegaria | Listed | Endangered | | AL, IL, IN, KY, OH, TN, VA, WV |
| Clams | Fanshell | Cyprogenia stegaria | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Fantail Darter | Etheostoma flabellare | | Not Listed | | |
| Birds | Fan-tailed Warbler | Basileuterus lachrymosus | Not Listed | Species of Concern | | |
| Flowering Plants | Fassett's locoweed | Oxytropis campestris var. chartacea | Listed | Threatened | | WI |
| Fishes | Fathead Minnow | Pimephales promelas | | Not Listed | | |
| Fishes | Fatmucket | Lampsilis siliquoidea | | Not Listed | | |
| Clams | Fat pocketbook | Potamilus capax | Listed | Endangered | | AR, IA, IL, IN, KY, LA, MO, MS, TN |
| Fishes | Fat Sleeper | Dormitator maculatus | | Not Listed | | |
| Clams | Fat threeridge (mussel) | Amblema neislerii | Listed | Endangered | Proposed Delisting | FL, GA |
| Snails | Fat-whorled (=Bonneville) pondsnail | Stagnicola bonnevillensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Faurie's panic grass | Panicum fauriei fauriei | Not Listed | Resolved Taxon | | HI |
| Clams | Fawnsfoot Mussel | Truncilla donaciformis | | Not Listed | | |
| Crustaceans | Faxon's clam shrimp | Eulimnadia agassizii | Not Listed | Species of Concern | | MA |
| Mammals | Fea's muntjac | Muntiacus feae | Listed | Endangered | | |
| Birds | Fea's Petrel | Pterodroma feae | Not Listed | Species of Concern | | |
| Flowering Plants | Feather River monardella | Monardella stebbinsii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Feather River stonecrop | Sedum albomarginatum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Fell fields claytonia | Claytonia megarhiza bellidiflora | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Felt leaf rock-mint | Monardella hypoleuca lanata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Felt-leaf violet | Viola tomentosa | Not Listed | Resolved Taxon | | CA |
| Insects | Fender's blue butterfly | Icaricia icarioides fenderi | Listed | Threatened | | OR |
| Insects | Fender's rhyacophilan caddisfly | Rhyacophila fenderi | Not Listed | Resolved Taxon | | OR |
| Insects | Fender's soliperlan stonefly | Soliperla fenderi | Not Listed | Species of Concern | | WA |
| Snails | Fenney Spring hydrobe | Aphaostracon xynoelictum | Not Listed | Species of Concern | | |
| Flowering Plants | Fern-leaved ironwood | Lyonothamnus floribundus asplenifolius | Not Listed | Species of Concern | | CA |
| Insects | Fern yellow-faced bee | Hylaeus filicum | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ferris' milk-vetch | Astragalus tener var. ferrisae | Not Listed | Species of Concern | | CA |
| Insects | Ferris''s copper | Lycaena ferrisi | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Ferruginous Hawk | Buteo regalis | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Few-flowered jewelflower | Streptanthus sparsiflorus | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Few-flowered navarretia | Navarretia leucocephala ssp. pauciflora (=N. pauciflora) | Listed | Endangered | | CA |
| Flowering Plants | fewflower milkweed | Asclepias lanceolata | | Not Listed | | |
| Ferns and Allies | Fibrillose lip fern | Cheilanthes fibrillosa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Fickeisen plains cactus | Pediocactus peeblesianus ssp. fickeiseniae | Listed | Endangered | | AZ |
| Flowering Plants | Field goldeneye | Viguiera phenax | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Field, long-hairy chickweed | Cerastium arvense villosissimum | Not Listed | Species of Concern | | PA |
| Mammals | Field's mouse | Pseudomys fieldi | Listed | Endangered | | |
| Birds | Field Sparrow | Spizella pusilla | Not Listed | Species of Concern | | |
| Insects | Fig seed diving beetle | Desmopachria cenchramis | Not Listed | Species of Concern | | |
| Reptiles | Fiji banded iguana | Brachylophus fasciatus | Listed | Endangered | | |
| Reptiles | Fiji crested iguana | Brachylophus vitiensis | Listed | Endangered | | |
| Birds | Fiji petrel | Pseudobulweria macgillivrayi | Listed | Endangered | | |
| Birds | Fiji Shrikebill | Clytorhynchus vitiensis | Not Listed | Species of Concern | | |
| Mammals | Finback whale | Balaenoptera physalus | Listed | Endangered | | |
| Clams | Finelined pocketbook | Hamiota altilis | Listed | Threatened | | AL, GA, TN |
| Clams | Finerayed pigtoe | Fusconaia cuneolus | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Finerayed pigtoe | Fusconaia cuneolus | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Finerayed pigtoe | Fusconaia cuneolus | Listed | Endangered | | AL, KY, TN, VA |
| Fishes | Finescale Dace | Chrosomus neogaeus | | Not Listed | | |
| Insects | Finitiman yellow-faced bee | Hylaeus finitima | Not Listed | Resolved Taxon | | HI |
| Birds | fiordland crested penguin | Eudyptes pachyrhynchus | Listed | Threatened | | |
| Insects | Fischer's lelpidostoman caddisfly | Lepidostoma fischeri | Not Listed | Resolved Taxon | | OR |
| Flowering Plants | Fish Creek fleabane | Erigeron piscaticus | Petitioned for Listing, Under Review | Under Review | | AZ |
| Flowering Plants | Fish Creek rock-daisy | Perityle saxicola | Not Listed | Resolved Taxon | | AZ |
| Fishes | Fish Creek Springs tui chub | Siphateles bicolor euchila | Not Listed | Species of Concern | | NV |
| Mammals | Fisher | Pekania pennanti | Not Listed | Resolved Taxon | | ID, MT, WY |
| Mammals | Fisher | Pekania pennanti | Not Listed | Resolved Taxon | | CA, NV, OR |
| Mammals | Fisher | Pekania pennanti | Listed | Endangered | | CA |
| Mammals | Fisher | Pekania pennanti | Not Listed | Species of Concern | | |
| Mammals | Fisher | Pekania pennanti | Not Listed | Resolved Taxon | | |
| Flowering Plants | Fish Lake naiad | Najas flexilis | Not Listed | Species of Concern | | UT |
| Snails | Fish Lake physa | Physella microstriata | Not Listed | Species of Concern | | UT |
| Fishes | Fish Lake Valley tui chub | Siphateles obesus ssp | Proposed for Listing | Proposed Endangered | | NV |
| Flowering Plants | Fish Slough milk-vetch | Astragalus lentiginosus var. piscinensis | Listed | Threatened | | CA |
| Snails | Fish Slough springsnail | Pyrgulopsis perturbata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Fish's milkwort | Polygala cornuta var. fishiae | Not Listed | Species of Concern | | CA |
| Mammals | Fish Spring pocket gopher | Thomomys umbrinus abstrusus | Not Listed | Species of Concern | | NV |
| Snails | Fish Springs marshsnail | Stagnicola pilsbryi | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Fitch's hedgehog cactus | Echinocereus reichenbachii fitchii | Not Listed | Resolved Taxon | | TX |
| Birds | Five-striped Sparrow | Aimophila quinquestriata | Not Listed | Species of Concern | | |
| Snails | Flag pyrg | Pyrgulopsis breviloba | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Flagstaff pennyroyal | Hedeoma diffusum | Not Listed | Resolved Taxon | | AZ |
| Lichens | Flaky square britches | Hypotrachyna virginica | Not Listed | Species of Concern | | NC |
| Fishes | Flame chub | Hemitremia flammea | Not Listed | Species of Concern | | AL, GA, TN |
| Birds | Flammulated Owl | Psiloscops flammeolus | Not Listed | Status Undefined | | |
| Fishes | Flannelmouth sucker | Catostomus latipinnis | Not Listed | Species of Concern | | AZ, CA, NV, UT |
| Flowering Plants | Flat dune sedge | Cyperus onerosus | Not Listed | Species of Concern | | TX |
| Fishes | Flat Floater Mussel | Utterbackiana suborbiculata | | Not Listed | | |
| Fishes | Flathead Catfish | Pylodictis olivaris | | Not Listed | | |
| Fishes | Flathead chub | Platygobio gracilis | Not Listed | Species of Concern | | AL, AR, CO, IA, IL, KS, KY, LA, MN, MO, MT, ND, NE, NM, OK, SD, TN, WY |
| Mammals | Flat-headed cat | Prionailurus (=Felis) planiceps | Listed | Endangered | | |
| Snails | Flathead Pondsnail | Stagnicola elrodi | Not Listed | Resolved Taxon | | |
| Snails | Flat pebblesnail | Lepyrium showalteri | Listed | Endangered | | AL |
| Clams | Flat pigtoe | Pleurobema marshalli | Delisted | Extinction | | AL, MS |
| Flowering Plants | Flat-seeded spurge | Chamaesyce platysperma | Not Listed | Species of Concern | | AZ, CA |
| Snails | Flat-spired three-toothed Snail | Triodopsis platysayoides | Listed | Threatened | | WV |
| Reptiles | Flat-tailed horned lizard | Phrynosoma mcallii | Not Listed | Resolved Taxon | | AZ |
| Reptiles | Flat-tailed tortoise | Pyxis planicauda | Petitioned for Listing, Under Review | Under Review | | |
| Reptiles | Flattened musk turtle | Sternotherus depressus | Listed | Threatened | | AL |
| Snails | Flat-topped Steptoe pyrg | Pyrgulopsis planulata | Petitioned for Listing, Under Review | Under Review | | NV |
| Snails | Flaxen elimia | Elimia boykiniana | Not Listed | Species of Concern | | AL, GA |
| Flowering Plants | Flax-like monardella | Monardella linoides oblonga | Not Listed | Species of Concern | | CA |
| Flowering Plants | Fleshy-fruit gladecress | Leavenworthia crassa | Listed | Endangered | | AL |
| Flowering Plants | Fleshy owl's-clover | Castilleja campestris ssp. succulenta | Listed | Threatened | | CA |
| Mammals | Fletcher dark kangaroo mouse | Microdipodops megacephalus nasutus | Not Listed | Species of Concern | | NV |
| Flowering Plants | Flett's violet | Viola flettii | Not Listed | Resolved Taxon | | WA |
| Snails | Flint River pyrg | Pyrgulopsis sp. | Not Listed | Species of Concern | | AL |
| Insects | Flint's net-spinning caddisfly | Cheumatopsyche flinti | Not Listed | Resolved Taxon | | TX |
| Birds | Floreana tree-Finch | Camarhynchus pauper | Listed | Endangered | | |
| Birds | Flores hawk-eagle | Spizaetus floris | Petitioned for Listing, Under Review | Under Review | | |
| Clams | Florida arc-mussel | Alasmidonta wrightiana | Not Listed | Species of Concern | | |
| Insects | Florida asaphomyian tabanid fly | Asaphomyia floridensis | Not Listed | Species of Concern | | |
| Insects | Florida atala butterfly | Eumaeus atala florida | Not Listed | Species of Concern | | |
| Mammals | Florida black bear | Ursus americanus floridanus | Not Listed | Resolved Taxon | | GA |
| Amphibians | Florida bog frog | Rana okaloosae | Not Listed | Resolved Taxon | | |
| Amphibians | Florida Bog Frog | Lithobates okaloosae | | Not Listed | | |
| Flowering Plants | Florida bonamia | Bonamia grandiflora | Listed | Threatened | | FL |
| Mammals | Florida bonneted bat | Eumops floridanus | Listed | Endangered | | FL |
| Flowering Plants | Florida brickell-bush | Brickellia mosieri | Listed | Endangered | | FL |
| Ferns and Allies | Florida bristle fern | Trichomanes punctatum ssp. floridanum | Listed | Endangered | | FL |
| Insects | Florida brown checkered summer sedge | Polycentropus floridensis | Not Listed | Resolved Taxon | | |
| Birds | Florida Burrowing Owl | Athene cunicularia floridana | Not Listed | Species of Concern | | |
| Crustaceans | Florida cave amphipod | Crangonyx grandimanus | Petitioned for Listing, Under Review | Under Review | | FL |
| Crustaceans | Florida Cave crayfish | Procambarus lucifugus | Petitioned for Listing, Under Review | Under Review | | |
| Crustaceans | Florida Cave crayfish | Procambarus lucifugus ssp. lucifugus | Petitioned for Listing, Under Review | Under Review | | FL |
| Insects | Florida ceraclean longhorn caddisfly | Ceraclea floridana | Not Listed | Species of Concern | | |
| Conifers and Cycads | Florida coontie | Zamia integrifolia pigmaea | Not Listed | Resolved Taxon | | |
| Amphibians | Florida crawfish frog | Rana areolata aesopus | Not Listed | Species of Concern | | |
| Crustaceans | Florida fairy shrimp | Dexteria floridana | Not Listed | Resolved Taxon | | |
| Fishes | Florida Gar | Lepisosteus platyrhincus | | Not Listed | | |
| Flowering Plants | Florida golden aster | Chrysopsis floridana | Delisted | Recovery | | FL |
| Birds | Florida grasshopper sparrow | Ammodramus savannarum floridanus | Listed | Endangered | | FL |
| Flowering Plants | Florida hartwrightia | Hartwrightia floridana | Petitioned for Listing, Under Review | Under Review | | GA |
| Flowering Plants | Florida hornwort | Ceratophyllum floridanum | Not Listed | Resolved Taxon | | |
| Flowering Plants | Florida indigo | Indigofera mucronata var. keyensis | Not Listed | Resolved Taxon | | |
| Insects | Florida intertidal firefly | Micronaspis floridana | Petitioned for Listing, Under Review | Under Review | | FL |
| Reptiles | Florida Keys mole skink | Plestiodon egregius egregius | Proposed for Listing | Proposed Threatened | | FL |
| Clams | Florida lance | Elliptio waltoni | Not Listed | Species of Concern | | |
| Insects | Florida leafwing Butterfly | Anaea troglodyta floridalis | Listed | Endangered | | FL |
| Mammals | Florida long-tailed weasel | Mustela frenata peninsulae | Not Listed | Species of Concern | | |
| Flowering Plants | Florida loosestrife | Lythrum flagellare | Not Listed | Resolved Taxon | | |
| Mammals | Florida Manatee | Trichechus manatus latirostris | Proposed for Listing | Proposed Threatened | | |
| Mammals | Florida mastiff-bat | Eumops glaucinus floridanus | Not Listed | Species of Concern | | |
| Mammals | Florida mink | Mustela vison lutensis | Not Listed | Resolved Taxon | | |
| Snails | Florida mountainsnail | Oreohelix florida | Not Listed | Species of Concern | | NM |
| Snails | Florida Mountain Woodlandsnail | Ashmunella walkeri | Not Listed | Resolved Taxon | | |
| Mammals | Florida mouse | Peromyscus floridanus | Not Listed | Species of Concern | | |
| Insects | Florida oxyethiran micro caddisfly | Oxyethira florida | Not Listed | Species of Concern | | |
| Mammals | Florida panther | Puma (=Felis) concolor coryi | Listed | Endangered | | FL |
| Lichens | Florida perforate cladonia | Cladonia perforata | Listed | Endangered | | FL |
| Flowering Plants | Florida pineland crabgrass | Digitaria pauciflora | Listed | Threatened | | FL |
| Reptiles | Florida pinesnake | Pituophis melanoleucus mugitus | Not Listed | Resolved Taxon | | GA, SC |
| Fishes | Florida Pompano | Trachinotus carolinus | | Not Listed | | |
| Flowering Plants | Florida pondweed | Potamogeton floridanus | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Florida prairie-clover | Dalea carthagenensis floridana | Listed | Endangered | | FL |
| Reptiles | Florida Red-bellied turtle | Pseudemys nelsoni | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Florida salt marsh vole | Microtus pennsylvanicus dukecampbelli | Listed | Endangered | | FL |
| Birds | Florida sandhill crane | Antigone canadensis ssp. pratensis | Not Listed | Resolved Taxon | | GA |
| Birds | Florida scrub-jay | Aphelocoma coerulescens | Listed | Threatened | | FL |
| Reptiles | Florida scrub lizard | Sceloporus woodi | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Florida semaphore Cactus | Consolea corallicola | Listed | Endangered | | FL |
| Flowering Plants | Florida skullcap | Scutellaria floridana | Listed | Threatened | | FL |
| Crustaceans | Florida Stone Crab | Menippe mercenaria | | Not Listed | | |
| Conifers and Cycads | Florida torreya | Torreya taxifolia | Listed | Endangered | | FL, GA |
| Snails | Florida tree snail | Liguus fasciatus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Florida water-parsnip | Sium suave | Not Listed | Species of Concern | | |
| Flowering Plants | Florida willow | Salix floridana | Petitioned for Listing, Under Review | Under Review | | |
| Conifers and Cycads | Florida yew | Taxus floridana | Not Listed | Species of Concern | | |
| Flowering Plants | Florida ziziphus | Ziziphus celata | Listed | Endangered | | FL |
| Insects | Fluminense swallowtail butterfly | Parides ascanius | Listed | Endangered | | |
| Clams | Fluted Elephantear | Elliptio mcmichaeli | Not Listed | Status Undefined | | |
| Clams | Fluted kidneyshell | Ptychobranchus subtentus | Listed | Endangered | | AL, KY, TN, VA |
| Snails | Fluted pebblesnail | Somatogyrus hendersoni | Not Listed | Species of Concern | | AL |
| Clams | Fluted-Shell | Lasmigona costata | | Not Listed | | |
| Insects | Flying earwig Hawaiian damselfly | Megalagrion nesiotes | Listed | Endangered | | HI |
| Insects | Flyn's hick cave beetle | Pseudanophthalmus simplex | Not Listed | Species of Concern | | TN |
| Insects | Flypoison borer moth | Papaipema sp. | Not Listed | Species of Concern | | PA |
| Flowering Plants | Flyr's brickell-bush | Brickellia cordifolia | Not Listed | Species of Concern | | |
| Insects | Folkerts' hydroporus diving beetle | Hydroporus folkertsi | Not Listed | Species of Concern | | AL |
| Flowering Plants | Foothill mariposa lily | Calochortus weedii intermedius | Not Listed | Species of Concern | | CA |
| Amphibians | Foothill yellow-legged frog | Rana boylii | Listed | Endangered | | CA |
| Amphibians | Foothill yellow-legged frog | Rana boylii | Listed | Threatened | | CA |
| Amphibians | Foothill yellow-legged frog | Rana boylii | Listed | Endangered | | CA |
| Amphibians | Foothill yellow-legged frog | Rana boylii | Listed | Threatened | | CA |
| Flowering Plants | Footsteps of spring | Sanicula arctopoides | Not Listed | Species of Concern | | |
| Flowering Plants | Forbes bidens | Bidens forbesii | Not Listed | Resolved Taxon | | HI |
| Insects | Forbes' Kauai long-horned beetle | Plagithmysus forbesianus | Not Listed | Species of Concern | | HI |
| Insects | Forbes' Maui long-horned beetle | Plagithmysus forbesii | Not Listed | Species of Concern | | HI |
| Birds | Forbes' parakeet | Cyanoramphus auriceps forbesi | Listed | Endangered | | |
| Flowering Plants | Forbes saxifrage | Micranthes pensylvanica | Not Listed | Resolved Taxon | | IA, IL, IN, MN, MO, WI |
| Insects | Ford's aphodius scarab | Aphodius fordi | Not Listed | Species of Concern | | GA |
| Insects | Ford's rhyncogonus weevil | Rhyncogonus segnis fordi | Not Listed | Species of Concern | | HI |
| Insects | Ford's sand dune moth | Psammobotys fordi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Forest Camp sandwort | Arenaria macradenia kuschei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Forked buckwheat | Eriogonum bifurcatum | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Forked fiddleneck | Amsinckia vernicosa furcata | Not Listed | Species of Concern | | CA |
| Clams | Forkshell | Epioblasma lewisii | Not Listed | Resolved Taxon | | AL, KY, TN |
| Mammals | Formosan rock macaque | Macaca cyclopis | Listed | Threatened | | |
| Mammals | Formosan sika deer | Cervus nippon taiouanus | Listed | Endangered | | |
| Mammals | Formosan yellow-throated marten | Martes flavigula chrysospila | Listed | Endangered | | |
| Reptiles | Forsten's tortoise | Indotestudo forstenii | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Forster's Tern | Sterna forsteri | Not Listed | Species of Concern | | |
| Insects | Fort Dick limnephilus caddisfly | Limnephilus atercus | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Fort Mountain Sedge | Carex communis var. amplisquama | Not Listed | Species of Concern | | GA |
| Insects | Fort Ross trigonoscuta weevil | Trigonoscuta rossi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Fosberg's love grass | Eragrostis fosbergii | Listed | Endangered | | HI |
| Fishes | Foskett speckled dace | Rhinichthys osculus ssp. | Delisted | Recovery | | OR |
| Snails | Fossil springsnail | Pyrgulopsis simplex | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Foster's Rockdaisy | Perityle fosteri | Not Listed | Resolved Taxon | | |
| Fishes | Fountain darter | Etheostoma fonticola | Listed | Endangered | | TX |
| Flowering Plants | Fountain thistle | Cirsium fontinale var. fontinale | Listed | Endangered | | CA |
| Amphibians | Fourche Mountain salamander | Plethodon fourchensis | Not Listed | Resolved Taxon | | AR |
| Flowering Plants | Four-petal pawpaw | Asimina tetramera | Listed | Endangered | | FL |
| Amphibians | Four-Toed Salamander | Hemidactylium scutatum | | Not Listed | | |
| Insects | Fowler's cave beetle | Pseudanophthalmus fowlerae | Not Listed | Resolved Taxon | | TN |
| Birds | Fox Sparrow | Passerella iliaca | Not Listed | Species of Concern | | |
| Flowering Plants | Foxtail cactus | escobaria alversonii | Not Listed | Species of Concern | | |
| Clams | Fragile Papershell | Potamilus fragilis | | Not Listed | | |
| Snails | Fragile supercoil | Glyphyalinia clingmani | Not Listed | Species of Concern | | NC |
| Snails | Fragile tree snail | Samoana fragilis | Listed | Endangered | | GU, MP |
| Flowering Plants | Fragrant flatsedge | Cyperus odoratus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Fragrant fritillary | Fritillaria liliacea | Not Listed | Species of Concern | | CA |
| Flowering Plants | Fragrant prickly-apple | Cereus eriophorus var. fragrans | Listed | Endangered | | FL |
| Flowering Plants | Franciscan manzanita | Arctostaphylos franciscana | Listed | Endangered | | CA |
| Mammals | Francois' langur | Trachypithecus (=Presbytis) francoisi | Listed | Endangered | | |
| Snails | Franklin Mountain talussnail | Sonorella metcalfi | Not Listed | Species of Concern | | TX |
| Snails | Franklin Mountain wood snail | Ashmunella pasonis | Not Listed | Species of Concern | | TX |
| Insects | Franklin's bumble bee | Bombus franklini | Listed | Endangered | | CA, OR |
| Mammals | Franklin's ground squirrel | Spermophilus franklinii | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Franklin's Gull | Leucophaeus pipixcan | Not Listed | Species of Concern | | |
| Flowering Plants | Franklin tree | Franklinia alatamaha | Not Listed | Species of Concern | | GA |
| Flowering Plants | Frank Smith's violet | Viola franksmithii | Not Listed | Resolved Taxon | | UT |
| Crustaceans | Franz's amphipod | Stygobromus franzi | Not Listed | Resolved Taxon | | MD |
| Crustaceans | Franz's isopod | Caecidotea franzi | Not Listed | Species of Concern | | MD, PA |
| Conifers and Cycads | Fraser fir | Abies fraseri | Not Listed | Species of Concern | | NC, VA |
| Insects | Fraser fir geometrid moth | Semiothisa fraserata | Not Listed | Species of Concern | | NC, VA |
| Flowering Plants | Fraser's yellow loosestrife | Lysimachia fraseri | Not Listed | Species of Concern | | CO, NC |
| Fishes | Frecklebelly madtom | Noturus munitus | Not Listed | Resolved Taxon | | AL, LA, MS, TN |
| Fishes | Frecklebelly madtom | Noturus munitus | Listed | Threatened | | GA, TN |
| Fishes | Freckled darter | Percina lenticula | Not Listed | Resolved Taxon | | AL, GA, LA, MS |
| Flowering Plants | Fredonia wild-buckwheat | Eriogonum mortonianum | Petitioned for Listing, Under Review | Under Review | | AZ |
| Flowering Plants | Freed's jewelflower | Streptanthus brachiatus hoffmanii | Not Listed | Species of Concern | | CA |
| Snails | Freemouth Hydrobe snail | Aphaostracon chalarogyrus | Not Listed | Status Undefined | | |
| Birds | Freira | Pterodroma madeira | Listed | Endangered | | |
| Flowering Plants | Fremont County rockcress | Boechera pusilla | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | Fremont's bladder-pod | Lesquerella fremontii | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | Fremont's rosinweed | Calycadenia fremontii | Not Listed | Species of Concern | | CA |
| Crustaceans | French Broad crayfish | Cambarus reburrus | Not Listed | Species of Concern | | NC |
| Flowering Plants | French Broad heartleaf | Hexastylis rhombiformis | Not Listed | Species of Concern | | NC |
| Insects | French Frigate Shoal seed bug | Nysius frigatensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | French's shootingstar | Dodecatheon frenchii | Not Listed | Resolved Taxon | | AR, IL, IN, KY, MO |
| Fishes | Freshwater Drum | Aplodinotus grunniens | | Not Listed | | |
| Fishes | Freshwater Pipefish | Pseudophallus mindii | | Not Listed | | |
| Flowering Plants | Fresno County bird's-beak | Cordylanthus tenuis barbatus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Fresno Creek thelypody | Thelypodium tenue | Not Listed | Resolved Taxon | | TX |
| Mammals | Fresno kangaroo rat | Dipodomys nitratoides exilis | Listed | Endangered | | CA |
| Birds | Friendly Ground-Dove | Gallicolumba stairi | Listed | Endangered | | AS |
| Snails | Frigid Ambersnail | Catinella gelida | Not Listed | Resolved Taxon | | IA |
| Birds | Fringe-backed fire-eye | Pyriglena atra | Listed | Endangered | | |
| Flowering Plants | Fringed campion | Silene polypetala | Listed | Endangered | | AL, FL, GA |
| Flowering Plants | Fringed false-hellebore | Veratrum fimbriatum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Fringed loosestrife | Lysimachia hybrida | Not Listed | Resolved Taxon | | |
| Snails | Fringed Mountainsnail | Radiocentrum ferrissi | Not Listed | Resolved Taxon | | |
| Mammals | Fringed myotis | Myotis thysanodes | Not Listed | Species of Concern | | CO |
| Arachnids | Fringed Ornamental Tarantula | Poecilotheria ornata | Listed | Endangered | | |
| Mammals | Fringed-tailed myotis | Myotis thysanodes pahasapensis | Not Listed | Species of Concern | | CO, NE, SD, WY |
| Flowering Plants | Fringed (unnamed ssp.) lewisia | Lewisia cotyledon ssp. | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Frisco buckwheat | Eriogonum soredium | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Frisco clover | Trifolium friscanum | Not Listed | Resolved Taxon | | UT |
| Insects | Frison's seratellan mayfly | Seratella frisoni | Not Listed | Species of Concern | | AL, IL, MO |
| Flowering Plants | Front Range cinquefoil | Potentilla effusa rupincola | Not Listed | Species of Concern | | CO |
| Insects | Frosted Elfin | Callophrys irus irus, C. i. hadros, C. i. arsace | Not Listed | Status Undefined | | GA, SC |
| Amphibians | Frosted Flatwoods salamander | Ambystoma cingulatum | Listed | Threatened | | FL, GA, SC |
| Insects | Frost's spring serican scarab | Serica frosti | Not Listed | Species of Concern | | |
| Flowering Plants | Fruit rock-cress | Arabis fructicosa | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | Ft. Tejon wooly-sunflower | Eriophyllum lanatum hallii | Not Listed | Species of Concern | | CA |
| Insects | Fullaway's banana omoides moth | Omoides fullawayi | Not Listed | Species of Concern | | HI |
| Insects | Fullaway's seed bug | Nysius fullawayi | Not Listed | Species of Concern | | HI |
| Birds | Fulvous whistling duck | Dendrocygna bicolor | Not Listed | Species of Concern | | AZ, CA |
| Conifers and Cycads | Funeral ephedra | Ephedra funerea | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Furbish lousewort | Pedicularis furbishiae | Listed | Threatened | | ME |
| Insects | Furry yellow-faced bee | Hylaeus pubescens | Not Listed | Species of Concern | | HI |
| Snails | Fusiform elimia | Elimia fusiformis | Not Listed | Resolved Taxon | | AL |
| Clams | Fuzzy pigtoe | Pleurobema strodeanum | Listed | Threatened | | AL, FL |
| Mammals | Gaimard's rat-kangaroo | Bettongia gaimardi | Listed | Endangered | | |
| Flowering Plants | Gairdner's yampah | Perideridia gairdneri gairdneri | Not Listed | Species of Concern | | CA |
| Birds | Galapagos hawk | Buteo galapagoensis | Listed | Endangered | | |
| Birds | Galapagos penguin | Spheniscus mendiculus | Listed | Endangered | | |
| Birds | Galapagos petrel | Pterodroma phaeopygia | Listed | Threatened | | |
| Reptiles | Galapagos tortoise | Geochelone nigra (=elephantopus) | Listed | Endangered | | |
| Flowering Plants | Galena Creek rock-cress | Arabis rigidissima demota | Not Listed | Species of Concern | | NV |
| Flowering Plants | Gambel's watercress | Rorippa gambellii | Listed | Endangered | | CA |
| Insects | Gammon's stenelmis riffle beetle | Stenelmis gammoni | Not Listed | Species of Concern | | AL, NC, VA |
| Flowering Plants | Gander butterweed | Packera ganderi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Gander's cryptantha | Cryptantha ganderi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Gander's pitcher-sage | Lepechinia ganderi | Not Listed | Species of Concern | | CA |
| Insects | Gandy Creek cave springtail | Pseudosinella certa | Not Listed | Species of Concern | | WV |
| Flowering Plants | Garber's spurge | Chamaesyce garberi | Listed | Threatened | | FL |
| Snails | Garden Canyon talussnail | Sonorella dalli | Not Listed | Resolved Taxon | | |
| Insects | Garden cave beetle | Pseudanophthalmus hortulanus | Not Listed | Species of Concern | | VA |
| Flowering Plants | Garrett bladder-pod | Lesquerella garrettii | Not Listed | Species of Concern | | UT |
| Flowering Plants | Garrett's beardtongue | Penstemon scariosus garrettii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Garrett's mint | Dicerandra christmanii | Listed | Endangered | | FL |
| Flowering Plants | Gaspe Peninsula arrow-grass | Triglochin gaspense | Not Listed | Species of Concern | | ME |
| Reptiles | Gavial | Gavialis gangeticus | Listed | Endangered | | |
| Flowering Plants | Gaviota Tarplant | Deinandra increscens ssp. villosa | Listed | Endangered | | CA |
| Mammals | Gelada baboon | Theropithecus gelada | Listed | Threatened | | |
| Flowering Plants | Gentian pinkroot | Spigelia gentianoides | Listed | Endangered | | AL, FL |
| Flowering Plants | Gentner's Fritillary | Fritillaria gentneri | Listed | Endangered | | CA, OR |
| Flowering Plants | Gentry's indigobush | Dalea tentaculoides | Not Listed | Resolved Taxon | | AZ |
| Reptiles | Geometric turtle | Psammobates geometricus | Listed | Endangered | | |
| Amphibians | Georgetown Salamander | Eurycea naufragia | Listed | Threatened | | TX |
| Flowering Plants | Georgia aster | Symphyotrichum georgianum | Not Listed | Resolved Taxon | | AL, GA, NC, SC |
| Insects | Georgia beloneurian stonefly | Beloneuria georgiana | Not Listed | Resolved Taxon | | GA, NC |
| Amphibians | Georgia blind salamander | Eurycea wallacei | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | Georgia bully | Sideroxylon thornei | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | Georgia lead-plant | Amorpha georgiana georgiana | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC |
| Insects | Georgian cave beetle | Pseudanophthalmus georgiae | Not Listed | Species of Concern | | GA |
| Clams | Georgia pigtoe | Pleurobema hanleyianum | Listed | Endangered | | AL, GA, TN |
| Flowering Plants | Georgia plume | Elliottia racemosa | Not Listed | Resolved Taxon | | GA, SC |
| Flowering Plants | Georgia rockcress | Arabis georgiana | Listed | Threatened | | AL, GA |
| Insects | Germanus eopenthes click beetle | Eopenthes germanus | Not Listed | Species of Concern | | HI |
| Birds | Ghizo white-eye | Zosterops luteirostris | Candidate for Listing | Candidate | | |
| Flowering Plants | Ghost orchid | Dendrophylax lindenii | Proposed for Listing | Proposed Endangered | | FL |
| Mammals | Giant armadillo | Priodontes maximus | Listed | Endangered | | |
| Clams | Giant Floater | Pyganodon grandis | | Not Listed | | |
| Reptiles | Giant garter snake | Thamnophis gigas | Listed | Threatened | | CA |
| Birds | Giant ibis | Pseudibis gigantea | Listed | Endangered | | |
| Mammals | Giant kangaroo rat | Dipodomys ingens | Listed | Endangered | | CA |
| Flowering Plants | Giant koke`e | Cyanea leptostegia | Not Listed | Species of Concern | | HI |
| Fishes | Giant Manta Ray | Manta birostris | Listed | Threatened | | |
| Mammals | Giant otter | Pteronura brasiliensis | Listed | Endangered | | |
| Annelid Worms | Giant Palouse earthworm | Driloleirus americanus | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Mammals | Giant panda | Ailuropoda melanoleuca | Listed | Endangered | | |
| Mammals | Giant pangolin | Manis gigantea | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Giant sable antelope | Hippotragus niger variani | Listed | Endangered | | |
| Birds | Giant scops owl | Mimizuku (=Otus) gurneyi | Listed | Endangered | | |
| Flowering Plants | Giant spanishneedle | Palafoxia arida gigantea | Not Listed | Species of Concern | | AZ, CA |
| Fishes | Giant Trevally, Ulua | Caranx ignobilis | | Not Listed | | |
| Flowering Plants | Giant water-dropwort | Oxypolis greenmanii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Gibbens beardtongue | Penstemon gibbensii | Not Listed | Resolved Taxon | | CO, UT |
| Mammals | Gibbons | Hylobates spp. (including Nomascus) | Listed | Endangered | | |
| Flowering Plants | Gierisch mallow | Sphaeralcea gierischii | Listed | Endangered | | AZ, UT |
| Insects | Giffard's ectemnius sphecid wasp | Ectemnius giffardi | Not Listed | Species of Concern | | HI |
| Insects | Giffard's `ohe omoides moth | Omoides giffardi | Not Listed | Species of Concern | | HI |
| Insects | Giffard's rhyncogonus weevil | Rhyncogonus giffardi | Not Listed | Species of Concern | | HI |
| Insects | Gifford's nesotocus weevil | Nesotocus giffordi | Not Listed | Species of Concern | | HI |
| Fishes | Gila chub | Gila intermedia | Listed | Endangered | | AZ, NM |
| Insects | Gila mayfly | Lachlania dencyanna | Petitioned for Listing, Under Review | Under Review | | NM |
| Reptiles | Gila monster lizard | Heloderma suspectum | Not Listed | Resolved Taxon | | AZ, CA, NM, NV, UT |
| Reptiles | Gila monster lizard | Heloderma suspectum | Not Listed | Resolved Taxon | | UT |
| Snails | Gila springsnail | Pyrgulopsis gilae | Not Listed | Resolved Taxon | | NM |
| Fishes | Gila topminnow (incl. Yaqui) | Poeciliopsis occidentalis | Listed | Endangered | | AZ, NM |
| Fishes | Gila trout | Oncorhynchus gilae | Listed | Threatened | | AZ, NM |
| Snails | Gila Tryonia snail | Tryonia gilae | Petitioned for Listing, Under Review | Under Review | | AZ |
| Birds | Gila Woodpecker | Melanerpes uropygialis | Not Listed | Species of Concern | | |
| Birds | Gilded Flicker | Colaptes chrysoides | Not Listed | Species of Concern | | |
| Flowering Plants | Gilman's buckwheat | Eriogonum gilmanii | Not Listed | Resolved Taxon | | CA |
| Fishes | Gilt Darter | Percina evides | | Not Listed | | |
| Mammals | Giraffe | Giraffa camelopardalis | Proposed for Listing | Proposed Threatened | | |
| Insects | Giuliani's dubiraphian riffle beetle | Dubiraphia giulianii | Not Listed | Species of Concern | | CA |
| Insects | Giuliani's dune scarab | Pseudocotalpa giulianii | Not Listed | Resolved Taxon | | NV |
| Fishes | Gizzard Shad | Dorosoma cepedianum | | Not Listed | | |
| Flowering Plants | Glabrous allocarya | Plagiobothrys glaber | Not Listed | Resolved Taxon | | CA |
| Mammals | Glacier Bay water shrew | Sorex alaskanus | Not Listed | Species of Concern | | AK |
| Mammals | Glacier bear | Ursus americanus emmonsii | Not Listed | Resolved Taxon | | AK |
| Snails | Gladiator elimia | Elimia hydei | Not Listed | Species of Concern | | AL |
| Flowering Plants | Gladiator milk-vetch | Astragalus xiphoides | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Glandular dwarf-flax | Hesperolinon adenophyllum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Glass Mountain coral-root | Hexalectris nitida | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Glass Mountain rock-daisy | Perityle vitreomontana | Not Listed | Resolved Taxon | | TX |
| Birds | Glaucous macaw | Anodorhynchus glaucus | Listed | Endangered | | |
| Flowering Plants | Glaucous tauschia | Tauschia glauca | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Glenwood nesosydne planthopper | Nesosydne cyrtandricola | Not Listed | Species of Concern | | HI |
| Insects | Globose dune beetle | Coelus globosus | Not Listed | Species of Concern | | CA |
| Reptiles | Glossy snake | arizona elegans | Not Listed | Species of Concern | | |
| Snails | Glossy Wolfsnail | Euglandina texasiana | Not Listed | Resolved Taxon | | |
| Flowering Plants | Goat Canyon cottonwood | Populus hinckleyana | Not Listed | Resolved Taxon | | TX |
| Snails | Goat Cave Woodlandsnail | Ashmunella bequaerti | Not Listed | Resolved Taxon | | |
| Snails | Goat Mountain woodlandsnail | Ashmunella harrisi | Not Listed | Resolved Taxon | | |
| Mammals | Goat Peak pika | Ochotona princeps nigrescens | Not Listed | Species of Concern | | NM |
| Snails | Goddess Supercoil | Paravitrea alethia | Not Listed | Resolved Taxon | | |
| Flowering Plants | Godfrey's blazingstar | Liatris provincialis | Not Listed | Species of Concern | | |
| Flowering Plants | Godfrey's butterwort | Pinguicula ionantha | Listed | Threatened | | FL |
| Flowering Plants | Godfrey's golden aster | Chrysopsis godfreyi | Not Listed | Species of Concern | | |
| Flowering Plants | Godfrey's spiderlily | Hymenocallis godfreyi | Not Listed | Species of Concern | | |
| Flowering Plants | GodfreyÂ’s stitchwort | Minuartia godfreyi | Petitioned for Listing, Under Review | Under Review | | GA, SC |
| Flowering Plants | Godfry's privet | Forestiera godfreyi | Not Listed | Status Undefined | | GA |
| Insects | Goeden's lepidostoman caddisfly | Lepidostoma astaneum | Not Listed | Species of Concern | | OR |
| Mammals | Goeldi's marmoset | Callimico goeldii | Listed | Endangered | | |
| Mammals | Goff's southeastern pocket gopher | Geomys pinetis goffi | Not Listed | Resolved Taxon | | |
| Mammals | Goldbeach western pocket gopher | Thomomys mazama helleri | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Golden bladder-pod | Lesquerella aurea | Not Listed | Resolved Taxon | | CO, NM |
| Flowering Plants | Golden buckwheat | Eriogonum chrysops | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Goldenbush | Isocoma arguta | Not Listed | Species of Concern | | CA |
| Flowering Plants | Golden carpet | Gilmania luteola | Not Listed | Resolved Taxon | | CA |
| Birds | golden-cheeked warbler | Setophaga chrysoparia | Listed | Endangered | | TX |
| Birds | Golden conure | Aratinga guarouba | Listed | Threatened | | |
| Amphibians | Golden coqui | Eleutherodactylus jasperi | Listed | Threatened | | PR |
| Birds | Golden Eagle | Aquila chrysaetos | Not Listed | Species of Concern | | ID, MT, TX, WY |
| Insects | Golden eopenthes click beetle | Eopenthes auratus | Not Listed | Species of Concern | | HI |
| Flowering Plants | Golden glade cress | Leavenworthia aurea | Not Listed | Resolved Taxon | | OK |
| Insects | Golden-horned caddisfly | Neothremma genella | Not Listed | Species of Concern | | CA |
| Mammals | Golden langur | Trachypithecus (=Presbytis) geei | Listed | Endangered | | |
| Clams | Golden orb | Quadrula aurea | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | golden paintbrush | Castilleja levisecta | Delisted | Recovery | | OR, WA |
| Snails | Golden pebblesnail | Somatogyrus aureus | Not Listed | Species of Concern | | AL |
| Fishes | Golden Redhorse | Moxostoma erythrurum | | Not Listed | | |
| Mammals | Golden-rumped tamarin | Leontopithecus spp. | Listed | Endangered | | |
| Flowering Plants | Goldenseal | Hydrastis canadensis | Not Listed | Resolved Taxon | | AL, AR, CT, DE, GA, IA, IL, IN, KY, MD, MI, MN, MO, MS, NC, NY, OH, PA, TN, VA, VT, WI, WV |
| Flowering Plants | Golden sedge | Carex lutea | Listed | Endangered | | FL, NC, SC |
| Fishes | Golden Shiner | Notemigonus crysoleucas | | Not Listed | | |
| Birds | Golden-shouldered parakeet | Psephotus chrysopterygius | Listed | Endangered | | |
| Flowering Plants | Golden-spined hedgehog cactus | Echinocereus viridiflorus cylindricus | Not Listed | Species of Concern | | TX |
| Flowering Plants | Golden-spined prickly-pear | Opuntia aureispina | Not Listed | Resolved Taxon | | TX |
| Lichens | Golden spruce dots | Arthonia cupressina | Not Listed | Species of Concern | | |
| Flowering Plants | Golden wave tickseed | Coreopsis intermedia | Not Listed | Species of Concern | | LA, TX |
| Birds | Golden White-eye | Cleptornis marchei | Not Listed | Species of Concern | | |
| Birds | Golden-winged warbler | Vermivora chrysoptera | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC, TN, VA |
| Fishes | Goldeye | Hiodon alosoides | | Not Listed | | |
| Fishes | Goldfish | Carassius auratus | | Not Listed | | |
| Fishes | Goldline darter | Percina aurolineata | Listed | Threatened | | AL, GA, TN |
| Insects | Gold rush hanging fly | Orbittacus obscurus | Not Listed | Species of Concern | | CA |
| Fishes | Goldstripe Darter | Etheostoma parvipinne | | Not Listed | | |
| Amphibians | Goliath Frog | Conraua goliath | Listed | Threatened | | |
| Snails | Gonzales tryonia | Tryonia circumstriata (=stocktonensis) | Listed | Endangered | | TX |
| Flowering Plants | Goodding fameflower | Talinum gooddingii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Goodding's ash | Fraxinus gooddingii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Gooddings bladder-pod | Lesquerella gooddingii | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | Goodding''s onion | Allium gooddingii | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | Goodrich's Blazingstar | Mentzelia goodrichii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Goose Creek milkvetch | Astragalus anserinus | Not Listed | Resolved Taxon | | ID, NV, UT |
| Fishes | Goose Lake lamprey | Lampetra tridentata | Not Listed | Species of Concern | | CA, OR |
| Fishes | Goose Lake redband trout | Oncorhynchus mykiss ssp. | Not Listed | Species of Concern | | CA, OR |
| Fishes | Goose Lake sucker | Catostomus occidentalis lacusanserinus | Not Listed | Species of Concern | | CA, OR |
| Fishes | Goose Lake tui chub | Siphateles bicolor thalassinus | Not Listed | Status Undefined | | CA, OR |
| Snails | Goose Valley pebblesnail | Fluminicola anserinus | Not Listed | Resolved Taxon | | CA |
| Arachnids | Gooty Ornamental Tarantula | Poecilotheria metallica | Petitioned for Listing, Under Review | Under Review | | |
| Amphibians | Gopher Frog | Lithobates capito | Petitioned for Listing, Under Review | Under Review | | GA, SC |
| Reptiles | Gopher tortoise | Gopherus polyphemus | Not Listed | Resolved Taxon | | AL, FL, GA, SC |
| Reptiles | Gopher tortoise | Gopherus polyphemus | Listed | Threatened | | AL, LA, MS |
| Mammals | Goral | Naemorhedus goral | Listed | Endangered | | |
| Ferns and Allies | gorge filmy fern | Hymenophyllum tayloriae | Not Listed | Species of Concern | | NC |
| Flowering Plants | Gorge fleabane | Erigeron oreganus | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | Gorge leafy liverwort | Plagiochila caduciloba | Not Listed | Status Undefined | | GA, NC |
| Flowering Plants | Gorge moss | Bryocrumia vivicolor | Not Listed | Species of Concern | | NC |
| Birds | Gorgeted wood-quail | Odontophorus strophium | Listed | Endangered | | |
| Mammals | Gorilla | Gorilla gorilla | Listed | Endangered | | |
| Flowering Plants | Gorman aster | Eucephalus gormanii | Not Listed | Species of Concern | | CA, NV, OR |
| Mammals | Gould's mouse | Pseudomys gouldii | Listed | Endangered | | |
| Arachnids | Government Canyon Bat Cave meshweaver | Cicurina vespera | Listed | Endangered | | TX |
| Arachnids | Government Canyon Bat Cave spider | Tayshaneta microps | Listed | Endangered | | TX |
| Conifers and Cycads | Gowen cypress | Cupressus goveniana ssp. goveniana | Listed | Threatened | | CA |
| Flowering Plants | Graceful peperomia | Peperomia obovatilimba | Not Listed | Resolved Taxon | | HI |
| Birds | Grace's Warbler | Setophaga graciae | Not Listed | Species of Concern | | |
| Insects | Gracile anchotefflus ground beetle | Anchotefflus gracilis | Not Listed | Species of Concern | | HI |
| Crustaceans | Grady's cave amphipod | Stygobromus gradyi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Graham beardtongue | Penstemon grahamii | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | Graham catseye | Cryptantha grahamii | Not Listed | Resolved Taxon | | UT |
| Mammals | Graham Mountains long-tailed vole | Microtus longicaudus leucophaeus | Not Listed | Resolved Taxon | | AZ |
| Mammals | Graham Mountains pocket gopher | Thomomys umbrinus grahamensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Graham's Columbine | Aquilegia grahamii | Not Listed | Resolved Taxon | | |
| Arachnids | Graham's harvestman | Banksula grahami | Not Listed | Status Undefined | | |
| Flowering Plants | Graham's twinpod | Physaria grahamii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Grand Canyon catchfly | Silene rectiramea | Not Listed | Resolved Taxon | | AZ |
| Arachnids | Grand Canyon cave pseudoscorpion | Archeolarca cavicola | Petitioned for Listing, Under Review | Under Review | | AZ |
| Flowering Plants | Grand Canyon rose | Rosa stellata abyssa | Not Listed | Species of Concern | | AZ |
| Reptiles | Grand Cayman ground iguana | Cyclura lewisi | Listed | Endangered | | |
| Insects | Grande stripetail stonefly | Isoperla jewetti | Not Listed | Resolved Taxon | | NM, TX |
| Crustaceans | Grandfather Mountain crayfish | Cambarus eeseeohensis | Not Listed | Status Undefined | | NC |
| Flowering Plants | Grand Junction catseye | Cryptantha aperta | Not Listed | Species of Concern | | CO |
| Flowering Plants | Grand Junction milk-vetch | Astragalus linifolius | Not Listed | Resolved Taxon | | CO |
| Snails | Grand Wash springsnail | Pyrgulopsis bacchus | Petitioned for Listing, Under Review | Under Review | | AZ |
| Flowering Plants | Granite Dome Goldenrod | Solidago simulans | Not Listed | Species of Concern | | NC |
| Reptiles | Granite night lizard | Xantusia henshawi | Not Listed | Species of Concern | | |
| Snails | Granite pebblesnail | Somatogyrus hinkleyi | Not Listed | Species of Concern | | AL |
| Reptiles | Granite spiny lizard | sceloporus orcutti | Not Listed | Species of Concern | | |
| Snails | Grapevine Springs elongate tryonia | Tryonia margae | Not Listed | Species of Concern | | CA |
| Snails | Grapevine Springs squat tryonia | Tryonia rowlandsi | Not Listed | Species of Concern | | CA |
| Birds | Grasshopper Sparrow | Ammodramus savannarum | Not Listed | Species of Concern | | |
| Birds | Grasshopper Sparrow | Ammodramus savannarum ammolegus | Not Listed | Species of Concern | | |
| Birds | Grasshopper Sparrow | Ammodramus savannarum perpallidus | Not Listed | Species of Concern | | CA |
| Birds | Grasshopper Sparrow | Ammodramus savannarum pratensis | Not Listed | Species of Concern | | |
| Flowering Plants | Grass milk-vetch | Astragalus chloodes | Not Listed | Resolved Taxon | | UT |
| Birds | Grass owl | Tyto longimembris | Not Listed | Resolved Taxon | | |
| Fishes | Grass Pickerel | Esox americanus | | Not Listed | | |
| Fishes | Grass Valley speckled dace | Rhinichthys osculus reliquus | Not Listed | Resolved Taxon | | NV |
| Insects | Grassy Cove cave beetle | Pseudanophthalmus jonesi | Not Listed | Species of Concern | | TN |
| Arachnids | Grassy Creek Cave spider | Nesticus dilutus | Not Listed | Species of Concern | | TN |
| Snails | Grated tryonia | Tryonia clathrata | Not Listed | Resolved Taxon | | NV |
| Fishes | Gravel Chub | Erimystax x-punctatus | | Not Listed | | |
| Birds | Gray-backed Tern | Onychoprion lunatus | Not Listed | Species of Concern | | |
| Reptiles | Gray-banded king snake | Lampropeltis mexicana alterna | Not Listed | Resolved Taxon | | TX |
| Mammals | Gray bat | Myotis grisescens | Listed | Endangered | | AL, AR, GA, IA, IL, IN, KS, KY, MO, MS, NC, OH, OK, SC, TN, VA, WV |
| Flowering Plants | gray cat's-eye | Oreocarya leucophaea | Not Listed | Status Undefined | | WA |
| Reptiles | Gray-checkered whiptail | Cnemidophorus dixoni | Not Listed | Species of Concern | | NM, TX |
| Mammals | Gray (=entellus) langur | Semnopithecus (=Presbytis) entellus | Listed | Endangered | | |
| Birds | Gray-faced Petrel | Pterodroma gouldi | Not Listed | Species of Concern | | |
| Mammals | Gray-footed Chipmunk | Tamias canipes | Not Listed | Species of Concern | | NM, TX |
| Snails | grayfoot mantleslug | philomycus bisdodus | Not Listed | Resolved Taxon | | |
| Mammals | Gray fox | Urocyon cinereoargenteus ssp. cinereoargenteus | Not Listed | Status Undefined | | |
| Birds | Gray-headed Chickadee | Poecile cinctus | Not Listed | Species of Concern | | |
| Birds | Gray-headed Chickadee | Poecile cinctus lathami | Not Listed | Species of Concern | | |
| Birds | Gray Nightjar | Caprimulgus jotaka | Not Listed | Species of Concern | | |
| Insects | Gray oechalia stink bug | Oechalia grisea | Not Listed | Species of Concern | | HI |
| Fishes | Gray redhorse | moxostoma congestum | Not Listed | Species of Concern | | |
| Flowering Plants | Gray rock-daisy | Perityle cinerea | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Gray's lily | Lilium grayi | Not Listed | Species of Concern | | NC |
| Crustaceans | Grayson crayfish ostracod | Ascetocthere cosmeta | Not Listed | Species of Concern | | NC, VA |
| Flowering Plants | Gray's saxifrage | Saxifraga caroliniana | Not Listed | Species of Concern | | GA, NC, TN, VA, WV |
| Birds | Gray vireo | Vireo vicinior | Not Listed | Species of Concern | | |
| Mammals | Gray whale | Eschrichtius robustus | Delisted | Recovery | | |
| Mammals | Gray whale | Eschrichtius robustus | Listed | Endangered | | |
| Mammals | Gray wolf | Canis lupus | Listed | Threatened | | MN |
| Mammals | Gray wolf | Canis lupus | Delisted | Recovery | | ID, MT, OR, UT, WA, WY |
| Mammals | Gray wolf | Canis lupus | Listed | Endangered | | CA, MI, MN, NV, OR, WA, WI |
| Mammals | Gray wolf | Canis lupus | Listed | Experimental Population, Non-Essential | | CO |
| Mammals | Gray wolf | Canis lupus | Not Listed | Resolved Taxon | | AZ, CA, ID, MT, NV, OR, UT, WA, WY |
| Mammals | Gray wolf | Canis lupus | Not Listed | Resolved Taxon | | CA, CO, ID, MT, NV, OR, UT, WA, WY |
| Fishes | Great Barracuda, Kaku | Sphyraena barracuda | | Not Listed | | |
| Reptiles | Great Basin collared lizard | Crotaphytus bicinctores | | Not Listed | | |
| Flowering Plants | Great Basin fishhook cactus | Sclerocactus pubispinus | Not Listed | Resolved Taxon | | NV, UT |
| Snails | Great Basin ramshorn | Helisoma newberryi | Not Listed | Resolved Taxon | | CA, OR, WY |
| Fishes | Great Basin redband trout | Oncorhynchus mykiss ssp. | Not Listed | Resolved Taxon | | |
| Birds | Great Black-backed Gull | Larus marinus | Not Listed | Species of Concern | | |
| Birds | Great blue heron | Ardea herodias | Not Listed | Species of Concern | | |
| Birds | Great Blue Heron | Ardea herodias fannini | Not Listed | Species of Concern | | |
| Birds | Great Blue Heron | Ardea herodias occidentalis | Not Listed | Species of Concern | | |
| Birds | Great Cormorant | Phalacrocorax carbo | Not Listed | Species of Concern | | |
| Birds | Great Crested Flycatcher | Myiarchus crinitus | Not Listed | Species of Concern | | |
| Insects | Greater Adams Cave beetle | Pseudanophthalmus pholeter | Not Listed | Resolved Taxon | | KY |
| Birds | Greater adjutant | Leptoptilos dubius | Listed | Endangered | | |
| Mammals | Greater Monkey-Faced Bat | Pteralopex flanneryi | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Greater redhorse | Moxostoma valenciennesi | Not Listed | Species of Concern | | IL, IN, KY, MI, MN, ND, NY, OH, WI |
| Birds | Greater sage-grouse | Centrocercus urophasianus | Not Listed | Resolved Taxon | | CA, CO, ID, MT, ND, NV, OR, SD, UT, WA, WY |
| Birds | Greater sage-grouse | Centrocercus urophasianus | Proposed for Listing | Proposed Threatened | | CA, NV |
| Birds | Greater sage-grouse | Centrocercus urophasianus | Not Listed | Resolved Taxon | | |
| Reptiles | Greater Saint Croix Skink | Spondylurus magnacruzae | Not Listed | Resolved Taxon | | VI |
| Birds | Greater Sandhill Crane | Grus canadensis tabida | Not Listed | Status Undefined | | |
| Reptiles | Greater Virgin Islands Skink | Spondylurus spilonotus | Not Listed | Resolved Taxon | | VI |
| Mammals | Greater western mastiff-bat | Eumops perotis californicus | Not Listed | Species of Concern | | AZ, CA, NM, TX |
| Birds | Great Frigatebird | Fregata minor | Not Listed | Species of Concern | | |
| Birds | Great Frigatebird | Fregata minor palmerstoni | Not Listed | Species of Concern | | |
| Birds | Great green macaw | Ara ambiguus | Listed | Endangered | | |
| Birds | Great horned owl | Bubo virginianus | | Not Listed | | |
| Birds | Great Indian bustard | Ardeotis (=Choriotis) nigriceps | Listed | Endangered | | |
| Mammals | Great Indian rhinoceros | Rhinoceros unicornis | Listed | Endangered | | |
| Amphibians | Great Plains Toad | Anaxyrus cognatus | | Not Listed | | |
| Insects | Great Sand Dunes Anthicid Beetle | Amblyderus werneri | Not Listed | Resolved Taxon | | |
| Insects | Great Sand Dunes Tiger Beetle | Cicindela theatina | Not Listed | Resolved Taxon | | |
| Birds | Great Shearwater | Puffinus gravis | Not Listed | Species of Concern | | |
| Birds | Great Skua | Stercorarius skua | Not Listed | Species of Concern | | |
| Fishes | Greenback Cutthroat trout | Oncorhynchus clarkii stomias | Listed | Threatened | | CO |
| Insects | Greenbanded 'ohe'ohe leafroller | Spheterista pterotropiana | Not Listed | Species of Concern | | HI |
| Clams | Green blossom (pearlymussel) | Epioblasma torulosa gubernaculum | Delisted | Extinction | | TN, VA |
| Crustaceans | Greenbrier Cave amphipod | Stygobromus emarginatus | Not Listed | Resolved Taxon | | MD, WV |
| Crustaceans | Greenbrier Cave crayfish | Cambarus nerterius | Petitioned for Listing, Under Review | Under Review | | WV |
| Snails | Greenbrier cavesnail | Fontigens turritella | Not Listed | Species of Concern | | WV |
| Insects | Greenbrier Valley cave beetle | Pseudanophthalmus fuscus fuscus | Not Listed | Species of Concern | | WV |
| Arachnids | Greenbrier Valley cave pseudoscorpion | Kleptochthonius henroti | Not Listed | Species of Concern | | WV |
| Insects | Green carposinid moth | Carposina viridis | Not Listed | Species of Concern | | HI |
| Crustaceans | Green Crab | Carcinus maenas | | Not Listed | | |
| Flowering Plants | Greene's mariposa lily | Calochortus greenei | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Greene's popcornflower | Plagiobothrys greenei | Not Listed | Species of Concern | | |
| Insects | Greenest tiger beetle | Cicindela tranquebarica viridissima | Not Listed | Species of Concern | | CA |
| Flowering Plants | Greene's tuctoria | Tuctoria greenei | Listed | Endangered | | CA |
| Flowering Plants | Green fiddleneck | Amsinckia vernicosa | Not Listed | Resolved Taxon | | CA |
| Snails | Greenfield rams-horn | Taphius eucosmius eucosmius | Not Listed | Resolved Taxon | | NC |
| Clams | Green floater | Lasmigona subviridis | Proposed for Listing | Proposed Threatened | | GA, MD, NC, NJ, NY, PA, TN, VA, WV |
| Flowering Plants | Greenflower nipple cactus | Mammillaria viridiflora | Not Listed | Resolved Taxon | | AZ |
| Amphibians | Green Frog | Lithobates clamitans | | Not Listed | | |
| Amphibians | Green Frog | Lithobates clamitans | | Not Listed | | |
| Insects | Green glyphodes moth | Glyphodes exaula | Not Listed | Species of Concern | | HI |
| Flowering Plants | Greenhorn adobe-lily | Fritillaria striata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Greenhorn fritillary | Fritillaria brandegeei | Not Listed | Resolved Taxon | | CA |
| Birds | Greenland white-tailed eagle | Haliaeetus albicilla groenlandicus | Listed | Endangered | | |
| Flowering Plants | Green liveforever | Dudleya virens | Not Listed | Species of Concern | | CA |
| Flowering Plants | Greenman's desert-parsley | Lomatium greenmanii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Greenman's hexalectris | Hexalectris grandiflora | Not Listed | Resolved Taxon | | TX |
| Birds | Green Parakeet | Aratinga holochlora | Not Listed | Species of Concern | | |
| Flowering Plants | Green Pitcher Plant | Sarracenia oreophila | Listed | Endangered | | AL, GA, NC |
| Amphibians | Green salamander | Aneides aeneus | Not Listed | Status Undefined | | GA, NC, SC |
| Fishes | Green sawfish | Pristis zijsron | Listed | Endangered | | |
| Crustaceans | Greensboro burrowing crayfish | Cambarus catagius | Not Listed | Resolved Taxon | | NC |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | AL, FL, GA, MD, NC, PR, SC, TX, VA |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Endangered | | |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | HI, UM |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | VI |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Endangered | | AS, GU, MP |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Endangered | | GU, MP, PW |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | |
| Reptiles | Green sea turtle | Chelonia mydas | Listed | Threatened | | CA |
| Fishes | Greenside Darter | Etheostoma blennioides | | Not Listed | | |
| Insects | Green Springs Mountain farulan caddisfly | Farula davisi | Not Listed | Species of Concern | | OR |
| Fishes | green sturgeon | Acipenser medirostris | | Not Listed | | |
| Fishes | green sturgeon | Acipenser medirostris | Listed | Threatened | | |
| Fishes | Green Sunfish | Lepomis cyanellus | | Not Listed | | |
| Flowering Plants | Greensword | Argyroxiphium virescens | Not Listed | Resolved Taxon | | HI |
| Birds | Green-tailed Towhee | Pipilo chlorurus | Not Listed | Species of Concern | | |
| Fishes | Greenthroat darter | Etheostoma lepidum | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | Green-tinged paintbrush | Castilleja chlorotica | Not Listed | Species of Concern | | CA, NV, OR |
| Amphibians | Green Toad | Anaxyrus debilis | | Not Listed | | |
| Insects | Greenwell's long-horned beetle | Plagithmysus greenwelli | Not Listed | Species of Concern | | HI |
| Birds | Green-winged teal | Anas crecca | Not Listed | Status Undefined | | |
| Flowering Plants | Greenwood's Heath goldenrod | Ericameria lignumviridis | Not Listed | Resolved Taxon | | |
| Birds | Grenada gray-fronted dove | Leptotila rufaxilla wellsi | Listed | Endangered | | |
| Birds | Grenada hook-billed kite | Chondrohierax uncinatus mirus | Listed | Endangered | | |
| Mammals | Grevy's zebra | Equus grevyi | Listed | Threatened | | |
| Birds | grey-cheeked parakeet | Brotogeris pyrrhoptera | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Grey-headed blackbird | Turdus poliocephalus poliocephalus | Not Listed | Resolved Taxon | | |
| Birds | Grey-necked rockfowl | Picathartes oreas | Listed | Endangered | | |
| Insects | Grey's silverspot | Speyeria atlantis greyi | Not Listed | Species of Concern | | NV |
| Birds | Grey-winged cotinga | Tijuca condita | Not Listed | Status Undefined | | |
| Flowering Plants | Griffith's saltbush | Atriplex griffithsii | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | Grimes vetchling | Lathyrus grimesii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Grimy ivesia | Ivesia rhypara rhypara | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Grizzled skipper | Pyrgus centaureae | Not Listed | Species of Concern | | DE, KY, MD, MI, NC, NJ, NY, OH, PA, VA, WV |
| Mammals | Grizzly bear | Ursus arctos horribilis | Listed | Experimental Population, Non-Essential | | |
| Mammals | Grizzly bear | Ursus arctos horribilis | Listed | Threatened | | ID, MT, WA, WY |
| Fishes | Grotto Sculpin | Cottus specus | Listed | Endangered | | MO |
| Birds | Ground parrot | Pezoporus wallicus | Listed | Endangered | | |
| Flowering Plants | Ground-spreading tick-trefoil | Desmodium humifusum | Not Listed | Species of Concern | | CT, DE, MA, MD, NJ, NY, PA |
| Arachnids | Grubbs' cave pseudoscorpion | Aphrastochthonius grubbsi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Guaco | Mikania stevensiana | Not Listed | Resolved Taxon | | PR, VI |
| Fishes | Guadalupe bass | Micropterus treculii | Not Listed | Species of Concern | | TX |
| Arachnids | Guadalupe cave pseudoscorpion | Archeolarca guadalupensis | Not Listed | Resolved Taxon | | TX |
| Fishes | Guadalupe Darter | Percina apristis | | Not Listed | | |
| Clams | Guadalupe Fatmucket | Lampsilis bergmanni | Listed | Endangered | | TX |
| Flowering Plants | Guadalupe fescue | Festuca ligulata | Listed | Endangered | | TX |
| Mammals | Guadalupe fur seal | Arctocephalus townsendi | Listed | Threatened | | |
| Flowering Plants | Guadalupe Island lupine | Lupinus guadalupensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Guadalupe Mountain necklacepod | Sophora gypsophila | | Not Listed | | |
| Flowering Plants | Guadalupe Mountain sedge | carex mckittrickensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Guadalupe Mountains mescal bean | Sophora gypsophila guadalupensis | Not Listed | Resolved Taxon | | NM, TX |
| Insects | Guadalupe Mountains tiger beetle | Cicindela politula petrophila | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Guadalupe Mountain violet | Viola guadalupensis | Not Listed | Resolved Taxon | | TX |
| Birds | Guadalupe Murrelet | Synthliboramphus hypoleucus | Not Listed | Resolved Taxon | | CA |
| Clams | Guadalupe Orb | Cyclonaias necki | Listed | Endangered | | TX |
| Flowering Plants | Guadalupe pincushion cactus | Escobaria guadalupensis | Not Listed | Resolved Taxon | | TX |
| Fishes | Guadalupe roundnose Minnow | Dionda nigrotaeniata | Not Listed | Species of Concern | | |
| Flowering Plants | Guadalupe smooth aster | Aster laevis guadalupensis | Not Listed | Species of Concern | | NM, TX |
| Mammals | Guadalupe southern pocket gopher | Thomomys umbrinus guadalupensis | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Guadalupe valerian | Valeriana texana | Not Listed | Resolved Taxon | | NM, TX |
| Birds | Guadeloupe house wren | Troglodytes aedon guadeloupensis | Listed | Endangered | | |
| Snails | Guadelupe Woodlandsnail | Ashmunella carlsbadensis | Petitioned for Listing, Under Review | Under Review | | |
| Amphibians | Guajon | Eleutherodactylus cooki | Listed | Threatened | | PR |
| Fishes | Gualala Roach | Hesperoleucus parvipinnis | Not Listed | Species of Concern | | CA |
| Birds | Guam broadbill | Myiagra freycineti | Delisted | Extinction | | GU |
| Birds | Guam kingfisher | Todiramphus cinnamominus | Listed | Endangered | | GU |
| Birds | Guam kingfisher | Todiramphus cinnamominus | Listed | Experimental Population, Non-Essential | | |
| Birds | Guam rail | Gallirallus owstoni | Listed | Experimental Population, Non-Essential | | GU, MP |
| Birds | Guam rail | Gallirallus owstoni | Listed | Endangered | | GU |
| Birds | Guam rufous-fronted fantail | Rhipidura rufifrons uraniae | Not Listed | Resolved Taxon | | GU |
| Snails | Guam tree snail | Partula radiolata | Listed | Endangered | | GU |
| Birds | Guam white-throated ground-dove | Gallicolumba xanthonura xanthonura | Not Listed | Resolved Taxon | | GU, MP |
| Conifers and Cycads | Guatemalan Fir (=pinabete) | Abies guatemalensis | Listed | Threatened | | |
| Mammals | Guatemalan jaguarundi | Herpailurus (=Felis) yagouaroundi fossata | Listed | Endangered | | |
| Mammals | Guizhou snub-nosed monkey | Rhinopithecus brelichi | Listed | Endangered | | |
| Flowering Plants | Gulf beach sunflower | Helianthus debilis vestitus | Not Listed | Species of Concern | | |
| Mammals | Gulf Coast hog-nosed skunk | Conepatus leuconotus texensis | Not Listed | Resolved Taxon | | TX |
| Mammals | Gulf Coast jaguarundi | Puma yagouaroundi cacomitli | Listed | Endangered | | TX |
| Flowering Plants | Gulfcoast lupine | Lupinus westianus | Not Listed | Species of Concern | | |
| Reptiles | Gulf Coast Smooth Softshell Turtle | Apalone mutica calvata | | Not Listed | | |
| Insects | Gulf Coast solitary bee | Hesperapis oraria | | Not Listed | | AL, MS |
| Amphibians | Gulf Coast Waterdog | Necturus beyeri | | Not Listed | | |
| Fishes | Gulf Flounder | Paralichthys albigutta | | Not Listed | | |
| Fishes | Gulf Grouper | Mycteroperca jordani | Listed | Endangered | | |
| Amphibians | Gulf Hammock dwarf siren | Pseudobranchus striatus lustricolus | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Gulf Menhaden | Brevoortia patronus | | Not Listed | | |
| Clams | Gulf moccasinshell | Medionidus penicillatus | Listed | Endangered | | AL, FL, GA |
| Mammals | Gulf of Mexico Bryde's Whale | Balaenoptera edeni | Listed | Endangered | | |
| Reptiles | Gulf salt marsh snake | Nerodia clarkii | Not Listed | Species of Concern | | |
| Fishes | Gulf sturgeon | Acipenser oxyrinchus (=oxyrhynchus) desotoi | Listed | Threatened | | AL, FL, LA, MS |
| Flowering Plants | Gulf Sweet pitcherplant | Sarracenia rubra ssp. gulfensis | Petitioned for Listing, Under Review | Under Review | | GA |
| Birds | Gull-billed Tern | Gelochelidon nilotica | Not Listed | Species of Concern | | |
| Flowering Plants | Gumbo milk-vetch | Astragalus ampullarius | Not Listed | Species of Concern | | AZ, UT |
| Mammals | Gunnison Island kangaroo rat | Dipodomys microps alfredi | Not Listed | Species of Concern | | UT |
| Flowering Plants | Gunnison milk-vetch | Astragalus anisus | Not Listed | Species of Concern | | CO |
| Birds | Gunnison Sage-grouse | Centrocercus minimus | Listed | Threatened | | CO, UT |
| Mammals | Gunnison's prairie dog | Cynomys gunnisoni | Not Listed | Resolved Taxon | | CO |
| Birds | Gurney's pitta | Pitta gurneyi | Listed | Endangered | | |
| Flowering Plants | Guthrie's (=Pyne's) ground-plum | Astragalus bibullatus | Listed | Endangered | | TN |
| Crustaceans | Guyandotte River crayfish | Cambarus veteranus | Listed | Endangered | | WV |
| Flowering Plants | Gypsum milk-vetch | Astragalus gypsodes | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | Gypsum scalebroom | Lepidospartum burgessii | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Gypsum Valley Cryptantha | Cryptantha gypsophila | Not Listed | Resolved Taxon | | |
| Flowering Plants | Gypsum wild-buckwheat | Eriogonum gypsophilum | Listed | Threatened | Proposed Delisting | NM, TX |
| Insects | Haas' `iliahi long-horned beetle | Plagithmysus haasi | Not Listed | Species of Concern | | HI |
| Snails | Hacheta Grande woodlandsnail | Ashmunella hebardi | Not Listed | Resolved Taxon | | NM |
| Clams | Haddleton lampmussel | Lampsilis haddletoni | Not Listed | Species of Concern | | |
| Insects | Haddock's rhyacophilan caddisfly | Rhyacophila haddocki | Not Listed | Species of Concern | | OR |
| Flowering Plants | haha | Cyanea crispa | Listed | Endangered | | HI |
| Flowering Plants | haha | Cyanea dunbariae | Listed | Endangered | | HI |
| Flowering Plants | haha | Cyanea duvalliorum | Listed | Endangered | | HI |
| Flowering Plants | haha | Cyanea gibsonii | Listed | Endangered | | HI |
| Flowering Plants | haha | Cyanea magnicalyx | Listed | Endangered | | HI |
| Flowering Plants | haha | Cyanea maritae | Listed | Endangered | | HI |
| Flowering Plants | haha | Cyanea mauiensis | Listed | Endangered | | HI |
| Flowering Plants | haha | Cyanea munroi | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea acuminata | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea asarifolia | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea asplenifolia | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea calycina | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea copelandii ssp. copelandii | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea copelandii ssp. haleakalaensis | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea dolichopoda | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea eleeleensis | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea glabra | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea grimesiana ssp. grimesiana | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea grimesiana ssp. obatae | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea hamatiflora ssp. carlsonii | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea hamatiflora ssp. hamatiflora | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea humboldtiana | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea kolekoleensis | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea koolauensis | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea kuhihewa | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea kunthiana | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea lanceolata | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea lobata | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea longiflora | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea longissima | Not Listed | Species of Concern | | HI |
| Flowering Plants | Haha | Cyanea mannii | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea marksii | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea mceldowneyi | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea obtusa | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea pinnatifida | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea procera | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea profuga | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea pseudofauriei | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Haha | Cyanea purpurellifolia | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea recta | Listed | Threatened | | HI |
| Flowering Plants | Haha | Cyanea remyi | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea rivularis | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea shipmanii | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea stictophylla | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea st.-johnii | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea superba | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea truncata | Listed | Endangered | | HI |
| Flowering Plants | Haha | Cyanea undulata | Listed | Endangered | | HI |
| Flowering Plants | haha nui | Cyanea horrida | Listed | Endangered | | HI |
| Insects | Hahnel's Amazonian swallowtail butterfly | Parides hahneli | Listed | Endangered | | |
| Ferns and Allies | Hairy halberd fern | Tectaria coriandrifolia | Not Listed | Species of Concern | | |
| Flowering Plants | Hairy Lemmon's needlegrass | Stipa lemmonii pubescens | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hairy Orcutt grass | Orcuttia pilosa | Listed | Endangered | | CA |
| Flowering Plants | Hairy-peduncled beaked-rush | Rhynchospora crinipes | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | Hairy pod vetch | Vicia minutiflora | Not Listed | Resolved Taxon | | OK, TX |
| Flowering Plants | Hairy rattleweed | Baptisia arachnifera | Listed | Endangered | | GA |
| Flowering Plants | Hairy stickleaf | Mentzelia hirsutissima stenophylla | Not Listed | Resolved Taxon | | CA |
| Mammals | Hairy-Tailed Bats | Lasiurus sp. | | Not Listed | | |
| Mammals | Hairy-Tailed Bats | Lasiurus sp. | | Not Listed | | |
| Crustaceans | hairy water flea | Dumontia oregonensis | Not Listed | Species of Concern | | |
| Flowering Plants | Hairy wild indigo | Baptisia calycosa villosa | Not Listed | Species of Concern | | |
| Birds | hairy woodpecker | Picoides villosus | Not Listed | Status Undefined | | |
| Mammals | Haitian solenodon | Solenodon paradoxus | Listed | Endangered | | |
| Flowering Plants | haiwale | Cyrtandra ferripilosa | Listed | Endangered | | HI |
| Flowering Plants | haiwale | Cyrtandra nanawaleensis | Listed | Endangered | | HI |
| Flowering Plants | haiwale | Cyrtandra wagneri | Listed | Endangered | | HI |
| Flowering Plants | Haiwale | Cyrtandra gracilis | Listed | Endangered | | HI |
| Flowering Plants | Haiwale | Cyrtandra paliku | Listed | Endangered | | HI |
| Flowering Plants | Haiwale | Cyrtandra waiolani | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra biserrata | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra crenata | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra dentata | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra filipes | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra giffardii | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra halawensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra hematos | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra kaulantha | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra kealiae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra limahuliensis | Listed | Threatened | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra lydgatei | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra macrocalyx | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra menziesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra munroi | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra oenobarba | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra oxybapha | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra pickeringii | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra polyantha | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra pruinosa | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra sandwicensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra sessilis | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra subumbellata | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra tintinnabula | Listed | Endangered | | HI |
| Flowering Plants | Ha`iwale | Cyrtandra viridiflora | Listed | Endangered | | HI |
| Flowering Plants | Hala pepe | Dracaena fernaldii | Listed | Endangered | | HI |
| Flowering Plants | Hala pepe | Dracaena forbesii | Listed | Endangered | | HI |
| Flowering Plants | Hala pepe | Dracaena konaensis | Listed | Endangered | | HI |
| Insects | Haleakala deropristus ground beetle | Deropristus deroderus | Not Listed | Species of Concern | | HI |
| Insects | Haleakala ectemnius sphecid wasp | Ectemnius haleakalae | Not Listed | Species of Concern | | HI |
| Insects | Haleakala flightless thyrocopa moth | Thyrocopa apatela | Not Listed | Species of Concern | | HI |
| Insects | Haleakala micromus brown lacewing | Micromus haleakalae | Not Listed | Species of Concern | | HI |
| Insects | Haleakala pseudobroscus ground beetle | Pseudobroscus lentus | Not Listed | Species of Concern | | HI |
| Insects | Haleakala yellow-faced bee | Hylaeus haleakalae | Not Listed | Species of Concern | | HI |
| Fishes | Halloween darter | Percina crypta | Petitioned for Listing, Under Review | Under Review | | AL, FL, GA |
| Flowering Plants | Hall's bulrush | Schoenoplectiella hallii | Not Listed | Resolved Taxon | | AL, GA, IA, IL, IN, KS, KY, MA, MI, MO, NE, OH, OK, SC, TX, WI |
| Flowering Plants | Hall's bush mallow | Malacothamnus hallii | | Not Listed | | |
| Flowering Plants | Hall's daisy | Erigeron aequifolius | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hall's madia | Madia hallii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Hall's monardella | Monardella macrantha hallii | Not Listed | Resolved Taxon | | CA |
| Ferns and Allies | Hall's Pocket moss | Fissidens hallii | Not Listed | Status Undefined | | |
| Flowering Plants | Hall's tarweed | Hemizonia halliana | Not Listed | Resolved Taxon | | CA |
| Snails | Hamilton Holospira | Holospira hamiltoni | Not Listed | Resolved Taxon | | |
| Flowering Plants | Hamilton milk-vetch | Astragalus hamiltonii | Not Listed | Resolved Taxon | | UT |
| Snails | Hamlin Valley pyrg | Pyrgulopsis hamlinensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Hammitt's clay-cress | sibaropsis hammittii | Not Listed | Species of Concern | | |
| Flowering Plants | Hanaupah laphamia | Perityle villosa | Not Listed | Species of Concern | | CA |
| Snails | Hanna's Vertigo | Vertigo hannai | Not Listed | Resolved Taxon | | |
| Insects | Hanson's appalachian stonefly | Hansonoperla appalachia | Not Listed | Resolved Taxon | | KY, MA, NH, SC, TN |
| Flowering Plants | Hao | Rauvolfia sandwicensis sandwicensis | Not Listed | Resolved Taxon | | HI |
| Snails | Hapawai | Neritina vespertina | | Not Listed | | |
| Crustaceans | Hara's cave amphipod | Stygobromus harai | Not Listed | Resolved Taxon | | CA |
| Mammals | Harbor Porpoise | Phocoena phocoena | Not Listed | Status Undefined | | |
| Flowering Plants | Hardham's bedstraw | Galium hardhamiae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hardham's evening-primrose | Camissonia hardhamiae | Not Listed | Species of Concern | | CA |
| Crustaceans | Hardin crayfish | Orconectes wrighti | Petitioned for Listing, Under Review | Under Review | | MS, TN |
| Flowering Plants | Hardtoe seepweed | Suaeda nigra | Not Listed | Species of Concern | | TX |
| Flowering Plants | Hardy Creek barberry | Berberis nervosa mendocinensis | Not Listed | Species of Concern | | CA |
| Snails | Hardy pyrg | Pyrgulopsis marcida | Not Listed | Resolved Taxon | | NV |
| Insects | Hardy's aegialian scarab | Aegialia hardyi | Not Listed | Resolved Taxon | | NV |
| Insects | Hardy's dune beetle | Anomala hardyorum | Not Listed | Resolved Taxon | | |
| Fishes | Harelip sucker | Moxostoma lacerum | Not Listed | Resolved Taxon | | AL, GA, IN, KY, OH, TN, VA |
| Fishes | Harlequin Darter | Etheostoma histrio | | Not Listed | | |
| Birds | Harlequin duck | Histrionicus histrionicus | Not Listed | Resolved Taxon | | AK, AR, AZ, CA, CO, CT, DE, IA, ID, KS, MA, MD, ME, MN, MO, MT, NE, NH, NJ, NM, NV, OK, OR, RI, SD, TX, UT, WA, WY |
| Snails | Harney Lake springsnail | Pyrgulopsis hendersoni | Not Listed | Resolved Taxon | | |
| Flowering Plants | Harperella | Ptilimnium nodosum | Listed | Endangered | | AL, AR, GA, MD, NC, OK, PA, SC, VA, WV |
| Flowering Plants | Harper's beauty | Harperocallis flava | Listed | Endangered | | FL |
| Flowering Plants | Harper's dodder | Cuscuta harperi | Not Listed | Species of Concern | | AL, GA |
| Flowering Plants | Harper's fimbristylis | Fimbristylis perpusilla | Petitioned for Listing, Under Review | Under Review | | GA, SC, VA |
| Flowering Plants | Harper's heartleaf | Hexastylis speciosa | Petitioned for Listing, Under Review | Under Review | | AL |
| Birds | Harpy eagle | Harpia harpyja | Listed | Endangered | | |
| Mammals | Harquahala southern pocket gopher | Thomomys umbrinus subsimilis | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Harrington beardtongue | Penstemon harringtonii | Not Listed | Species of Concern | | CO |
| Insects | Harris' mimic swallowtail butterfly | Eurytides lysithous harrisianus | Listed | Endangered | | |
| Birds | Harris's Hawk | Parabuteo unicinctus harrisi | Not Listed | Species of Concern | | |
| Birds | Harris's Sparrow | Zonotrichia querula | Not Listed | Species of Concern | | |
| Mammals | Hartmann's mountain zebra | Equus zebra hartmannae | Listed | Threatened | | |
| Flowering Plants | Hart's ragwort | Packera hartiana | Not Listed | Species of Concern | | AZ, NM |
| Flowering Plants | Hartweg's golden sunburst | Pseudobahia bahiifolia | Listed | Endangered | | CA |
| Flowering Plants | Hartweg's Locust | Robinia hartwigii | Not Listed | Species of Concern | | NC |
| Crustaceans | Hatchie Burrowing crayfish | Fallicambarus hortoni | | Not Listed | | TN |
| Insects | Hatch's click beetle | Eanus hatchi | Not Listed | Species of Concern | | WA |
| Snails | Hat Creek pebblesnail | Fluminicola umbilicatus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hau kuahiwi | Hibiscadelphus crucibracteatus | Not Listed | Species of Concern | | HI |
| Flowering Plants | Hau kuahiwi | Hibiscadelphus giffardianus | Listed | Endangered | | HI |
| Flowering Plants | Hau kuahiwi | Hibiscadelphus hualalaiensis | Listed | Endangered | | HI |
| Flowering Plants | Hau kuahiwi | Hibiscadelphus woodii | Listed | Endangered | | HI |
| Birds | Hawaii akepa | Loxops coccineus | Listed | Endangered | | HI |
| Insects | Hawaii alani long-horned beetle | Plagithmysus vicinus | Not Listed | Species of Concern | | HI |
| Birds | Hawai'i 'Amakihi | Chlorodrepanis virens | Not Listed | Species of Concern | | |
| Flowering Plants | Hawaiian aster | Aster sandwicensis | Not Listed | Resolved Taxon | | HI |
| Insects | Hawaiian bean leafroller | Omoides monogona | Not Listed | Species of Concern | | HI |
| Flowering Plants | Hawaiian bluegrass | Poa sandvicensis | Listed | Endangered | | HI |
| Insects | Hawaiian chersodromian dance fly | Chersodromia hawaiiensis | Not Listed | Species of Concern | | HI |
| Birds | Hawaiian common gallinule | Gallinula galeata sandvicensis | Listed | Endangered | | HI |
| Birds | Hawaiian coot (alae ke`oke`o) | Fulica alai | Listed | Endangered | | HI |
| Flowering Plants | Hawaiian cotton | Gossypium tomentosum | Not Listed | Resolved Taxon | | HI |
| Birds | Hawaiian crow | Corvus hawaiiensis | Listed | Endangered | | |
| Insects | Hawaiian deinomimesan sphecid wasp | Deinomimesa hawaiiensis | Not Listed | Species of Concern | | HI |
| Birds | Hawaiian duck | Anas wyvilliana | Listed | Endangered | | HI |
| Flowering Plants | Hawaiian gardenia | Gardenia brighamii | Listed | Endangered | | HI |
| Birds | Hawaiian goose | Branta (=Nesochen) sandvicensis | Listed | Threatened | | HI |
| Insects | Hawaiian hairstreak butterfly | Vaga blackburni | Not Listed | Resolved Taxon | | HI |
| Mammals | Hawaiian hoary bat | Lasiurus cinereus semotus | Listed | Endangered | | HI |
| Insects | Hawaiian hopseed looper | Scotorythra paratactis | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Hawaiian Hypogeal Shrimp | Calliasmata pholidata | | Not Listed | | |
| Birds | Hawaiian (='lo) Hawk | Buteo solitarius | Delisted | Recovery | | HI |
| Insects | Hawaiian long-palp bristletail | Neomachiloides heteropus | Not Listed | Species of Concern | | HI |
| Insects | Hawaiian lo`ulu omoides moth | Omoides pritchardii | Not Listed | Species of Concern | | HI |
| Mammals | Hawaiian monk seal | Monachus schauinslandi | Listed | Endangered | | |
| Birds | Hawaiian petrel | Pterodroma sandwichensis | Listed | Endangered | | CA, HI, OR, UM, WA |
| Insects | Hawaiian picture-wing fly | Drosophila aglaia | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila differens | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila digressa | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila hemipeza | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila heteroneura | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila montgomeryi | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila mulli | Listed | Threatened | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila musaphilia | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila neoclavisetae | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila obatai | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila ochrobasis | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila sharpi | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila substenoptera | Listed | Endangered | | HI |
| Insects | Hawaiian picture-wing fly | Drosophila tarphytrichia | Listed | Endangered | | HI |
| Insects | Hawaiian proterhinid beetles | Proterhinus spp. (ca 72) | Not Listed | Species of Concern | | HI |
| Insects | Hawaiian rhopalid bug | Ithamar hawaiiense | Not Listed | Species of Concern | | HI |
| Crustaceans | Hawaiian River Shrimp | Macrobrachium grandimanus | | Not Listed | | |
| Birds | Hawaiian Short-eared Owl | Asio flammeus sandwichensis | Not Listed | Species of Concern | | HI |
| Arachnids | Hawaiian spider | Doryonychus raptor | Not Listed | Resolved Taxon | | |
| Birds | Hawaiian stilt | Himantopus mexicanus knudseni | Listed | Endangered | Proposed Reclassification to Threatened | HI |
| Flowering Plants | Hawaiian vetch | Vicia menziesii | Listed | Endangered | | HI |
| Insects | Hawaiian yellow-faced bee | Hylaeus kuakea | Listed | Endangered | | HI |
| Insects | Hawaiian yellow-faced bee | Hylaeus longiceps | Listed | Endangered | | HI |
| Insects | Hawaiian yellow-faced bee | Hylaeus mana | Listed | Endangered | | HI |
| Insects | Hawaii clubbed long-horned beetle | Plagithmysus claviger | Not Listed | Species of Concern | | HI |
| Birds | Hawaii creeper | Loxops mana | Listed | Endangered | | HI |
| Insects | Hawaii decorus long-horned beetle | Plagithmysus decorus | Not Listed | Species of Concern | | HI |
| Insects | Hawaii elegant long-horned beetle | Plagithmysus elegans | Not Listed | Species of Concern | | HI |
| Birds | Hawaii Elepaio | Chasiempis sandwichensis | Not Listed | Species of Concern | | |
| Insects | Hawaii opuhe long-horned beetle | Plagithmysus sulphurescens | Not Listed | Species of Concern | | HI |
| Insects | Hawaii podagricus long-horned beetle | Plagithmysus podagricus | Not Listed | Species of Concern | | HI |
| Snails | Hawai`i tree snail | Partulina confusa | Not Listed | Species of Concern | | HI |
| Snails | Hawai`i tree snail | Partulina horneri | Not Listed | Species of Concern | | HI |
| Snails | Hawai`i tree snail | Partulina physa | Not Listed | Species of Concern | | HI |
| Insects | Hawaii uhiuhi long-horned beetle | Plagithmysus mezoneuri | Not Listed | Species of Concern | | HI |
| Reptiles | Hawksbill sea turtle | Eretmochelys imbricata | Listed | Endangered | | AL, AS, CT, DE, FL, GA, GU, HI, LA, MA, MD, ME, MP, MS, NC, NH, NJ, NY, PR, PW, RI, TX, VA, VI |
| Crustaceans | Hay's Spring amphipod | Stygobromus hayi | Listed | Endangered | | DC, MD |
| Flowering Plants | Hayun Iagu (=(Guam), Tronkon guafi (Rota)) | Serianthes nelsonii | Listed | Endangered | | GU, MP |
| Fishes | Headwater catfish | Ictalurus lupus | Not Listed | Resolved Taxon | | NM, TX |
| Insects | Headwater chilostigman caddisfly | Chilostigma itascae | Not Listed | Species of Concern | | MN |
| Flowering Plants | Hearst's ceanothus | Ceanothus hearstiorum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Hearsts' manzanita | Arctostaphylos hookeri hearstiorum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Heart-leaved pitcher-sage | Lepechinia cardiophylla | Not Listed | Species of Concern | | CA |
| Flowering Plants | Heart-leaved plantain | Plantago cordata | Not Listed | Resolved Taxon | | AL, AR, DC, GA, IA, IL, IN, KY, MD, MI, MO, NC, NY, OH, TN, VA, WI |
| Flowering Plants | Heart-leaved, skullcap | Scutellaria ovata pseudoarguta | Not Listed | Species of Concern | | VA, WV |
| Flowering Plants | Heartscale | Atriplex cordulata | Not Listed | Species of Concern | | CA |
| Snails | Hearty elimia | Elimia jonesi | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | Heather leaf-flower | Phyllanthus ericoides | Not Listed | Species of Concern | | TX |
| Flowering Plants | Heau | Exocarpos luteolus | Listed | Endangered | | HI |
| Flowering Plants | Heau | Exocarpos menziesii | Listed | Endangered | | HI |
| Insects | Heavy metromenus ground beetle | Metromenus bardus | Not Listed | Species of Concern | | HI |
| Clams | Heavy pigtoe | Pleurobema taitianum | Listed | Endangered | | AL, MS |
| Insects | Hebard's noctuid moth | Erythroecia hebardi | Not Listed | Species of Concern | | DE, NJ, OH, VA |
| Flowering Plants | Heckard's Dwarf Pepper-grass | Lepidium latipes var. heckardii | Not Listed | Status Undefined | | |
| Flowering Plants | Heckner's lewisia | Lewisia cotyledon heckneri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Heckner's stonecrop | Sedum laxum heckneri | Not Listed | Resolved Taxon | | CA, NV, OR |
| Birds | Heermann's Gull | Larus heermanni | Not Listed | Species of Concern | | |
| Birds | Heinroth's shearwater | Puffinus heinrothi | Listed | Threatened | | |
| Flowering Plants | Heliograph Peak Fleabane | Erigeron heliographis | Not Listed | Resolved Taxon | | |
| Insects | Helios yellow butterfly | Eurema dina helios | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Heliotrope milk-vetch | Astragalus montii | Listed | Threatened | | UT |
| Mammals | Heliotrope pika | Ochotona princeps moorei | Not Listed | Species of Concern | | UT |
| Crustaceans | Hell Creek Cave crayfish | Cambarus zophonastes | Listed | Endangered | | AR |
| Insects | Heller Cave springtail | Typhlogastrura helleri | Petitioned for Listing, Under Review | Under Review | | PA |
| Flowering Plants | Heller's bird's-foot trefoil | Lotus unifoliolatus var. helleri | Not Listed | Species of Concern | | NC |
| Flowering Plants | Heller's blazingstar | Liatris helleri | Listed | Threatened | | NC |
| Insects | Helma's net-spinning caddisfly | Cheumatopsyche helma | Not Listed | Species of Concern | | KY, ME, PA, TN |
| Birds | Helmeted honeyeater | Lichenostomus melanops cassidix (=Meliphaga c.) | Listed | Endangered | | |
| Birds | Helmeted hornbill | Buceros (=Rhinoplax) vigil | Listed | Endangered | | |
| Birds | Helmeted woodpecker | Celeus galeatus | Candidate for Listing | Candidate | | |
| Snails | Helmet rocksnail | Lithasia duttoniana | | Not Listed | | TN |
| Insects | Helotes mold beetle | Batrisodes venyivi | Listed | Endangered | | TX |
| Flowering Plants | Hemlock, Mexican parsley | Conioselinum mexicanum | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Henderson's bentgrass | Agrostis hendersonii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Henderson's checkermallow | Sidalcea hendersonii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Henderson's horkelia | Horkelia hendersonii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Henne's eucosman moth | Eucosma hennei | Not Listed | Species of Concern | | CA |
| Birds | Henry's Common Nighthawk | Chordeiles minor henryi | Not Listed | Species of Concern | | |
| Flowering Plants | Henry's spider-lily | Hymenocallis henryae | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Henslow's Sparrow | Centronyx henslowii | Not Listed | Resolved Taxon | | |
| Birds | Herald Petrel | Pterodroma arminjoniana | Not Listed | Species of Concern | | |
| Insects | Hermes copper butterfly | Lycaena hermes | Listed | Threatened | | CA |
| Birds | Hermit Warbler | Setophaga occidentalis | Not Listed | Species of Concern | | |
| Birds | Herring Gull | Larus argentatus | Not Listed | Species of Concern | | |
| Crustaceans | Hershler groundwater sebid | Seborgia hershleri | Not Listed | Resolved Taxon | | |
| Insects | Hessel's hairstreak butterfly | Mitoura hesseli | Not Listed | Resolved Taxon | | |
| Flowering Plants | Hess's fleabane | Erigeron hessii | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | Hester's cory cactus | Escobaria hesteri | Not Listed | Species of Concern | | TX |
| Flowering Plants | Hetch Hetchy monkey-flower | Mimulus filicaulis | Not Listed | Species of Concern | | CA |
| Insects | Hexagenia Mayfly | Hexagenia limbata | | Not Listed | | |
| Flowering Plants | Hicaquillo | Dendropemon sintenisii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Hickman's onion | Allium hickmanii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Hickman's potentilla | Potentilla hickmanii | Listed | Endangered | | CA |
| Flowering Plants | Hickman's sidalcea | Sidalcea hickmanii hickmanii | Not Listed | Resolved Taxon | | CA |
| Clams | Hickorynut | Obovaria olivaria | | Not Listed | | |
| Amphibians | Hickory Nut Gorge green salamander | Aneides caryaensis | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Hickory Shad | Alosa mediocris | | Not Listed | | |
| Flowering Plants | Hidden bluecurls | Trichostema latens | Not Listed | Status Undefined | | FL |
| Insects | Hidden eopenthes click beetle | Eopenthes celatus | Not Listed | Species of Concern | | HI |
| Mammals | Hidden Forest Uinta chipmunk | Eutamias umbrinus nevadensis | Not Listed | Species of Concern | | NV |
| Flowering Plants | Hidden Lake bluecurls | Trichostema austromontanum ssp. compactum | Delisted | Recovery | | CA |
| Snails | Hidden pebblesnail | Somatogyrus decipiens | Not Listed | Species of Concern | | AL |
| Reptiles | Hierro giant lizard | Gallotia simonyi simonyi | Listed | Endangered | | |
| Flowering Plants | Higgin's barberry | Berberis higginsiae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Higgins biscuitroot | Cymopterus acaulis higginsii | Not Listed | Species of Concern | | UT |
| Clams | Higgins eye (pearlymussel) | Lampsilis higginsii | Listed | Endangered | | IA, IL, MN, MO, NE, SD, WI |
| Fishes | Highfin Carpsucker | Carpiodes velifer | | Not Listed | | |
| Flowering Plants | Highlands moss | Schlotheimia lancifolia | Not Listed | Species of Concern | | NC |
| Flowering Plants | Highlands scrub hypericum | Hypericum cumulicola | Listed | Endangered | | FL |
| Insects | Highlands tiger beetle | Cicindelidia highlandensis | Not Listed | Resolved Taxon | | |
| Fishes | High Rock Springs tui chub | Siphateles bicolor ssp. | Not Listed | Resolved Taxon | | CA |
| Fishes | Highscale shiner | Notropis hypsilepis | Not Listed | Species of Concern | | AL, GA |
| Snails | High-spired elimia | Elimia hartmaniana | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | Higo Chumbo | Harrisia portoricensis | Listed | Threatened | | PR |
| Flowering Plants | Higuero de sierra | Crescentia portoricensis | Listed | Endangered | | PR |
| Fishes | Hihiwai | Neritina granosa | | Not Listed | | |
| Fishes | Hiko White River springfish | Crenichthys baileyi grandis | Listed | Endangered | | NV |
| Insects | Hilaris yellow-faced bee | Hylaeus hilaris | Listed | Endangered | | HI |
| Flowering Plants | Hillebrand's reedgrass | Calamagrostis hillebrandii | Listed | Endangered | | HI |
| Mammals | Hill's Horseshoe Bat | Rhinoiophus hilli | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Hill's pondweed | Potamogeton hillii | Not Listed | Resolved Taxon | | CT, MA, MI, NY, OH, PA, VT |
| Insects | Hilo hypenan noctuid moth | Hypena newelli | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Hilo ischaemum | Ischaemum byrone | Listed | Endangered | | HI |
| Mammals | Hilton Head white-tailed deer | Odocoileus virginianus hiltonensis | Not Listed | Species of Concern | | SC |
| Flowering Plants | Hinckley oak | Quercus hinckleyi | Listed | Threatened | | TX |
| Flowering Plants | Hinckley's bricklebush | Brickellia brachyphylla montanus | Not Listed | Species of Concern | | ID |
| Flowering Plants | Hinckley's columbine | Aquilegia chrysantha hinckleyana | Not Listed | Species of Concern | | TX |
| Flowering Plants | Hinckley's jacob's ladder | Polemonium pauciflorum hinckleyi | Not Listed | Species of Concern | | AZ, TX |
| Insects | Hine's emerald dragonfly | Somatochlora hineana | Listed | Endangered | | IL, MI, MO, WI |
| Flowering Plants | Hirst Brothers' Panic grass | Dichanthelium (=Panicum) hirstii | Not Listed | Resolved Taxon | | DE, GA, NC, NJ |
| Snails | Hirsute sierra sideband | Monadenia mormonum hirsuta | Not Listed | Species of Concern | | CA |
| Insects | Hirsute yellow-faced bee | Hylaeus hirsutulus | Not Listed | Species of Concern | | HI |
| Flowering Plants | Hispid birds-beak | Cordylanthus mollis hispidus | Not Listed | Species of Concern | | CA |
| Mammals | Hispid hare | Caprolagus hispidus | Listed | Endangered | | |
| Flowering Plants | Hitchcock's blue-eyed grass | Sisyrinchium hitchcockii | Not Listed | Species of Concern | | |
| Crustaceans | Hiwassee headwater crayfish | Cambarus hiwasseensis | Not Listed | Species of Concern | | GA, NC |
| Mammals | hoary bat | Lasiurus cinereus | Not Listed | Status Undefined | | |
| Flowering Plants | Hoawa | Pittosporum halophilum | Listed | Endangered | | HI |
| Flowering Plants | Hoawa | Pittosporum hawaiiense | Listed | Endangered | | HI |
| Flowering Plants | Ho`awa | Pittosporum napaliense | Listed | Endangered | | HI |
| Crustaceans | Hobb's cave amphipod | Crangonyx hobbsi | Petitioned for Listing, Under Review | Under Review | | FL |
| Flowering Plants | Hoffmann's buckwheat | Eriogonum hoffmannii hoffmannii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hoffmann's cactus | Opuntia bigelovii hoffmannii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hoffmann's cryptantha | Cryptantha hoffmannii | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Hoffmann's rock-cress | Arabis hoffmannii | Listed | Endangered | | CA |
| Flowering Plants | Hoffmann's slender-flowered gilia | Gilia tenuiflora ssp. hoffmannii | Listed | Endangered | | CA |
| Flowering Plants | Hoffman's sanicle | Sanicula hoffmannii | Not Listed | Resolved Taxon | | CA |
| Ferns and Allies | Hohiu | Dryopteris glabra var. pusilla | Listed | Endangered | | HI |
| Flowering Plants | Hoja menuda | Psidium sintenisii | Not Listed | Species of Concern | | PR, VI |
| Snails | Hoko vertigo | Vertigo sp | | Not Listed | | WA |
| Flowering Plants | Holei | Ochrosia haleakalae | Listed | Endangered | | HI |
| Flowering Plants | Holei | Ochrosia kilaueaensis | Listed | Endangered | | HI |
| Flowering Plants | Hole-In-The-Rock prairie-clover | Dalea flavescens epica | Not Listed | Species of Concern | | UT |
| Fishes | Holiday darter | Etheostoma brevirostrum | Not Listed | Status Undefined | | AL, GA, TN |
| Flowering Plants | Hollisteria | Hollisteria lanata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Holly-leaved tetracoccus | Tetracoccus ilicifolius | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Holmgren milk-vetch | Astragalus holmgreniorum | Listed | Endangered | | AZ, UT |
| Flowering Plants | Holmgren's buckwheat | Eriogonum holmgrenii | Not Listed | Species of Concern | | NV |
| Flowering Plants | Holmgren's lupine | Lupinus holmgrenianus | Not Listed | Resolved Taxon | | CA, NV |
| Insects | Holsinger's Cave Beetle | Pseudanophthalmus holsingeri | Not Listed | Resolved Taxon | | VA |
| Crustaceans | Holsinger's groundwater amphipod | Stygobromus holsingeri | Not Listed | Resolved Taxon | | |
| Flatworms and Roundworms | Holsinger's groundwater planarian | Sphalloplana holsingeri | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | Holy Ghost ipomopsis | Ipomopsis sancti-spiritus | Listed | Endangered | | NM |
| Insects | Homerus swallowtail butterfly | Papilio homerus | Listed | Endangered | | |
| Mammals | Homossassa shrew | Sorex longirostris eionis | Not Listed | Resolved Taxon | | |
| Arachnids | Hom's micro-blind harvestman | Microcina homi | Not Listed | Species of Concern | | CA |
| Birds | Honduran emerald hummingbird | Amazilia luciae | Listed | Endangered | | |
| Flowering Plants | Honohono | Haplostachys haplostachya | Listed | Endangered | | HI |
| Flowering Plants | Honolulu melicope | Melicope hosakae | Not Listed | Resolved Taxon | | HI |
| Snails | Hood ancylid | Ferrissia mcneili | Not Listed | Species of Concern | | |
| Birds | Hooded Crane | Grus monacha | Listed | Endangered | | |
| Birds | Hooded Oriole | Icterus cucullatus | Not Listed | Species of Concern | | |
| Birds | Hook-billed hermit (hummingbird) | Ramphodon (=Glaucis) dohrnii | Listed | Endangered | | |
| Flowering Plants | Hooker's manzanita | arctostaphylos hookeri ssp. hookeri | Not Listed | Species of Concern | | |
| Flowering Plants | Hoover's button-celery | Eryngium aristulatum hooveri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Hoover's coyot bush | Baccharis plummerae glabrata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hoover's desert-parsley | Lomatium tuberosum | Not Listed | Species of Concern | | WA |
| Flowering Plants | Hoover's rosinweed | Calycadenia hooveri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Hoover's spurge | Chamaesyce hooveri | Listed | Threatened | | CA |
| Flowering Plants | Hoover's tauschia | Tauschia hooveri | Not Listed | Species of Concern | | WA |
| Flowering Plants | Hoover's woolly-star | Eriastrum hooveri | Delisted | Recovery | Original Data in Error - New Information Discovered | CA |
| Insects | Hopping's blister beetle | Lytta hoppingi | Not Listed | Species of Concern | | CA |
| Birds | Horned Grebe | Podiceps auritus | Not Listed | Status Undefined | | |
| Birds | Horned guan | Oreophasis derbianus | Listed | Endangered | | |
| Ferns and Allies | Hornwort | Megaceros aenigmaticus | Not Listed | Status Undefined | | GA, NC, TN |
| Ferns and Allies | Hornyhead Chub | Nocomis biguttatus | | Not Listed | | |
| Mammals | Horse | Equus caballus | Not Listed | Resolved Taxon | | AZ, CA, ID, MT, NM, NV, OK, UT, WY |
| Snails | Horseshoe Canyon Talussnail | Sonorella binneyi | Not Listed | Resolved Taxon | | |
| Snails | Horseshoe Canyon Woodlandsnail | Ashmunella lenticula | Not Listed | Resolved Taxon | | |
| Insects | Horseshoe Crab | Limulus polyphemus | | Not Listed | | |
| Snails | Horseshoe liptooth | Polygyra hippocrepis | Not Listed | Species of Concern | | TX |
| Snails | Horseshoe Liptooth | Daedalochila hippocrepis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Horseshoe milk-vetch | Astragalus equisolensis | Not Listed | Resolved Taxon | | UT |
| Snails | Horseshoe snail | Micrarionta intercisa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hoskett Meadows lupine | Lupinus culbertsonii culbertsonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Hospital Canyon larkspur | Delphinium californicum interius | Not Listed | Species of Concern | | CA |
| Insects | Hostile yellow-faced bee | Hylaeus hostilis | Not Listed | Species of Concern | | HI |
| Fishes | Hot Creek Valley tui chub | Siphateles bicolor ssp. 5 | Not Listed | Species of Concern | | NV |
| Lichens | Hot dots | Arthonia kermesina | Not Listed | Species of Concern | | NC |
| Mammals | Hot Springs cotton rat | Sigmodon fulviventer goldmani | Not Listed | Species of Concern | | NM |
| Flowering Plants | Hot springs fimbristylis | Fimbristylis thermalis | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Houghton's goldenrod | Solidago houghtonii | Listed | Threatened | | MI, NY |
| Flowering Plants | Houston meadowrue | Thalictrum texanum | Not Listed | Species of Concern | | TX |
| Flowering Plants | Houston tansyaster | Rayjacksonia aurea | Not Listed | Species of Concern | | TX |
| Amphibians | Houston toad | Bufo houstonensis | Listed | Endangered | | TX |
| Insects | Howarth's cave cricket | Caconemobius howarthi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Howell phacelia | Phacelia howelliana | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Howell's alkali grass | Puccinellia howellii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Howell's bentgrass | Agrostis howellii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Howell's fawn-lily | Erythronium howellii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Howell's fleabane | Erigeron howellii | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | Howell's gumplant | Grindelia howellii | Not Listed | Species of Concern | | ID, MT |
| Flowering Plants | Howell's jewelflower | Streptanthus howellii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Howell's lewisia | Lewisia cotyledon howellii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Howell's lomatium | Lomatium howellii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Howell's lousewort | Pedicularis howellii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Howell's mariposa lily | Calochortus howellii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Howell's montia | Montia howellii | Not Listed | Species of Concern | | CA, WA |
| Flowering Plants | Howell's onion | Allium pleianthum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Howell's sandwort | Minuartia howellii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Howell''s spectacular thelypody | Thelypodium howellii ssp. spectabilis | Listed | Threatened | | OR |
| Flowering Plants | Howell's spineflower | Chorizanthe howellii | Listed | Endangered | | CA |
| Flowering Plants | Howell's tauschia | Tauschia howellii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Howe's hedgehog cactus | Echinocereus engelmannii howei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Huachuca groundsel | Senecio huachucanus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Huachuca milk-vetch | Astragalus hypoxylus | Not Listed | Resolved Taxon | | AZ |
| Snails | Huachuca springsnail | Pyrgulopsis thompsoni | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Huachuca water-umbel | Lilaeopsis schaffneriana var. recurva | Listed | Endangered | | AZ, NM |
| Snails | Huachuca Woodlandsnail | Ashmunella levettei | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Hualapai Mexican vole | Microtus mexicanus hualpaiensis | Delisted | Original Data in Error - Not a listable entity | | AZ |
| Mammals | Hualapai southern pocket gopher | Thomomys umbrinus hualpaiensis | Not Listed | Species of Concern | | AZ |
| Insects | Hubbard's cave beetle | Pseudanophthalmus hubbardi | Not Listed | Resolved Taxon | | VA |
| Snails | Hubbs pyrg | Pyrgulopsis hubbsi | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Huber's Pepperwort | Lepidium huberi | Not Listed | Resolved Taxon | | |
| Insects | Hubricht's cave beetle | Pseudanophthalmus hubrichti | Not Listed | Resolved Taxon | | VA |
| Snails | Hubricht's vertigo | Vertigo hubrichti | Not Listed | Species of Concern | | IA, MN, WI |
| Birds | Hudson Bay Dunlin | Calidris alpina hudsonia | Not Listed | Species of Concern | | |
| Insects | Hudson clubtail dragonfly | Gomphus adelphus | Not Listed | Resolved Taxon | | MA, NY |
| Birds | Hudsonian Godwit | Limosa haemastica | Not Listed | Species of Concern | | |
| Snails | Hueco Cavesnail | Phreatodrobia conica | Not Listed | Resolved Taxon | | |
| Snails | hueco mountains talus snail | sonorella huecoensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Hueco rock-daisy | Perityle huecoensis | Not Listed | Resolved Taxon | | TX |
| Insects | Hulan yellow-faced bee | Hylaeus hula | Not Listed | Species of Concern | | HI |
| Flowering Plants | Hulumoa | Korthalsella degeneri | Listed | Endangered | | HI |
| Flowering Plants | Humboldt Bay gumplant | Grindelia stricta blakei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Humboldt Bay owl's clover | Castilleja ambigua humboldtiensis | Not Listed | Species of Concern | | CA |
| Insects | Humboldt ground beetle | Scaphinotus longiceps | Not Listed | Species of Concern | | CA |
| Flowering Plants | Humboldt lily | Lilium humboldtii ocellatum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Humboldt milk-vetch | Astragalus agnicidus | Not Listed | Species of Concern | | CA |
| Birds | Humboldt penguin | Spheniscus humboldti | Listed | Threatened | | |
| Fishes | Humpback chub | Gila cypha | Listed | Threatened | | AZ, CO, UT |
| Mammals | Humpback whale | Megaptera novaeangliae | Listed | Endangered | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Not Listed | Resolved Taxon | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Listed | Threatened | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Listed | Endangered | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Listed | Endangered | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Delisted | Recovery | | |
| Mammals | Humpback whale | Megaptera novaeangliae | Listed | Endangered | | |
| Fishes | Humpback Whitefish | Coregonus pidschian | | Not Listed | | |
| Snails | Humped tree snail | Partula gibba | Listed | Endangered | | GU, MP |
| Insects | Hungerford's crawling water Beetle | Brychius hungerfordi | Listed | Endangered | | MI |
| Mammals | Hunting Island white-tailed deer | Odocoileus virginianus venatoria | Not Listed | Species of Concern | | SC |
| Insects | Hurd's metapogon robberfly | Metapogon hurdi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Hutchinson's delphinium | Delphinium hutchinsonae | Not Listed | Species of Concern | | CA |
| Fishes | Hutton tui chub | Gila bicolor ssp. | Listed | Threatened | | OR |
| Birds | Hyacinth macaw | Anodorhynchus hyacinthinus | Listed | Threatened | | |
| Insects | Hydaspe fritillary butterfly | Speyeria hydaspe conquista | Not Listed | Resolved Taxon | | CO, NM |
| Insects | Iao Valley nesosydne planthopper | Nesosydne acuta | Not Listed | Species of Concern | | HI |
| Birds | Ibadan malimbe | Malimbus ibadanensis | Listed | Endangered | | |
| Reptiles | Ibiza wall lizard | Podarcis pityusensis | Listed | Threatened | | |
| Insects | Icebox Cave beetle | Pseudanophthalmus frigidus | Not Listed | Resolved Taxon | | KY |
| Flowering Plants | Ice grass | Phippsia algida | Not Listed | Resolved Taxon | | AK, CO, WY |
| Snails | Ichetucknee siltsnail | Floridobia mica | Not Listed | Resolved Taxon | | |
| Snails | Idaho banded mountainsnail | Oreohelix idahoensis idahoensis | Not Listed | Species of Concern | | ID |
| Insects | Idaho dunes tiger beetle | Cicindela arenicola | Not Listed | Species of Concern | | ID |
| Flowering Plants | Idaho penstemon | Penstemon idahoensis | Not Listed | Species of Concern | | ID, UT |
| Insects | Idaho pointheaded grasshopper | Acrolophitus pulchellus | Not Listed | Species of Concern | | ID |
| Insects | Idaho snowfly | Capnia zukeli | Not Listed | Resolved Taxon | | ID |
| Snails | Idaho springsnail | Pyrgulopsis idahoensis | Delisted | Original Data in Error - Taxonomic Revision | | ID |
| Flowering Plants | Idria buckwheat | Eriogonum vestitum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Ihi | Portulaca villosa | Listed | Endangered | | HI |
| Ferns and Allies | Ihi`ihi | Marsilea villosa | Listed | Endangered | | HI |
| Birds | `I`iwi | Drepanis coccinea | Listed | Threatened | | HI |
| Fishes | Ikan temoleh (minnow) | Probarbus jullieni | Listed | Endangered | | |
| Flowering Plants | `Ilihia | Cyrtandra begoniifolia | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Illinois cave amphipod | Gammarus acherondytes | Listed | Endangered | | IL |
| Insects | Illinois cave beetle | Pseudanophthalmus illinoisensis | Not Listed | Species of Concern | | IL |
| Amphibians | Illinois chorus frog | Pseudacris illinoensis | Not Listed | Resolved Taxon | | AR, IL, MO |
| Reptiles | Illinois mud turtle | Kinosternon flavescens spooneri | Not Listed | Resolved Taxon | | IA, IL, MO |
| Birds | Imperial parrot | Amazona imperialis | Listed | Endangered | | |
| Birds | Imperial pheasant | Lophura imperialis | Listed | Endangered | | |
| Birds | Imperial woodpecker | Campephilus imperialis | Listed | Endangered | | |
| Reptiles | Inagua Island turtle | Trachemys stejnegeri malonei | Listed | Endangered | | |
| Flowering Plants | Incised groovebur | Agrimonia incisa | Not Listed | Species of Concern | | |
| Fishes | Inconnu | Stenodus leucichthys | | Not Listed | | |
| Fishes | Independence Valley speckled dace | Rhinichthys osculus lethoporus | Listed | Endangered | | NV |
| Fishes | Independence Valley tui chub | Siphateles bicolor isolata | Not Listed | Species of Concern | | NV |
| Mammals | Indiana bat | Myotis sodalis | Listed | Endangered | | AL, AR, CT, DE, GA, IA, IL, IN, KS, KY, MD, MI, MO, MS, NC, NE, NJ, NY, OH, OK, PA, SC, TN, VA, VT, WI, WV |
| Crustaceans | Indiana crayfish | Orconectes indianensis | Not Listed | Species of Concern | | IL, IN |
| Snails | Indiana river snail | Goniobasis semicarinata indianensis | Not Listed | Resolved Taxon | | IN |
| Reptiles | Indian (=Bengal) monitor | Varanus bengalensis | Listed | Endangered | | |
| Flowering Plants | Indian Creek mushroom | Gloeocantharellus purpurascens | Not Listed | Resolved Taxon | | NC |
| Reptiles | Indian flap-shelled turtle | Lissemys punctata punctata | Delisted | Original Data in Error - Erroneous Data | | |
| Insects | Indian Grave Point (=Soothsayer) cave beetle | Pseudanophthalmus tiresias | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | Indian Knob mountainbalm | Eriodictyon altissimum | Listed | Endangered | | CA |
| Mammals | Indian pangolin | Manis crassicaudata | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Indian pipe | Monotropa uniflora | Not Listed | Species of Concern | | |
| Reptiles | Indian python | Python molurus molurus | Listed | Endangered | | |
| Reptiles | Indian sawback turtle | Kachuga tecta tecta | Listed | Endangered | | |
| Reptiles | Indian softshell turtle | Trionyx gangeticus | Listed | Endangered | | |
| Flowering Plants | Indian Valley brodiaea | Brodiaea coronaria rosea | Not Listed | Species of Concern | | CA |
| Flowering Plants | Indian Valley sedge | Carex parryana | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | Indian Valley spineflower | Aristocapsa insignis | Not Listed | Resolved Taxon | | CA |
| Birds | Indigo macaw | Anodorhynchus leari | Listed | Endangered | | |
| Mammals | Indochina hog deer | Axis porcinus annamiticus | Listed | Endangered | | |
| Mammals | Indri lemur | Indri indri | Listed | Endangered | | |
| Clams | Inflated floater | Pyganodon gibbosa | | Not Listed | | GA |
| Clams | Inflated heelsplitter | Potamilus inflatus | Listed | Threatened | | AL, LA, MS |
| Clams | Inflated spike | Elliptio purpurella | Not Listed | Status Undefined | | GA |
| Insects | Inquirer Cave beetle | Pseudanophthalmus inquisitor | Not Listed | Resolved Taxon | | TN |
| Insects | Insignis yellow-faced bee | Hylaeus insignis | Not Listed | Species of Concern | | HI |
| Mammals | Insular hispid Cotton rat | Sigmodon hispidus insulicola | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Insular long-tongued bat | Monophylus plethodon frater | Not Listed | Resolved Taxon | | PR, VI |
| Fishes | Interior redband trout | Oncorhynchus mykiss gibbsi | Not Listed | Species of Concern | | ID, MT, NV, OR |
| Flowering Plants | Intermediate groundsel | Senecio dimorphophyllus intermedius | Not Listed | Resolved Taxon | | CO, UT |
| Snails | Interrupted (=Georgia) Rocksnail | Leptoxis foremani | Listed | Endangered | | AL, GA |
| Birds | Inyo California towhee | Melozone crissalis eremophilus | Listed | Threatened | Proposed Delisting | CA |
| Flowering Plants | Inyo hulsea | Hulsea vestita inyoensis | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Inyo lomatium | Lomatium foeniculaceum inyoense | Not Listed | Resolved Taxon | | CA, ID |
| Flowering Plants | Inyo lupine | Lupinus inyoensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Inyo mariposa lily | Calochortus excavatus | Not Listed | Species of Concern | | CA |
| Amphibians | Inyo Mountains slender salamander | Batrachoseps campi | Not Listed | Status Undefined | | CA |
| Flowering Plants | Inyo penstemon | Penstemon papillatus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Inyo rock daisy | Perityle inyoensis | Petitioned for Listing, Under Review | Under Review | | CA |
| Flowering Plants | Ione (incl. Irish Hill) buckwheat | Eriogonum apricum (incl. var. prostratum) | Listed | Endangered | | CA |
| Flowering Plants | Ione manzanita | Arctostaphylos myrtifolia | Listed | Threatened | | CA |
| Crustaceans | Iowa amphipod | Stygobromus iowae | Not Listed | Resolved Taxon | | IA |
| Fishes | Iowa Darter | Etheostoma exile | | Not Listed | | |
| Snails | Iowa Pleistocene snail | Discus macclintocki | Listed | Endangered | | IA, IL, WI |
| Snails | Iowa Pleistocene Succineid | Succinea sp. | Not Listed | Species of Concern | | IA, MN |
| Snails | Iowa Pleistocene Vertigo | Vertigo sp. | Not Listed | Species of Concern | | IA |
| Insects | Iowa skipper | Atrytone arogos iowa | Petitioned for Listing, Under Review | Under Review | | AR, CO, IA, IL, KS, MN, MT, ND, NE, OK, SD, TX, WY |
| Insects | Ioxanthan looper | Kauaiina ioxantha | Not Listed | Species of Concern | | HI |
| Mammals | Iriomote cat | Prionailurus (=Felis) bengalensis iriomotensis | Listed | Endangered | | |
| Flowering Plants | Irion County wild-buckwheat | Eriogonum nealleyi | Not Listed | Resolved Taxon | | TX |
| Fishes | Ironcolor Shiner | Notropis chalybaeus | | Not Listed | | |
| Snails | Iron Creek woodlandsnail | Ashmunella mendax | Not Listed | Resolved Taxon | | |
| Crustaceans | Irons Fork Burrowing crayfish | Procambarus reimeri | Not Listed | Status Undefined | | AR |
| Flowering Plants | Isely milk-vetch | Astragalus iselyi | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Island alumroot | Heuchera maxima | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Island Barberry | Berberis pinnata ssp. insularis | Listed | Endangered | | CA |
| Flowering Plants | Island bedstraw | Galium buxifolium | Delisted | Recovery | | CA |
| Mammals | Island fox | Urocyon littoralis | Not Listed | Status Undefined | | CA |
| Reptiles | Island glass lizard | Ophisaurus compressus | Not Listed | Species of Concern | | |
| Flowering Plants | Island green dudleya | dudleya virens ssp. insularis | Not Listed | Species of Concern | | |
| Fishes | Island Grouper | Mycteroperca fusca | Listed | Threatened | | |
| Flowering Plants | Island hazardia | Hazardia cana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Island jepsonia | Jepsonia malvifolia | Not Listed | Species of Concern | | CA |
| Birds | Island loggerhead shrike | Lanius ludovicianus ssp. anthonyi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Island malacothrix | Malacothrix squalida | Listed | Endangered | | CA |
| Insects | Island marble Butterfly | Euchloe ausonides insulanus | Listed | Endangered | | WA |
| Flowering Plants | Island morning-glory | Calystegia macrostegia amplissima | Not Listed | Species of Concern | | CA |
| Reptiles | Island night lizard | Xantusia riversiana | Delisted | Recovery | | CA |
| Flowering Plants | Island oak | Quercus tomentella | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Island phacelia | Phacelia insularis ssp. insularis | Listed | Endangered | | CA |
| Flowering Plants | Island poppy | Eschscholzia ramosa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Island rush-rose | Helianthemum greenei | Listed | Threatened | | CA |
| Birds | Island Scrub-Jay | Aphelocoma insularis | Not Listed | Species of Concern | | |
| Flowering Plants | Island snapdragon | Gambelia speciosa | Not Listed | Species of Concern | | CA |
| Flowering Plants | Island tree mallow | Lavatera assurgentiflora | Not Listed | Species of Concern | | CA |
| Flowering Plants | Island tree poppy | Dendromecon rigida rhamnoides | Not Listed | Species of Concern | | CA |
| Flowering Plants | Island wallflower | Erysimum insulare insulare | Not Listed | Species of Concern | | CA |
| Amphibians | Israel painted frog | Discoglossus nigriventer | Listed | Endangered | | |
| Birds | Italian grey Partridge | Perdix perdix italica | Not Listed | Resolved Taxon | | |
| Birds | Ivory-billed woodpecker | Campephilus principalis | Listed | Endangered | Proposed Delisting | AR |
| Birds | Ivory Gull | Pagophila eburnea | Not Listed | Species of Concern | | |
| Arachnids | Ivory Ornamental Tarantula | Poecilotheria subfusca | Listed | Endangered | | |
| Flowering Plants | Ivory-spined agave | Agave utahensis eborispina | Not Listed | Resolved Taxon | | CA, NV |
| Insects | Jacalitos Jerusalem cricket | Stenopelmatus nigrocapitatus | Not Listed | Resolved Taxon | | |
| Insects | Jacalitos shield-backed katydid | Ateloplus joaquin | Not Listed | Resolved Taxon | | |
| Flowering Plants | Jackie's Bluet | Hedyotis pooleana | Not Listed | Resolved Taxon | | |
| Snails | Jackson Lake snail | Helisoma jacksonense | Not Listed | Species of Concern | | WY |
| Snails | Jackson Lake springsnail | Pyrgulopsis robusta | Not Listed | Resolved Taxon | | WY |
| Crustaceans | Jackson Prairie crayfish | Procambarus barbiger | Petitioned for Listing, Under Review | Under Review | | MS |
| Mammals | Jacumba little pocket mouse | Perognathus longimembris internationalis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Jacumba milk-vetch | Astragalus douglasii perstrictus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Jaeger's bush milk-vetch | Astragalus pachypus jaegeri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Jaeger's caulostramina | Caulostramina jaegeri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Jaeger's thelypody | Thelypodium repandum | Not Listed | Species of Concern | | ID |
| Mammals | Jaguar | Panthera onca | Listed | Endangered | | AZ, NM |
| Reptiles | Jamaican boa | Epicrates subflavus | Listed | Endangered | | |
| Mammals | Jamaican Greater Funnel-Eared Bat | Natalus jamaicensis | Petitioned for Listing, Under Review | Under Review | | |
| Reptiles | Jamaican iguana | Cyclura collei | Listed | Endangered | | |
| Insects | Jamaican kite swallowtail butterfly | Eurytides marcellinus | Candidate for Listing | Candidate | | |
| Clams | James spinymussel | Parvaspina collina | Listed | Endangered | | NC, VA, WV |
| Flowering Plants | Jan's catchfly | Silene nachlingerae | Not Listed | Species of Concern | | NV |
| Birds | Japanese Crane | Grus japonensis | Listed | Endangered | | |
| Birds | Japanese crested ibis | Nipponia nippon | Listed | Endangered | | |
| Amphibians | Japanese giant salamander | Andrias japonicus (=davidianus j.) | Listed | Endangered | | |
| Mammals | Japanese macaque | Macaca fuscata | Listed | Threatened | | |
| Flowering Plants | Jared's peppergrass | Lepidium jaredii jaredii | Not Listed | Species of Concern | | CA |
| Mammals | Javan rhinoceros | Rhinoceros sondaicus | Listed | Endangered | | |
| Flowering Plants | Jaynes Canyon buckwheat | Eriogonum diclinum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Jeff Davis Parish indian paintbrush | Castilleja coccinea | Not Listed | Resolved Taxon | | LA |
| Crustaceans | Jefferson County crayfish | Fallicambarus gilpini | | Not Listed | | AR |
| Crustaceans | Jemez Mountains Amphipod | Stygobromus jemezensis | Not Listed | Resolved Taxon | | |
| Amphibians | Jemez Mountains salamander | Plethodon neomexicanus | Listed | Endangered | | NM |
| Snails | Jemez Woodlandsnail | Ashmunella ashmuni | Not Listed | Resolved Taxon | | |
| Flowering Plants | Jennifer�s monardella | Monardella stoneana | Not Listed | Resolved Taxon | | |
| Fishes | Jenny Creek sucker | Catostomus rimiculus ssp. | Not Listed | Species of Concern | | CA, OR |
| Mammals | Jentink's duiker | Cephalophus jentinki | Listed | Endangered | | |
| Flowering Plants | Jepson's onion | Allium jepsonii | Not Listed | Species of Concern | | CA |
| Birds | Jerdon's courser | Rhinoptilus bitorquatus | Listed | Endangered | | |
| Flowering Plants | Jessica's aster | Symphyotrichum jessicae | Not Listed | Species of Concern | | ID, WA |
| Flowering Plants | Jesup's milk-vetch | Astragalus robbinsii var. jesupii | Listed | Endangered | | NH, VT |
| Reptiles | Jicotea | Pseudemys stejnegeri | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Jobé bluecurls | Trichostema hobe | Not Listed | Status Undefined | | FL |
| Algae | Johnny Darter | Etheostoma nigrum | | Not Listed | | |
| Flowering Plants | Johnson's seagrass | Halophila johnsonii | Delisted | Original Data in Error - Not a listable entity | | |
| Flowering Plants | Johnston catseye | Cryptantha johnstonii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Johnston's buckwheat | Eriogonum microthecum johnstonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Johnston's frankenia | Frankenia johnstonii | Delisted | Recovery | | TX |
| Flowering Plants | Johnston's rock-cress | Arabis johnstonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Jointed buckwheat | Eriogonum intrafractum | Not Listed | Species of Concern | | CA |
| Amphibians | Jollyville Plateau Salamander | Eurycea tonkawae | Listed | Threatened | | TX |
| Flowering Plants | Jones catseye | Cryptantha jonesiana | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Jones' columbine | Aquilegia jonesii | Not Listed | Resolved Taxon | | MT, WY |
| Flowering Plants | Jones Cycladenia | Cycladenia humilis var. jonesii | Listed | Threatened | | AZ, UT |
| Flowering Plants | Jones' dogbane | Apocynum X floribundum | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Jones' globe-mallow | Sphaeralcea caespitosa | Not Listed | Species of Concern | | NV, UT |
| Flowering Plants | Jones golden aster | Heterotheca jonesii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Jones layia | Layia jonesii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Jones' oxytrope | Oxytropis oreophila var. jonesii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Jones' selenia | Selenia jonesii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Josselyn's sedge | Carex josselynii | Not Listed | Resolved Taxon | | ME |
| Insects | Jugorum megalagrion damselfly | Megalagrion jugorum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | July gold | Dedeckera eurekensis | Not Listed | Species of Concern | | CA |
| Amphibians | Junaluska salamander | Eurycea junaluska | Not Listed | Resolved Taxon | | NC |
| Fishes | June sucker | Chasmistes liorus | Listed | Threatened | | UT |
| Arachnids | Jung's micro-blind harvestman | Microcina jungi | Petitioned for Listing, Under Review | Under Review | | CA |
| Birds | Junin grebe | Podiceps taczanowskii | Listed | Endangered | | |
| Birds | Junin rail | Laterallus tuerosi | Listed | Endangered | | |
| Birds | Juniper Titmouse | Baeolophus ridgwayi | Not Listed | Species of Concern | | |
| Mammals | Kabul (straight-horned) markhor | Capra falconeri megaceros | Listed | Threatened | | |
| Flowering Plants | Kachina daisy | Erigeron kachinensis | Not Listed | Species of Concern | | CO, UT |
| Birds | Kaempfer's tody-tyrant | Hemitriccus kaempferi | Listed | Endangered | | |
| Birds | Kagu | Rhynochetos jubatus | Listed | Endangered | | |
| Insects | Kaholuamano noctuid moth | Hypena senicula | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kaibab bladderpod | Lesquerella kaibabensis | | Not Listed | | AZ |
| Flowering Plants | Kaibab paintbrush | Castilleja kaibabensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Kaibab plains cactus | Pediocactus paradinei | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Kaiparowits milk-vetch | Astragalus malacoides | Not Listed | Resolved Taxon | | UT |
| Insects | Kaiser-I-Hind swallowtail butterfly | Teinopalpus imperialis | Candidate for Listing | Candidate | | |
| Birds | Kakapo | Strigops habroptilus | Listed | Endangered | | |
| Birds | Kalinowski's tinamou | Nothoprocta kalinowskii | Not Listed | Status Undefined | | |
| Fishes | Kaluga sturgeon | Huso dauricus | Listed | Endangered | | |
| Flowering Plants | Kamakahala | Labordia cyrtandrae | Listed | Endangered | | HI |
| Flowering Plants | Kamakahala | Labordia fagraeoidea fagraeoidea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kamakahala | Labordia helleri | Listed | Endangered | | HI |
| Flowering Plants | Kamakahala | Labordia lydgatei | Listed | Endangered | | HI |
| Flowering Plants | Kamakahala | Labordia pumila | Listed | Endangered | | HI |
| Flowering Plants | Kamakahala | Labordia tinifolia var. lanaiensis | Listed | Endangered | | HI |
| Flowering Plants | Kamakahala | Labordia tinifolia var. wahiawaensis | Listed | Endangered | | HI |
| Flowering Plants | Kamakahala | Labordia triflora | Listed | Endangered | | HI |
| Flowering Plants | Kamanomano | Cenchrus agrimonioides | Listed | Endangered | | HI |
| Flowering Plants | Kamapua`a | Kadua fluviatilis | Listed | Endangered | | HI |
| Flowering Plants | Kamchatka Point manzanita | Arctostaphylos uva-ursi suborbiculata | Not Listed | Resolved Taxon | | CA |
| Snails | Kanab ambersnail | Oxyloma haydeni kanabensis | Delisted | Original Data in Error - Not a listable entity | | AZ, UT |
| Fishes | Kanawha minnow | Phenacobius teretulus | Not Listed | Species of Concern | | NC, VA, WV |
| Arachnids | Kandy Parachute Spider | Poecilotheria smithi | Listed | Endangered | | |
| Flowering Plants | Kankakee globe-mallow | Iliamna remota | Not Listed | Species of Concern | | IL, IN, VA |
| Lichens | Kansas aschisma moss | Aschisma kansanum | Not Listed | Resolved Taxon | | |
| Mammals | Kansas bog lemming | Synaptomys cooperi paludis | Not Listed | Resolved Taxon | | KS |
| Flatworms and Roundworms | Kansas Planarian | Sphalloplana kansensis | Not Listed | Resolved Taxon | | |
| Crustaceans | Kansas well amphipod | Bactrurus hubrichti | Not Listed | Resolved Taxon | | KS, MO, OK |
| Flowering Plants | Kapu melicope | Melicope radiata | Not Listed | Resolved Taxon | | HI |
| Insects | Karner blue butterfly | Lycaeides melissa samuelis | Listed | Endangered | | MI, MN, NH, NY, OH, WI |
| Snails | Karok hesperian | Vespericola karokorum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Karst pond xyris | Xyris longisepala | Petitioned for Listing, Under Review | Under Review | | FL |
| Insects | Karst snowfly | Allocapnia cunninghami | Petitioned for Listing, Under Review | Under Review | | KY, TN |
| Mammals | Kashmir stag | Cervus elaphus hanglu | Listed | Endangered | | |
| Flowering Plants | Kate's-mountain clover | Trifolium virginicum | Not Listed | Resolved Taxon | | MD, PA, VA, WV |
| Insects | Kauai `ahakea long-horned beetle | Plagithmysus permundus | Not Listed | Species of Concern | | HI |
| Birds | Kauai akialoa (honeycreeper) | Akialoa stejnegeri | Delisted | Extinction | | |
| Birds | Kaua'i 'Amakihi | Chlorodrepanis stejnegeri | Not Listed | Species of Concern | | |
| Insects | Kauai annectant long-horned beetle | Plagithmysus annectans | Not Listed | Species of Concern | | HI |
| Insects | Kauai band-legged seed bug | Neseis alternata | Not Listed | Species of Concern | | HI |
| Crustaceans | Kauai cave amphipod | Spelaeorchestia koloana | Listed | Endangered | | HI |
| Arachnids | Kauai cave wolf or pe'e pe'e maka 'ole spider | Adelocosa anops | Listed | Endangered | | HI |
| Insects | Kauai disenochus ground beetle | Disenochus micantipennis | Not Listed | Species of Concern | | HI |
| Birds | Kauai Elepaio | Chasiempis sclateri | Not Listed | Species of Concern | | |
| Insects | Kauai eopenthes click beetle | Eopenthes kauaiensis | Not Listed | Species of Concern | | HI |
| Insects | Kauai flightless stag beetle | Apterocyclus honoluluensis | Not Listed | Species of Concern | | HI |
| Insects | Kauai forest rhyncogonus weevil | Rhyncogonus sylvicola | Not Listed | Species of Concern | | HI |
| Flowering Plants | Kauai hau kuahiwi | Hibiscadelphus distans | Listed | Endangered | | HI |
| Insects | Kauai holio long-horned beetle | Plagithmysus polystictus | Not Listed | Species of Concern | | HI |
| Insects | Kauai kalia long-horned beetle | Plagithmysus ignotus | Not Listed | Species of Concern | | HI |
| Insects | Kauai naenae philodoria moth | Philodoria naenaeiella | Not Listed | Species of Concern | | HI |
| Insects | Kauai nesomimesan sphecid wasp | Nesomimesa kauaiensis | Not Listed | Species of Concern | | HI |
| Insects | Kauai nesotocus weevil | Nesotocus kauaiensis | Not Listed | Species of Concern | | HI |
| Birds | Kauai nukupuu | Hemignathus hanapepe | Delisted | Extinction | | |
| Birds | Kauai `o`o (honeyeater) | Moho braccatus | Delisted | Extinction | | |
| Insects | Kauai parti-colored oliarus planthopper | Oliarus consimilis | Not Listed | Species of Concern | | HI |
| Insects | Kauai swamp long-horned beetle | Plagithmysus paludis | Not Listed | Species of Concern | | HI |
| Insects | Kauai thinfooted bush cricket | Thaumatogryllus variegatus | Not Listed | Species of Concern | | HI |
| Insects | Kauai yellow-faced bee | Hylaeus kauaiensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Kauila | Alphitonia ponderosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kauila | Colubrina oppositifolia | Listed | Endangered | | HI |
| Flowering Plants | Kaulu | Pteralyxia kauaiensis | Listed | Endangered | | HI |
| Flowering Plants | Kaulu | Pteralyxia laurifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kaulu | Pteralyxia macrocarpa | Listed | Endangered | | HI |
| Insects | Kaumana Cave cricket | Caconemobius varius | Not Listed | Species of Concern | | HI |
| Flowering Plants | Kawa`u | Zanthoxylum dipetalum dipetalum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kaweah brodiaea | Brodiaea insignis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Kaweah Lakes fawn-lily | Erythronium grandiflorum pusateri | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Kaweah monkeyflower | Mimulus norrisii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Kaw Whitelip | Webbhelix chadwicki | Not Listed | Resolved Taxon | | |
| Flowering Plants | Kay Gramma | Bouteloua kayi | | Not Listed | | |
| Insects | Keanae nesosydne planthopper | Nesosydne sulcata | Not Listed | Species of Concern | | HI |
| Flowering Plants | Kearney's blue-star | Amsonia kearneyana | Listed | Endangered | | AZ |
| Flowering Plants | Kearney's sumac | Rhus kearneyi | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Keck's beardtongue | Penstemon leiophyllus var. keckii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Keck's Checker-mallow | Sidalcea keckii | Listed | Endangered | | CA |
| Flowering Plants | Keeled bladderpod | Lesquerella carinata | Not Listed | Species of Concern | | ID, MT, WY |
| Snails | Keeled Mountainsnail | Oreohelix carinifera | Not Listed | Resolved Taxon | | |
| Snails | Keeled sideband | Monadenia circumcarinata | Not Listed | Species of Concern | | CA |
| Mammals | Keen's myotis | myotis keenii | Not Listed | Species of Concern | | |
| Flowering Plants | Keever's bristle-moss | Orthotrichum keeverae | Not Listed | Species of Concern | | NC |
| Flowering Plants | Kelso Creek monkey-flower | Mimulus shevockii | Not Listed | Resolved Taxon | | CA |
| Insects | Kelso Dune glaresis scarab | Glaresis arenata | Not Listed | Species of Concern | | CA |
| Insects | Kelso giant sand treader cricket | Macrobaenetes kelsoensis | Not Listed | Species of Concern | | CA |
| Insects | Kelso jerusalem cricket | Ammopelmatus kelsoensis | Not Listed | Species of Concern | | CA |
| Reptiles | Kemp's ridley sea turtle | Lepidochelys kempii | Listed | Endangered | | AL, FL, GA, LA, MD, MS, NC, SC, TX, VA |
| Insects | Kendall's yucca skipper butterfly | Megathymus coloradensis kendalli | Not Listed | Resolved Taxon | | TX |
| Fishes | Kendall Warm Springs dace | Rhinichthys osculus thermalis | Listed | Endangered | | WY |
| Crustaceans | Kenk's amphipod | Stygobromus kenki | Not Listed | Resolved Taxon | | DC, MD, VA |
| Fishes | Kentucky arrow darter | Etheostoma spilotum | Listed | Threatened | | KY |
| Crustaceans | Kentucky cave shrimp | Palaemonias ganteri | Listed | Endangered | | KY |
| Clams | Kentucky creekshell | Villosa ortmanni | Proposed for Listing | Proposed Endangered | | KY |
| Flowering Plants | Kentucky glade cress | Leavenworthia exigua laciniata | Listed | Threatened | | KY |
| Mammals | Kentucky red-backed vole | Clethrionomys gapperi maurus | Not Listed | Species of Concern | | KY |
| Birds | Kentucky Warbler | Geothlypis formosa | Not Listed | Species of Concern | | |
| Flowering Plants | Kenwood Marsh checker-mallow | Sidalcea oregana ssp. valida | Listed | Endangered | | CA |
| Fishes | Kern brook lamprey | Lampetra hubbsi | Not Listed | Resolved Taxon | | CA |
| Amphibians | Kern Canyon slender salamander | Batrachoseps simatus | Proposed for Listing | Proposed Threatened | | CA |
| Flowering Plants | Kern mallow | Eremalche kernensis | Listed | Endangered | | CA |
| Amphibians | Kern Plateau salamander | Batrachoseps robustus | Not Listed | Resolved Taxon | | CA |
| Insects | Kern primrose sphinx moth | Euproserpinus euterpe | Listed | Threatened | | CA |
| Flowering Plants | Kern River daisy | Erigeron multiceps | Not Listed | Species of Concern | | CA |
| Fishes | Kern River rainbow trout | Oncorhynchus mykiss gilberti | Not Listed | Species of Concern | | CA |
| Snails | Kern shoulderband | Helminthoglypta callistoderma | Not Listed | Species of Concern | | CA |
| Flowering Plants | Kernville poppy | Eschscholzia procera | Not Listed | Species of Concern | | CA |
| Flowering Plants | Kerr crowfoot | Ranunculus fascicularis cuneiformis | Not Listed | Resolved Taxon | | TX |
| Insects | Kerr's agrotis noctuid moth | Agrotis kerri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kerr's milk-vetch | Astragalus kerrii | Not Listed | Species of Concern | | |
| Mammals | Key deer | Odocoileus virginianus clavium | Listed | Endangered | | FL |
| Arachnids | Key gnaphosid spider | Cesonia irvingi | Not Listed | Species of Concern | | |
| Mammals | Key Largo cotton mouse | Peromyscus gossypinus allapaticola | Listed | Endangered | | FL |
| Mammals | Key Largo woodrat | Neotoma floridana smalli | Listed | Endangered | | FL |
| Reptiles | Key ring-necked snake | Diadophis punctatus acricus | Proposed for Listing | Proposed Endangered | | FL |
| Insects | Keys scaly cricket | Cycloptilum irregularis | Not Listed | Species of Concern | | |
| Insects | Keys shortwinged conehead katydid | Belocephalus sleighti | Not Listed | Species of Concern | | |
| Reptiles | Key striped mud turtle | Kinosternon bauri | | Not Listed | | |
| Snails | Keys vertigo | Vertigo hebardi | Not Listed | Species of Concern | | |
| Flowering Plants | Key tree cactus | Pilosocereus robinii | Listed | Endangered | | FL |
| Mammals | Key Vaca raccoon | Procyon lotor auspicatus | Not Listed | Species of Concern | | |
| Mammals | Key West raccoon | Procyon lotor incautus | Not Listed | Species of Concern | | |
| Crustaceans | Kiamichi Crayfish | Orconectes saxatilis | Not Listed | Resolved Taxon | | |
| Clams | Kidneyshell | Ptychobranchus fasciolaris | | Not Listed | | |
| Flowering Plants | Kilauea naupaka | Scaevola kilaueae | Not Listed | Resolved Taxon | | HI |
| Insects | Kilauea pa`iniu omoides moth | Omoides iridias | Not Listed | Species of Concern | | HI |
| Mammals | Killer whale | Orcinus orca | Listed | Endangered | | |
| Flowering Plants | Kincaid's Lupine | Lupinus sulphureus ssp. kincaidii | Listed | Threatened | | OR, WA |
| Snails | Kingman springsnail | Pyrgulopsis conica | Petitioned for Listing, Under Review | Under Review | | AZ |
| Birds | King Rail | Rallus elegans | Not Listed | Species of Concern | | |
| Flowering Plants | King's beardtongue | Penstemon kingii | Not Listed | Resolved Taxon | | NV |
| Insects | Kings Canyon cryptochian caddisfly | Cryptochia excella | Not Listed | Species of Concern | | CA |
| Insects | King's Creek ecclisomyian caddisfly | Ecclisomyia bilera | Not Listed | Species of Concern | | CA |
| Insects | King's Creek parapsyche caddisfly | Parapsyche extensa | Not Listed | Species of Concern | | CA |
| Flowering Plants | King's gold | Tropidocarpum californicum | | Not Listed | | |
| Snails | Kings River pyrg | Pyrgulopsis imperialis | Petitioned for Listing, Under Review | Under Review | | NV |
| Amphibians | Kings River slender salamander | Batrachoseps regius | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Kingston bedstraw | Galium hilendiae kingstonense | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Kingston Mountains cinquefoil | Ivesia patellifera | Not Listed | Species of Concern | | CA |
| Snails | Kingston Oregonian | Cryptomastix sanburni | Not Listed | Resolved Taxon | | |
| Snails | Kintla Lake mountain snail | Oreohelix speciessix | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Kio`ele | Kadua coriacea | Listed | Endangered | | HI |
| Flowering Plants | Kiponapona | Phyllostegia racemosa | Listed | Endangered | | HI |
| Reptiles | Kirtland's snake | Clonophis kirtlandii | Petitioned for Listing, Under Review | Under Review | | IL, IN, KY, MI, OH, PA |
| Birds | Kirtland's Warbler | Setophaga kirtlandii | Delisted | Recovery | | MI, OH, SC, WI |
| Crustaceans | Kisatchie painted crayfish | Faxonius maletae | Petitioned for Listing, Under Review | Under Review | | LA, TX |
| Sponges | Kissimmee sponge | Ephydatia subtilis | Not Listed | Species of Concern | | |
| Snails | Kitchen Creek Mountain snail | Oreohelix speciesseven | Petitioned for Listing, Under Review | Under Review | | |
| Insects | Kite's neotrichian micro caddisfly | Neotrichia kitae | Not Listed | Species of Concern | | MO |
| Mammals | Kittatiny red-backed vole | Clethrionomys gapperi rupicola | Not Listed | Resolved Taxon | | PA |
| Birds | Kittlitz's murrelet | Brachyramphus brevirostris | Not Listed | Resolved Taxon | | AK |
| Fishes | Kiyi | Coregonus kiyi | Not Listed | Species of Concern | | IL, IN, MI, MN, NY, WI |
| Flowering Plants | Klamath gentian | Gentiana plurisetosa | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Klamath iris | Iris tenax klamathensis | Not Listed | Resolved Taxon | | CA |
| Fishes | Klamath Lake Sculpin | Cottus princeps | | Not Listed | | |
| Fishes | Klamath Lamprey | Entosphenus similis | | Not Listed | | |
| Fishes | Klamath largescale sucker | Catostomus snyderi | Not Listed | Species of Concern | | CA, OR |
| Insects | Klamath limnephilan caddisfly | Limnephilus alconura | Not Listed | Resolved Taxon | | OR |
| Flowering Plants | Klamath manzanita | Arctostaphylos klamathensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Klamath Mountain buckwheat | Eriogonum hirtellum | Not Listed | Resolved Taxon | | CA |
| Fishes | Klamath Smallscale Sucker | Catostomus rimiculus | | Not Listed | | |
| Fishes | Klamath Speckled Dace | Rhinichthys osculus klamathensis | | Not Listed | | |
| Flowering Plants | Kleberg's saltbush | Atriplex klebergorum | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Klein's evening-primrose | Oenothera kleinii | Not Listed | Species of Concern | | CO |
| Flowering Plants | Knapp's brickellia | Brickellia knappiana | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Kneeland Prairie penny-cress | Thlaspi californicum | Listed | Endangered | | CA |
| Flowering Plants | Knieskern's Beaked-rush | Rhynchospora knieskernii | Listed | Threatened | | NJ |
| Snails | Knobby Rams-horn | Vorticifex sp | Not Listed | Resolved Taxon | | CA |
| Snails | Knobby rocksnail | Lithasia curta | Not Listed | Status Undefined | | AL |
| Snails | Knob mudalia | Leptoxis minor | Not Listed | Species of Concern | | AL |
| Snails | Knotty elimia | Elimia interrupta | Not Listed | Species of Concern | | NC, TN |
| Snails | Knotty pebblesnail | Somatogyrus constrictus | Not Listed | Species of Concern | | AL |
| Flowering Plants | Knowlton's cactus | Pediocactus knowltonii | Listed | Endangered | | CO, NM |
| Insects | Knoxville hydroptilan micro caddisfly | Hydroptila decia | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | Knudsen dubautia | Dubautia knudsenii knudsenii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Koai`e | Acacia koaia | Not Listed | Species of Concern | | HI |
| Mammals | Koala | Phascolarctos cinereus | Listed | Threatened | | |
| Insects | Koa shield bug | Coleotichus blackburniae | Not Listed | Species of Concern | | HI |
| Insects | Koa yellow-faced bee | Hylaeus koae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Kobuk locoweed | Oxytropis kobukensis | Not Listed | Resolved Taxon | | AK |
| Birds | Koch's pitta | Pitta kochi | Listed | Endangered | | |
| Flowering Plants | Kodachrome bladderpod | Lesquerella tumulosa | Listed | Endangered | | UT |
| Flowering Plants | Kodachrome peppergrass | Lepidium montanum stellae | Not Listed | Resolved Taxon | | UT |
| Insects | Koebele's rhyncogonus weevil | Rhyncogonus koebelei | Not Listed | Species of Concern | | HI |
| Flowering Plants | Koehler's rock-cress | Arabis koehleri koehleri | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Kofa barberry | Berberis harrisoniana | Not Listed | Resolved Taxon | | AZ |
| Insects | Kohala long-horned beetle | Plagithmysus kohalae | Not Listed | Species of Concern | | HI |
| Insects | Kohala Mountain sedge omoides moth | Omoides anastreptoides | Not Listed | Species of Concern | | HI |
| Flowering Plants | Kohe malama malama o Kanaloa | Kanaloa kahoolawensis | Listed | Endangered | | HI |
| Flowering Plants | Koholapehu | Dubautia latifolia | Listed | Endangered | | HI |
| Birds | Kokako (wattlebird) | Callaeas cinerea | Listed | Endangered | | |
| Flowering Plants | Koki`o | Kokia cookei | Listed | Endangered | | HI |
| Flowering Plants | Koki`o | Kokia drynarioides | Listed | Endangered | | HI |
| Flowering Plants | Koki`o | Kokia kauaiensis | Listed | Endangered | | HI |
| Flowering Plants | Koki`o | Kokia lanceolata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Koki`o ke`oke`o | Hibiscus arnottianus ssp. immaculatus | Listed | Endangered | | HI |
| Flowering Plants | Koki`o ke`oke`o | Hibiscus waimeae ssp. hannerae | Listed | Endangered | | HI |
| Flowering Plants | Kokrines oxytrope | Oxytropis kokrinensis | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | Kolea | Myrsine fernseei | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kolea | Myrsine fosbergii | Listed | Endangered | | HI |
| Flowering Plants | Kolea | Myrsine juddii | Listed | Endangered | | HI |
| Flowering Plants | Kolea | Myrsine knudsenii | Listed | Endangered | | HI |
| Flowering Plants | Kolea | Myrsine lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kolea | Myrsine linearifolia | Listed | Threatened | | HI |
| Flowering Plants | Kolea | Myrsine mezii | Listed | Endangered | | HI |
| Flowering Plants | Kolea | Myrsine petiolata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Kolea | Myrsine vaccinioides | Listed | Endangered | | HI |
| Flowering Plants | Kolea | Myrsine wawraea | Not Listed | Resolved Taxon | | HI |
| Reptiles | Komodo Island monitor | Varanus komodoensis | Listed | Endangered | | |
| Flowering Plants | Kona bittercress | Cardamine flexuosa | Not Listed | Resolved Taxon | | HI |
| Insects | Kona giant looper | Scotorythra megalophylla | Not Listed | Resolved Taxon | | HI |
| Insects | Kona yellow-faced bee | Hylaeus kona | Not Listed | Species of Concern | | HI |
| Insects | Konza Prairie Mayfly | Leptophlebia konza | Not Listed | Resolved Taxon | | |
| Flowering Plants | kookoolau | Bidens hillebrandiana ssp. hillebrandiana | Listed | Endangered | | HI |
| Flowering Plants | Ko`oko`olau | Bidens amplectens | Listed | Endangered | | HI |
| Flowering Plants | Ko`oko`olau | Bidens campylotheca ssp. campylotheca | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens campylotheca ssp. pentamera | Listed | Endangered | | HI |
| Flowering Plants | Ko`oko`olau | Bidens campylotheca ssp. waihoiensis | Listed | Endangered | | HI |
| Flowering Plants | Ko`oko`olau | Bidens cervicata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens conjuncta | Listed | Endangered | | HI |
| Flowering Plants | Ko`oko`olau | Bidens degeneri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens hawaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens macrocarpa ovatifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens mauiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens menziesii leptodonta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens micrantha caduca | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens micrantha kaalana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens micrantha laciniata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens micrantha ssp. ctenophylla | Listed | Endangered | | HI |
| Flowering Plants | Ko`oko`olau | Bidens micrantha ssp. kalealaha | Listed | Endangered | | HI |
| Flowering Plants | Ko`oko`olau | Bidens molokaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens obtusiloba | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens pulchella | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens sandvicensis confusa | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ko`oko`olau | Bidens sandvicensis ssp. sandvicensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens sandwicensis setosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ko`oko`olau | Bidens wiebkei | Listed | Endangered | | HI |
| Insects | Ko`olau giant looper | Scotorythra nesiotes | Not Listed | Resolved Taxon | | HI |
| Insects | Ko`olau spurwing long-legged fly | Campsicnemus mirabilis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ko`oloa`ula | Abutilon menziesii | Listed | Endangered | | HI |
| Flowering Plants | kopa | Kadua cordata remyi | Listed | Endangered | | HI |
| Flowering Plants | Kopiko | Psychotria grandiflora | Listed | Endangered | | HI |
| Flowering Plants | Kopiko | Psychotria hexandra var. oahuensis | Listed | Endangered | | HI |
| Flowering Plants | Kopiko | Psychotria hobdyi | Listed | Endangered | | HI |
| Snails | Koster's springsnail | Juturnia kosteri | Listed | Endangered | | NM |
| Flowering Plants | Kotzebue's, grass-of-parnassus | Parnassia kotzebuei pumila | Not Listed | Resolved Taxon | | WA |
| Mammals | Kouprey | Bos sauveli | Listed | Endangered | | |
| Flowering Plants | Kral's water-plantain | Sagittaria secundifolia | Listed | Threatened | | AL, GA |
| Insects | Kramer's cave beetle | Pseudanophthalmus krameri | Not Listed | Species of Concern | | OH |
| Insects | Krauss' long-horned beetle | Plagithmysus kraussi | Not Listed | Species of Concern | | HI |
| Insects | Kretschmarr Cave mold beetle | Texamaurops reddelli | Listed | Endangered | | TX |
| Flowering Plants | Kruckeberg's jewelflower | Streptanthus morrisonii kruckebergii | Not Listed | Species of Concern | | CA |
| Ferns and Allies | Kruckeberg's swordfern | Polystichum kruckebergii | Not Listed | Resolved Taxon | | CA, ID, MT, NV, OR, WA |
| Flowering Plants | Krug's white morning-glory | Ipomoea krugii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Kuahiwi laukahi | Plantago hawaiensis | Listed | Endangered | | HI |
| Flowering Plants | Kuahiwi laukahi | Plantago princeps | Listed | Endangered | | HI |
| Flowering Plants | Kuawawaenohu | Schiedea lychnoides | Listed | Endangered | | HI |
| Flowering Plants | Kuenzler hedgehog cactus | Echinocereus fendleri var. kuenzleri | Listed | Threatened | | NM, TX |
| Mammals | Kuhl's (=Bawean) deer | Axis porcinus kuhli | Listed | Endangered | | |
| Insects | Kuhns' Oahu long-horned beetle | Plagithmysus kuhnsi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Kulu`i | Nototrichium humile | Listed | Endangered | | HI |
| Ferns and Allies | Kupukupu makali`i | Menisciopsis boydiae | Listed | Endangered | | HI |
| Insects | Kusche's nesosydne planthopper | Nesosydne kuschei | Not Listed | Species of Concern | | HI |
| Flowering Plants | Lace-leaf Rockdaisy | Perityle ambrosiifolia | Not Listed | Resolved Taxon | | |
| Arachnids | Lacey's cave pseudoscorpion | Larca laceyi | Not Listed | Species of Concern | | CA |
| Snails | Lacy elimia (snail) | Elimia crenatella | Listed | Threatened | | AL |
| Birds | Ladder backed Woodpecker | Picoides scalaris | Not Listed | Species of Concern | | |
| Snails | Ladybug Saddle talussnail | Sonorella sp. | Not Listed | Species of Concern | | AZ |
| Insects | Laetan yellow-faced bee | Hylaeus laeta | Not Listed | Species of Concern | | HI |
| Crustaceans | Lagniappe crayfish | Procambarus lagniappe | | Not Listed | | MS |
| Flowering Plants | La Graciosa thistle | Cirsium loncholepis | Listed | Endangered | | CA |
| Flowering Plants | Laguna alumroot | Heuchera brevistaminea | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Laguna Beach liveforever | Dudleya stolonifera | Listed | Threatened | | CA |
| Flowering Plants | Laguna Mountains aster | Machaeranthera asteroides lagunensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Laguna Mountains jewelflower | Streptanthus bernardinus | Not Listed | Resolved Taxon | | CA |
| Insects | Laguna Mountains skipper | Pyrgus ruralis lagunae | Listed | Endangered | | CA |
| Flowering Plants | Laguna Mountains sunflower | Hulsea californica | Not Listed | Resolved Taxon | | CA |
| Insects | Lahaina rhyncogonus weevil | Rhyncogonus lahainae | Not Listed | Species of Concern | | HI |
| Fishes | Lahontan Creek tui chub | Siphateles bicolor obesa | Not Listed | Resolved Taxon | | NV |
| Fishes | Lahontan cutthroat trout | Oncorhynchus clarkii henshawi | Listed | Threatened | | CA, NV, OR, UT |
| Fishes | Lahontan Shiner | Richardsonius egregius | | Not Listed | | |
| Flowering Plants | Lake Alamanor bluecup | Legousia speculum-veneris | Not Listed | Resolved Taxon | | CA |
| Fishes | Lake Chub | Couesius plumbeus | | Not Listed | | |
| Fishes | Lake Chubsucker | Erimyzon sucetta | | Not Listed | | |
| Flowering Plants | Lake County dwarf-flax | Hesperolinon didymocarpum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Lake County stonecrop | Parvisedum leiocarpum | Listed | Endangered | | CA |
| Snails | Lake Disc | Discus brunsoni | Not Listed | Resolved Taxon | | |
| Flowering Plants | Lake Erie pinkweed | Polygonum pensylvanicum eglandulosum | Not Listed | Resolved Taxon | | MO, OH |
| Reptiles | Lake Erie water snake | Nerodia sipedon insularum | Delisted | Recovery | | OH |
| Fishes | Lake Herring | Coregonus artedi | | Not Listed | | |
| Insects | Lake Huron locust | Trimerotropis huroniana | Not Listed | Species of Concern | | MI, WI |
| Flowering Plants | Lakela's mint | Dicerandra immaculata | Listed | Endangered | | FL |
| Arachnids | Lake Placid funnel wolf spider | Sosippus placidus | Not Listed | Species of Concern | | |
| Flowering Plants | Lakeside ceanothus | Ceanothus cyaneus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Lakeside daisy | Hymenoxys herbacea | Listed | Threatened | | IL, MI, OH |
| Fishes | Lake sturgeon | Acipenser fulvescens | | Not Listed | | AL, AR, GA, IA, IL, IN, KS, KY, LA, MI, MN, MO, MS, NE, NY, OH, PA, SD, TN, VT, WI, WV |
| Insects | Lake Tahoe benthic stonefly | Capnia lacustra | Not Listed | Species of Concern | | CA, NV |
| Fishes | Lake Trout | Salvelinus namaycush | | Not Listed | | |
| Snails | Lake Valley pyrg | Pyrgulopsis sublata | Not Listed | Resolved Taxon | | NV |
| Fishes | Lake Whitefish | Coregonus clupeaformis | | Not Listed | | |
| Insects | Lallemant's cave beetle | Pseudanophthalmus lallemanti | Not Listed | Species of Concern | | WV |
| Corals | Lamarck's Sheet Coral | Agaricia lamarcki | Not Listed | Status Undefined | | |
| Snails | Lamb Rams-horn | Planorbella oregonensis | Not Listed | Resolved Taxon | | |
| Mammals | Lamotte's Roundleaf Bat | Hipposideros lamottei | Petitioned for Listing, Under Review | Under Review | | |
| Insects | Lanai kalanian leaf bug | Kalania hawaiiensis | Not Listed | Species of Concern | | HI |
| Insects | Lanai `ohi`a long-horned beetle | Plagithmysus lanaiensis | Not Listed | Species of Concern | | HI |
| Insects | Lanai oliarus planthopper | Oliarus lanaiensis | Not Listed | Resolved Taxon | | HI |
| Insects | Lanai pomace fly | Drosophila lanaiensis | Not Listed | Species of Concern | | HI |
| Insects | Lanai rhyncogonus weevil | Rhyncogonus lanaiensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Lanai sandalwood (=`iliahi) | Santalum haleakalae var. lanaiense | Listed | Endangered | | HI |
| Snails | Lanai tree snail | Partulina crassa | Not Listed | Species of Concern | | HI |
| Snails | Lanai tree snail | Partulina semicarinata | Listed | Endangered | | HI |
| Snails | Lanai tree snail | Partulina variabilis | Listed | Endangered | | HI |
| Insects | Lanai yellow-faced bee | Hylaeus angustula | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Lance leaf wild-buckwheat | Eriogonum lancifolium | Not Listed | Resolved Taxon | | UT |
| Snails | Landyes pyrg | Pyrgulopsis landyei | Petitioned for Listing, Under Review | Under Review | | NV |
| Flowering Plants | Lane Mountain milk-vetch | Astragalus jaegerianus | Listed | Endangered | | CA |
| Insects | Lange's El Segundo Dune weevil | Onychobaris langei | Not Listed | Species of Concern | | CA |
| Insects | Lange's metalmark butterfly | Apodemia mormo langei | Listed | Endangered | | CA |
| Snails | Langford's tree snail | Partula langfordi | Listed | Endangered | | MP |
| Insects | Langston's blue butterfly | Euphilotes enoptes langstoni | Not Listed | Resolved Taxon | | CA |
| Birds | Lanyu Scops owl | Otus elegans botelensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Laramie columbine | Aquilegia laramiensis | Not Listed | Species of Concern | | WY |
| Flowering Plants | Laramie false sagebrush | Sphaeromeria simplex | Not Listed | Species of Concern | | WY |
| Amphibians | Larch Mountain salamander | Plethodon larselli | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Insects | Large aegialian scarab | Aegialia magnifica | Not Listed | Resolved Taxon | | NV |
| Birds | Large-billed savannah sparrow | Passerculus sandwichensis rostratus | Not Listed | Species of Concern | | AZ, CA |
| Amphibians | Large-blotched ensatina | Ensatina eschscholtzii klauberi | Not Listed | Species of Concern | | CA |
| Mammals | Large desert marsupial-mouse | Sminthopsis psammophila | Listed | Endangered | | |
| Mammals | Large-eared hutia | Capromys auritus | Listed | Endangered | | |
| Flowering Plants | Large-flowered Barbara's buttons | Marshallia grandiflora | Petitioned for Listing, Under Review | Under Review | | NC |
| Flowering Plants | Large-flowered fiddleneck | Amsinckia grandiflora | Listed | Endangered | | CA |
| Flowering Plants | Large-flowered skullcap | Scutellaria montana | Listed | Threatened | | GA, TN |
| Flowering Plants | Large-flowered woolly meadowfoam | Limnanthes pumila ssp. grandiflora | Listed | Endangered | | OR |
| Flowering Plants | Large-fruited bladder-pod | Lesquerella macrocarpa | Not Listed | Species of Concern | | WY |
| Flowering Plants | Large-fruited sand-verbena | Abronia macrocarpa | Listed | Endangered | | TX |
| Birds | Large Kauai (=kamao) Thrush | Myadestes myadestinus | Delisted | Extinction | | |
| Flowering Plants | Largeleaf grass of Parnassus | Parnassia grandifolia | Not Listed | Species of Concern | | |
| Flowering Plants | Large-leaved filaree | erodium macrophyllum | Not Listed | Species of Concern | | |
| Flowering Plants | Large-leaved jointweed | Polygonella macrophylla | Not Listed | Species of Concern | | |
| Insects | large marble butterfly | Euchloe ausonides | Petitioned for Listing, Under Review | Under Review | | AK, CA, CO, ID, MI, MN, MT, ND, NE, NM, NV, OR, SD, UT, WA, WY |
| Algae | Largemouth Bass | Micropterus salmoides | | Not Listed | | |
| Fishes | Largemouthed leatherskin | Scomberoides lysan | | Not Listed | | |
| Flowering Plants | Large-petaled ash | Fraxinus cuspidata macropetala | Not Listed | Resolved Taxon | | AZ, CA, NM, NV |
| Flowering Plants | Large red buckwheat | Eriogonum grande rubescens | Not Listed | Species of Concern | | CA |
| Fishes | Largescaled Spinycheek Sleeper | Eleotris amblyopsis | | Not Listed | | |
| Fishes | largescale sucker | Catostomus macrocheilus | Not Listed | Status Undefined | | |
| Fishes | Large Shovelnose Sturgeon | Pseudoscaphirhynchus kaufmanni | Petitioned for Listing, Under Review | Under Review | | |
| Reptiles | Large-spotted leopard lizard | gambelia wislizenii ssp. wislizenii | Not Listed | Species of Concern | | |
| Fishes | Largetooth Sawfish | Pristis pristis | Listed | Endangered | | |
| Insects | Laricis tree cricket | Oecanthus laricis | Not Listed | Species of Concern | | MI, OH |
| Birds | Lark Bunting | Calamospiza melanocorys | Not Listed | Species of Concern | | |
| Birds | Lark Sparrow | Chondestes grammacus | Not Listed | Species of Concern | | |
| Flowering Plants | Larkspur | Delphinium leucophaeum | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Reptiles | Lar Valley viper | Vipera latifii | Listed | Endangered | | |
| Mammals | La Sal pika | Ochotona princeps lasalensis | Not Listed | Species of Concern | | UT |
| Flowering Plants | Las Animas colubrina | Colubrina californica | Not Listed | Resolved Taxon | | AZ, CA |
| Flowering Plants | Lassen County bluegrass | Poa X limosa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Lassen desert-parsley | Lomatium ravenii | Not Listed | Resolved Taxon | | CA, ID, NV, OR, UT |
| Flowering Plants | Lassics lupine | Lupinus constancei | Listed | Endangered | | CA |
| Flowering Plants | Last Chance townsendia | Townsendia aprica | Listed | Threatened | | UT |
| Flowering Plants | Las Vegas bearpoppy | Arctomecon californica | Not Listed | Resolved Taxon | | AZ, NV |
| Flowering Plants | Las Vegas buckwheat | Eriogonum corymbosum var. nilesii | Not Listed | Resolved Taxon | | NV, UT |
| Fishes | Las Vegas dace | Rhinichthys deaconi | Not Listed | Resolved Taxon | | NV |
| Insects | Lateral bluet | Enallagma laterale | Not Listed | Species of Concern | | DE, IN, MA, ME, NJ, NY, PA |
| Flowering Plants | Lau `ehu | Panicum niihauense | Listed | Endangered | | HI |
| Birds | Laughing gull | larus atricilla | Not Listed | Species of Concern | | AS |
| Flowering Plants | Laulihilihi | Schiedea stellarioides | Listed | Endangered | | HI |
| Fishes | Laurel dace | Chrosomus saylori | Listed | Endangered | | TN |
| Snails | Lava rock mountainsnail | Oreohelix waltoni | Not Listed | Species of Concern | | ID |
| Flowering Plants | Lavin's milk-vetch | Astragalus oophorus lavinii | Not Listed | Species of Concern | | CA, NV |
| Birds | Lawrence's Goldfinch | Spinus lawrencei | Not Listed | Species of Concern | | |
| Flowering Plants | Layne's butterweed | Senecio layneae | Listed | Threatened | | CA |
| Insects | Laysan agrotis noctuid moth | Agrotis laysanensis | Not Listed | Resolved Taxon | | HI |
| Birds | Laysan Albatross | Phoebastria immutabilis | Not Listed | Species of Concern | | |
| Insects | Laysan dropseed noctuid moth | Hypena laysanensis | Not Listed | Resolved Taxon | | HI |
| Birds | Laysan duck | Anas laysanensis | Listed | Endangered | | HI |
| Birds | Laysan finch | Telespiza cantans | Listed | Endangered | | HI |
| Insects | Laysan hedyleptan moth | Hedylepta laysanensis | Not Listed | Resolved Taxon | | HI |
| Insects | Laysan oodemas weevil | Oodemas laysanensis | Not Listed | Species of Concern | | HI |
| Insects | Laysan rhyncogonus weevil | Rhyncogonus bryani | Not Listed | Species of Concern | | HI |
| Birds | Lazuli Bunting | Passerina amoena | Not Listed | Species of Concern | | |
| Birds | Leach's Storm-Petrel | Oceanodroma leucorhoa | Not Listed | Species of Concern | | |
| Mammals | Leadbeater's Possum | Gymnobelideus leadbeateri | Listed | Endangered | | |
| Clams | Leafshell | Epioblasma flexuosa | Not Listed | Resolved Taxon | | AL, TN |
| Flowering Plants | Leafy prairie-clover | Dalea foliosa | Listed | Endangered | | AL, IL, TN |
| Flowering Plants | Leafy reedgrass | Calamagrostis foliosa | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Lean crayfish | Cambarus strigosus | Not Listed | Status Undefined | | GA |
| Lichens | Lea's Bog lichen | Phaeophyscia leana | Not Listed | Status Undefined | | IL, KY, PA, TN |
| Birds | Least Bell's vireo | Vireo bellii pusillus | Listed | Endangered | | CA |
| Birds | Least bittern | Ixobrychus exilis | Not Listed | Species of Concern | | AZ, CA, NV, OR, UT |
| Fishes | Least Brook Lamprey | Lampetra aepyptera | | Not Listed | | |
| Fishes | Least chub | Iotichthys phlegethontis | Not Listed | Resolved Taxon | | UT |
| Fishes | Least Cisco | Coregonus sardinella | | Not Listed | | |
| Crustaceans | Least crayfish | Cambarellus diminutus | | Not Listed | | AL, MS |
| Fishes | Least Darter | Etheostoma microperca | | Not Listed | | |
| Fishes | Least Madtom | Noturus hildebrandi | | Not Listed | | |
| Flowering Plants | Least, Ozark trillium | Trillium pusillum ozarkanum | Not Listed | Species of Concern | | AR, KY, MO, OK, TN |
| Birds | Least Storm-Petrel | Oceanodroma microsoma | Not Listed | Species of Concern | | |
| Birds | Least tern | Sternula antillarum | Not Listed | Species of Concern | | |
| Birds | Least tern | Sternula antillarum | Delisted | Recovery | | AR, CO, IA, IL, IN, KS, KY, LA, MO, MS, MT, ND, NE, NM, OK, SD, TN, TX |
| Birds | Least Tern | Sternula antillarum antillarum | Not Listed | Species of Concern | | |
| Birds | Least Tern | Sternula antillarum athalassos | Not Listed | Species of Concern | | |
| Flowering Plants | Least, Virginia trillium | Trillium pusillum virginianum | Not Listed | Species of Concern | | VA |
| Reptiles | Leatherback sea turtle | Dermochelys coriacea | Listed | Endangered | | AL, CA, FL, GA, MD, NC, PR, SC, TX, VA, VI |
| Fishes | Leatherside chub | Snyderichthys copei | Not Listed | Species of Concern | | ID, UT, WY |
| Birds | Le Conte's Sparrow | Ammospiza leconteii | Not Listed | Species of Concern | | |
| Birds | LeConte''s Thrasher | Toxostoma lecontei | Not Listed | Species of Concern | | AZ, CA, NV |
| Insects | Leech's chaetarthrian water scavenger beetle | Chaetarthria leechi | Not Listed | Species of Concern | | CA |
| Insects | Leech's skyline diving beetle | Hydroporus leechi | Not Listed | Species of Concern | | CA |
| Crustaceans | Lee County cave isopod | Lirceus usdagalun | Listed | Endangered | | VA |
| Flowering Plants | Leedy's roseroot | Rhodiola integrifolia ssp. leedyi | Listed | Threatened | | MN, NY, SD |
| Flowering Plants | Lee pincushion cactus | Coryphantha sneedii var. leei | Listed | Threatened | | NM, TX |
| Arachnids | Lee's micro-blind harvestman | Microcina leei | Not Listed | Species of Concern | | CA |
| Clams | Lefevre's pearly mussel | Epioblasma lefevrei | Not Listed | Resolved Taxon | | AR, MO |
| Flowering Plants | Legenere | Legenere limosa | Not Listed | Species of Concern | | CA |
| Flowering Plants | lehua makanoe | Lysimachia daphnoides | Listed | Endangered | | HI |
| Flowering Plants | Leichtlin camassia | Camassia leichtlinii leichtlinii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Le`ie rhyncogonus weevil | Rhyncogonus freycinetiae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Lemhi beardtongue | Penstemon lemhiensis | Not Listed | Species of Concern | | ID, MT |
| Insects | Lemmer's pinnion moth | Lithophane lemmeri | Not Listed | Resolved Taxon | | |
| Ferns and Allies | Lemmon fern cloak | Notholaena lemmonii | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Lemmon fleabane | Erigeron lemmonii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Lemmon globe berry | Physalis solanaceus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Lemmon's clover | Trifolium lemmonii | Not Listed | Resolved Taxon | | CA, CO, NV |
| Flowering Plants | Lemmon's jewelflower | Streptanthus lemmonii | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Lemmon's Lupine | Lupinus lemmonii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Lemmon's morning-glory | Ipomoea tenuiloba lemmonii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Lemmon's paintbrush | Castilleja lemmonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Lemon colored fawn-lily | Erythronium citrinum rodrickii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Lemon lily | Lilium parryi | Not Listed | Species of Concern | | AZ, CA |
| Mammals | Lemurs | Lemuridae (incl. genera Lemur, Phaner, Hapalemur, Lepilemur, Microcebus, Allocebus, Cheirogaleus, Varecia) | Listed | Endangered | | |
| Insects | Lenat's ceraclean caddisfly | Ceraclea sp. | Not Listed | Species of Concern | | NC |
| Flowering Plants | Leo Brewer's manzanita | Arctostaphylos uva-ursi leobreweri | Not Listed | Resolved Taxon | | CA |
| Insects | Leona's little blue butterfly | Philotiella leona | Not Listed | Resolved Taxon | | OR |
| Flowering Plants | Leoncita false-foxglove | Agalinis calycina | Petitioned for Listing, Under Review | Under Review | | NM, TX |
| Insects | Leon River winter stonefly | Taeniopteryx starki | Not Listed | Resolved Taxon | | TX |
| Fishes | Leon Springs pupfish | Cyprinodon bovinus | Listed | Endangered | | TX |
| Mammals | Leopard | Panthera pardus | Listed | Endangered | | |
| Mammals | Leopard | Panthera pardus | Listed | Threatened | | |
| Mammals | Leopard cat | Prionailurus (=Felis) bengalensis bengalensis | Listed | Endangered | | |
| Fishes | Leopard Dace | Rhinichthys falcatus | | Not Listed | | |
| Fishes | Leopard darter | Percina pantherina | Listed | Threatened | | AR, OK |
| Fishes | Leopard Shark | Triakis semifasciata | | Not Listed | | |
| Snails | leslis canyon talussnail | sonorella pedregosensis | Not Listed | Resolved Taxon | | |
| Insects | Lesser Adams Cave beetle | Pseudanophthalmus catorycetes | Not Listed | Resolved Taxon | | KY |
| Birds | Lesser Common Nighthawk | Chordeiles minor minor | Not Listed | Species of Concern | | |
| Mammals | Lesser long-nosed bat | Leptonycteris curasoae yerbabuenae | Delisted | Recovery | | AZ, NM |
| Birds | Lesser nighthawk | chordeiles acutipennis | Not Listed | Species of Concern | | |
| Birds | Lesser prairie-chicken | Tympanuchus pallidicinctus | Listed | Endangered | | |
| Birds | Lesser prairie-chicken | Tympanuchus pallidicinctus | Listed | Threatened | | |
| Birds | Lesser prairie-chicken | Tympanuchus pallidicinctus | Petitioned for Listing, Under Review | Under Review | | CO, KS, NM, OK, TX |
| Mammals | Lesser rabbit bandicoot | Macrotis leucura | Listed | Endangered | | |
| Birds | Lesser rhea (incl. Darwin's) | Rhea (=Pterocnemia) pennata | Listed | Endangered | | |
| Reptiles | Lesser Saint Croix Skink | Capitellum parvicruzae | Not Listed | Resolved Taxon | | VI |
| Flowering Plants | Lesser saltbrush | atriplex minuscula | Not Listed | Species of Concern | | |
| Birds | Lesser scaup | Aythya affinis | Not Listed | Species of Concern | | |
| Amphibians | Lesser Siren | Siren intermedia | | Not Listed | | |
| Amphibians | Lesser slender salamander | Batrachoseps minor | Not Listed | Status Undefined | | CA |
| Mammals | Lesser slow loris | Nycticebus pygmaeus | Listed | Threatened | | |
| Reptiles | Lesser Virgin Islands Skink | Spondylurus semitaeniatus | Proposed for Listing | Proposed Endangered | | VI |
| Birds | Lesser White-cheeked Pintail | Anas bahamensis bahamensis | Not Listed | Species of Concern | | PR, VI |
| Birds | Lesser Yellowlegs | Tringa flavipes | Not Listed | Species of Concern | | |
| Mammals | Lesueur's rat-kangaroo | Bettongia lesueur | Listed | Endangered | | |
| Birds | Lewis's Woodpecker | Melanerpes lewis | Not Listed | Species of Concern | | |
| Flowering Plants | Lewton's polygala | Polygala lewtonii | Listed | Endangered | | FL |
| Mammals | L'hoest's monkey | Cercopithecus lhoesti | Listed | Endangered | | |
| Birds | Light-footed Ridgway's rail | Rallus obsoletus levipes | Listed | Endangered | | CA |
| Insects | Lihue oliarus planthopper | Oliarus lihue | Not Listed | Species of Concern | | HI |
| Flowering Plants | Lilia de los llanos | Echeandia chandleri | Not Listed | Species of Concern | | TX |
| Flowering Plants | Liliwai | Acaena exigua | Listed | Endangered | | HI |
| Clams | Lilliput | Toxolasma parvum | | Not Listed | | |
| Snails | Lily Shoals elimia | Elimia annettae | Petitioned for Listing, Under Review | Under Review | | AL |
| Insects | Limestone cave beetle | Pseudanophthalmus calcareus | Not Listed | Species of Concern | | KY |
| Flowering Plants | Limestone fameflower | Talinum calcaricum | Not Listed | Resolved Taxon | | AL, KY, TN |
| Flowering Plants | Limestone penstemon | Penstemon calcareus | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Limestone rosewood | Vauquelinia californica pauciflora | Not Listed | Species of Concern | | AZ, NM |
| Amphibians | Limestone salamander | Hydromantes brunus | Petitioned for Listing, Under Review | Under Review | | CA |
| Flowering Plants | Limestone violet | Viola purpurea charlestonensis | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | Limestone wild-buckwheat | Eriogonum eremicum | Not Listed | Resolved Taxon | | UT |
| Mammals | Limpia Creek pocket gopher | Thomomys umbrinus texensis | Not Listed | Species of Concern | | TX |
| Snails | Limpia Creek Springsnail | Pyrgulopsis davisi | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Limpia southern pocket gopher | Thomomys umbrinus limpiae | Not Listed | Species of Concern | | TX |
| Birds | Limpkin | Aramus guarauna elucus | Not Listed | Species of Concern | | |
| Flowering Plants | Lincoln County bladder-pod | Lesquerella lata | Not Listed | Resolved Taxon | | NM |
| Birds | Lincoln's Sparrow | Melospiza lincolnii | Not Listed | Species of Concern | | |
| Insects | Linda's Roadside-skipper | Amblyscirtes linda | Petitioned for Listing, Under Review | Under Review | | AR, IL, KY, OK, TN |
| Flowering Plants | Lindheimer's nailwort | Paronychia lindheimeri var. lindheimeri | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Lindheimer's tickseed | Desmodium lindheimeri | Not Listed | Species of Concern | | TX |
| Fishes | Lined chub | Hybopsis lineapunctata | Not Listed | Resolved Taxon | | AL, GA, TN |
| Clams | Lined pocketbook | Lampsilis binominata | Not Listed | Species of Concern | | AL, GA |
| Arachnids | Linville Caverns Spider | Nesticus carolinensis | Not Listed | Species of Concern | | NC |
| Mammals | Lion | Panthera leo ssp. leo | Listed | Endangered | | |
| Mammals | Lion | Panthera leo ssp. melanochaita | Listed | Threatened | | |
| Mammals | Lion-tailed macaque | Macaca silenus | Listed | Endangered | | |
| Amphibians | Lipan salamander | Eurycea species 3 | Petitioned for Listing, Under Review | Under Review | | TX |
| Fishes | lipstick darter | Etheostoma chuckwachatte | Not Listed | Species of Concern | | GA |
| Flowering Plants | Little Aguja (=Creek) Pondweed | Potamogeton clystocarpus | Listed | Endangered | | TX |
| Flowering Plants | Little amphianthus | Amphianthus pusillus | Listed | Threatened | | AL, GA, SC |
| Birds | Little Blue Heron | Egretta caerulea | Not Listed | Species of Concern | | |
| Birds | Little blue macaw | Cyanopsitta spixii | Listed | Endangered | | |
| Flowering Plants | Little Bluestem | Schizachyrium scoparium | | Not Listed | | |
| Mammals | Little brown bat | Myotis lucifugus | Petitioned for Listing, Under Review | Under Review | | AK, AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY |
| Crustaceans | Little Brown Mudbug | Lacunicambarus thomai | | Not Listed | | |
| Fishes | Little Colorado spinedace | Lepidomeda vittata | Listed | Threatened | | AZ |
| Fishes | Little Colordao River sucker | Catostomus | | Not Listed | | |
| Mammals | Little earth hutia | Capromys sanfelipensis | Listed | Endangered | | |
| Insects | Little Kennedy cave beetle | Pseudanophthalmus cordicollis | Not Listed | Resolved Taxon | | VA |
| Fishes | Little Kern golden Trout | Oncorhynchus aguabonita whitei | Listed | Threatened | | CA |
| Fishes | Little Lake speckled dace | Rhinichthys osculus ssp. | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Little-leaf brongniartia | Brongniartia minutifolia | Not Listed | Species of Concern | | TX |
| Mammals | Little Mariana fruit Bat | Pteropus tokudae | Delisted | Extinction | | GU |
| Flowering Plants | Little mousetail | Myosurus minimus apus | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Little oecetis longhorn caddisfly | Oecetis parva | Petitioned for Listing, Under Review | Under Review | | FL |
| Mammals | Little planigale | Planigale ingrami subtilissima | Listed | Endangered | | |
| Insects | Little riffle beetle | Dubiraphia parva | Not Listed | Species of Concern | | LA, OK |
| Crustaceans | Little River crayfish | Cambarus spicatus | Petitioned for Listing, Under Review | Under Review | | SC |
| Flowering Plants | Little San Bernardino Mountains gilia | Gilia maculata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Little San Bernardino Mountains gilia | Linanthus maculates | Not Listed | Status Undefined | | |
| Lichens | Little's fissidens moss | Fissidens littlei | Not Listed | Resolved Taxon | | |
| Fishes | Little Spectacle Case | Villosa lienosa | | Not Listed | | |
| Flowering Plants | Little Sur manzanita | Arctostaphylos edmundsii | Not Listed | Species of Concern | | CA |
| Crustaceans | Little Tennessee crayfish | Cambarus georgiae | Not Listed | Status Undefined | | GA, NC |
| Birds | Little willow flycatcher | Empidonax traillii brewsteri | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Clams | Littlewing pearlymussel | Pegias fabula | Listed | Endangered | | KY, TN |
| Snails | Live Oak Glass | Nesovitrea suzannae | Not Listed | Resolved Taxon | | |
| Flowering Plants | Livermore nailwort | Paronychia monticola | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Livermore sandwort | Arenaria livermorensis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Livermore sweet-cicely | Osmorhiza mexicana bipatriata | Not Listed | Species of Concern | | TX |
| Amphibians | Llanero Coqui | Eleutherodactylus juanariveroi | Listed | Endangered | | PR |
| Flowering Plants | Lloyd's hedgehog cactus | Echinocereus lloydii | Delisted | Original Data in Error - Not a listable entity | | NM, TX |
| Flowering Plants | Lloyd''s Mariposa cactus | Sclerocactus mariposensis | Listed | Threatened | | TX |
| Fishes | Loach minnow | Tiaroga cobitis | Listed | Endangered | | AZ, NM |
| Flowering Plants | Lobed Barren Strawberry | Geum lobatum | Not Listed | Species of Concern | | NC |
| Insects | Lobed roachfly | Tallaperla lobata | Petitioned for Listing, Under Review | Under Review | | VA |
| Corals | Lobed Star Coral | Orbicella annularis | Listed | Threatened | | |
| Insects | Lobe-wing brown lacewing | Micromus lobipennis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Loch Lomond coyote thistle | Eryngium constancei | Listed | Endangered | | CA |
| Snails | Lockes pyrg | Pyrgulopsis lockensis | Not Listed | Resolved Taxon | | NV |
| Mammals | Lodgepole chipmunk | Tamias speciosus speciosus | Not Listed | Species of Concern | | CA |
| Insects | Logan's Agarodes caddisfly | Agarodes logani | Petitioned for Listing, Under Review | Under Review | | FL |
| Flowering Plants | Logan wild-buckwheat | Eriogonum loganum | Not Listed | Resolved Taxon | | UT |
| Birds | Loggerhead Kingbird | Tyrannus caudifasciatus | Not Listed | Species of Concern | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Endangered | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Threatened | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Endangered | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Threatened | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Endangered | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Endangered | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Endangered | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Threatened | | |
| Reptiles | Loggerhead sea turtle | Caretta caretta | Listed | Threatened | | AL, FL, GA, LA, MD, MS, NC, SC, TX, VA |
| Fishes | Logperch | Percina caprodes | | Not Listed | | |
| Flowering Plants | Loma Prieta hoita | hoita strobilina | Not Listed | Species of Concern | | |
| Insects | Lompoc grasshopper | Trimerotropis occulens | Not Listed | Resolved Taxon | | |
| Flowering Plants | Lompoc yerba santa | Eriodictyon capitatum | Listed | Endangered | | CA |
| Flowering Plants | Lonestar Sandmint | Rhododon angulatus | | Not Listed | | |
| Flowering Plants | Long Beach seedbox | Ludwigia brevipes | Not Listed | Status Undefined | | AR, DE, GA, MD, NC, NJ, SC, VA |
| Flowering Plants | Long-bearded, Peck's mariposa | Calochortus longebarbatus peckii | Not Listed | Species of Concern | | CA, NV, OR |
| Birds | Long-billed Curlew | Numenius americanus | Not Listed | Resolved Taxon | | AZ, CA, CO, IA, ID, KS, LA, MN, MT, ND, NE, NM, NV, OK, OR, SD, TX, UT, WA, WI, WY |
| Mammals | Long-eared myotis | Myotis evotis | Not Listed | Species of Concern | | CO, NE, NM, UT, WA |
| Birds | Long-eared Owl | asio otus | Not Listed | Species of Concern | | |
| Fishes | Longear Sunfish | Lepomis megalotis | | Not Listed | | |
| Fishes | Longfin dace | Agosia chrysogaster | Not Listed | Species of Concern | | AZ, NM |
| Fishes | Longfin Smelt | Spirinchus thaleichthys | Listed | Endangered | | CA |
| Fishes | Longfin Smelt | Spirinchus thaleichthys | | Not Listed | | |
| Insects | Long-footed nesosydne planthopper | Nesosydne longipes | Not Listed | Species of Concern | | HI |
| Flowering Plants | Long-haired phlox | Phlox pilosa longipilosa | Not Listed | Resolved Taxon | | OK |
| Flowering Plants | Long-haired star-tulip | Calochortus longebarbatus longebarbatus | Not Listed | Species of Concern | | WA |
| Fishes | Longhead darter | Percina macrocephala | Not Listed | Resolved Taxon | | KY, NY, OH, PA, TN, WV |
| Insects | Long-headed cave beetle | Pseudanophthalmus longiceps | Not Listed | Species of Concern | | VA |
| Crustaceans | Longhorn fairy shrimp | Branchinecta longiantenna | Listed | Endangered | | CA |
| Snails | Longitudinal pyrg | Pyrgulopsis anguina | Not Listed | Resolved Taxon | | NV, UT |
| Fishes | Longjaw cisco | Coregonus alpenae | Delisted | Extinction | | IL, IN, MI, NY, OH, PA, WI |
| Flowering Plants | Longleaf phlox | Phlox longifolia ssp. longifolia | Not Listed | Resolved Taxon | | UT |
| Birds | Long-legged bustard | Sypheotides indica | Not Listed | Status Undefined | | |
| Crustaceans | Long-legged cave amphipod | Stygobromus longipes | Not Listed | Species of Concern | | TX |
| Mammals | Long-legged myotis | Myotis volans | Not Listed | Species of Concern | | CO |
| Birds | Long-legged warbler | Trichocichla rufa | Listed | Endangered | | |
| Snails | Longmouth Pondsnail | Stagnicola elrodiana | Not Listed | Resolved Taxon | | |
| Insects | Long-necked long-horned beetle | Plagithmysus longicollis | Not Listed | Species of Concern | | HI |
| Fishes | Longnose darter | Percina nasuta | Petitioned for Listing, Under Review | Under Review | | AR, MO, OK |
| Reptiles | Long-nosed leopard lizard | gambelia wislizenii | Not Listed | Species of Concern | | |
| Fishes | Longnose Gar | Lepisosteus osseus | | Not Listed | | |
| Fishes | longnose sucker | Catostomus catostomus | Not Listed | Status Undefined | | |
| Flowering Plants | Long-petaled lewisia | Lewisia longipetala | Not Listed | Species of Concern | | CA |
| Flowering Plants | Long's bittercress | Cardamine longii | Not Listed | Resolved Taxon | | DE, MA, MD, ME, NC, NH, NJ, NY, RI, VA |
| Flowering Plants | Long's bulrush | Scirpus longii | Not Listed | Species of Concern | | CT, DE, MA, ME, NH, NJ, NY, RI |
| Clams | Longsolid | Fusconaia subrotunda | Listed | Threatened | | AL, IL, IN, KY, MS, NC, NY, OH, PA, SC, TN, VA, WV |
| Flowering Plants | Long spur columbine | Aquilegia longissima | Not Listed | Species of Concern | | TX |
| Flowering Plants | Longspurred mint | Dicerandra cornutissima | Listed | Endangered | | FL |
| Flowering Plants | Long-stalked holly | Ilex collina | Not Listed | Resolved Taxon | | NC, VA, WV |
| Snails | Longstreet Spring snail | Fluminicola sp. | Not Listed | Resolved Taxon | | NV |
| Insects | Long-tailed caddisfly | Farula sp. | Not Listed | Species of Concern | | CA |
| Mammals | Long-tailed chinchilla | Chinchilla lanigera | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Long-tailed Duck | Clangula hyemalis | Not Listed | Resolved Taxon | | |
| Birds | Long-tailed ground roller | Uratelornis chimaera | Listed | Endangered | | |
| Mammals | Long-tailed langur | Presbytis potenziani | Listed | Threatened | | |
| Mammals | Long-tailed macaque | Macaca fascicularis | | Not Listed | | |
| Mammals | Long-tailed marsupial-mouse | Sminthopsis longicaudata | Listed | Endangered | | |
| Mammals | Long-tailed otter | Lontra (=Lutra) longicaudis (incl. platensis) | Listed | Endangered | | |
| Mammals | Long-tailed pangolin | Manis tetradactyla | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Long-tailed shrew | Sorex dispar | Not Listed | Resolved Taxon | | DE, MA, MD, ME, NC, NH, NJ, NY, PA, TN, VA, VT, WV |
| Flowering Plants | Long Valley milk-vetch | Astragalus johannis-howellii | Not Listed | Resolved Taxon | | CA, NV |
| Fishes | Long Valley speckled dace | Rhinichthys nevadensis caldera | Proposed for Listing | Proposed Endangered | | CA |
| Insects | loopy five firefly | Photuris forresti | | Not Listed | | GA, SC, TN |
| Insects | Lora Aborn's moth | Lorita abornana | Not Listed | Resolved Taxon | | CA |
| Mammals | Lord Howe Long-Eared Bat | Nyctophilus howensis | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Lord Howe pied currawong | Strepera graculina crissalis | Candidate for Listing | Candidate | | |
| Birds | Lord Howe wood rail | Gallirallus (=Tricholimnas) sylvestris | Listed | Endangered | | |
| Flowering Plants | Lori's Columbine | Aquilegia loriae | Not Listed | Resolved Taxon | | |
| Mammals | Los Angeles little pocket mouse | Perognathus longimembris brevinasus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Los Angeles sunflower | Helianthus nuttallii parishii | Not Listed | Species of Concern | | CA |
| Insects | Los Olmos tiger beetle | Cicindela nevadica olmosa | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Los Pinitos Dodder | Cuscuta dentatasquamata | Not Listed | Resolved Taxon | | |
| Flowering Plants | Lost Creek wild buckwheat | Eriogonum mitophyllum | Not Listed | Resolved Taxon | | |
| Insects | Lost ethmiid moth | Ethmia monachella | Not Listed | Species of Concern | | CO |
| Flowering Plants | Lost Hills saltbush | Atriplex vallicola | Not Listed | Species of Concern | | CA |
| Arachnids | Lost Nantahala Cave spider | Nesticus cooperi | Not Listed | Species of Concern | | NC |
| Fishes | Lost River sucker | Deltistes luxatus | Listed | Endangered | | CA, OR |
| Insects | Lotis blue butterfly | Lycaeides argyrognomon lotis | Listed | Endangered | | CA |
| Mammals | Louie's pocket gopher | Thomomys mazama louiei | Not Listed | Resolved Taxon | | WA |
| Mammals | Louisiana black bear | Ursus americanus luteolus | Delisted | Recovery | | LA, MS, TX |
| Flowering Plants | Louisiana blue-star | Amsonia ludoviciana | Not Listed | Resolved Taxon | | GA, LA, MS |
| Insects | Louisiana Eye silkmoth | Automeris louisiana | Not Listed | Status Undefined | | LA, MS |
| Clams | Louisiana Fatmucket | Lampsilis hydiana | | Not Listed | | |
| Clams | Louisiana pearlshell | Margaritifera hembeli | Listed | Threatened | | LA |
| Clams | Louisiana Pigtoe | Pleurobema riddellii | Proposed for Listing | Proposed Threatened | | |
| Reptiles | Louisiana pinesnake | Pituophis ruthveni | Listed | Threatened | | LA, TX |
| Mammals | Louisiana prairie vole | Microtus ochrogaster ludovicianus | Not Listed | Resolved Taxon | | LA, TX |
| Ferns and Allies | Louisiana quillwort | Isoetes louisianensis | Listed | Endangered | | AL, LA, MS |
| Amphibians | Louisiana Slimy Salamander | Plethodon kisatchie | Not Listed | Species of Concern | | |
| Birds | Louisiana Waterthrush | Parkesia motacilla | Not Listed | Species of Concern | | |
| Insects | Louisville Cave beetle | Pseudanophthalmus troglodytes | Not Listed | Resolved Taxon | | KY |
| Crustaceans | Louisville crayfish | Orconectes jeffersoni | Not Listed | Species of Concern | | KY |
| Flowering Plants | loulu | Pritchardia aylmer-robinsonii | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia bakeri | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia glabrata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | loulu | Pritchardia hardyi | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia kaalae | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | loulu | Pritchardia lanigera | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia maideniana | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia martii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | loulu | Pritchardia minor | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | loulu | Pritchardia munroi | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia napaliensis | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia remota | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia schattaueri | Listed | Endangered | | HI |
| Flowering Plants | loulu | Pritchardia viscosa | Listed | Endangered | | HI |
| Flowering Plants | Loulu | Pritchardia affinis | Not Listed | Resolved Taxon | | |
| Flowering Plants | loulu lelo | Pritchardia hillebrandii | Not Listed | Resolved Taxon | | HI |
| Insects | Lovegrass noctuid moth | Hypena plagiota | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Low beardtongue | Penstemon humilis var. humilis | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | Low beardtongue | Penstemon nanus | Not Listed | Species of Concern | | UT |
| Flowering Plants | Low bush monkeyflower | Diplacus aridus | Not Listed | Resolved Taxon | | CA |
| Mammals | Lower Keys cotton rat | Sigmodon hispidus exsputus | Not Listed | Resolved Taxon | | |
| Mammals | Lower Keys marsh rabbit | Sylvilagus palustris hefneri | Listed | Endangered | | FL |
| Mammals | Lowland anoa | Bubalus depressicornis | Listed | Endangered | | |
| Amphibians | Lowland leopard (=San Felipe leopard) frog | Rana yavapaiensis | Not Listed | Species of Concern | | AZ, CA, NM, UT |
| Birds | Lucifer Hummingbird | Calothorax lucifer | Not Listed | Species of Concern | | |
| Birds | Lucy's warbler | Vermivora luciae | Not Listed | Status Undefined | | |
| Arachnids | Lum's micro-blind harvestman | Microcina lumi | Not Listed | Species of Concern | | CA |
| Insects | Lupine blue butterfly | Plebejus lupini texanus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Lupine, San Mateo tre | Lupinus arboreus eximius | Not Listed | Species of Concern | | CA |
| Insects | Luzon peacock swallowtail butterfly | Papilio chikae | Listed | Endangered | | |
| Insects | Lynn's clubtail | Gomphus lynnae | Not Listed | Species of Concern | | WA |
| Flowering Plants | Lyon's pentachaeta | Pentachaeta lyonii | Listed | Endangered | | CA |
| Flowering Plants | Lyrate bladderpod | Lesquerella lyrata | Listed | Threatened | | AL |
| Snails | Lyrate mountainsnail | Oreohelix haydeni haydeni | Not Listed | Species of Concern | | UT |
| Snails | Lyrate rocksnail | Leptoxis lirata | Not Listed | Resolved Taxon | | AL |
| Birds | macaroni penguin | Eudyptes chrysolophus | Not Listed | Species of Concern | | |
| Flowering Plants | MacDougal''s Yellowtops | Flaveria mcdougalii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | MacFarlane's four-o'clock | Mirabilis macfarlanei | Listed | Threatened | | ID, OR |
| Birds | MacGillivray's Seaside Sparrow | Ammospiza maritima macgillivraii | Not Listed | Resolved Taxon | | GA, SC |
| Birds | Macgillivray's warbler | oporornis tolmiei | Not Listed | Species of Concern | | |
| Crustaceans | MacKenzie's cave amphipod | Stygobromus mackenziei | Not Listed | Resolved Taxon | | CA |
| Insects | MacNeill sooty wing skipper | Hesperopsis gracielae | Not Listed | Species of Concern | | AZ, CA, NV, UT |
| Flowering Plants | Macoun's Cinquefoil | Potentilla macounii | Not Listed | Resolved Taxon | | |
| Insects | Maculated manfreda skipper | Stallingsia maculosus | Not Listed | Resolved Taxon | | TX |
| Birds | Madagascar pochard | Aythya innotata | Listed | Endangered | | |
| Reptiles | Madagascar radiated tortoise | Geochelone radiata | Listed | Endangered | | |
| Birds | Madagascar red owl | Tyto soumagnei | Listed | Endangered | | |
| Birds | Madagascar sea eagle | Haliaeetus vociferoides | Listed | Endangered | | |
| Birds | Madagascar serpent eagle | Eutriorchis astur | Listed | Endangered | | |
| Snails | Madera Talussnail | Sonorella clappi | Not Listed | Resolved Taxon | | |
| Crustaceans | Madison Cave isopod | Antrolana lira | Listed | Threatened | | VA, WV |
| Arachnids | Madla Cave Meshweaver | Cicurina madla | Listed | Endangered | | TX |
| Insects | Magazine Mountain mold beetle | Arianops sandersoni | Not Listed | Species of Concern | | AR |
| Snails | Magazine Mountain shagreen | Inflectarius magazinensis | Delisted | Recovery | | AR |
| Snails | Magdalena Mountainsnail | Oreohelix magdalenae | Not Listed | Resolved Taxon | | |
| Birds | Magenta petrel | Pterodroma magentae | Listed | Endangered | | |
| Birds | Magnificent Frigatebird | Fregata magnificens | Not Listed | Species of Concern | | |
| Snails | Magnificent ramshorn | Planorbella magnifica | Listed | Endangered | | NC |
| Flowering Plants | Maguire daisy | Erigeron maguirei | Delisted | Recovery | | UT |
| Flowering Plants | Maguire primrose | Primula maguirei | Listed | Threatened | | UT |
| Flowering Plants | Mahoe | Alectryon macrococcus | Listed | Endangered | | HI |
| Snails | Maiden rocksnail | Leptoxis formosa | Not Listed | Resolved Taxon | | AL |
| Insects | Maiden Spring cave beetle | Pseudanophthalmus virginicus | | Not Listed | | VA |
| Insects | Makah copper butterfly | Tharsalea mariposa makah | Not Listed | Status Undefined | | WA |
| Ferns and Allies | Makou | Botrychium subbifoliatum | Not Listed | Species of Concern | | HI |
| Flowering Plants | Makou | Brachionidium ciliolatum | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Makou | Peucedanum sandwicense | Listed | Threatened | | HI |
| Flowering Plants | Makou | Ranunculus hawaiensis | Listed | Endangered | | HI |
| Flowering Plants | Makou | Ranunculus mauiensis | Listed | Endangered | | HI |
| Mammals | Malabar large-spotted civet | Viverra civettina (=megaspila c.) | Listed | Endangered | | |
| Birds | Maleo megapode | Macrocephalon maleo | Listed | Endangered | | |
| Crustaceans | Malheur Cave amphipod | Stygobromus hubbsi | Not Listed | Resolved Taxon | | CA, NV, OR |
| Fishes | Malheur mottled sculpin | Cottus bairdii | Not Listed | Species of Concern | | CA, NV, OR |
| Arachnids | Malheur pseudoscorpion | Apochthonius malheuri | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Malheur Sculpin | Cottus bendirei | | Not Listed | | |
| Flowering Plants | Malheur Valley fiddleneck | Amsinckia carinata | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Malheur wire-lettuce | Stephanomeria malheurensis | Listed | Endangered | | OR |
| Birds | Mallard | Anas platyrhynchos | Not Listed | Status Undefined | | |
| Flowering Plants | Malone Mountains Moonpod | Selinocarpus maloneanus | Not Listed | Resolved Taxon | | |
| Crustaceans | Mammoth Spring crayfish | Faxonius marchandi | Not Listed | Resolved Taxon | | AR, MO |
| Fishes | Manantial Roundnose Minnow | Dionda argentosa | | Not Listed | | |
| Flowering Plants | Mancos columbine | Aquilegia micrantha mancosana | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Mancos milk-vetch | Astragalus humillimus | Listed | Endangered | | CO, NM |
| Mammals | Mandrill | Mandrillus (=Papio) sphinx | Listed | Endangered | | |
| Mammals | Maned wolf | Chrysocyon brachyurus | Listed | Endangered | | |
| Flowering Plants | Manena | Melicope cinerea | Not Listed | Resolved Taxon | | HI |
| Birds | Mangrove clapper rail | Rallus longirostris insularum | Not Listed | Species of Concern | | |
| Birds | Mangrove Cuckoo | Coccyzus minor | Not Listed | Species of Concern | | |
| Flowering Plants | Manhart's sedge | Carex manhartii | Not Listed | Species of Concern | | NC |
| Snails | Manitou cavesnail | Antrorbis breweri | Petitioned for Listing, Under Review | Under Review | | AL |
| Flowering Plants | Mann's bluegrass | Poa mannii | Listed | Endangered | | HI |
| Flowering Plants | Manoa bidens | Bidens coarctata | Not Listed | Resolved Taxon | | HI |
| Mammals | Mantled howler monkey | Alouatta palliata | Listed | Endangered | | |
| Snails | Manus Island tree snail | Papustyla pulcherrima | Listed | Endangered | | |
| Birds | Manx Shearwater | Puffinus puffinus | Not Listed | Species of Concern | | |
| Birds | Many-colored Fruit-Dove | Ptilinopus perousii perousii | Not Listed | Resolved Taxon | | AS |
| Flowering Plants | Many-flowered navarretia | Navarretia leucocephala ssp. plieantha | Listed | Endangered | | CA |
| Flowering Plants | Many-flowered nehe | Lipochaeta profusa profusa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Many-flowered unicorn plant | Proboscidea spicata | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Manyflower grasspink | Calopogon multiflorus | Not Listed | Status Undefined | | |
| Amphibians | Many-Lined Salamander | Stereochilus marginatus | | Not Listed | | |
| Flowering Plants | Many-stemmed liveforever | Dudleya multicaulis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Ma`ohi`ohi | Stenogyne rugosa subulata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea amplexicaulis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea apokremnos | Listed | Endangered | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea globosa foliosior | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea globosa globosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea globosa graminifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea hawaiiensis | Listed | Endangered | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea kealiae | Listed | Endangered | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea ligustrina nematopoda | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Ma`oli`oli | Schiedea pubescens | Listed | Endangered | | HI |
| Flowering Plants | Ma`oloa | Neraudia melastomifolia | Not Listed | Resolved Taxon | | HI |
| Birds | Mao (= maomao) (honeyeater) | Gymnomyza samoensis | Listed | Endangered | | AS |
| Flowering Plants | Mapele | Cyrtandra cyaneoides | Listed | Endangered | | HI |
| Snails | Maple Canyon Woodlandsnail | Ashmunella todseni | Not Listed | Resolved Taxon | | |
| Clams | Mapleleaf | Quadrula quadrula | | Not Listed | | |
| Flowering Plants | Maple-leaf oak | Quercus shumardii acerifolia | Not Listed | Species of Concern | | AR |
| Flowering Plants | Mapleleaf Oak | Quercus acerifolia | Not Listed | Resolved Taxon | | |
| Flowering Plants | Maraca | Canna pertusa | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Maravillas milkwort | Polygala maravillasensis | Not Listed | Species of Concern | | TX |
| Fishes | Maravillas red shiner | Cyprinella lutrensis blairi | Not Listed | Resolved Taxon | | TX |
| Mammals | Marble Canyon kangaroo rat | Dipodomys microps leucotis | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Marble Canyon Spurge | Euphorbia aaronrossii | | Not Listed | | |
| Mammals | Marbled cat | Pardofelis (=Felis) marmorata | Listed | Endangered | | |
| Snails | Marbled disc | Discus marmorensis | Not Listed | Species of Concern | | ID |
| Birds | Marbled Godwit | Limosa fedoa | Not Listed | Species of Concern | | |
| Birds | Marbled Murrelet | Brachyramphus marmoratus | Not Listed | Species of Concern | | |
| Birds | Marbled Murrelet | Brachyramphus marmoratus | Listed | Threatened | | CA, OR, WA |
| Fishes | Marbled Sculpin | Cottus klamathensis | | Not Listed | | |
| Insects | Marbled underwing moth | Catocala marmorata | Not Listed | Resolved Taxon | | DE, IL, IN, KY, MO, NC, NJ, NY, OH, PA, SC, VA, VT, WV |
| Flowering Plants | Marble Mountain catchfly | Silene marmorensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Marble-seeded, few-spined prickly-pear | Opuntia engelmannii flexospina | Not Listed | Species of Concern | | TX |
| Flowering Plants | Marcescent dudleya | Dudleya cymosa ssp. marcescens | Listed | Threatened | | CA |
| Insects | Mardon skipper | Polites mardon | Not Listed | Resolved Taxon | | CA, OR, WA |
| Birds | Margaretta's hermit | Phaethornis malaris margarettae | Listed | Endangered | | |
| Insects | Margarita River skimmer | Macromia margarita | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC, TN, VA |
| Mammals | Margay | Leopardus (=Felis) wiedii | Listed | Endangered | | |
| Fishes | Margined sculpin | Cottus marginatus | Not Listed | Species of Concern | | WA |
| Reptiles | Maria Island ground lizard | Cnemidophorus vanzoi | Listed | Endangered | | |
| Reptiles | Maria Island snake | Liophus ornatus | Listed | Endangered | | |
| Birds | Mariana (=aga) Crow | Corvus kubaryi | Listed | Endangered | | MP |
| Birds | Mariana common moorhen (pulattat) | Gallinula chloropus guami | Listed | Endangered | | GU, MP |
| Insects | Mariana eight-spot butterfly | Hypolimnas octocula marianensis | Listed | Endangered | | GU, MP |
| Mammals | Mariana fruit Bat (=Mariana flying fox) | Pteropus mariannus mariannus | Listed | Threatened | | GU, MP |
| Birds | Mariana Fruit-Dove | Ptilinopus roseicapilla | Not Listed | Resolved Taxon | | GU, MP |
| Birds | Mariana Kingfisher | Todiramphus albicilla | Not Listed | Species of Concern | | |
| Birds | Mariana mallard | Anas oustaleti | Delisted | Extinction | | GU, MP |
| Insects | Marianas euploea butterfly | Euploea eleutho | Not Listed | Resolved Taxon | | MP |
| Birds | Mariana swiftlet | Aerodramus bartschi | Listed | Endangered | | GU, MP |
| Insects | Mariana wandering butterfly | Vagrans egistina | Listed | Endangered | | GU, MP |
| Flowering Plants | Maricao cimarron | Byrsonima lucida | Not Listed | Species of Concern | | |
| Flowering Plants | Maricao cimarron | Byrsonima spicata | Not Listed | Species of Concern | | PR, VI |
| Insects | Maricopa tiger beetle | Cicindela oregona maricopa | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Marin bentgrass | Agrostis blasdalei marinensis | Not Listed | Resolved Taxon | | CA |
| Arachnids | Marin blind harvestman | Calicina diminua | Not Listed | Status Undefined | | |
| Flowering Plants | Marin checkermallow | Sidalcea hickmanii viridis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Marin dwarf-flax | Hesperolinon congestum | Listed | Threatened | | CA |
| Insects | Marin elfin | Incisalia mossii ssp. | Not Listed | Species of Concern | | CA |
| Mammals | Marine otter | Lontra (=Lutra) felina | Listed | Endangered | | |
| Flowering Plants | Marin knotweed | Polygonum marinense | Not Listed | Species of Concern | | CA |
| Flowering Plants | Marin manzanita | Arctostaphylos virgata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mariposa clarkia | Clarkia biloba australis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mariposa lily | Calochortus simulans | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mariposa lily | Calochortus venustus sanguineus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mariposa lupine | Lupinus citrinus deflexus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mariposa pussypaws | Calyptridium pulchellum | Listed | Threatened | | CA |
| Flowering Plants | Maritime california-lilac | Ceanothus maritimus | Not Listed | Species of Concern | | CA |
| Mammals | Maritime Texas pocket gopher | Geomys personatus maritimus | Not Listed | Species of Concern | | TX |
| Mammals | Markhor | Capra falconeri | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Marquesan monarch | Pomarea mendozae mira | Not Listed | Resolved Taxon | | |
| Birds | Marquesas pigeon | Ducula galeata | Listed | Endangered | | |
| Flowering Plants | Marron bacora | Solanum conocarpum | Listed | Endangered | | VI |
| Insects | Marron's San Carlos riffle beetle | Huleechius marroni carolus | Not Listed | Species of Concern | | AZ |
| Mammals | Marsh deer | Blastocerus dichotomus | Listed | Endangered | | |
| Flowering Plants | Marsh Sandwort | Arenaria paludicola | Listed | Endangered | | CA |
| Snails | Marsh Slug | Deroceras heterura | Not Listed | Resolved Taxon | | |
| Flowering Plants | Marsh valerian | Valeriana uliginosa | Not Listed | Resolved Taxon | | IL, IN, ME, MI, NH, NY, OH, VT, WI |
| Mammals | Martha's Vineyard short-tailed shrew | Blarina brevicauda aloga | Not Listed | Resolved Taxon | | MA |
| Mammals | Martha's Vineyard white-footed mouse | Peromyscus leucopus fusus | Not Listed | Resolved Taxon | | MA |
| Insects | Martin cave beetle | Pseudanophthalmus pusillus | Not Listed | Species of Concern | | TN |
| Birds | Martinique trembler (thrasher) | Cinclocerthia ruficauda gutturalis | Listed | Endangered | | |
| Birds | Marungu sunbird | Nectarinia prigoginei | Listed | Endangered | | |
| Insects | Mary Alice's smallheaded fly | Eulonchus marialiciae | Not Listed | Species of Concern | | NC |
| Flowering Plants | Maryland bur-marigold | Bidens bidentoides mariana | Not Listed | Species of Concern | | MD |
| Insects | Maryland cave beetle | Pseudanopthalmus sp. | Not Listed | Species of Concern | | MD |
| Fishes | Maryland darter | Etheostoma sellare | Listed | Endangered | | MD |
| Snails | Maryland glyph | Glyphyalinia raderi | Not Listed | Species of Concern | | VA |
| Flowering Plants | Mary's bluet | Hedyotis butterwickiae | Not Listed | Resolved Taxon | | TX |
| Mammals | Marysville California kangaroo rat | Dipodomys californicus eximius | Not Listed | Species of Concern | | CA |
| Birds | Mascarene black petrel | Pterodroma aterrima | Listed | Endangered | | |
| Birds | Masked bobwhite (quail) | Colinus virginianus ridgwayi | Listed | Endangered | | AZ |
| Birds | Masked Booby | Sula dactylatra dactylatra | Not Listed | Species of Concern | | |
| Birds | Masked Duck | Nomonyx dominicus | Not Listed | Species of Concern | | |
| Snails | Masked duskysnail | Lyogyrus spb | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | Masonic Mountain jewelflower | Streptanthus oliganthus | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Mason's lilaeopsis | Lilaeopsis masonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mason's sky-pilot | Polemonium chartaceum | Not Listed | Resolved Taxon | | CA |
| Ferns and Allies | Mat-forming quillwort | Isoetes tegetiformans | Listed | Endangered | | GA |
| Flowering Plants | Mat-forming water-hyssop | Bacopa innominata | Not Listed | Resolved Taxon | | MD, VA |
| Flowering Plants | Mathias' coyote-thistle | Eryngium mathiasiae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mathis spiderling | Boerhavia mathisiana | Not Listed | Species of Concern | | TX |
| Flowering Plants | Mat leastdaisy | Chaetopappa hersheyi | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Matthew's wild-buckwheat | Eriogonum corymbosum matthewsae | Not Listed | Resolved Taxon | | UT |
| Insects | Mattoni''s blue | Euphilotes pallescens mattonii | Not Listed | Resolved Taxon | | CA, NV |
| Insects | Mattoni's blue | Euphilotes rita mattoni | Not Listed | Species of Concern | | NV |
| Insects | Maui `akala long-horned beetle | Plagithmysus rubi | Not Listed | Species of Concern | | HI |
| Birds | Maui akepa | Loxops ochraceus | Delisted | Extinction | | |
| Insects | Maui alani long-horned beetle | Plagithmysus alani | Not Listed | Species of Concern | | HI |
| Birds | Maui 'Alauahio | Paroreomyza montana | Not Listed | Species of Concern | | |
| Insects | Maui banana omoides moth | Omoides musicola | Not Listed | Species of Concern | | HI |
| Mammals | Maui dolphin | Cephalorhynchus hectori maui | Listed | Endangered | | |
| Insects | Maui dubautia long-horned beetle | Plagithmysus dubautianus | Not Listed | Species of Concern | | HI |
| Insects | Maui forest long-horned beetle | Plagithmysus sylvai | Not Listed | Species of Concern | | HI |
| Insects | Maui koa long-horned beetle | Plagithmysus koae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Maui love grass | Eragrostis mauiensis | Not Listed | Resolved Taxon | | HI |
| Insects | Maui mamaki long-horned beetle | Plagithmysus pipturicola | Not Listed | Species of Concern | | HI |
| Birds | Maui nukupuu | Hemignathus affinis | Delisted | Extinction | | |
| Birds | Maui parrotbill (Kiwikiu) | Pseudonestor xanthophrys | Listed | Endangered | | HI |
| Flowering Plants | Maui reedgrass | Calamagrostis expansa | Listed | Endangered | | HI |
| Flowering Plants | Maui remya | Remya mauiensis | Listed | Endangered | | HI |
| Insects | Maui similar long-horned beetle | Plagithmysus simillimus | Not Listed | Species of Concern | | HI |
| Insects | Maui speculifer long-horned beetle | Plagithmysus speculifer | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina anceyana | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina carnicolor | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina crocea | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina dolei | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina fusoidea | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina germana | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina gouldii | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina grisea | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina induta | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina kaaeana | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina lemmoni | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina marmorata | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina mutabilis | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina natti | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina nivea | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina perdix | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina plumbea | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina porcellana | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina radiata | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina splendida | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina tapaniana | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina terebra | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina thaanumiana | Not Listed | Species of Concern | | |
| Snails | Maui tree snail | Partulina ustulata | Not Listed | Species of Concern | | HI |
| Snails | Maui tree snail | Partulina winniei | Not Listed | Species of Concern | | HI |
| Insects | Maui wide-necked long-horned beetle | Plagithmysus laticollis | Not Listed | Species of Concern | | HI |
| Insects | Maui yellow-faced bee | Nesoprosopis mauiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Mauna Loa (=Ka'u) silversword | Argyroxiphium kauense | Listed | Endangered | | HI |
| Insects | Mauna Loa metrargan seed bug | Metrarga obscura | Not Listed | Species of Concern | | HI |
| Flowering Plants | Maunalua bidens | Bidens graciloides | Not Listed | Resolved Taxon | | HI |
| Insects | Maureen's gymnocthebius minute moss beetle | Gymnocthebius maureenae | Not Listed | Species of Concern | | MS |
| Insects | Maureen's hydraenan minute moss beetle | Hydraena maureenae | Not Listed | Species of Concern | | VA |
| Birds | Mauritius cuckoo-shrike | Coquus typicus | Listed | Endangered | | |
| Birds | Mauritius fody | Foudia rubra | Listed | Endangered | | |
| Birds | Mauritius kestrel | Falco punctatus | Listed | Endangered | | |
| Birds | Mauritius olivaceous Bulbul | Hypsipetes borbonicus olivaceus | Listed | Endangered | | |
| Birds | Mauritius parakeet | Psittacula echo | Listed | Endangered | | |
| Reptiles | Mayaguana iguana | Cyclura carinata bartschi | Listed | Threatened | | |
| Insects | Mayfly | Fallceon eatoni | Not Listed | Resolved Taxon | | AZ |
| Amphibians | Mazama newt | Taricha granulosa mazamae | Petitioned for Listing, Under Review | Under Review | | OR |
| Flowering Plants | McCart's whitlow-wort | Paronychia maccartii | Not Listed | Resolved Taxon | | TX |
| Fishes | McCloud R. redband trout | Oncorhynchus mykiss ssp. | Not Listed | Resolved Taxon | | CA |
| Birds | McCown's Longspur | Calcarius mccownii | Not Listed | Species of Concern | | |
| Flowering Plants | McDonald''s rock-cress | Arabis mcdonaldiana | Listed | Endangered | | CA, OR |
| Birds | McKay's Bunting | Plectrophenax hyperboreus | Not Listed | Status Undefined | | AK |
| Flowering Plants | Mckittrick pennyroyal | Hedeoma apiculatum | Delisted | Original Data in Error - New Information Discovered | | NM, TX |
| Flowering Plants | McKittrick snowberry | Symphoricarpos guadalupensis | Not Listed | Species of Concern | | TX |
| Snails | Mckittrick Woodlandsnail | Ashmunella edithae | Not Listed | Resolved Taxon | | |
| Mammals | McNeill's deer | Cervus elaphus macneilii | Listed | Endangered | | |
| Flowering Plants | Meadow checkermallow | Sidalcea campestris | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Meadow joint-vetch | Aeschynomene pratensis | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Meadow pussytoes | Antennaria arcuata | Not Listed | Species of Concern | | ID, NV, WY |
| Crustaceans | Meadow River Mudbug | Cambarus pauleyi | | Not Listed | | |
| Fishes | Meadow Valley Wash desert sucker | Catostomus clarkii | Not Listed | Resolved Taxon | | NV |
| Fishes | Meadow Valley Wash speckled dace | Rhinichthys osculus ssp. | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Mead's milkweed | Asclepias meadii | Listed | Threatened | | IA, IL, IN, KS, MO, WI |
| Mammals | Mearns' southern pocket gopher | Thomomys umbrinus mearnsi | Not Listed | Species of Concern | | NM |
| Flowering Plants | Mecca aster | Xylorhiza cognata | Not Listed | Species of Concern | | CA |
| Snails | Median-gland Nevada springsnail | Pyrgulopsis pisteri | Not Listed | Resolved Taxon | | NV |
| Mammals | Mediterranean monk seal | Monachus monachus | Listed | Endangered | | |
| Flowering Plants | Mehamehame | Flueggea neowawraea | Listed | Endangered | | HI |
| Insects | Melanothrix yellow-faced bee | Nesoprosopis melanothrix | Not Listed | Resolved Taxon | | HI |
| Arachnids | Melones harvestman | Banksula melones | Not Listed | Status Undefined | | |
| Insects | Meltwater lednian stonefly | Lednia tumana | Listed | Threatened | | MT |
| Flowering Plants | Mendocino bush-mallow | Malacothamnus mendocinensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mendocino coast paintbrush | Castilleja mendocinensis | Not Listed | Species of Concern | | CA |
| Conifers and Cycads | Mendocino cypress | Cupressus goveniana pigmaea | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mendocino gentian | Gentiana setigera | Not Listed | Species of Concern | | CA, NV, OR |
| Lichens | Menzies' anacolia moss | anacolia menziesii | Not Listed | Species of Concern | | |
| Flowering Plants | Menzies' wallflower | Erysimum menziesii | Listed | Endangered | | CA |
| Snails | Meramac River vertigo | Vertigo meramecensis | Not Listed | Species of Concern | | IA, MO |
| Snails | Merced Canyon shoulderband | Helminthoglypta allynsmithi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Merced clarkia | Clarkia lingulata | Not Listed | Resolved Taxon | | CA |
| Mammals | Merced kangaroo rat | Dipodomys heermanni dixoni | Not Listed | Species of Concern | | CA |
| Flowering Plants | Merced monardella | Monardella leucocephala | Not Listed | Species of Concern | | CA |
| Flowering Plants | Merced phacelia | Phacelia ciliata opaca | Not Listed | Species of Concern | | CA |
| Insects | Meridion blackwater mayfly | Pseudirion meridionalis | Not Listed | Resolved Taxon | | |
| Insects | Meridith cave beetle | Pseudanophthalmus sidus | Not Listed | Species of Concern | | TN |
| Birds | Merlin | falco columbarius | Not Listed | Species of Concern | | |
| Birds | Merriam's Montezuma quail | Cyrtonyx montezumae merriami | Listed | Endangered | | |
| Mammals | Mer Rouge pocket gopher | Geomys bursarius breviceps | Not Listed | Resolved Taxon | | LA |
| Flowering Plants | Mesa Verde cactus | Sclerocactus mesae-verdae | Listed | Threatened | | CO, NM |
| Flowering Plants | Mesa Verde stickleaf | Hackelia gracilenta | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Mescalero milkwort | Polygala rimulicola mescalerorum | Not Listed | Species of Concern | | NM |
| Flowering Plants | Metcalf Canyon jewelflower | Streptanthus albidus ssp. albidus | Listed | Endangered | | CA |
| Snails | Metcalf Holospira | Holospira metcalfi | Not Listed | Resolved Taxon | | |
| Insects | Mexicali Lubber grasshopper | Spaniacris deserticola | Not Listed | Resolved Taxon | | |
| Fishes | Mexican blindcat (catfish) | Prietella phreatophila | Listed | Endangered | | TX |
| Mammals | Mexican bobcat | Lynx (=Felis) rufus escuinapae | Listed | Endangered | Proposed Delisting | |
| Birds | Mexican Chickadee | Poecile sclateri | Not Listed | Species of Concern | | |
| Birds | Mexican duck | Anas diazi | Delisted | Original Data in Error - Taxonomic Revision | | AZ, NM, TX |
| Clams | Mexican fawnsfoot | Truncilla cognata | Proposed for Listing | Proposed Endangered | | TX |
| Flowering Plants | Mexican flannelbush | Fremontodendron mexicanum | Listed | Endangered | | CA |
| Fishes | Mexican Golden Trout | Oncorhynchus chrysogaster | | Not Listed | | |
| Birds | Mexican hooded oriole | Icterus cucullatus cucullatus | Not Listed | Species of Concern | | TX |
| Mammals | Mexican long-nosed bat | Leptonycteris nivalis | Listed | Endangered | | NM, TX |
| Mammals | Mexican long-tongued bat | Choeronycteris mexicana | Not Listed | Species of Concern | | AZ, CA, NM, TX |
| Mammals | Mexican prairie dog | Cynomys mexicanus | Listed | Endangered | | |
| Fishes | Mexican Redhorse | Moxostoma austrinum | | Not Listed | | |
| Birds | Mexican spotted owl | Strix occidentalis lucida | Listed | Threatened | | AZ, CO, NM, TX, UT |
| Fishes | Mexican stoneroller | Campostoma ornatum | Not Listed | Species of Concern | | AZ, TX |
| Fishes | Mexican Tetra | Astyanax mexicanus | | Not Listed | | |
| Birds | Mexican Whip-poor-will | Antrostomus arizonae | Not Listed | Species of Concern | | |
| Mammals | Mexican wolf | Canis lupus baileyi | Listed | Endangered | | AZ, NM, TX |
| Mammals | Mexican wolf | Canis lupus baileyi | Listed | Experimental Population, Non-Essential | | AZ, NM |
| Insects | Meyrick's banana omoides moth | Omoides meyricki | Not Listed | Species of Concern | | HI |
| Mammals | Mhorr gazelle | Gazella dama mhorr | Listed | Endangered | | |
| Insects | Miami Blue Butterfly | Cyclargus thomasi bethunebakeri | Listed | Endangered | | FL |
| Crustaceans | Miami Cave crayfish | Procambarus milleri | Proposed for Listing | Proposed Threatened | | FL |
| Flowering Plants | Miami palmetto | Sabal etonia | Not Listed | Resolved Taxon | | |
| Insects | Miami roundhead scarab | Cyclocephala miamiensis | Not Listed | Species of Concern | | |
| Insects | Miami tiger beetle | Cicindelidia floridana | Listed | Endangered | | FL |
| Mammals | Micco cottontail rabbit | Sylvilagus floridanus ammophilus | Not Listed | Resolved Taxon | | |
| Mammals | Micco hispid cotton rat | Sigmodon hispidus littoralis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Miccosukee gooseberry | Ribes echinellum | Listed | Threatened | | FL, SC |
| Flowering Plants | Michaux's sumac | Rhus michauxii | Listed | Endangered | | AL, GA, NC, SC, VA |
| Insects | Michigan bog grasshopper | Appalachia arcana | Not Listed | Species of Concern | | MI |
| Flowering Plants | Michigan monkey-flower | Mimulus michiganensis | Listed | Endangered | | MI |
| Birds | Micronesian megapode | Megapodius laperouse | Listed | Endangered | | MP |
| Birds | Micronesian Myzomela | Myzomela rubratra | Not Listed | Species of Concern | | |
| Birds | Micronesian starling | Aplonis opaca | Not Listed | Status Undefined | | |
| Insects | Microreas agrotis noctuid moth | Agrotis microreas | Not Listed | Species of Concern | | HI |
| Insects | Middlekauf's shieldback katydid | Idiostatus middlekaufi | Not Listed | Species of Concern | | CA |
| Insects | Midget snaketail | Ophiogomphus howei | Not Listed | Species of Concern | | KY, MA, ME, NC, NY, PA, TN, VA, WI |
| Crustaceans | Midvalley Fairy Shrimp | Branchinecta mesovallensis | Not Listed | Resolved Taxon | | |
| Insects | Midway agrotis noctuid moth | Agrotis fasciata | Not Listed | Resolved Taxon | | HI |
| Birds | Migrant Loggerhead Shrike | Lanius ludovicianus migrans | Not Listed | Species of Concern | | |
| Birds | Mikado pheasant | Syrmaticus mikado | Listed | Endangered | | |
| Crustaceans | (Miktoniscus) isopod | miktoniscus | Not Listed | Species of Concern | | |
| Birds | Military macaw | Ara militaris | Listed | Endangered | | |
| Snails | Milk Ranch Talussnail | Sonorella micromphala | Not Listed | Resolved Taxon | | |
| Flowering Plants | Millboro leatherflower | Clematis viticaulis | Not Listed | Species of Concern | | VA |
| Snails | Mill Creek Mountainsnail | Oreohelix howardi | Not Listed | Resolved Taxon | | |
| Fishes | Miller Lake lamprey | Entosphenus minimus | Not Listed | Resolved Taxon | | OR |
| Fishes | Millicoma dace | Rhinichthys cataractae | Not Listed | Species of Concern | | OR |
| Clams | mimbres springsnail | pyrgulopsis species | Not Listed | Status Undefined | | |
| Snails | Mimic cavesnail | Phreatodrobia imitata | Not Listed | Resolved Taxon | | TX |
| Crustaceans | Mimic crayfish | Distocambarus carlsoni | Petitioned for Listing, Under Review | Under Review | | SC |
| Reptiles | Mimic glass lizard | Ophisaurus mimicus | Not Listed | Species of Concern | | |
| Fishes | Mimic Shiner | Notropis volucellus | | Not Listed | | |
| Snails | Mimic talussnail | Sonorella imitator | Not Listed | Resolved Taxon | | AZ |
| Snails | Mimic tryonia | Tryonia imitator | Not Listed | Species of Concern | | CA |
| Birds | Mindoro imperial (=zone-tailed) pigeon | Ducula mindorensis | Listed | Endangered | | |
| Snails | Mineral Creek mountainsnail | Oreohelix pilsbryi | Petitioned for Listing, Under Review | Under Review | | NM |
| Flowering Plants | Mineral King draba | Draba cruciata cruciata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Minnesota dwarf trout lily | Erythronium propullans | Listed | Endangered | | MN |
| Snails | Minnesota Pleistocene succineid | Succinea sp. | Not Listed | Species of Concern | | IA, MN |
| Crustaceans | Minor cave amphipod | Crangonyx minor | Not Listed | Resolved Taxon | | IA, IL, IN, MI |
| Crustaceans | Minute cave amphipod | Stygobromus parvus | Not Listed | Resolved Taxon | | WV |
| Insects | Minute checkerspot butterfly | Poladryas minuta minuta | Not Listed | Resolved Taxon | | NM, TX |
| Insects | Minute helicoverpan noctuid moth | Helicoverpa minuta | Not Listed | Resolved Taxon | | HI |
| Snails | Minute tryonia | Tryonia ericae | Not Listed | Resolved Taxon | | NV |
| Snails | Mirey Ridge supercoil snail | Paravitrea clappi | Not Listed | Resolved Taxon | | NC, TN |
| Insects | Mission blue butterfly | Icaricia icarioides missionensis | Listed | Endangered | | CA |
| Flowering Plants | Mission Canyon bluecup | Githopsis diffusa filicaulis | Not Listed | Species of Concern | | CA |
| Snails | Mission Creek oregonian | Cryptomastix magnidentata | Not Listed | Species of Concern | | ID |
| Flowering Plants | Mission Dolores campion | Silene verecunda verecunda | Not Listed | Resolved Taxon | | CA |
| Reptiles | Mississippi diamondback terrapin | Malaclemys terrapin pileata | Not Listed | Species of Concern | | |
| Crustaceans | Mississippi flatwoods crayfish | Procambarus cometes | | Not Listed | | MS |
| Reptiles | Mississippi Green Water Snake | Nerodia cyclopion | | Not Listed | | |
| Birds | Mississippi Kite | Ictinia mississippiensis | Not Listed | Species of Concern | | |
| Reptiles | Mississippi redbelly turtle | Pseudemys concinna | Not Listed | Species of Concern | | MS |
| Birds | Mississippi sandhill crane | Antigone canadensis pulla | Listed | Endangered | | MS |
| Fishes | Mississippi Silvery Minnow | Hybognathus nuchalis | | Not Listed | | |
| Flowering Plants | Missouri bladderpod | Physaria filiformis | Listed | Threatened | | AR, MO |
| Insects | Missouri glyphopsyche caddisfly | Glyphopsyche missouri | Not Listed | Species of Concern | | MO |
| Insects | Mitchell's satyr Butterfly | Neonympha mitchellii mitchellii | Listed | Endangered | | AL, IN, MI, MS, OH, VA |
| Fishes | Miyako tango (=Toyko bitterling) | Tanakia tanago | Listed | Endangered | | |
| Fishes | Moapa dace | Moapa coriacea | Listed | Endangered | | NV |
| Snails | Moapa pebblesnail | Pyrgulopsis avernalis | Not Listed | Resolved Taxon | | NV |
| Fishes | Moapa speckled dace | Rhinichthys osculus moapae | Not Listed | Resolved Taxon | | NV |
| Snails | Moapa Valley pyrg | Pyrgulopsis carinifera | Not Listed | Resolved Taxon | | NV |
| Insects | Moapa warm springs riffle beetle | Stenelmis moapa | Not Listed | Resolved Taxon | | NV |
| Fishes | Moapa White River springfish | Crenichthys baileyi moapae | Not Listed | Resolved Taxon | | NV |
| Fishes | Mobile Logperch | Percina kathae | | Not Listed | | |
| Flowering Plants | Mock pennyroyal | Stachydeoma graveolens | Not Listed | Species of Concern | | |
| Flowering Plants | Modest rock-cress | Arabis modesta | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Modoc bedstraw | Galium glabrescens modocense | Not Listed | Resolved Taxon | | CA |
| Fishes | Modoc Sucker | Catostomus microps | Delisted | Recovery | | CA, OR |
| Insects | Moestan blister beetle | Lytta moesta | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mogollon fleabane | Erigeron anchana | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Mogollon hawkweed | hieracium fendleri | Not Listed | Species of Concern | | |
| Flowering Plants | Mogollon thistle | Cirsium parryi mogollonicum | Not Listed | Species of Concern | | AZ |
| Snails | Mogollon woodlandsnail | Ashmunella mogollonensis | Not Listed | Resolved Taxon | | |
| Mammals | Mohave ground squirrel | Spermophilus mohavensis | Petitioned for Listing, Under Review | Under Review | | CA |
| Snails | Mohave shoulderband | Helminthoglypta greggi | Not Listed | Resolved Taxon | | CA |
| Fishes | Mohave tui chub | Gila bicolor ssp. mohavensis | Listed | Endangered | | CA |
| Flowering Plants | Mohr's Barbara's buttons | Marshallia mohrii | Listed | Threatened | | AL, GA |
| Insects | Mojave Desert blister beetle | Lytta inseparata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mojave fishhook cactus | Sclerocactus polyancistrus | Not Listed | Resolved Taxon | | CA, NV |
| Reptiles | Mojave fringe-toed Lizard | Uma scoparia | Not Listed | Status Undefined | | CA |
| Reptiles | Mojave green rattlesnake | crotalus scutulatus ssp. scutulatus | Not Listed | Species of Concern | | |
| Flowering Plants | Mojave indigo bush | Psorothamnus arborescens arborescens | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mojave monkey-flower | Mimulus mohavensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mojave Panicgrass | Panicum mohavense | Not Listed | Resolved Taxon | | |
| Insects | Mojave poppy bee | Perdita meconis | Petitioned for Listing, Under Review | Under Review | | NV |
| Insects | Mojave rabbitbrush longhorn beetle | Crossidius mojavensis mojavensis | Not Listed | Resolved Taxon | | CA |
| Mammals | Mojave river vole | Microtus californicus mohavensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mojave spineflower | Chorizanthe spinosa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mojave tarweed | Hemizonia mohavensis | Not Listed | Species of Concern | | CA |
| Insects | Molestan blister beetle | Lytta molesta | Not Listed | Species of Concern | | CA |
| Insects | Molokai antlion | Distoleon perjerus | Not Listed | Species of Concern | | HI |
| Birds | Molokai creeper | Paroreomyza flammea | Delisted | Extinction | | |
| Flowering Plants | Molokai cyanea | Cyanea solenocalyx | Not Listed | Resolved Taxon | | HI |
| Insects | Molokai fractured long-horned beetle | Plagithmysus fractus | Not Listed | Species of Concern | | HI |
| Flowering Plants | Molokai goosefoot | Chenopodium oahuense | Not Listed | Resolved Taxon | | HI |
| Insects | Molokai megalagrion damselfly | Megalagrion molokaiense | Not Listed | Species of Concern | | HI |
| Birds | Molokai `oloma`o | Myadestes lanaiensis rutha | Listed | Endangered | | |
| Insects | Molokai rhyncogonus weevil | Rhyncogonus molokaiensis | Not Listed | Species of Concern | | HI |
| Insects | Molokai sedge omoides moth | Omoides anastrepta | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina dwightii | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina mighelsiana | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina mucida | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina proxima | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina redfieldii | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina rufa | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina subpolita | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina tessellata | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina theodorei | Not Listed | Species of Concern | | HI |
| Snails | Moloka`i tree snail | Partulina virgulata | Not Listed | Species of Concern | | HI |
| Insects | Molokai yellow-faced bee | Nesoprosopis neglecta | Not Listed | Resolved Taxon | | HI |
| Reptiles | Mona boa | Epicrates monensis monensis | Listed | Threatened | | PR |
| Reptiles | Mona ground Iguana | Cyclura stejnegeri | Listed | Threatened | | PR |
| Insects | Monarch butterfly | Danaus plexippus | Proposed for Listing | Proposed Threatened | | AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY |
| Reptiles | Mona Skink | Spondylurus monae | Not Listed | Resolved Taxon | | PR, VI |
| Mammals | Mongolian saiga (antelope) | Saiga tatarica mongolica | Listed | Endangered | | |
| Reptiles | Monito gecko | Sphaerodactylus micropithecus | Delisted | Recovery | | PR |
| Fishes | Monitor Valley speckled dace | Rhinichthys osculus ssp. | Not Listed | Species of Concern | | NV |
| Reptiles | Monito Skink | Spondylurus monitoe | Not Listed | Resolved Taxon | | PR, VI |
| Clams | Monkeyface | Theliderma metanevra | | Not Listed | | |
| Fishes | Monkey Springs pupfish | Cyprinodon spp | Not Listed | Status Undefined | | |
| Insects | Mono Basin skipper | Hesperia uncas giulianii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mono buckwheat | Eriogonum ampullaceum | Not Listed | Resolved Taxon | | CA, NV |
| Insects | Mono checkerspot | Euphydryas editha monoensis | Not Listed | Species of Concern | | CA, NV |
| Insects | Monocolor yellow-faced bee | Nesoprosopis homeochroma | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Mono Hot Springs evening-primrose | Camissonia sierrae alticola | Not Listed | Species of Concern | | CA |
| Crustaceans | Mono Lake brine shrimp | Artemia monica | Not Listed | Species of Concern | | CA |
| Insects | Mono Lake hygrotus diving beetle | Hygrotus artus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mono Lake lupine | Lupinus duranii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mono manzanita | Arctostaphylos uva-ursi monoensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mono milk-vetch | Astragalus monoensis monoensis | Not Listed | Species of Concern | | CA |
| Mammals | Monomoy white-footed mouse | Peromyscus leucopus ammodytes | Not Listed | Species of Concern | | MA |
| Flowering Plants | Mono phacelia | Phacelia monoensis | Not Listed | Species of Concern | | CA, NV |
| Mammals | Montague tundra vole | Microtus oeconomus elymocetes | Not Listed | Species of Concern | | AK |
| Crustaceans | Montana Groundwater Amphipod | Stygobromus montanensis | Not Listed | Resolved Taxon | | |
| Crustaceans | Montana well Amphipod | Stygobromus puteanus | Not Listed | Resolved Taxon | | |
| Mammals | Montane Monkey-Faced Bat | Pteralopex pulchra | Petitioned for Listing, Under Review | Under Review | | |
| Clams | Montane peaclam | Pisidium ultramontanum | Not Listed | Resolved Taxon | | CA, OR |
| Flowering Plants | Montara manzanita | Arctostaphylos montaraensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Monte Neva paintbrush | Castilleja salsuginosa | Not Listed | Species of Concern | | NV |
| Flowering Plants | Monterey ceanothus | Ceanothus cuneatus rigidus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Monterey clover | Trifolium trichocalyx | Listed | Endangered | | CA |
| Conifers and Cycads | Monterey cypress | Cupressus macrocarpa | Not Listed | Species of Concern | | CA |
| Arachnids | Monterey Dunes scorpion | Pauroctonus maritimus | Not Listed | Species of Concern | | CA |
| Mammals | Monterey dusky-footed woodrat | Neotoma fuscipes luciana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Monterey gilia | Gilia tenuiflora ssp. arenaria | Listed | Endangered | | CA |
| Flowering Plants | Monterey knotweed | Polygonum aviculare ssp. depressum | Not Listed | Resolved Taxon | | CA |
| Mammals | Monterey ornate shrew | Sorex ornatus salarius | Not Listed | Species of Concern | | CA |
| Conifers and Cycads | Monterey pine | Pinus radiata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Monterey spineflower | Chorizanthe pungens var. pungens | Listed | Threatened | | CA |
| Flowering Plants | Monterrey manzanita | Arctostaphylos montereyensis | Not Listed | Species of Concern | | CA |
| Amphibians | Monte Verde golden toad | Bufo periglenes | Listed | Endangered | | |
| Snails | Montezuma Well springsnail | Pyrgulopsis montezumensis | Not Listed | Resolved Taxon | | AZ |
| Fishes | Mooneye | Hiodon tergisus | | Not Listed | | |
| Snails | Moon pebblesnail | Somatogyrus obtusus | Not Listed | Species of Concern | | AL |
| Birds | Moorea Polynesian warbler | Acrocephalus caffer longirostris | Not Listed | Resolved Taxon | | |
| Crustaceans | Moore Fairy Shrimp | Streptocephalus moorei | Not Listed | Resolved Taxon | | |
| Mammals | Moose | Alces alces | | Not Listed | | |
| Insects | Morand's checkerspot | Euphydryas anicia morandi | Not Listed | Species of Concern | | NV |
| Insects | Morand's checkerspot butterfly | Euphilotes anicia morandi | Not Listed | Resolved Taxon | | |
| Birds | Morden's owlet | Otus ireneae | Listed | Endangered | | |
| Flowering Plants | Morefield''s Leather Flower | Clematis morefieldii | Listed | Endangered | | AL, GA, TN |
| Reptiles | Morelet's crocodile | Crocodylus moreletii | Delisted | Recovery | | |
| Flowering Plants | Moreno currant | Ribes canthariforme | Not Listed | Species of Concern | | CA |
| Snails | Morgan Creek Mountainsnail | Oreohelix swopei | Not Listed | Resolved Taxon | | |
| Fishes | Mormon White River Springfish | Crenichthys baileyi thermophilus | Not Listed | Species of Concern | | NV |
| Mammals | Moroccan gazelle | Gazella dorcas massaesyla | Listed | Endangered | | |
| Snails | Morongo desertsnail | Eremarionta morongoana | Not Listed | Species of Concern | | CA |
| Insects | Morrison bumblebee | Bombus morrisoni | Petitioned for Listing, Under Review | Under Review | | AZ, CA, CO, ID, NM, NV, OR, SD, TX, UT, WA, WY |
| Insects | Morrison's blister beetle | Lytta morrisoni | Not Listed | Species of Concern | | CA |
| Crustaceans | Morrison's cave amphipod | Stygobromus morrisoni | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | Morrison's jewelflower | Streptanthus morrisonii morrisonii | Not Listed | Species of Concern | | CA |
| Insects | Morro Bay blue butterfly | Icaricia icarioides moroensis | Not Listed | Species of Concern | | CA |
| Mammals | Morro Bay kangaroo rat | Dipodomys heermanni morroensis | Listed | Endangered | | CA |
| Insects | Morro Bay Polyphyllan Scarab Beetle | Polyphylla morroensis | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Morro manzanita | Arctostaphylos morroensis | Listed | Threatened | | CA |
| Snails | Morro shoulderband (=Banded dune) snail | Helminthoglypta walkeriana | Listed | Threatened | | CA |
| Insects | Morse's Little Plain Brown sedge | Lepidostoma morsei | | Not Listed | | FL |
| Insects | Morse's net-spinning caddisfly | Cheumatopsyche morsei | Not Listed | Species of Concern | | LA |
| Flowering Plants | Mosquin's clarkia | Clarkia mosquinii mosquinii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Moss gentian | Gentiana fremontii | Not Listed | Resolved Taxon | | CA |
| Snails | Mossy elimia | Elimia troostiana | Not Listed | Species of Concern | | TN |
| Flowering Plants | Most beautiful jewelflower | Streptanthus albidus peramoenus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mother Lode yampah | Perideridia bacigalupii | Not Listed | Resolved Taxon | | CA |
| Amphibians | Mottled coqui | Eleutherodactylus eneidae | Not Listed | Species of Concern | | PR, VI |
| Birds | Mottled Petrel | Pterodroma inexpectata | Not Listed | Species of Concern | | |
| Mammals | Mountain anoa | Bubalus quarlesi | Listed | Endangered | | |
| Flowering Plants | Mountain avens | Geum peckii | Not Listed | Resolved Taxon | | NH |
| Mammals | Mountain beaver | Aplodontia rufa californica | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mountain bittercress | Cardamine clematitis | Not Listed | Species of Concern | | NC |
| Birds | Mountain Bluebird | Sialia currucoides | Not Listed | Species of Concern | | |
| Flowering Plants | Mountain blue-eyed grass | Sisyrinchium sarmentosum | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Fishes | Mountain Brook Lamprey | Ichthyomyzon greeleyi | | Not Listed | | |
| Crustaceans | Mountain cave amphipod | Stygobromus montanus | Not Listed | Resolved Taxon | | AR |
| Birds | Mountain Chickadee | Poecile gambeli | Not Listed | Species of Concern | | |
| Clams | Mountain creekshell | Villosa vanuxemensis | | Not Listed | | |
| Mammals | Mountain (=Cuvier's) gazelle | Gazella cuvieri | Listed | Endangered | | |
| Flowering Plants | Mountain golden heather | Hudsonia montana | Listed | Threatened | | NC |
| Snails | Mountain Holospira | Holospira oritis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Mountain Labordia | Labordia hirtella | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Mountain lady's-slipper | Cypripedium montanum | Not Listed | Resolved Taxon | | AK, CA, MT, NV, OR, WA, WY |
| Fishes | Mountain Madtom | Noturus eleutherus | | Not Listed | | |
| Fishes | Mountain Mullet | Agonostomus monticola | | Not Listed | | |
| Flowering Plants | Mountain naupaka | Scaevola gaudichaudii | Not Listed | Resolved Taxon | | HI |
| Corals | Mountainous Star Coral | Orbicella faveolata | Listed | Threatened | | |
| Flowering Plants | Mountain phacelia | Phacelia orogenes | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mountain pimpernel | Taenidia montana | Not Listed | Resolved Taxon | | MD, PA, VA, WV |
| Birds | Mountain Plover | Charadrius montanus | Not Listed | Resolved Taxon | | CO, MT, UT |
| Flowering Plants | Mountain Purple pitcherplant | Sarracenia purpurea var. montana | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC |
| Mammals | Mountain pygmy possum | Burramys parvus | Listed | Endangered | | |
| Birds | Mountain quail | Oreortyx pictus | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | Mountain rattlesnake root | Prenanthes roanensis | Not Listed | Resolved Taxon | | NC, TN, VA |
| Fishes | Mountain Redbelly Dace | Chrosomus oreas | | Not Listed | | |
| Insects | Mountain silverspot butterfly | Speyeria nokomis nitocris | Not Listed | Resolved Taxon | | AZ, CO, NM |
| Flowering Plants | Mountain-slope Thistle | Cirsium scapanolepis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Mountains Springs bush lupine | Lupinus excubitus medius | Not Listed | Species of Concern | | CA |
| Fishes | Mountain Sucker | Pantosteus platyrhynchus | | Not Listed | | |
| Flowering Plants | Mountain sweet pitcher-plant | Sarracenia rubra ssp. jonesii | Listed | Endangered | | NC, SC |
| Mammals | Mountain tapir | Tapirus pinchaque | Listed | Endangered | | |
| Flowering Plants | mountain thaspium | Thaspium pinnatifidum | Not Listed | Species of Concern | | NC |
| Fishes | mountain whitefish | Prosopium williamsoni | Not Listed | Resolved Taxon | | |
| Fishes | mountain whitefish | Prosopium williamsoni | Not Listed | Resolved Taxon | | CA, CO, ID, MT, NV, OR, WA, WY |
| Amphibians | Mountain yellow-legged frog | Rana muscosa | Listed | Endangered | | CA |
| Amphibians | Mountain yellow-legged frog | Rana muscosa | Listed | Endangered | | CA |
| Amphibians | Mountain yellow-legged frog | Rana muscosa | | Not Listed | | |
| Mammals | Mountain zebra | Equus zebra zebra | Listed | Endangered | | |
| Insects | Mount Charleston blue butterfly | Icaricia (Plebejus) shasta charlestonensis | Listed | Endangered | | NV |
| Mammals | Mount Ellen pocket gopher | Thomomys umbrinus dissimilis | Not Listed | Species of Concern | | UT |
| Mammals | Mount Ellen Uinta chipmunk | Tamias umbrinus sedulus | Not Listed | Species of Concern | | UT |
| Mammals | Mount Graham red squirrel | Tamiasciurus fremonti grahamensis | Listed | Endangered | | AZ |
| Insects | Mount Hermon June beetle | Polyphylla barbata | Listed | Endangered | | CA |
| Amphibians | Mount Lyell salamander | Hydromantes platycephalus | Not Listed | Species of Concern | | CA |
| Birds | Mount Pinos sooty grouse | Dendragapus fuliginosus howardi | Not Listed | Resolved Taxon | | CA |
| Snails | Mount Riley Woodlandsnail | Ashmunella rileyensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Mount Tamalpais jewelflower | Streptanthus glandulosus pulchellus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mouse buckwheat | Eriogonum nudum murinum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mouse-ear chickweed | Linum hudsonioides | Not Listed | Resolved Taxon | | TX |
| Mammals | Mouse-Eared Bats | Myotis sp. | | Not Listed | | |
| Flowering Plants | Mouse-leaved dudleya | Dudleya abramsii murina | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mt. Diablo bird's-beak | Cordylanthus nidularius | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mt. Diablo jewelflower | Streptanthus hispidus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Diablo manzanita | Arctostaphylos auriculata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mt. Diablo phacelia | Phacelia phacelioides | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Eddy buckwheat | Eriogonum umbellatum humistratum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mt. Eddy draba | Draba carnosula | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Eke peperomia | Peperomia eekana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Mt. Gleason paintbrush | Castilleja gleasonii | Not Listed | Species of Concern | | CA |
| Insects | Mt. Haleakala seed bug | Neseis haleakalae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Mt. Hamilton coreopsis | Coreopsis hamiltonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Hamilton harebell | Campanula sharsmithiae | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Hamilton jewelflower | Streptanthus callistus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Hamilton thistle | Cirsium fontinale campylon | Not Listed | Species of Concern | | CA |
| Insects | Mt. Hood farulan caddisfly | Farula jewetti | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Mt. Hood primitive brachycentrid caddisfly | Eobrachycentrus gelidae | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Mt. Lassen smelowskia | Smelowskia ovalis congesta | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Mt. Leconte moss | Leptothymenium sharpii | Not Listed | Species of Concern | | NC, TN |
| Mammals | Mt. Lyell shrew | Sorex lyelli | Not Listed | Resolved Taxon | | CA |
| Snails | Mt. Matafao different snail | Diastole matafaoi | Not Listed | Species of Concern | | AS |
| Flowering Plants | Mt. Pinos larkspur | Delphinium parryi ssp. purpureum | Not Listed | Resolved Taxon | | CA |
| Birds | Mt. Rainier white-tailed ptarmigan | Lagopus leucura rainierensis | Listed | Threatened | | WA |
| Flowering Plants | Mt. Saint Helena morning-glory | Calystegia collina oxyphylla | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Tamalpais thistle | Cirsium hydrophilum vaseyi | Not Listed | Species of Concern | | CA |
| Insects | Mt. Tantalus short-wing fern planthopper | Nesorestias filicicola | Not Listed | Species of Concern | | HI |
| Insects | Mt. Tantalus wingless thread bug | Nesidiolestes insularis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Mt. Tedoc linanthus | Linanthus nuttallii howellii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Trumbull beardtongue | Penstemon distans | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Mt. Vision ceanothus | Ceanothus gloriosus porrectus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Mt. Whitney draba | Draba cruciata integrifolia | Not Listed | Resolved Taxon | | CA |
| Clams | Mucket | Ortmanniana ligamentina | | Not Listed | | |
| Fishes | Mud Darter | Etheostoma asprigene | | Not Listed | | |
| Snails | Muddy rocksnail | Lithasia salebrosa | Not Listed | Species of Concern | | AL, TN |
| Snails | Mud elimia | Elimia alabamensis | | Not Listed | | AL |
| Snails | Mud pebblesnail | Somatogyrus sargenti | Not Listed | Species of Concern | | AL |
| Amphibians | Mudpuppy | Necturus maculosus | | Not Listed | | |
| Reptiles | Mugger crocodile | Crocodylus palustris palustris | Listed | Endangered | | |
| Lichens | Muhlenberg''s smile | Rinodina chrysomelaena | Not Listed | Species of Concern | | |
| Insects | Muir's ala`a long-horned beetle | Plagithmysus muiri | Not Listed | Species of Concern | | HI |
| Flowering Plants | Muir's raillardella | Carlquistia muirii | Not Listed | Resolved Taxon | | CA |
| Mammals | Mule deer | Odocoileus hemionus | | Not Listed | | |
| Flowering Plants | Mulford's milk-vetch | Astragalus mulfordiae | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Insects | Munro's nesotocus weevil | Nesotocus munroi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Munz cholla | Opuntia munzii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Munz's hedgehog cactus | Echinocereus engelmannii munzii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Munz's mariposa lily | Calochortus palmeri munzii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Munz's onion | Allium munzii | Listed | Endangered | | CA |
| Flowering Plants | Munz''s sage | Salvia munzii | | Not Listed | | |
| Flowering Plants | Murdock's evening primrose | Oenothera murdockii | Not Listed | Resolved Taxon | | |
| Birds | Murphy's Petrel | Pterodroma ultima | Not Listed | Species of Concern | | |
| Flowering Plants | Murta | Marlierea sintenisii | Not Listed | Resolved Taxon | | PR, VI |
| Sponges | Muscular sponge | Anheteromyia biceps | Not Listed | Resolved Taxon | | MI |
| Arachnids | Music Hall Cave pseudoscorpion | Pseudogarypus orpheus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Musinea Ragwort | Senecio musiniensis | Not Listed | Resolved Taxon | | |
| Mammals | Musk deer | Moschus spp. (all species) | Listed | Endangered | | |
| Fishes | Muskellunge | Esox masquinongy | Not Listed | Status Undefined | | |
| Fishes | Muskellunge | Esox masquinongy | | Not Listed | | |
| Flowering Plants | Mussentuchit gilia | Gilia tenuis | Not Listed | Resolved Taxon | | UT |
| Insects | Mutatan yellow-faced bee | Nesoprosopis mutata | Not Listed | Resolved Taxon | | HI |
| Insects | Mutated rhyncogonus weevil | Rhyncogonus mutatus | Not Listed | Species of Concern | | HI |
| Insects | Muticus eopenthes click beetle | Eopenthes muticus | Not Listed | Species of Concern | | HI |
| Flowering Plants | Myers' pincushionplant | Navarretia myersii ssp. deminuta | Not Listed | Species of Concern | | |
| Insects | Myrtle's silverspot butterfly | Speyeria zerene myrtleae | Listed | Endangered | | CA |
| Arachnids | Mysore Ornamental Tarantula | Poecilotheria striata | Petitioned for Listing, Under Review | Under Review | | |
| Insects | mysterious lantern firefly | Photuris mysticalampas | | Not Listed | | DE, MD |
| Insects | Mystic cave beetle | Pseudanophthalmus hadenoecus | Not Listed | Species of Concern | | WV |
| Snails | Naegele Springsnail | Pyrgulopsis metcalfi | Not Listed | Resolved Taxon | | |
| Flowering Plants | Naenae | Dubautia kalalauensis | Listed | Endangered | | HI |
| Flowering Plants | Naenae | Dubautia kenwoodii | Listed | Endangered | | HI |
| Flowering Plants | Na`ena`e | Dubautia arborea | Not Listed | Species of Concern | | HI |
| Flowering Plants | Na`ena`e | Dubautia herbstobatae | Listed | Endangered | | HI |
| Flowering Plants | Na`ena`e | Dubautia imbricata ssp. imbricata | Listed | Endangered | | HI |
| Flowering Plants | Na`ena`e | Dubautia knudsenii filiformis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Na`ena`e | Dubautia menziesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Na`ena`e | Dubautia microcephala | Not Listed | Species of Concern | | HI |
| Flowering Plants | Na`ena`e | Dubautia pauciflorula | Listed | Endangered | | HI |
| Flowering Plants | Na`ena`e | Dubautia plantaginea ssp. humilis | Listed | Endangered | | HI |
| Flowering Plants | Na`ena`e | Dubautia plantaginea ssp. magnifolia | Listed | Endangered | | HI |
| Flowering Plants | Na`ena`e | Dubautia waialealae | Listed | Endangered | | HI |
| Flowering Plants | Na`ena`e-pua-melemele | Dubautia laxa waianensis | Not Listed | Resolved Taxon | | HI |
| Insects | Nahiku nesosydne planthopper | Nesosydne cyrtandrae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Naio | Myoporum sandwicense stellatum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nama nama | nama stenocarpum | Not Listed | Species of Concern | | |
| Fishes | Naniha Goby, `O`Opu Naniha | Stenogobius hawaiiensis | | Not Listed | | |
| Flowering Plants | Nani wai`ale`ale | Viola kauaiensis var. wahiawaensis | Listed | Endangered | | HI |
| Mammals | Nantucket short-tailed shrew | Blarina brevicauda compacta | Not Listed | Species of Concern | | MA |
| Flowering Plants | Nanu | Gardenia mannii | Listed | Endangered | | HI |
| Flowering Plants | Nanu | Gardenia remyi | Listed | Endangered | | HI |
| Flowering Plants | Napa bluegrass | Poa napensis | Listed | Endangered | | CA |
| Clams | Narrow catspaw | Epioblasma lenior | Not Listed | Resolved Taxon | | AL, TN |
| Insects | Narrow-foot hygrotus diving beetle | Hygrotus diversipes | Not Listed | Resolved Taxon | | WY |
| Reptiles | Narrow-headed gartersnake | Thamnophis rufipunctatus | Listed | Threatened | | AZ, NM |
| Flowering Plants | Narrowleaf Carolina scalystem | Elytraria caroliniensis angustifolia | Not Listed | Status Undefined | | |
| Flowering Plants | Narrowleaf evening-primrose | Oenothera acutissima | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | Narrow-leaved hedyotis | Hedyotis angusta umbrosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Narrow-leaved nightshade | Solanum tenuilobatum | Not Listed | Species of Concern | | CA |
| Fishes | Narrownose smoothhound shark | Mustelus schmitti | Listed | Threatened | | |
| Clams | Narrow pigtoe | Fusconaia escambia | Listed | Threatened | | AL, FL |
| Fishes | Narrow sawfish | Anoxypristis cuspidata | Listed | Endangered | | |
| Insects | Narrows cave beetle | Pseudanophthalmus egberti | | Not Listed | | VA |
| Flowering Plants | Narrow-seeded yampah | Perideridia leptocarpa | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Nashville crayfish | Orconectes shoupi | Not Listed | Status Undefined | | |
| Crustaceans | Nashville crayfish | Orconectes shoupi | Listed | Endangered | Proposed Delisting | TN |
| Birds | Nashville warbler | vermivora ruficapilla | Not Listed | Species of Concern | | |
| Flowering Plants | Nashville waterweed | Elodea canadensis | Not Listed | Resolved Taxon | | TN |
| Fishes | Nassau grouper | Epinephelus striatus | Listed | Threatened | | |
| Insects | Natchez stonefly | Alloperla natchez | Not Listed | Species of Concern | | MS |
| Flowering Plants | Native geranium | Geranium cuneatum hololeucum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | (=Native yellow hibiscus) ma`o hau hele | Hibiscus brackenridgei | Listed | Endangered | | HI |
| Insects | Natural Bridge cave beetle | Pseudanophthalmus pontis | | Not Listed | | VA |
| Flowering Plants | Naturita milk-vetch | Astragalus naturitensis | Not Listed | Resolved Taxon | | CO, NM |
| Mammals | Navaho Mountain Mexican vole | Microtus mexicanus navaho | Not Listed | Species of Concern | | AZ, UT |
| Insects | Navajo jerusalem cricket | Stenopelmatus navajo | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Navajo Mountain phlox | Phlox cluteana | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Navajo sedge | Carex specuicola | Listed | Threatened | | AZ, CO, UT |
| Flowering Plants | Navasota False Foxglove | Agalinis navasotensis | Proposed for Listing | Proposed Endangered | | |
| Flowering Plants | Navasota ladies-tresses | Spiranthes parksii | Listed | Endangered | | TX |
| Reptiles | Navassa curley-tailed lizard | Leiocephalus eremitus | Not Listed | Resolved Taxon | | |
| Reptiles | Navassa dusky dwarf boa | Tropidophis melanurus bucculentus | Not Listed | Species of Concern | | |
| Reptiles | Navassa Island iguana | Cyclura cornuta nigerrima | Not Listed | Resolved Taxon | | |
| Insects | Nearctic paduniellan caddisfly | Paduniella nearctica | Not Listed | Species of Concern | | AR |
| Mammals | Nebraska bog lemming | Synaptomys cooperi relictus | Not Listed | Resolved Taxon | | NE |
| Insects | (Nebria gebleri cascadensis) ground beetle | nebria gebleri ssp. cascadensis | Not Listed | Species of Concern | | |
| Insects | (Nebria kincaidi balli) ground beetle | nebria kincaidi ssp. balli | Not Listed | Species of Concern | | |
| Insects | (Nebria paradisi) ground beetle | nebria paradisi | Not Listed | Species of Concern | | |
| Crustaceans | Neches Crayfish | Procambarus nechesae | Not Listed | Resolved Taxon | | |
| Flowering Plants | Neches River rose-mallow | Hibiscus dasycalyx | Listed | Threatened | | TX |
| Insects | Necker bunchgrass seed bug | Nysius suffusus | Not Listed | Species of Concern | | HI |
| Insects | Necker goosefoot seed bug | Nysius neckerensis | Not Listed | Species of Concern | | HI |
| Insects | Necker itodacnus click beetle | Itodacnus novicornis | Not Listed | Species of Concern | | HI |
| Insects | Necker oodemas weevil | Oodemas neckeri | Not Listed | Species of Concern | | HI |
| Insects | Necker petrochroan leaf miner | Hyposmocoma neckerensis | Not Listed | Species of Concern | | HI |
| Insects | Necker rhyncogonus weevil | Rhyncogonus biformis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Necklace gladecress | Leavenworthia torulosa | Not Listed | Resolved Taxon | | AL, KY, TN |
| Flowering Plants | Needleleaf waternymph | Najas filifolia | Petitioned for Listing, Under Review | Under Review | | GA |
| Flowering Plants | Needle palm | Rhapidophyllum hystrix | Not Listed | Resolved Taxon | | |
| Flowering Plants | Needles knotweed | Persicaria maculosa | Not Listed | Resolved Taxon | | AZ, CA |
| Flowering Plants | Negro mato | Caesalpinia monensis | Not Listed | Resolved Taxon | | PR, VI |
| Mammals | Negros Naked-Backed Fruit Bat | Dobsonia chapmani | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | nehe | Lipochaeta fauriei | Listed | Endangered | | HI |
| Flowering Plants | nehe | Lipochaeta lobata var. leptophylla | Listed | Endangered | | HI |
| Flowering Plants | nehe | Lipochaeta lobata var. lobata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | nehe | Lipochaeta micrantha | Listed | Endangered | | HI |
| Flowering Plants | nehe | Lipochaeta venosa | Listed | Endangered | | HI |
| Flowering Plants | nehe | Lipochaeta waimeaensis | Listed | Endangered | | HI |
| Flowering Plants | nehe | Melanthera kamolensis | Listed | Endangered | | HI |
| Flowering Plants | nehe | Melanthera populifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | nehe | Melanthera subcordata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | nehe | Melanthera tenuifolia | Listed | Endangered | | HI |
| Flowering Plants | Nehe | Lipochaeta integrifolia gracilis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta integrifolia major | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta integrifolia megacephala | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta lavarum longifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta lavarum salicifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta lavarum skottsbergii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta perdita | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta profusa robustior | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta subcordata membranacea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta succulenta succulenta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Nehe | Lipochaeta tenuis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Nehe kuhiwa | Phyllostegia electra | Not Listed | Resolved Taxon | | HI |
| Fishes | Nekogigi (catfish) | Coreobagrus ichikawai | Listed | Endangered | | |
| Flowering Plants | Nellie''s cory cactus | Escobaria minima | Listed | Endangered | | TX |
| Mammals | Nelson's antelope ground squirrel | Ammospermophilus nelsoni | Not Listed | Species of Concern | | CA |
| Insects | Nelson's cave beetle | Pseudanophthalmus nelsoni | Not Listed | Species of Concern | | VA |
| Flowering Plants | Nelson's checker-mallow | Sidalcea nelsoniana | Delisted | Recovery | | OR, WA |
| Insects | Nelson's miloderes weevil | Miloderes nelsoni | Not Listed | Species of Concern | | CA |
| Birds | Nelson's Sparrow | Ammodramus nelsoni | Not Listed | Species of Concern | | |
| Insects | Neojuvenile tiger beetle | Cicindela obsoleta neojuvenilis | Not Listed | Species of Concern | | TX |
| Fishes | Neosho madtom | Noturus placidus | Listed | Threatened | | KS, MO, OK |
| Clams | Neosho Mucket | Lampsilis rafinesqueana | Listed | Endangered | | AR, KS, MO, OK |
| Snails | Nerite pebblesnail | Fluminicola spc | Not Listed | Resolved Taxon | | |
| Snails | Neritiform Steptoe Ranch pyrg | Pyrgulopsis neritella | Petitioned for Listing, Under Review | Under Review | | NV |
| Amphibians | Neuse River waterdog | Necturus lewisi | Listed | Threatened | | NC |
| Clams | Neuse slabshell | Elliptio judithae | Not Listed | Species of Concern | | NC |
| Insects | Nevada admiral | Limenitus weidemeyerii nevadae | Not Listed | Species of Concern | | NV |
| Flowering Plants | Nevada oryctes | Oryctes nevadensis | Not Listed | Species of Concern | | CA, NV |
| Insects | Nevada viceroy | Limenitus archippus lahontani | Not Listed | Species of Concern | | NV |
| Flowering Plants | Nevada waterweed | Elodea bifoliata | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Nevada willowherb | Epilobium nevadense | Not Listed | Species of Concern | | NV, UT |
| Insects | Nevares Spring naucorid bug (=Furnace Creek) | Ambrysus funebris | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Nevin's barberry | Berberis nevinii | Listed | Endangered | | CA |
| Flowering Plants | Nevin's wooly-sunflower | Eriophyllum nevinii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Nevius' stonecrop | Sedum nevii | Not Listed | Species of Concern | | AL, GA, TN |
| Fishes | Newark Valley tui chub | Siphateles bicolor newarkensis | Not Listed | Species of Concern | | NV |
| Mammals | New Caledonia Long-Eared Bat | Nyctophilus nebulosus | Petitioned for Listing, Under Review | Under Review | | |
| Arachnids | New Comanche Trail cave harvestman | texella | Not Listed | Species of Concern | | |
| Snails | Newcomb's littorine snail | Algamorda newcombiana | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Snails | Newcomb's snail | Erinna newcombi | Listed | Threatened | | HI |
| Snails | Newcomb's tree snail | Newcombia canaliculata | Not Listed | Species of Concern | | HI |
| Snails | Newcomb's tree snail | Newcombia perkinsi | Not Listed | Species of Concern | | HI |
| Snails | Newcomb's tree snail | Newcombia pfeifferi | Not Listed | Species of Concern | | HI |
| Snails | Newcomb's tree snail | Newcombia sulcata | Not Listed | Species of Concern | | HI |
| Snails | Newcomb's tree snail | Nucombia plicata | Not Listed | Species of Concern | | HI |
| Snails | Newcomb's Tree snail | Newcombia cumingi | Listed | Endangered | | HI |
| Birds | Newell''s shearwater | Puffinus newelli | Listed | Threatened | | HI, UM |
| Mammals | New England cottontail | Sylvilagus transitionalis | Not Listed | Resolved Taxon | | ME, NY |
| Flowering Plants | New England violet | Viola novae-angliae | Not Listed | Resolved Taxon | | ME, MI, MN, NY, WI |
| Insects | New Guinea birdwing butterfly | Ornithoptera meridionalis | Not Listed | Resolved Taxon | | |
| Mammals | New Holland mouse | Pseudomys novaehollandiae | Listed | Endangered | | |
| Flowering Plants | New Jersey rush | Juncus caesariensis | Not Listed | Species of Concern | | NC, VA |
| Insects | New Mammoth Cave cave beetle | Pseudanophthalmus scutilis | Not Listed | Species of Concern | | TN |
| Reptiles | New Mexican ridge-nosed rattlesnake | Crotalus willardi obscurus | Listed | Threatened | | AZ, NM |
| Mammals | New Mexico meadow jumping mouse | Zapus hudsonius luteus | Listed | Endangered | | AZ, CO, NM |
| Snails | New Mexico Ramshorn snail | Pecosorbis kansasensis | Not Listed | Resolved Taxon | | NM, TX |
| Snails | New Mexico springsnail | Pyrgulopsis thermalis | Not Listed | Resolved Taxon | | NM |
| Crustaceans | New River Crayfish | Cambarus chasmodactylus | | Not Listed | | |
| Crustaceans | New River riffle crayfish | Cambarus chasmodactylus | | Not Listed | | NC, VA, WV |
| Flowering Plants | New York Mountains cryptantha | Cryptantha tumulosa | Not Listed | Resolved Taxon | | CA, NV |
| Birds | New Zealand bushwren | Xenicus longipes | Listed | Endangered | | |
| Mammals | New Zealand Greater Short-Tailed Bat | Mystacina robusta | Petitioned for Listing, Under Review | Under Review | | |
| Birds | New Zealand shore plover | Thinornis novaeseelandiae | Listed | Endangered | | |
| Birds | New Zealand thrush (wattlebird) | Turnagra capensis | Listed | Endangered | | |
| Fishes | Niangua darter | Etheostoma nianguae | Listed | Threatened | | MO |
| Birds | Niceforo's wren | Thryothorus nicefori | Not Listed | Status Undefined | | |
| Flowering Plants | Nichol's Turk's head cactus | Echinocactus horizonthalonius var. nicholii | Listed | Endangered | | AZ |
| Insects | Nickajack Cave beetle | Pseudanophthalmus nickajackensis | Not Listed | Resolved Taxon | | TN |
| Crustaceans | Nickajack Cave isopod | Caecidotea nickajackensis | Not Listed | Species of Concern | | TN |
| Flowering Plants | Nickel's cory cactus | Coryphantha sulcata nickelsiae | Not Listed | Species of Concern | | TX |
| Insects | Nickerbean Blue Butterfly | Cyclargus ammon | Listed | Similarity of Appearance (Threatened) | | |
| Clams | Nicklin's pearlymussel | Megalonaias nicklineana | Listed | Endangered | | |
| Birds | Night (=Australian) parrot | Geopsittacus occidentalis | Listed | Endangered | | |
| Birds | Nightingale reed warbler (old world warbler) | Acrocephalus luscinia | Listed | Endangered | | MP |
| Insects | Nigrohamatum megalagrion damselfly | Megalagrion nigrohamatum nigrohamatum | Not Listed | Species of Concern | | HI |
| Insects | Nihoa banza conehead katydid | Banza nihoa | Not Listed | Species of Concern | | HI |
| Insects | Nihoa eupelmus wasp | Eupelmus nihoaensis | Not Listed | Species of Concern | | HI |
| Birds | Nihoa finch | Telespiza ultima | Listed | Endangered | | HI |
| Insects | Nihoa long-horned beetle | Plagithmysus nihoae | Not Listed | Species of Concern | | HI |
| Birds | Nihoa millerbird (old world warbler) | Acrocephalus familiaris kingi | Listed | Endangered | | HI |
| Insects | Nihoa nysius seed bug | Nysius nihoae | Not Listed | Species of Concern | | HI |
| Insects | Nihoa oodemas weevil | Oodemas breviscapum | Not Listed | Species of Concern | | HI |
| Insects | Nihoa rhyncogonus weevil | Rhyncogonus exsul | Not Listed | Species of Concern | | HI |
| Insects | Nihoa sclerodermus wasp | Sclerodermus nihoaensis | Not Listed | Species of Concern | | HI |
| Insects | Nihoa stenotrupis weevil | Stenotrupis pritcharsdiae | Not Listed | Species of Concern | | HI |
| Insects | Nihoa two-spotted asteriid fly | Bryania bipunctata | Not Listed | Species of Concern | | HI |
| Flowering Plants | Ni`ihau love grass | Eragrostis variabilis | Not Listed | Resolved Taxon | | HI |
| Insects | Niihau odynerus vespid wasp | Odynerus niihauensis | Not Listed | Species of Concern | | HI |
| Reptiles | Nile crocodile | Crocodylus niloticus | Listed | Threatened | | |
| Flowering Plants | Nine Mile Canyon phacelia | Phacelia novenmillensis | Not Listed | Species of Concern | | CA |
| Snails | Ninemile Pyrg | Pyrgulopsis nonaria | Not Listed | Resolved Taxon | | |
| Flowering Plants | Nino de cota | Laplacea portoricensis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Nioi | Eugenia koolauensis | Listed | Endangered | | HI |
| Flowering Plants | Nipomo ceanothus | Ceanothus impressus nipomensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Nipomo Mesa lupine | Lupinus nipomensis | Listed | Endangered | | CA |
| Flowering Plants | Nipple Bench phacelia | Phacelia mammillarensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Nissenan manzanita | Arctostaphylos nissenana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Nixon's Hawthorn | Crataegus nananixonii | Not Listed | Resolved Taxon | | |
| Insects | Nobletts cave beetle | Pseudanophthalmus paulus | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | No comment name | phytolacca sandwicensis | Not Listed | Species of Concern | | |
| Crustaceans | no common name | Amerigoniscus gipsocolus | Petitioned for Listing, Under Review | Under Review | | |
| Crustaceans | no common name | Artesia subterranea | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Abronia ammophila var. | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Abutilon eremitopetalum | Listed | Endangered | | HI |
| Flowering Plants | No common name | Abutilon parishii | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Abutilon sandwicense | Listed | Endangered | | HI |
| Flowering Plants | No common name | Abutilon virginianum | Not Listed | Species of Concern | | PR, VI |
| Corals | No common name | Acanthastrea brevis | Not Listed | Status Undefined | | |
| Corals | No common name | Acanthastrea hemprichii | Not Listed | Status Undefined | | |
| Corals | No common name | Acanthastrea ishigakiensis | Not Listed | Status Undefined | | |
| Corals | No common name | Acanthastrea regularis | Not Listed | Status Undefined | | |
| Lichens | No common name | acarospora clauzadeana | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Achnatherum contractum | Not Listed | Species of Concern | | CO, WY |
| Flowering Plants | No common name | Achnatherum curvifolium | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Achnatherum swallenii | Not Listed | Resolved Taxon | | ID, WY |
| Flowering Plants | No common name | Achyranthes atollensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Achyranthes mutica | Listed | Endangered | | HI |
| Flowering Plants | No common name | Achyranthes splendens splendens | Not Listed | Resolved Taxon | | HI |
| Birds | No common name | Acrocephalus nijoi | Not Listed | Species of Concern | | |
| Birds | No common name | Acrocephalus yamashinae | Not Listed | Species of Concern | | |
| Corals | No common name | Acropora aculeus | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora acuminata | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora aspera | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora cuneata | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora dendrum | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora donei | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora globiceps | Listed | Threatened | | |
| Corals | No common name | Acropora horrida | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora jacquelineae | Listed | Threatened | | |
| Corals | No common name | Acropora listeri | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora lokani | Listed | Threatened | | |
| Corals | No common name | Acropora microclados | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora palmerae | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora paniculata | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora pharaonis | Listed | Threatened | | |
| Corals | No common name | Acropora polystoma | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora retusa | Listed | Threatened | | |
| Corals | No common name | Acropora rudis | Listed | Threatened | | |
| Corals | No common name | Acropora speciosa | Listed | Threatened | | |
| Corals | No common name | Acropora striata | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora tenella | Listed | Threatened | | |
| Corals | No common name | Acropora vaughani | Not Listed | Status Undefined | | |
| Corals | No common name | Acropora verweyi | Not Listed | Status Undefined | | |
| Ferns and Allies | No common name | Adiantum vivesii | Delisted | Original Data in Error - Not a listable entity | | PR |
| Flowering Plants | No common name | Aerva sericea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Agalinis purpurea carteri | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Agastache cusickii | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Insects | No common name | agathon arizonicus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Agave eggersiana | Listed | Endangered | | VI |
| Flowering Plants | No common name | Agave mckelveyana | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Agave murpheyi | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Agave schottii treleasei | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Agave toumeyana bella | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Agave utahensis kaibabensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Ageratina luciae-brauniae | Not Listed | Species of Concern | | KY, TN |
| Birds | No common name | Agropsar philippensis | Not Listed | Species of Concern | | |
| Insects | No common name | agylla septentrionalis | Not Listed | Resolved Taxon | | |
| Birds | No common name | Akialoa ellisiana | Not Listed | Species of Concern | | |
| Birds | No common name | Akialoa lanaiensis | Not Listed | Species of Concern | | |
| Arachnids | No common name | albiorix anophthalmus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Aletes filifolius | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Aletes humilis | Not Listed | Species of Concern | | CO, WY |
| Insects | No common name | alexicles aspersa | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Allionia cristata | Not Listed | Resolved Taxon | | AZ |
| Insects | No common name | Allomyia hector | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Allowissadula holosericea | Not Listed | Resolved Taxon | | TX |
| Birds | No common name | Alopecoenas stairi | Not Listed | Species of Concern | | |
| Ferns and Allies | No common name | Alsophila brooksii | Not Listed | Resolved Taxon | | PR, VI |
| Corals | No common name | Alveopora allingi | Not Listed | Status Undefined | | |
| Corals | No common name | Alveopora fenestrata | Not Listed | Status Undefined | | |
| Corals | No common name | Alveopora verrilliana | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Amaranthus brownii | Listed | Endangered | | HI |
| Insects | No common name | Ameletus edmundsi | Not Listed | Resolved Taxon | | |
| Crustaceans | No common name | amergoniscus centalis | Not Listed | Status Undefined | | |
| Crustaceans | No common name | amergoniscus gipsocolus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Amorpha canescens | Not Listed | Resolved Taxon | | MO |
| Flowering Plants | No common name | Amsonia fugatei | Not Listed | Species of Concern | | NM |
| Flowering Plants | No common name | Amsonia tabernaemontana gattingeri | Not Listed | Species of Concern | | TN |
| Corals | No common name | Anacropora puertogalerae | Not Listed | Status Undefined | | |
| Corals | No common name | Anacropora spinosa | Listed | Threatened | | |
| Flowering Plants | No common name | Angelica scabrida | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Angelica wheeleri | Not Listed | Resolved Taxon | | UT |
| Birds | No common name | Anser serrirostris | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Antennaria aromatica | Not Listed | Resolved Taxon | | CA, MT, NV, OR, WY |
| Flowering Plants | No common name | Antennaria soliceps | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Apacheria chiricahuensis | Not Listed | Resolved Taxon | | AZ, NM |
| Arachnids | No common name | Aphrastochthonius pachysetus | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | apocheiridium reddelli | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Aquilegia barnebyi | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | No common name | Aquilegia caerulea daileyae | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Aquilegia desertorum | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Aquilegia saximontana | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Arabis missouriensis deamii | Not Listed | Species of Concern | | AR, IN, MI, MO, WI |
| Flowering Plants | No common name | Arabis suffrutescens horizontalis | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Arceuthobium apachense | Not Listed | Resolved Taxon | | AZ |
| Arachnids | No common name | archeolarca welbourni | Not Listed | Resolved Taxon | | |
| Birds | No common name | Ardea intermedia | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Arenaria franklinii thompsonii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Arenaria kingii rosea | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Arenaria stenomeres | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Argemone glauca inermis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | arida mattturneri | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Aristida chaseae | Listed | Endangered | | PR |
| Flowering Plants | No common name | Arnica amplexicaulis piperi | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Arnica cordifolia | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Arnica lonchophylla | Not Listed | Species of Concern | | CA, MN |
| Flowering Plants | No common name | Arnica venosa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Artemisia biennis diffusa | Not Listed | Species of Concern | | WY |
| Flowering Plants | No common name | Artemisia ludoviciana estesii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Artemisia papposa | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Artemisia unalaskensis aleutica | Not Listed | Resolved Taxon | | AK |
| Birds | No common name | Artemisiospiza belli | Not Listed | Species of Concern | | |
| Crustaceans | No common name | Artesia welbourni | Not Listed | Resolved Taxon | | |
| Birds | No common name | Arundinax aedon | Not Listed | Species of Concern | | |
| Ferns and Allies | No common name | Asplenium dielerectum | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Asplenium diellaciniatum | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Asplenium (=Diellia) dielfalcatum (=falcata) | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Asplenium dielmannii | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Asplenium dielpallidum | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Asplenium peruvianum var. insulare | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Asplenium schizophyllum | Not Listed | Species of Concern | | HI |
| Ferns and Allies | No common name | Asplenium unisorum | Listed | Endangered | | HI |
| Flowering Plants | No common name | Aster kingii barnebyana | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Astragalus amphioxys musimonum | Not Listed | Species of Concern | | AZ, NV |
| Flowering Plants | No common name | Astragalus avonensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Astragalus collinus laurentii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Astragalus diaphanus diurnus | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | No common name | Astragalus gilviflorus var. purpureus | Not Listed | Species of Concern | | WY |
| Flowering Plants | No common name | Astragalus jejunus articulatus | Not Listed | Species of Concern | | WY |
| Flowering Plants | No common name | Astragalus lentiginosus ambiguus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Astragalus lentiginosus antonius | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Astragalus limnocharis limnocharis | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Astragalus limnocharis tabulaeus | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Astragalus oophorus lonchocalyx | Not Listed | Species of Concern | | NV, UT |
| Flowering Plants | No common name | Astragalus pulsiferae suksdorfii | Not Listed | Species of Concern | | WA |
| Flowering Plants | No common name | Astragalus subcinereus basalticus | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Astragalus vexilliflexus nubilus | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Astranthium robustum | Not Listed | Resolved Taxon | | TX |
| Corals | No common name | Astreopora cucullata | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Atriplex canescens gigantea | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Atriplex welshii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Auerodendron pauciflorum | Listed | Endangered | | PR |
| Flowering Plants | No common name | Aureolaria patula | Not Listed | Species of Concern | | AL, GA, KY, TN |
| Flowering Plants | No common name | Bahia bigelovii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Balsamorhiza rosea | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Balsamorhiza sericea | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Baptisia calycosa calycosa | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Baptisia simplicifolia | Not Listed | Species of Concern | | |
| Corals | No common name | Barabattoai laddi | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Basiphyllaea corallicola | Not Listed | Resolved Taxon | | PR, VI |
| Insects | No common name | Batrisodes grubbsi | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Bazzania nudicaulis | Not Listed | Species of Concern | | NC |
| Flowering Plants | No common name | Besseya bullii | Not Listed | Resolved Taxon | | IA, IL, IN, MI, MN, OH, WI |
| Fishes | No common name | Betta hendra | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | No common name | Betta miniopinna | | Not Listed | | |
| Fishes | No common name | Betta rutilans | Petitioned for Listing, Under Review | Under Review | | |
| Millipedes | No common name | Blancosoma scaturgo | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Bonamia menziesii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Bothriochloa exaristata | Not Listed | Resolved Taxon | | LA, TX |
| Ferns and Allies | No common name | Botrychium crenulatum | Not Listed | Species of Concern | | AZ, CA, MT, NV, OR, UT |
| Ferns and Allies | No common name | Botrychium mormo | Not Listed | Species of Concern | | MI, MN, WI |
| Ferns and Allies | No common name | Botrychium pallidum | Not Listed | Species of Concern | | UT |
| Ferns and Allies | No common name | Botrychium paradoxum | Not Listed | Species of Concern | | MT, UT |
| Insects | No common name | Brachycercus tuberculatus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Brassia caudata | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Braya humilis leiocarpa | Not Listed | Resolved Taxon | | MI, VT |
| Flowering Plants | No common name | Brickellia dentata | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Brickellia leptophylla | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Bromus texensis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Brunfelsia portoricensis | Not Listed | Species of Concern | | PR, VI |
| Crustaceans | No common name | Caecidotea bisetus | Not Listed | Resolved Taxon | | |
| Crustaceans | No common name | Caecidotea metcalfi | Not Listed | Resolved Taxon | | |
| Crustaceans | No common name | Caecidotea tridentata | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Caesalpinia drummondii | Not Listed | Resolved Taxon | | TX |
| Birds | No common name | Calidris falcinellus | Not Listed | Species of Concern | | |
| Birds | No common name | Calidris pygmea | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Calliandra locoensis | Not Listed | Resolved Taxon | | PR, VI |
| Birds | No common name | Calliope calliope | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Calochortus nitidus | Not Listed | Species of Concern | | ID, WA |
| Flowering Plants | No common name | Calochortus weedii vestus | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Calyptranthes estremerae | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Calyptranthes luquillensis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Calyptranthes peduncularis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Calyptranthes thomasiana | Listed | Endangered | | VI |
| Flowering Plants | No common name | Calyptranthes triflorum | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Camassia cusickii | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Camassia howellii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Camissonia atwoodii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Campanula rotundifolia sacajaweana | Not Listed | Resolved Taxon | | CA, NV, OR |
| Corals | No common name | Cantharellus noumeae | Listed | Endangered | | |
| Flowering Plants | No common name | Cardamine penduliflora | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Carex wahuensis herbstii | Not Listed | Species of Concern | | HI |
| Birds | No common name | Carpodacus roseus | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Cassia fasciculata macrosperma | Not Listed | Species of Concern | | MD, VA |
| Flowering Plants | No common name | Castilleja annua | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Castilleja fraterna | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Castilleja glandulifera | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Castilleja linoides | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Castilleja nervata | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Castilleja oresbia | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Castilleja parviflora olympica | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Castilleja rubida | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Castilleja xanthotricha | Not Listed | Resolved Taxon | | CA, NV, OR |
| Lichens | No common name | catapyrenium granulosum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Catesbaea melanocarpa | Listed | Endangered | | PR, VI |
| Snails | No common name | Catinella texana | Not Listed | Resolved Taxon | | |
| Corals | No common name | Caulastraea echinulata | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Ceanothus arboreus glaber | Not Listed | Species of Concern | | CA |
| Insects | No common name | Ceratopsyche vanaca | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | ceuthothrombium cavaticum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Chaenactis cusickii | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Flowering Plants | No common name | Chaenactis evermannii | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Chaenactis nevii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Chaenactis ramosa | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Chaenactis thompsonii | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Chamaechaenactis scaposa | Not Listed | Resolved Taxon | | CO, ID, UT |
| Flowering Plants | No common name | Chamaecrista glandulosa var. mirabilis | Listed | Endangered | | PR |
| Flowering Plants | No common name | Chamaerhodos nuttallii keweenawensis | Not Listed | Species of Concern | | MI |
| Flowering Plants | No common name | Chamaesyce celastroides stokesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Chamaesyce cumulicola | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Chamaesyce jejuna | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Chamaesyce multiformis multiformis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Chamaesyce ocellata rattanii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Chamaesyce porteriana porteriana | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Cheilolejeunea evansii | Not Listed | Species of Concern | | NC, SC |
| Arachnids | No common name | cheiridium reyesi | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Cheirodendron helleri helleri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cheirodendron helleri microcarpum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cheirodendron helleri sodalium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Chelone obliqua speciosa | Not Listed | Resolved Taxon | | AR, IA, IL, IN, KY, MI, MO |
| Flowering Plants | No common name | Chenopodium oahuense discospermum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Chiloscyphus gemmiparus | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | chitrella elliotti | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | chitrella major | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | chitrella welbourni | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | chitrellina chiricahuae | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Chorizanthe polygonoides longispina | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Chromolaena borinquensis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Chromolaena oteroi | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Chrysophyllum cainito | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Chrysosplenium iowense | Not Listed | Species of Concern | | IA, MN |
| Flowering Plants | No common name | Chrysothamnus eremobius | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Chrysothamnus molestus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Chrysothamnus nauseosus nanus | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | No common name | Chrysothamnus nauseosus texensis | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | No common name | Chrysothamnus parryi hinckleyi | Not Listed | Species of Concern | | TX |
| Flowering Plants | No common name | Chrysothamnus scopulorum | Not Listed | Resolved Taxon | | AZ, UT |
| Arachnids | No common name | cicurina barri | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina browni | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina caverna | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina coryelli | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina ezelli | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina gruta | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina holsingeri | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina machete | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina mckenziei | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina medina | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina menardia | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina obscura | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina orellia | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina pablo | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina pastura | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina patei | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina porteri | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina puentecilla | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina rainesi | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina reclusa | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina reddelli | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina reyesi | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina russelli | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina sansaba | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina selecta | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina serena | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina sheari | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina sprousei | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina stowersi | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina suttoni | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina travisae | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina ubicki | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina uvalde | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina venefica | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina vibora | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | cicurina watersi | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Cimicifuga laciniata | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Cimicifuga rubifolia | Not Listed | Species of Concern | | AL, IL, IN, KY, TN, VA |
| Insects | No common name | cisthene conjuncta | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Cladrastis kentukea | Not Listed | Resolved Taxon | | AL, AR, GA, IL, IN, KY, MO, MS, NC, OK, SC, TN |
| Flowering Plants | No common name | Claytonia lanceolata chrysantha | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Claytonia lanceolata flava | Not Listed | Species of Concern | | ID, MT, WY |
| Flowering Plants | No common name | Claytonia megarhiza nivalis | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Cleomella palmeriana | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Clermontia hawaiiensis hawaiiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Clermontia konaensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Clermontia loyana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Clermontia multiflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Clermontia munroi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Clinopodium ashei | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Clinopodium dentatum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Clusia flava | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Coccoloba rugosa | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Cocculus orbiculatus | Not Listed | Resolved Taxon | | HI |
| Birds | No common name | Coccyzus vieilloti | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Coelorachis tuberculosa | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Collinsia antonina | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Collomia renacta | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Columbiadoria hallii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Conostegia rufescens | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Coprosma faurei lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Coprosma montana orbicularis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Coprosma ochracea kaalae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Coprosma pubens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Coprosma pubens sessiliflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cordia bellonis | Listed | Endangered | | PR |
| Flowering Plants | No common name | Cordia wagnerorum | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Coreopsis grandiflora | Not Listed | Resolved Taxon | | AR |
| Flowering Plants | No common name | Coreopsis latifolia | Not Listed | Resolved Taxon | | GA, NC, SC, TN |
| Flowering Plants | No common name | Coreopsis pulchra | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | No common name | Coreopsis tripteris subrhomboidea | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Corydalis aquae-gelidae | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | No common name | Corydalis caseana brachycarpa | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Corydalis caseana hastata | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Coryphantha dasyacantha dasyacantha | Not Listed | Species of Concern | | TX |
| Flowering Plants | No common name | Coryphantha dasyacantha varicolor | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Coursetia axillaris | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Coursetia glabella | Not Listed | Species of Concern | | TX |
| Flowering Plants | No common name | Cranichis ricartii | Listed | Endangered | | PR |
| Flowering Plants | No common name | Crataegus stenosepala | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Crataegus sutherlandensis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Crataegus triflora | Not Listed | Species of Concern | | AL, GA, LA, MS |
| Flowering Plants | No common name | Crossosoma bigelovii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Croton fishlockii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Croton glandulosus simpsonii | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Croton impressus | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Croton microcarpus | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Cryptantha cinerea arenicola | Not Listed | Species of Concern | | AZ, UT |
| Flowering Plants | No common name | Cryptantha creutzfeldtii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Cryptantha interrupta | Not Listed | Resolved Taxon | | CA, ID, MT, NV, OR, WA |
| Flowering Plants | No common name | Cryptantha mensana | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Cryptantha paradoxa | Not Listed | Resolved Taxon | | CO, NM, UT |
| Flowering Plants | No common name | Cryptantha rollinsii | Not Listed | Species of Concern | | CO, UT |
| Flowering Plants | No common name | Cryptantha sobolifera | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Cryptantha subcapitata | Not Listed | Species of Concern | | WY |
| Flowering Plants | No common name | Cryptantha thompsonii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Cryptocarya mannii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Ctenium floridanum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Cucurbita texana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Cuphea aspera | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Cyanea angustifolia lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea angustifolia racemosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea arborea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea aspleniifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea comata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea giffardii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea grimesiana ssp. cylindrocalyx | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea hirtella | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea kauaulaensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Cyanea linearifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea parvifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea pohaku | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea pycnocarpa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea quercifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea scabra | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyanea sessilifolia | Not Listed | Resolved Taxon | | HI |
| Birds | No common name | Cyanecula svecica | Not Listed | Species of Concern | | |
| Ferns and Allies | No common name | Cyclosorus boydiae kipahuluensis | Not Listed | Resolved Taxon | | |
| Ferns and Allies | No common name | Cyclosorus boydiae var. boydiae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cymophyllus fraserianus | Not Listed | Resolved Taxon | | GA, KY, MD, NC, PA, SC, TN, VA, WV |
| Flowering Plants | No common name | Cymopterus basalticus | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | No common name | Cymopterus corrugatus | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Cymopterus davisii | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Cymopterus douglassii | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Cymopterus everetii | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Cymopterus goodrichii | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Cymopterus ibapensis | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Cymopterus megacephalus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Cymopterus newberryi | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | No common name | Cymopterus nivalis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Cymopterus ripleyi saniculoides | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Cymopterus rosei | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Cynanchum monense | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Cynanchum wigginsii | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Cyperus cephalanthus | Not Listed | Resolved Taxon | | LA, TX |
| Flowering Plants | No common name | Cyperus fauriei | Listed | Endangered | | HI |
| Flowering Plants | No common name | Cyperus granitophilus | Not Listed | Resolved Taxon | | AL, GA, NC, SC, VA |
| Flowering Plants | No common name | Cyperus neokunthianus | Listed | Endangered | | HI |
| Flowering Plants | No common name | Cyperus pennatiformis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Cyperus rockii | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Cyrtandra alata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra alnea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra ambigua | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra axilliflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra basipartita | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra bryanii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra carinata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra caudatisepala | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra christophersenii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra conradtii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra cordifolia brevipilita | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra cordifolia gynoglabra | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra crassior | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra cupuliformis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra elliptisepala | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra ferricolorata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra ferruginosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra forbesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra garnotiana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra georgiana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra grayana lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra grayi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra hawaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra hirsutula | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra honolulensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra hosakae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra intrapilosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra kaalae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra kahanensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra kalichii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra kohalae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra laevis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra laxiflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra lessoniana angustifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra lessoniana intrapubens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra longifolia longifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra longiloba | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra lysiosepala grayi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra lysiosepala haleakalensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra lysiosepala lysiosepala | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra malacophylla malacophylla | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra mannii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra niuensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra olona | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra paludosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra paludosa haupuensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra platyphylla hiloensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra pubens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra ramosissima | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra rivularis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra rockii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra scabrella | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra subintegra | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra turbiniformis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra vaniota | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra villicalyx pubentigyna | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X atomigyna | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X basipartita | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X crassifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X ferruginosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X forbesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X hillebrandii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X honolulensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X hosakae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X kipapaensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Cyrtandra X rockii | Not Listed | Resolved Taxon | | HI |
| Snails | No common name | Daedalochila scintilla | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Dalea gattingeri | Not Listed | Resolved Taxon | | AL, GA, TN |
| Fishes | No common name | Dallia pectoralis | | Not Listed | | |
| Flowering Plants | No common name | Daphnopsis helleriana | Listed | Endangered | | PR |
| Flowering Plants | No common name | Dasynotus daubenmirei | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Delissea fallax | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Delissea laciniata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Delissea lauliiana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Delissea parviflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Delissea rhytidosperma | Listed | Endangered | | HI |
| Flowering Plants | No common name | Delissea sinuata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Delissea undulata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Dendrobium guamense | Listed | Threatened | | GU, MP |
| Flowering Plants | No common name | Dendrographa leucophaea | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Dentaria incisa | Not Listed | Resolved Taxon | | TN |
| Ferns and Allies | No common name | Deparia kaalaana | Listed | Endangered | | HI |
| Flowering Plants | No common name | Descurainia torulosa | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Dichanthelium aciculare var. aciculare | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Dichanthelium nudicaule | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Dicliptera krugii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Didymodon anserinocapitatus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Digitaria floridana | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Digitaria gracillima | Not Listed | Species of Concern | | |
| Ferns and Allies | No common name | Diplazium molokaiense | Listed | Endangered | | HI |
| Flowering Plants | No common name | Dissochondrus biflorus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Ditaxis cyanophylla | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Dodecatheon poeticum | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Dodonaea eriocarpa costulata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea eriocarpa forbesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea eriocarpa lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea eriocarpa molokaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea eriocarpa oblonga | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea eriocarpa pallida | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea eriocarpa skottsbergii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea eriocarpa varians | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea sandwicensis latifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea sandwicensis simulans | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea stenoptera fauriei | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dodonaea stenoptera stenoptera | Not Listed | Resolved Taxon | | HI |
| Ferns and Allies | No common name | Doryopteris angelica | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Doryopteris takeuchii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Douglasia idahoensis | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Douglasia laevigata laevigata | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Douglasia nivalis nivalis | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Draba apiculata daviesiae | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | No common name | Draba aprica | Not Listed | Resolved Taxon | | AR, GA, MO, OK, SC |
| Flowering Plants | No common name | Draba argyraea | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Draba arida | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Draba asprella asprella | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Draba asprella kaibabensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Draba asprella stelligera | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Draba jaegeri | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Draba kassii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Draba lemmonii cyclomorpha | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Draba maguirei burkei | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Draba maguirei maguirei | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Draba mogollonica | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Draba murrayi | Not Listed | Species of Concern | | AK |
| Flowering Plants | No common name | Draba oreibata serpentina | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Draba paucifructa | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Draba pectinipila | Not Listed | Species of Concern | | CO, WY |
| Flowering Plants | No common name | Draba ruaxes | Not Listed | Resolved Taxon | | AK, WA |
| Flowering Plants | No common name | Draba smithii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Draba sphaeroides cusickii | Not Listed | Resolved Taxon | | CA, NV, OR, UT |
| Flowering Plants | No common name | Draba yukonensis | Not Listed | Species of Concern | | AK |
| Flowering Plants | No common name | Dracontium polyphyllum | Not Listed | Species of Concern | | PR, VI |
| Ferns and Allies | No common name | Dryopteris takeuchii | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Dubautia knudsenii degeneri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia laevigata parvifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia laxa blakei | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia linearis ssp. hillebrandii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia magnifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia molokaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia montana robustior | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia plantaginea acridentata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia plantaginea plantaginea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia platyphylla leptophylla | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia reticulata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia thyrsiflora cernua | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia thyrsiflora thyrsiflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia X fallax | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dubautia X thyrsiflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Dudleya saxosa collomiae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Dyschoriste crenulata | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | echeandia texensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Echinocereus ledingii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Echinodorus tenellus | Not Listed | Species of Concern | | KS |
| Flowering Plants | No common name | Echinomastus erectocentrus erectocentrus | Not Listed | Species of Concern | | AZ |
| Arachnids | No common name | eidmannella bullata | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | eidmannella delicata | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | eidmannella nasuta | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | eidmannella reclusa | Not Listed | Resolved Taxon | | |
| Ferns and Allies | No common name | Elaphoglossum serpens | Listed | Endangered | | PR |
| Flowering Plants | No common name | Eleocharis austrotexana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Eleocharis wolfii | Not Listed | Species of Concern | | IA, IL, IN, KS, LA, MN, MO, ND, NE, OH, WI |
| Flowering Plants | No common name | Elymus svensonii | Not Listed | Species of Concern | | KY, TN |
| Flowering Plants | No common name | Elytraria caroliniensis caroliniensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Embelia pacifica | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Encelia frutescens resinosa | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Encyclia kranzlinii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Encyclia oncidioides | Not Listed | Resolved Taxon | | PR, VI |
| Insects | No common name | Ephemerella apopsis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Epidendrum brittonianum | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Epidendrum lacerum | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Eragrostis deflexa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Eragrostis leptostachya | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Eragrostis paupera | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Ericameria cervina | Not Listed | Resolved Taxon | | AZ, NV, UT |
| Flowering Plants | No common name | Ericameria crispa | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Ericameria nauseosa var. iridis | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Ericameria watsonii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Ericameria zionis | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Erigeron arenarioides | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Erigeron arizonicus | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Erigeron bigelovii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Erigeron canaanii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Erigeron carringtonae | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Erigeron chrysopsidis brevifolius | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Erigeron flettii | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Erigeron garrettii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Erigeron huberi | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Erigeron hultenii | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Erigeron lackshewitz | Not Listed | Species of Concern | | MT |
| Flowering Plants | No common name | Erigeron leibergii | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Erigeron lobatus | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Erigeron maguirei harrisonii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Erigeron muirii | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Erigeron ovinus | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Erigeron perglaber | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Erigeron piperanus | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Erigeron pringlei | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Erigeron pulchellus tolsteadii | Not Listed | Species of Concern | | MN |
| Flowering Plants | No common name | Erigeron salmonensis | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Erigeron sionis | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Erigeron sivinskii | Not Listed | Species of Concern | | NM |
| Flowering Plants | No common name | Erigeron uncialis conjugans | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Erigeron untermannii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Erigeron wilkenii | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Erigeron zothecinus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Eriochloa michauxii simpsonii | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Eriogonum allenii | Not Listed | Resolved Taxon | | VA, WV |
| Flowering Plants | No common name | Eriogonum concinnum | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Eriogonum correllii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Eriogonum grayi | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Eriogonum heermannii subracemosum | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | No common name | Eriogonum lagopus | Not Listed | Species of Concern | | MT, WY |
| Flowering Plants | No common name | Eriogonum latens | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Eriogonum lewisii | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Eriogonum lobbii robustum | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Eriogonum longifolium harperi | Not Listed | Species of Concern | | AL, KY, TN |
| Flowering Plants | No common name | Eriogonum natum | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Eriogonum novonudum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Eriogonum nummulare | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Eriogonum ovalifolium caelestinum | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Eriogonum phoeniceum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Eriogonum polycladon | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | No common name | Eriogonum rubricaule | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Eriogonum scopulorum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Eriogonum thymoides | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | No common name | Eriogonum tumulosum | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | No common name | Eriogonum umbellatum hypoleium | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Eriogonum viridulum | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | No common name | Eriogonum visheri | Not Listed | Species of Concern | | ND, SD |
| Flowering Plants | No common name | Erithalis fruticosa | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Errazurizia rotundata | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Erythronium cliftonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Erythronium elegans | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Erythronium grandiflorum nudipetalum | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Erythronium helenae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Erythronium oregonum | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Eschscholzia multiflora twisselmannii | Not Listed | Species of Concern | | CA |
| Insects | No common name | Euchloe ausonides ssp. ausonides | | Not Listed | | CA |
| Flowering Plants | No common name | Eugenia bellonis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Eugenia bryanii | Listed | Endangered | | GU |
| Flowering Plants | No common name | Eugenia margarettae | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Eugenia underwoodii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Eugenia woodburyana | Listed | Threatened | | PR |
| Insects | No common name | euhyparpax rosea | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Eupatorium altissimum | Not Listed | Resolved Taxon | | NC, VA |
| Flowering Plants | No common name | Euphorbia austrina | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Euphorbia celastroides halawana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia celastroides haupuana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia celastroides humbertii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia celastroides kohalana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia celastroides nelsonii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia celastroides nematopoda | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia celastroides saxicola | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia celastroides waikoluensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia degeneri molokaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Euphorbia discoidalis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Euphorbia exserta | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Euphorbia innocua | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Euphorbia macropus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Euphorbia roemeriana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Euphorbia strictior | Not Listed | Resolved Taxon | | NM, TX |
| Corals | No common name | Euphyllia cristata | Not Listed | Status Undefined | | |
| Corals | No common name | Euphyllia paradivisa | Listed | Threatened | | |
| Corals | No common name | Euphyllia paraencora | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Eurhychium pringlei | Not Listed | Species of Concern | | NC, SC |
| Flowering Plants | No common name | Eurya sandwicensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Eurytaenia hinckleyi | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Exocarpos gaudichaudii | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Ferocactus eastwoodiae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Festuca hallii | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Festuca hawaiiensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Festuca molokaiensis | Listed | Endangered | | HI |
| Birds | No common name | Ficedula albicilla | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Fimbristylis hawaiiensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Flyriella parryi | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Forchhammeria polyandra | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Forestiera segregata pinetorum | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Frasera coloradensis | Not Listed | Species of Concern | | CO |
| Flowering Plants | No common name | Frasera idahoensis | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Frasera puberulenta | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Frasera tubulosa | Not Listed | Resolved Taxon | | CA |
| Arachnids | No common name | Fumontana deprehendor | Not Listed | Species of Concern | | NC |
| Flowering Plants | No common name | Gahnia lanaiensis | Delisted | Original Data in Error - Taxonomic Revision | | HI |
| Flowering Plants | No common name | Galactia eggersii | Not Listed | Species of Concern | | VI |
| Flowering Plants | No common name | Galinsoga semicalva percalva | Not Listed | Resolved Taxon | | AZ |
| Birds | No common name | Gallinula galeata | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Gardenia taitensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gaura demareei | Not Listed | Resolved Taxon | | AR, OK |
| Flowering Plants | No common name | Gentiana austromontana | Not Listed | Resolved Taxon | | NC, TN, VA, WV |
| Flowering Plants | No common name | Gentianella propinqua aleutica | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Gentianella wislizenii | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Geocarpon minimum | Listed | Threatened | | AR, LA, MO, OK, TX |
| Flowering Plants | No common name | Gesneria pauciflora | Listed | Threatened | | PR |
| Flowering Plants | No common name | Gilia mcvickerae | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Gilia nyensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Gilia pentstemonoides | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Gilia ripleyi | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | No common name | Glandularia maritima | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Gonocalyx concolor | Listed | Endangered | | PR |
| Flowering Plants | No common name | Gouania hillebrandii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Gouania meyenii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Gouania vitifolia | Listed | Endangered | | HI |
| Flowering Plants | No common name | Gouldia st-johnii munroi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis bobeoides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis congesta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis crassicaulis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis degeneri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis lanai | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis parvifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis pseudodichotoma | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis pubescens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis quadrangularis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis rotundifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gouldia terminalis subcordata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Graptopetalum rusbyi | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | No common name | Gunnera petaloidea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Gutierrezia petradoria | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Gutierrezia sarothrae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Gutierrezia sarothrae pomariensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Gutierrezia wrightii | Not Listed | Resolved Taxon | | AZ |
| Ferns and Allies | No common name | Gymnocarpium heterosporum | Not Listed | Resolved Taxon | | AK, MI, MN, WI |
| Flowering Plants | No common name | Gymnopogon chapmanianus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Hackelia hispida | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | No common name | Halimolobos perplexa lemhiensis | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Halimolobos perplexa perplexa | Not Listed | Resolved Taxon | | ID |
| Birds | No common name | Hapalocrex flaviventer | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Haplopappus carthamoides subsquarrosus | Not Listed | Species of Concern | | WY |
| Flowering Plants | No common name | Haplopappus racemosus congestus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Haplopappus spinulosus laevis | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Haplostachys bryanii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Haplostachys linearifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Haplostachys munroi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Haplostachys truncata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hastingsia atropurpurea | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Hastingsia bracteosa | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Hazardia brickellioides | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | No common name | Hechtia texensis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Hedeoma dentatum | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Hedeoma molle | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Hedeoma nanum californicum | Not Listed | Resolved Taxon | | AZ, CA, NV |
| Flowering Plants | No common name | Hedeoma pulcherrimum | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Hedyotis angusta angusta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis elatior | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Hedyotis foliosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis formosa | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Hedyotis glaucifolia helleri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis littoralis | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Hedyotis remyi nuttallii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis remyi plana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis schlechtendahliana nuttallii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis schlechtendahliana plana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis schlechtendahliana reticulata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hedyotis tryblium | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Hedysarum boreale gremiale | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Hedysarum occidentale canone | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Helenium arizonicum | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Helianthus carnosus | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Helianthus deserticola | Not Listed | Resolved Taxon | | AZ, NV, UT |
| Flowering Plants | No common name | Helianthus glaucophyllus | Not Listed | Resolved Taxon | | AL, NC, SC, TN |
| Flowering Plants | No common name | Helianthus laciniatus crenatus | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Helianthus porteri | Not Listed | Resolved Taxon | | AL, GA |
| Flowering Plants | No common name | Helianthus praetermissus | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Helianthus smithii | Not Listed | Resolved Taxon | | AL, GA, TN |
| Flowering Plants | No common name | Heliotropium polyphyllum horizontale | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Hermidium alipes pallidum | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | No common name | Herricka horrida | Not Listed | Species of Concern | | CO |
| Flowering Plants | No common name | Hesperocnide sandwicensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hesperomannia arborescens | Listed | Endangered | | HI |
| Flowering Plants | No common name | Hesperomannia arbuscula | Listed | Endangered | | HI |
| Flowering Plants | No common name | Hesperomannia lydgatei | Listed | Endangered | | HI |
| Flowering Plants | No common name | Heterodermia erinacea | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Heterotheca rutteri | Not Listed | Species of Concern | | AZ |
| Flowering Plants | No common name | Heuchera missouriensis | Not Listed | Resolved Taxon | | MO |
| Flowering Plants | No common name | Heuchera villosa arkansana | Not Listed | Resolved Taxon | | AR |
| Flowering Plants | No common name | Hexastylis contracta | Not Listed | Species of Concern | | KY, NC, TN |
| Flowering Plants | No common name | Hibiscadelphus bombycinus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hibiscadelphus wilderanus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hibiscus waimeae waimeae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Hieracium longiberbe | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Birds | No common name | Hierococcyx nisicolor | Not Listed | Species of Concern | | |
| Birds | No common name | Himatione fraithii | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Holocarpha virgata elongata | Not Listed | Species of Concern | | CA |
| Snails | No common name | Holospira millestriata | Not Listed | Resolved Taxon | | |
| Ferns and Allies | No common name | Huperzia haleakalae | Not Listed | Resolved Taxon | | HI |
| Birds | No common name | Hydrobates hornbyi | Not Listed | Species of Concern | | |
| Birds | No common name | Hydrobates monorhis | Not Listed | Species of Concern | | |
| Birds | No common name | Hydrobates socorroensis | Not Listed | Species of Concern | | |
| Birds | No common name | Hydrobates tethys | Not Listed | Species of Concern | | |
| Birds | No common name | Hydropsalis cayennensis | Not Listed | Species of Concern | | |
| Insects | No common name | Hydroptila abbotti | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Hymenocallis latifolia | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Hymenopappus filifolius idahoensis | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Hymenoxys helenioides | Not Listed | Resolved Taxon | | AZ, CO, NM, UT |
| Flowering Plants | No common name | Hymenoxys lapidicola | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | No common name | Hymenoxys quinquesquamata | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Hymenoxys subintegra | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Hypericum adpressum | Not Listed | Species of Concern | | AL, CT, DE, GA, IL, IN, KY, MA, MD, NJ, NY, PA, RI, SC, TN, VA |
| Flowering Plants | No common name | Hypericum dolabriforme | Not Listed | Resolved Taxon | | AL, GA, IN, KY, OH, TN |
| Fishes | No common name | ictalurus species | Not Listed | Status Undefined | | |
| Birds | No common name | Icterus portoricensis | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Ilex opaca arenicola | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Ilex sintenisii | Listed | Endangered | | PR |
| Flowering Plants | No common name | Ionactis elegans | Not Listed | Species of Concern | | NM |
| Flowering Plants | No common name | Ipomoea cairica lineariloba | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Ipomoea cardiophylla | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Ipomopsis aggregata webberi | Not Listed | Species of Concern | | WY |
| Flowering Plants | No common name | Ipomopsis globularis | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Ipomopsis spicata robruthii | Not Listed | Species of Concern | | WY |
| Insects | No common name | Isoperla sagittata | Petitioned for Listing, Under Review | Under Review | | |
| Corals | No common name | Isopora crateriformis | Listed | Threatened | | |
| Flowering Plants | No common name | Ivesia cryptocaulis | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Ivesia jaegeri | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | No common name | Ivesia longibracteata | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Ivesia multifoliolata | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Ivesia shockleyi ostleri | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Jamesia americana zionis | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Jamesia tetrapetala | Not Listed | Species of Concern | | NV, UT |
| Flowering Plants | No common name | Jaquinia umbellata | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Juncus mertensianus | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Juncus trifidus carolinianus | Not Listed | Resolved Taxon | | NC, NY, TN, VA, WV |
| Flowering Plants | No common name | Justicia borinquensis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Justicia culebritae | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Justicia warnockii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Kadua degeneri | Listed | Endangered | | HI |
| Flowering Plants | No common name | Kadua haupuensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Kadua parvula | Listed | Endangered | | HI |
| Flowering Plants | No common name | Kadua st.-johnii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Kalmiopsis leachiana | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Keysseria (=Lagenifera) erici | Listed | Endangered | | HI |
| Flowering Plants | No common name | Keysseria (=Lagenifera) helenae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Labordia decurrens decurrens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia fagraeoidea longisepala | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia fagraeoidea saint-johniana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia fagraeoidea waianaeana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hedyosmifolia kilaueana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hedyosmifolia magnifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hedyosmifolia robusta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hedyosmifolia rockii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hedyosmifolia skottsbergii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hirtella imbricata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hirtella laevis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hirtella laevisepala | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hirtella microcalyx | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia hirtella microphylla | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia kaalae brachypoda | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia kaalae fosbergii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia kaalae mendax | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia lorenciana | Listed | Endangered | | HI |
| Flowering Plants | No common name | Labordia molokaiana molokaiana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia molokaiana munroi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia molokaiana setosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia tinifolia euphorbioidea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia tinifolia forbesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia tinifolia honolulensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia tinifolia microgyna | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia tinifolia parvifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Labordia tinifolia tenuifolia | Not Listed | Resolved Taxon | | HI |
| Insects | No common name | Lachlania dencyannae | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Lachnocaulon beyrichianum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Lantana depressa | Not Listed | Species of Concern | | |
| Birds | No common name | Larvivora cyane | Not Listed | Species of Concern | | |
| Birds | No common name | Larvivora sibilans | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Lathyrus holochlorus | Not Listed | Resolved Taxon | | CA, HI, NV, OR |
| Flowering Plants | No common name | Leavenworthia exigua exigua | Not Listed | Resolved Taxon | | AL, GA, TN |
| Flowering Plants | No common name | Leavenworthia stylosa | Not Listed | Resolved Taxon | | AL, TN |
| Lichens | No common name | Lecanora masana | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Lecanora xanthosora | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Lechea cernua | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Lechea divaricata | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Lechea lakelae | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Lejeunea blomquistii | Not Listed | Species of Concern | | GA, NC |
| Flowering Plants | No common name | Lepanthes dodiana | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Lepanthes eltoroensis | Delisted | Recovery | | PR |
| Flowering Plants | No common name | Lepidium montanum neeseae | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Lepidium nanum | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Lepidium orbiculare | Listed | Endangered | | HI |
| Flowering Plants | No common name | Leptocereus grantianus | Listed | Endangered | | PR |
| Flowering Plants | No common name | Leptodactylon glabrum | Not Listed | Species of Concern | | ID, NV |
| Flowering Plants | No common name | Leptodactylon pungens hazeliae | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Flowering Plants | No common name | Lesquerella arctica scammanae | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Lesquerella condensata | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | lesquerella navajoensis | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | No common name | Lessingia arachnoidea | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Lessingia micradenia micradenia | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Lewisia columbiana wallowensis | Not Listed | Resolved Taxon | | CA, ID, MT, NV, OR |
| Flowering Plants | No common name | Lewisia cotyledon purdyi | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Lewisia maguirei | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Liatris cymosa | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Ligusticum porteri brevilobum | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Lilaeopsis carolinensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Limbella fryei | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | No common name | Limnephilus adapus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Limonium limbatum | Not Listed | Resolved Taxon | | AZ, NM, TX |
| Flowering Plants | No common name | Linum sulcatum harperi | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Lipochaeta heterophylla heterophylla | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lipochaeta integrifolia argentea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lipochaeta lavarum conferta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lipochaeta lavarum hillebrandiana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lipochaeta lavarum maneleana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lipochaeta lavarum ovata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lipochaeta lavarum stearnsii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lipochaeta ovata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lobelia appendiculata gattingeri | Not Listed | Resolved Taxon | | KY, TN |
| Flowering Plants | No common name | Lobelia dunbariae | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Lobelia hypoleuca rockii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lobelia koolauensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lobelia monostachya | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lobelia niihauensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lobelia oahuensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lobelia remyi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lomatium attenuatum | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Lomatium cuspidatum | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Lomatium hallii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Lomatium hendersonii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Lomatium laevigatum | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Lomatium minimum | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Lomatium oreganum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Lomatium quintuplex | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Lomatium rollinsii | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | No common name | Lomatium serpentinum | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | No common name | Lomatium thompsonii | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Lophocolea appalachiana | Not Listed | Species of Concern | | NC, TN |
| Flowering Plants | No common name | Lotus purshianus helleri | Not Listed | Species of Concern | | GA, NC, SC, VA |
| Birds | No common name | Loxops wolstenholmei | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Luina serpentina | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Lunania ekmanii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Lupinus burkei caeruleomontanus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Lupinus crassus | Not Listed | Species of Concern | | CO |
| Flowering Plants | No common name | Lupinus jonesii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Lupinus malacophyllus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Lupinus montigenus montigenus | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | No common name | Lupinus sabinii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Lupinus sericeus marianus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Luzula hawaiiensis oahuensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lygodesmia grandiflora stricta | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Lyonia truncata var. proctorii | Listed | Endangered | | PR |
| Flowering Plants | No common name | Lysiloma microphylla thornberi | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Lysimachia filifolia | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lysimachia forbesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Lysimachia iniki | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lysimachia kalalauensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Lysimachia lydgatei | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lysimachia maxima | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lysimachia pendens | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lysimachia scopulensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lysimachia venosa | Listed | Endangered | | HI |
| Flowering Plants | No common name | Lythrum ovalifolium | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Machaeranthera grindelioides depressa | Not Listed | Resolved Taxon | | AZ, NV, UT |
| Flowering Plants | No common name | Machaeranthera gypsitherma | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Machaeranthera laetevirens | Not Listed | Resolved Taxon | | ID, NV |
| Flowering Plants | No common name | Maesa walkeri | Listed | Threatened | | GU, MP |
| Flowering Plants | No common name | Malacothrix crispifolia | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Malacothrix intermedia | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Malvastrum hispidum | Not Listed | Resolved Taxon | | AL, IL, KS, KY, MO, NE, TN |
| Flowering Plants | No common name | Mammillaria thornberi | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Manfreda maculosa | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Manihot davisiae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Mappia racemosa | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Marsdenia elliptica | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Marshallia ramosa | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Matelea brevicoronata | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Matelea floridana | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Matelea parviflora | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Maytenus cymosa | Not Listed | Resolved Taxon | | PR, VI |
| Birds | No common name | Melanitta stejneger | Not Listed | Species of Concern | | |
| Insects | No common name | Melanoplus alexanderi | Not Listed | Resolved Taxon | | |
| Insects | No common name | Melanoplus chiricahuae | Not Listed | Resolved Taxon | | |
| Insects | No common name | Melanoplus missoulae | Not Listed | Resolved Taxon | | |
| Insects | No common name | Melanoplus pinaleno | Not Listed | Resolved Taxon | | |
| Insects | No common name | melanoplus speciesfiftytwo | Not Listed | Status Undefined | | |
| Insects | No common name | melanoplus speciesforty-eight | Not Listed | Status Undefined | | |
| Insects | No common name | Melanoplus speciesforty-nine | Petitioned for Listing, Under Review | Under Review | | |
| Insects | No common name | Melanoplus speciesforty-seven | Petitioned for Listing, Under Review | Under Review | | |
| Insects | No common name | Melanoplus speciesforty-two | Petitioned for Listing, Under Review | Under Review | | |
| Insects | No common name | Melanoplus speciesfourty | Petitioned for Listing, Under Review | Under Review | | |
| Insects | No common name | Melanoplus speciesfourty-one | Petitioned for Listing, Under Review | Under Review | | |
| Insects | No common name | melanoplus speciesnine | Not Listed | Status Undefined | | |
| Insects | No common name | Melanoplus speciesone | Petitioned for Listing, Under Review | Under Review | | |
| Insects | No common name | melanoplus speciessixtytwo | Not Listed | Status Undefined | | |
| Insects | No common name | melanoplus speciesthirtysix | Not Listed | Status Undefined | | |
| Insects | No common name | melanoplus speciestwentysix | Not Listed | Status Undefined | | |
| Insects | No common name | melanoplus speciestwentytwo | Not Listed | Status Undefined | | |
| Birds | No common name | Melanospiza bicolor | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Melanthera integrifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Melanthera parvifolia | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Melicope clusiifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Melicope cornuta var. cornuta | Listed | Endangered | | HI |
| Flowering Plants | No common name | Melicope cornuta var. decurrens | Listed | Endangered | | HI |
| Flowering Plants | No common name | Melicope pseudoanisata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Melicope remyi | Listed | Endangered | | HI |
| Flowering Plants | No common name | Melicope wawraeana | Not Listed | Resolved Taxon | | HI |
| Birds | No common name | Melopyrrha portoricensis | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Mentzelia multicaulis var. librina | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Mentzelia shultziorum | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Mesadenus portoricensis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Metrosideros collina newellii | Not Listed | Resolved Taxon | | HI |
| Arachnids | No common name | mexichthonius exoticus | Not Listed | Resolved Taxon | | |
| Lichens | No common name | Micarea ternaria | Not Listed | Resolved Taxon | | |
| Ferns and Allies | No common name | Microlepia strigosa var. mauiensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Microseris howellii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Microseris laciniata detlingii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Microseris nutans siskiyouensis | Not Listed | Resolved Taxon | | CA, NV, OR |
| Corals | No common name | Millepora foveolata | Not Listed | Status Undefined | | |
| Corals | No common name | Millepora tuberosa | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Mimulus hymenophyllus | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Mimulus jungermannioides | Not Listed | Species of Concern | | WA |
| Flowering Plants | No common name | Mimulus washoensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Minuartia marcescens | Not Listed | Species of Concern | | VT |
| Flowering Plants | No common name | Minuartia uniflora | Not Listed | Resolved Taxon | | AL, GA, NC, SC |
| Flowering Plants | No common name | Mitracarpus maxwelliae | Listed | Endangered | | PR |
| Flowering Plants | No common name | Mitracarpus polycladus | Listed | Threatened | | PR |
| Flowering Plants | No common name | Monardella diaboli | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Montia bostockii | Not Listed | Resolved Taxon | | AK |
| Corals | No common name | Montipora angulata | Not Listed | Status Undefined | | |
| Corals | No common name | Montipora australiensis | Listed | Threatened | | |
| Corals | No common name | Montipora calcarea | Not Listed | Status Undefined | | |
| Corals | No common name | Montipora caliculata | Not Listed | Status Undefined | | |
| Corals | No common name | Montipora lobulata | Not Listed | Status Undefined | | |
| Corals | No common name | Montipora turgescens | Not Listed | Status Undefined | | |
| Corals | No common name | Montipora verrilli | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Muhlenbergia pilosa | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Musineon lineare | Not Listed | Resolved Taxon | | ID, UT |
| Birds | No common name | Myotis melanorhinus | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Myrcia paganii | Listed | Endangered | | PR |
| Flowering Plants | No common name | Myriophyllum laxum | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Nama retrorsum | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | No common name | Nama xylopodum | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Napaea dioica | Not Listed | Resolved Taxon | | IA, IL, IN, MN, OH, WI |
| Arachnids | No common name | neoallochernes incertus | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | neoleptoneta anopica | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | neoleptoneta concinna | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | neoleptoneta devia | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | neoleptoneta valverde | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Neoparrya lithophila | Not Listed | Resolved Taxon | | CO |
| Insects | No common name | Neotrichia downsi | Not Listed | Resolved Taxon | | |
| Insects | No common name | Neotrichia juani | Not Listed | Resolved Taxon | | |
| Insects | No common name | Neotrichia sonora | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Neraudia angulata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Neraudia kauaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Neraudia ovata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Neraudia sericea | Listed | Endangered | | HI |
| Flowering Plants | No common name | Nervilia jacksoniae | Listed | Threatened | | GU, MP |
| Flowering Plants | No common name | Nesogenes rotensis | Listed | Endangered | | MP |
| Birds | No common name | Nesophlox evelynae | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Nestronia umbellula | Not Listed | Resolved Taxon | | AL, GA, MS, NC, SC, TN, VA |
| Flowering Plants | No common name | Neviusia alabamensis | Not Listed | Species of Concern | | AL, AR, GA, MO, MS, TN |
| Birds | No common name | Ninox japonica | Not Listed | Species of Concern | | |
| Ferns and Allies | No common name | Notholaena schaffneri | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Nototrichium sandwicense decipiens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense dubium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense forbesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense helleri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense kolekolense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense lanaiense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense lanceolatum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense latifolium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense leptopodum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense longespicatum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense macrophyllum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense mauiense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense niihauense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense olokeleanum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense pulchelloides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense pulchellum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense subcordatum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium sandwicense syringifolium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nototrichium viride | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Nuphar luteum ulvaceum | Not Listed | Species of Concern | | |
| Clams | No common name | Obovaria cf. unicolor | Proposed for Listing | Proposed Threatened | | AL, LA, MS |
| Flowering Plants | No common name | Ochrosia compta | Not Listed | Resolved Taxon | | HI |
| Lichens | No common name | Omphalora arizonica | Not Listed | Resolved Taxon | | |
| Insects | No common name | Oncopodura cruciata | Not Listed | Resolved Taxon | | |
| Insects | No common name | Oncopodura prietoi | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Onosmodium helleri | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Onosmodium molle molle | Not Listed | Resolved Taxon | | AL, IL, KY, TN |
| Ferns and Allies | No common name | Ophioglossum nudicaule | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Opuntia basilaris longiareolata | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Opuntia basilaris woodburyi | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Opuntia heacockul | Not Listed | Species of Concern | | CO |
| Flowering Plants | No common name | Opuntia phaeacantha flavispina | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Opuntia phaeacantha mojavensis | Not Listed | Resolved Taxon | | AZ, CA |
| Flowering Plants | No common name | Opuntia phaeacantha superbospina | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Opuntia spinosissima | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Opuntia triacantha | Not Listed | Resolved Taxon | | |
| Birds | No common name | Oreothlypis superciliosa | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Oreoxis trotteri | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Osmoxylon mariannense | Listed | Endangered | | MP |
| Flowering Plants | No common name | Oxypolis ternata | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Oxytheca watsonii | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | No common name | Oxytropis besseyi obnapiformis | Not Listed | Resolved Taxon | | CO, UT, WY |
| Flowering Plants | No common name | Oxytropis campestris johannensis | Not Listed | Resolved Taxon | | ME |
| Flowering Plants | No common name | Oxytropis campestris wanapum | Not Listed | Species of Concern | | WA |
| Flowering Plants | No common name | Oxytropis glaberrima | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Oxytropis sordida barnebyana | Not Listed | Species of Concern | | AK |
| Lichens | No common name | Ozobryum ogalalense | Not Listed | Resolved Taxon | | |
| Corals | No common name | Pachyseris rugosa | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Packera cardamine | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | No common name | Packera hesperia | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Panicum stevensianum | Not Listed | Species of Concern | | PR, VI |
| Fishes | No common name | Pantosteus discobolus | | Not Listed | | |
| Flowering Plants | No common name | Papaver pygmaeum | Not Listed | Species of Concern | | MT |
| Flowering Plants | No common name | Paronychia drummondii parviflora | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Paronychia virginica parksii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Parrya nudicaulis | Not Listed | Resolved Taxon | | AK, MT |
| Flowering Plants | No common name | Parthenium alpinum | Not Listed | Resolved Taxon | | CO, WY |
| Flowering Plants | No common name | Passiflora berteroana | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Passiflora bilobata | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Passiflora murucuja | Not Listed | Resolved Taxon | | PR, VI |
| Corals | No common name | Pavona diffluens | Listed | Threatened | | |
| Flowering Plants | No common name | Paxistima canbyi | Not Listed | Species of Concern | | NC, VA |
| Corals | No common name | Pectinia alcicornis | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Pedicularis rainierensis | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Pedicularis semibarbata charlestonensis | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Pediomelum aromaticum tuhyi | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Pediomelum pariensis | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Pelea anisata haupuana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea clusiaefolia pickeringii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea elliptica mauiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea grandifolia lianoides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea grandifolia montana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea grandifolia ovalifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea parvifolia sessilis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea peduncularis cordata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea peduncularis niuensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea peduncularis nummularia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pelea volcanica kohalae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peniocereus greggii transmontanus | Not Listed | Resolved Taxon | | AZ, CA, NM, TX |
| Flowering Plants | No common name | Penstemon ammophilum | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Penstemon angustifolius vernalensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Penstemon arenarius | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Penstemon arkansanus | Not Listed | Resolved Taxon | | AR |
| Flowering Plants | No common name | Penstemon atwoodii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Penstemon baccharifolius | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Penstemon barrettiae | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | No common name | Penstemon bicolor bicolor | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Penstemon bicolor roseus | Not Listed | Species of Concern | | AZ, NV |
| Flowering Plants | No common name | Penstemon cobaea purpureus | Not Listed | Resolved Taxon | | AR, MO, OK |
| Flowering Plants | No common name | Penstemon crandallii atractus | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Penstemon dissectus | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | No common name | Penstemon elegantulus | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Penstemon floribundus | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Penstemon flowersii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Penstemon francisci-pennellii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Penstemon goodrichii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Penstemon humilis brevifolius | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Penstemon humilis obtusifolius | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Penstemon leptanthus | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Penstemon moriahensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Penstemon navajoa | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Penstemon parviflorus | Not Listed | Species of Concern | | CO |
| Flowering Plants | No common name | Penstemon patricus | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | No common name | Penstemon peckii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Penstemon procerus modestus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Penstemon pudicus | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Penstemon thompsoniae jaegeri | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Penstemon thurberi anestius | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Penstemon virgatus pseudoputus | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Penstemon washingtonensis | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Penstemon yampaensis | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | No common name | Peperomia cookiana minutilimba | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peperomia degeneri | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Peperomia expallescens brevipilosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peperomia fauriei | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peperomia helleri knudsenii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peperomia lilifolia obtusata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peperomia megalopoda | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Peperomia myrtifolia | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Peperomia oahuensis st-johnii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peperomia obtusifolia | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Peperomia rigidilimba | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Peperomia rockii | Not Listed | Species of Concern | | HI |
| Fishes | No common name | Percina cf nasuta (Arkansas River basin) | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | No common name | Percina cf nasuta (upper White River basin) | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | No common name | Percina nigrofasciata | | Not Listed | | |
| Fishes | No common name | Percina sciera | | Not Listed | | |
| Flowering Plants | No common name | Perityle lemmonii | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | No common name | Perityle megalocephala intricata | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | No common name | Perityle parryi | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Perityle specuicola | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Perityle staurophylla | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Persea borbonia humilis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Peteria thompsonae | Not Listed | Resolved Taxon | | AZ, CA, ID, NV, UT |
| Flowering Plants | No common name | Petrophytum hendersonii | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Phacelia constancei | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | No common name | Phacelia dubia georgiana | Not Listed | Resolved Taxon | | AL, GA |
| Flowering Plants | No common name | Phacelia glaberrima | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Phacelia incana | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Phacelia inconspicua | Not Listed | Species of Concern | | ID, NV |
| Flowering Plants | No common name | Phacelia integrifolia texana | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Phacelia peckii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Phacelia verna | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | No common name | Pheidole elecebra | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Phialanthus myrtilloides | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Philadelphus mearnsii | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Philadelphus texensis texensis | Not Listed | Resolved Taxon | | TX |
| Ferns and Allies | No common name | Phlegmariurus stemmermanniae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phlox buckleyi | Not Listed | Resolved Taxon | | VA, WV |
| Flowering Plants | No common name | Phlox peckii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Snails | No common name | Phreatodrobia coronae | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Phyllanthus liebmannianus platylepis | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Phyllanthus pentaphyllus floridanus | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Phyllanthus saffordii | Listed | Endangered | | GU |
| Flowering Plants | No common name | Phyllanthus sandwicensis degeneri | Not Listed | Resolved Taxon | | HI |
| Birds | No common name | Phylloscopus examinandus | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Phyllostegia ambigua | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia bracteata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia brevidens | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia brevidens ambigua | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia brevidens degeneri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia brevidens heterodoxa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia brevidens hirsutula | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia brevidens pubescens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia floribunda | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia glabra var. lanaiensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia haliakalae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia helleri | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia hillebrandii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia hirsuta | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia hispida | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia imminuta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia kaalaensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia knudsenii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia mannii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia mollis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia mollis fagerlindii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia parviflora | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia pilosa | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia renovans | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia rockii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia stachyoides | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia variabilis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Phyllostegia velutina | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia waimeae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia warshaueri | Listed | Endangered | | HI |
| Flowering Plants | No common name | Phyllostegia wawrana | Listed | Endangered | | HI |
| Flowering Plants | No common name | Physalis viscosa elliotii | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Physaria acutifolia purpurea | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Physaria didymocarpa lyrata | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Physaria dornii | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Physaria eburniflora | Not Listed | Species of Concern | | WY |
| Flowering Plants | No common name | Physaria geyeri purpurea | Not Listed | Resolved Taxon | | ID |
| Corals | No common name | Physogyra lichtensteini | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Physostegia intermedia | Not Listed | Resolved Taxon | | OK, TX |
| Flowering Plants | No common name | Physostegia longisepala | Not Listed | Species of Concern | | LA, TX |
| Flowering Plants | No common name | Pieris phillyreifolia | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Pilea leptophylla | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Pilea multicaulis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Pilea richardii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Pilea yunquensis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Pinckneya bracteata | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Pisonia floridana | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Pisonia wagneriana | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Pittosporum acuminatum leptopodum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum acuminatum magnifolium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum acuminatum waimeanum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum argentifolium argentifolium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum argentifolium sessile | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum cauliflorum cauliflorum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum cauliflorum cladanthoides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum cauliflorum pedicellatum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum cladanthum gracilipes | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum confertiflorum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum confertiflorum longipes | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum confertiflorum microphyllum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum glabrum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum glabrum glomeratum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum glabrum intermedium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum glabrum tinifolium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum hosmeri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum insigne micranthum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum kauaiense repens | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum terminalioides lanaiense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum terminalioides macropus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pittosporum terminalioides mauiense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Pityopsis flexuosa | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Plagiobothrys distantiflorus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Plagiochila columbiana | Not Listed | Species of Concern | | DC, NC, VA |
| Flowering Plants | No common name | Plagiochila echinata | Not Listed | Species of Concern | | NC |
| Flowering Plants | No common name | Plagiochila virginica euryphylla | Not Listed | Species of Concern | | NC |
| Flowering Plants | No common name | Platanthera holochila | Listed | Endangered | | HI |
| Flowering Plants | No common name | Platanthera integra | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Platanthera zothecina | Not Listed | Species of Concern | | CO, UT |
| Flowering Plants | No common name | Plummera ambigens | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Poa curtifolia | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Poa laxiflora | Not Listed | Resolved Taxon | | AK, CA, NV, OR, WA |
| Flowering Plants | No common name | Poa macrocalyx | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Poa marcida | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Poa palustris | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Poa paucispicula | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Poa siphonoglossa | Listed | Endangered | | HI |
| Corals | No common name | Pocillopora danae | Not Listed | Status Undefined | | |
| Corals | No common name | Pocillopora elegans | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Podistera yukonensis | Not Listed | Species of Concern | | AK |
| Flowering Plants | No common name | Polemonium nevadense | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Polemonium pectinatum | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Polygala alba | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Polygala boykinii sparsifolia | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Polygala paucifolia | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Polygala piliophora | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Polygala rimulicola rimulicola | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Polygala subspinosa heterorhynca | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | No common name | Polygala verticillata | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Polygonum cascadense | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Polygonum utahense | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Polymnia laevigata | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Polyscias bisattenuata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Polyscias flynnii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Polyscias lydgatei | Listed | Endangered | | HI |
| Flowering Plants | No common name | Polyscias racemosa | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Polystichum calderonense | Listed | Endangered | | PR |
| Flowering Plants | No common name | Porella appalachiana | Not Listed | Species of Concern | | NC, SC |
| Corals | No common name | Porites horizontalata | Not Listed | Status Undefined | | |
| Corals | No common name | Porites napopora | Listed | Threatened | | |
| Corals | No common name | Porites nigrescens | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Porophyllum greggii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Porophyllum pygmaeum | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Portulaca caulerpoides | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Portulaca molokiniensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Portulaca smallii | Not Listed | Resolved Taxon | | GA, NC, SC, VA |
| Flowering Plants | No common name | Potamogeton lateralis | Not Listed | Resolved Taxon | | CT, MA, MI, MN, NH, NY, VT |
| Flowering Plants | No common name | Potentilla angelliae | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Potentilla cottamii | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | No common name | Potentilla sierrae-blancae | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Priva portoricensis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Proatriplex pleiantha | Not Listed | Resolved Taxon | | CO, NM, UT |
| Flowering Plants | No common name | Prunus alleghaniensis davisii | Not Listed | Species of Concern | | MI |
| Flowering Plants | No common name | Prunus havardii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Prunus minutiflora | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Prunus murrayana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Prunus texana | Not Listed | Resolved Taxon | | TX |
| Insects | No common name | Pseudocopaeodes eunus alinea | Not Listed | Resolved Taxon | | CA, NV |
| Insects | No common name | Pseudocopaeodes eunus flavus | Not Listed | Resolved Taxon | | CA, NV |
| Insects | No common name | Pseudocopaeodes eunus ssp. | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Pseudognaphalium macounii | Not Listed | Resolved Taxon | | DE, IL, NJ |
| Insects | No common name | Pseudosinella vita | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Psorothamnus kingii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Psorothamnus polydenius var. jonesii | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Psychilis krugii | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Psychotria insularum paradisii | Not Listed | Resolved Taxon | | HI |
| Ferns and Allies | No common name | Pteris lidgatei | Listed | Endangered | | HI |
| Insects | No common name | ptomaphagus cocytus | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Pycnanthemum curvipes | Not Listed | Resolved Taxon | | AL, GA, TN |
| Flowering Plants | No common name | Pycnanthemum floridanum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Pyrrocoma insecticruris | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Pyrrocoma liatriformis | Not Listed | Species of Concern | | ID, WA |
| Clams | No common name | Quadrula cylindrica | Not Listed | Status Undefined | | |
| Birds | No common name | Rallus obsoletus | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Randia portoricensis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Ranunculus austro-oreganus | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Ranunculus occidentalis nelsonii | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Ranunculus triternatus | Not Listed | Species of Concern | | WA |
| Flowering Plants | No common name | Rauvolfia helleri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Rauvolfia mauiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Rauvolfia molokaiensis parvifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Rauvolfia sandwicensis subacuminata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Remya kauaiensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Remya montgomeryi | Listed | Endangered | | HI |
| Insects | No common name | rhadine austinica | Not Listed | Resolved Taxon | | |
| Insects | No common name | rhadine insolita | Not Listed | Resolved Taxon | | |
| Insects | No common name | rhadine noctivaga | Not Listed | Resolved Taxon | | |
| Insects | No common name | rhadine russelli | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Rhinanthus arcticus | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Rhipsalis baccifera | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Rhododon ciliatus | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Rhynchosia cinerea | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Riccia californica | | Not Listed | | |
| Lichens | No common name | Riccia ozarkiana | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Rollandia angustifolia ochreata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Rollandia degenerana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Romanzoffia thompsonii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Rorippa aquatica | Not Listed | Resolved Taxon | | IL, IN, KY, LA, MI, MO, NC, NY, OH, OK, SC, TN, VA, VT, WI |
| Flowering Plants | No common name | Rorippa calycina | Not Listed | Species of Concern | | MT, ND, WY |
| Flowering Plants | No common name | Rosa stellata stellata | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Rubus bartonianus | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Flowering Plants | No common name | Rubus macraei | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Rubus missouricus | Not Listed | Resolved Taxon | | IL, MI, MO |
| Flowering Plants | No common name | Rubus nigerrimus | Not Listed | Species of Concern | | WA |
| Flowering Plants | No common name | Ruellia drummondiana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Rumex spiralis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Sageretia minutiflora | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Salvia dorrii clokeyi | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Sanicula kauaiensis | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Sanicula mariversa | Listed | Endangered | | HI |
| Flowering Plants | No common name | Sanicula purpurea | Listed | Endangered | | HI |
| Flowering Plants | No common name | Sanicula sandwicensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Santalum ellipticum littorale | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Santalum involutum | Listed | Endangered | | HI |
| Flowering Plants | No common name | Santalum salicifolium | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Saussurea weberi | Not Listed | Resolved Taxon | | CO, MT |
| Flowering Plants | No common name | Saxifraga bryophora tobiasiae | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Scaevola gaudichaudiana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Schiedea attenuata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea diffusa ssp. macraei | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea diffusa subsp. diffusa | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea haleakalensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea helleri | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea hookeri | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea implexa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Schiedea jacobii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea kaalae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea kauaiensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea laui | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea lydgatei | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea mannii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Schiedea membranacea | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea menziesii | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Schiedea nuttallii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea obovata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea salicaria | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea sarmentosa | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea spergulina var. leiopoda | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea spergulina var. spergulina | Listed | Threatened | | HI |
| Flowering Plants | No common name | Schiedea trinervis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea verticillata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schiedea viscosa | Listed | Endangered | | HI |
| Flowering Plants | No common name | Schisandra glabra | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Schizachyrium niveum | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Schizachyrium rhizomatum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Schoepfia arenaria | Listed | Threatened | | PR |
| Flowering Plants | No common name | Scleria hirtella | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Sclerocactus contortus | Not Listed | Resolved Taxon | | CO, NM |
| Flowering Plants | No common name | Sclerocactus spinosior | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Sclerocactus warnockii | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Sclerocactus whipplei heilii | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Sclerocactus whipplei reevesii | Not Listed | Resolved Taxon | | NM |
| Ferns and Allies | No common name | Selaginella utahensis | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | No common name | Senecio hydrophilus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Senecio lynceus leucoreus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Senecio neowebsteri | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Senecio spribillei | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Senecio warnockii | Not Listed | Resolved Taxon | | TX |
| Corals | No common name | Seriatopora aculeata | Listed | Threatened | | |
| Birds | No common name | Setophaga adelaidae | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Seymeria bipinnatisecta | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Shoshonea pulvinata | Not Listed | Species of Concern | | MT, WY |
| Flowering Plants | No common name | Sibara grisea | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | No common name | Sibara rosulata | Not Listed | Resolved Taxon | | CA |
| Birds | No common name | Sibirionetta formosa | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Sicyos hillebrandii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sicyos lanceoloideus | Listed | Endangered | | HI |
| Flowering Plants | No common name | Sicyos maximowiczii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sicyos pachycarpus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sicyos semitonsus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sida fallax | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sida inflexa | Not Listed | Species of Concern | | VA |
| Flowering Plants | No common name | Sidalcea candida | Not Listed | Resolved Taxon | | CO, NM, NV, UT, WY |
| Flowering Plants | No common name | Sidalcea cusickii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Sidalcea setosa | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Sida rubromarginata | Not Listed | Resolved Taxon | | |
| Corals | No common name | Siderastrea glynni | Listed | Endangered | | |
| Flowering Plants | No common name | Silene alexandri | Listed | Endangered | | HI |
| Flowering Plants | No common name | Silene aperta | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | No common name | Silene clokeyi | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Silene cryptopetala | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Silene degeneri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Silene hawaiiensis | Listed | Threatened | | HI |
| Flowering Plants | No common name | Silene lanceolata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Silene perlmanii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Silene scaposa lobata | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | No common name | Silene scaposa scaposa | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Silene seelyi | Not Listed | Species of Concern | | WA |
| Flowering Plants | No common name | Silene wrightii | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Silphium confertifolium | Not Listed | Species of Concern | | AL |
| Flowering Plants | No common name | Smelowskia borealis villosa | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Smelowskia holmgrenii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | No common name | Smelowskia pyriformis | Not Listed | Species of Concern | | AK |
| Flowering Plants | No common name | Smilax melastomifolia melastomifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Smilax pseudochina | Not Listed | Species of Concern | | GA |
| Flowering Plants | No common name | Solanum carolinense floridanum | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Solanum mucronatum | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Solanum woodburyi | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | No common name | Solidago arguta harrissii | Not Listed | Resolved Taxon | | MD, PA, VA, WV |
| Flowering Plants | No common name | Solidago mollis angustata | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Solidago ouachitensis | Not Listed | Resolved Taxon | | AR, OK |
| Flowering Plants | No common name | Solidago petiolaris | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Solidago sphathulata gillmanii | Not Listed | Species of Concern | | IN, MI, WI |
| Insects | No common name | sonorarctia fervida | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Sophora arizonica | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Sophora chrysophylla circularis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla elliptica | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla glabrata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla grisea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla kanaioensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla kauensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla makuaensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora chrysophylla unifoliata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Sophora leachiana | Not Listed | Species of Concern | | CA, NV, OR |
| Birds | No common name | Spatula querquedula | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Spermolepis hawaiiensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Sphaeralcea janeae | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Sphaeralcea procera | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | No common name | Sphaeralcea psoraloides | Not Listed | Species of Concern | | UT |
| Insects | No common name | sphingicampa raspa | Not Listed | Status Undefined | | |
| Insects | No common name | Sphinx eremitoides | Not Listed | Status Undefined | | |
| Flowering Plants | No common name | Spigelia texana | Not Listed | Resolved Taxon | | TX |
| Birds | No common name | Spodiopsar cineraceus | Not Listed | Species of Concern | | |
| Birds | No common name | Sporophila morelleti | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Stanleya pinnata gibberosa | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Stenandrium fascicularis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Stenogyne affinis degeneri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne angustifolia var. angustifolia | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne bifida | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne campanulata | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne cinerea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne cranwelliae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne haliakalae | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Stenogyne kaalae ssp. sherffii | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne kanehoana | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne kauaulaensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne kealiae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Stenogyne macrantha | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne microphylla | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne oxygona | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Stenogyne purpurea forbesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne rotundifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne rotundifolia oblonga | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne rugosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne rugosa mollis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne salicifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne scrophularioides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne sessilis hexantha | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne sessilis laniensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne sessilis wilkesii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stenogyne viridis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Stillingia sylvatica tenuis | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Streptanthus carinatus | Not Listed | Resolved Taxon | | AZ, TX |
| Flowering Plants | No common name | Stylocline citroleum | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Stylocline masonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Styphelia tameiameiae hexamera | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Suaeda rolandii | Not Listed | Species of Concern | | DE, NJ, NY |
| Snails | No common name | Succinea pseudavara | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Sullivantia hapemanii | Not Listed | Species of Concern | | MT, WY |
| Flowering Plants | No common name | Sullivantia oregana | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | No common name | Sullivantia purpusii | Not Listed | Resolved Taxon | | CO |
| Insects | No common name | Suwallia salish | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Synthyris canbyi | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | No common name | Synthyris missurica hirsuta | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | No common name | Synthyris missurica stellata | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Synthyris pinnatifida canescens | Not Listed | Resolved Taxon | | ID, MT |
| Flowering Plants | No common name | Synthyris pinnatifida lanuginosa | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Synthyris platycarpa | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Synthyris schizantha | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Syntrichia princeps | | Not Listed | | |
| Flowering Plants | No common name | Tabernaemontana rotensis | Listed | Threatened | | GU, MP |
| Flowering Plants | No common name | Tagetes lemmonii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Taraxacum carneocoloratum | Not Listed | Species of Concern | | AK |
| Arachnids | No common name | tartarocreagris intermedia | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Tauschia stricklandii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Tauschia tenuissima | Not Listed | Resolved Taxon | | ID, WA |
| Ferns and Allies | No common name | Tectaria amesiana | Not Listed | Species of Concern | | |
| Ferns and Allies | No common name | Tectaria estremerana | Listed | Endangered | | PR |
| Flowering Plants | No common name | Teloschistes villosus | Not Listed | Species of Concern | | CA |
| Flowering Plants | No common name | Tephrosia angustissima | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Ternstroemia subsessilis | Listed | Endangered | | PR |
| Flowering Plants | No common name | Tetramolopium arenarium | Listed | Endangered | | HI |
| Flowering Plants | No common name | Tetramolopium consanguineum consanguineum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetramolopium consanguineum leptophyllum | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Tetramolopium conyzoides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetramolopium filiforme | Listed | Endangered | | HI |
| Flowering Plants | No common name | Tetramolopium humile sublaeve | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Tetramolopium kavaiensis koloana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetramolopium lepidotum arbusculum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetramolopium lepidotum ssp. lepidotum | Listed | Endangered | | HI |
| Flowering Plants | No common name | Tetramolopium remyi | Listed | Endangered | | HI |
| Flowering Plants | No common name | Tetramolopium rockii | Listed | Threatened | | HI |
| Flowering Plants | No common name | Tetramolopium tenerrimum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetramolopius kavaiensis koloana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraneuris torreyana | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Tetraneuris turneri | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Tetraplasandra hawaiiensis hawaiiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra kahanana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra kohalae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra lanaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra lihuensis gracilipes | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra bisobtusa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra bryanii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra degeneri | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra hillebrandii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra hiloensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra leptomera | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra makalehana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra rhynchocarpoides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra meiandra simulans | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra munroi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra oahuensis eradiata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra oahuensis fauriei | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra oahuensis hailiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra oahuensis longipes | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra oahuensis pseudorhachis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra pupukeensis nitida | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra pupukeensis pupukeensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra pupukeensis venosa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra turbans | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra waialealae urceolata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Tetraplasandra waimeae angustior | Not Listed | Resolved Taxon | | HI |
| Arachnids | No common name | texella brevidenta | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | texella brevistyla | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | texella diplospina | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | texella fendi | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | texella grubbsi | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | texella hardeni | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | texella renkesae | Not Listed | Resolved Taxon | | |
| Arachnids | No common name | texella welbourni | Not Listed | Resolved Taxon | | |
| Crustaceans | No common name | texiweckelia relicta | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Thalictrum arkansanum | Not Listed | Species of Concern | | AR, OK, TX |
| Flowering Plants | No common name | Thalictrum heliophilum | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | No common name | Thalictrum mirabile | Not Listed | Species of Concern | | AL, KY, TN |
| Millipedes | No common name | thalkethops grallatrix | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Thelesperma caespitosum | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Thelesperma pubescens | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | No common name | Thelesperma subnudum alpinum | Not Listed | Species of Concern | | UT |
| Flowering Plants | No common name | Thelocactus bicolor flavidispinus | Not Listed | Species of Concern | | TX |
| Flowering Plants | No common name | Thelypodiopsis purpusii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Thelypodium eucosmum | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | No common name | Thelypodium laxiflorum | Not Listed | Resolved Taxon | | AZ, CO, NV, UT |
| Flowering Plants | No common name | Thelypodium sagittatum ovalifolium | Not Listed | Resolved Taxon | | NV, UT |
| Ferns and Allies | No common name | Thelypteris hastata heterodoxa | Not Listed | Species of Concern | | PR, VI |
| Ferns and Allies | No common name | Thelypteris inabonensis | Listed | Endangered | | PR |
| Ferns and Allies | No common name | Thelypteris verecunda | Listed | Endangered | | PR |
| Ferns and Allies | No common name | Thelypteris yaucoensis | Listed | Endangered | | PR |
| Flowering Plants | No common name | Thismia americana | Not Listed | Species of Concern | | IL |
| Flowering Plants | No common name | Thlaspi arcticum | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | No common name | Thlaspi montanum siskiyouense | Not Listed | Resolved Taxon | | CA, NV, OR |
| Birds | No common name | Thryophilus sinaloa | Not Listed | Species of Concern | | |
| Arachnids | No common name | thymoites minero | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Tinospora homosepala | Listed | Endangered | | GU |
| Flowering Plants | No common name | Tithonia thurberi | Not Listed | Resolved Taxon | | AZ |
| Birds | No common name | Todiramphus sacer | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Tofieldia glutinosa absona | Not Listed | Species of Concern | | ID |
| Flowering Plants | No common name | Toiyabea alpina | Not Listed | Species of Concern | | NV |
| Insects | No common name | Tomocerus grahami | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Tonestus graniticus | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Townsendia alpigena minima | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Townsendia jonesii tumulosa | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Tradescantia edwardsiana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Tradescantia ozarkana | Not Listed | Species of Concern | | AR, MO, OK |
| Flowering Plants | No common name | Tragia nigricans | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | No common name | Tragia saxicola | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Trematolobelia grandifolia | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Trematolobelia singularis | Listed | Endangered | | HI |
| Ferns and Allies | No common name | Trichomanes draytonianum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Trifolium andinum podocephalum | Not Listed | Species of Concern | | NV |
| Flowering Plants | No common name | Trillium pusillum monticulum | Not Listed | Species of Concern | | VA, WV |
| Flowering Plants | No common name | Triniteurybia aberrans | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Trisetum orthochaetum | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | No common name | Triteleia lemmonae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | No common name | Triteleiopsis palmeri | Not Listed | Resolved Taxon | | AZ |
| Birds | No common name | Troglodytes pacificus | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Trollius laxus laxus | Not Listed | Resolved Taxon | | CT, DE, NJ, NY, OH, PA |
| Corals | No common name | Tubastraea floreana | Listed | Endangered | | |
| Arachnids | No common name | tuberochernes ubicki | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Tuberolabium guamense | Listed | Threatened | | GU, MP |
| Flowering Plants | No common name | Urera glabra | Not Listed | Resolved Taxon | | HI |
| Insects | No common name | ursia furtiva | Petitioned for Listing, Under Review | Under Review | | TX |
| Flowering Plants | No common name | Urtica chamaedryoides | Not Listed | Resolved Taxon | | |
| Lichens | No common name | Usnea longissima | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Vaccinium vacillans missouriense | Not Listed | Resolved Taxon | | MO |
| Flowering Plants | No common name | Valeriana columbiana | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | No common name | Varronia rupicola | Listed | Threatened | | PR |
| Flowering Plants | No common name | Verbesina heterophylla | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Vernonia borinquensis | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | No common name | Vernonia proctorii | Listed | Endangered | | PR |
| Flowering Plants | No common name | Vernonia pulchella | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | No common name | Veronica peregrina | Not Listed | Resolved Taxon | | CA, NV, OR |
| Lichens | No common name | Verrucaria kootenaica | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Vigna o-wahuensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Viola adunca cascadensis | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | No common name | Viola egglestonii | Not Listed | Resolved Taxon | | AL, GA, IN, KY, TN |
| Flowering Plants | No common name | Viola helenae | Listed | Endangered | | HI |
| Flowering Plants | No common name | Viola lanaiensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Viola lithion | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | No common name | Viola oahuensis | Listed | Endangered | | HI |
| Flowering Plants | No common name | Viola robusta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Waldsteinia idahoensis | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | No common name | Waltheria pyrolaefolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Wikstroemia basicorda | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Wikstroemia hanalei | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Wikstroemia isae | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Wikstroemia leptantha | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Wikstroemia monticola occidentalis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Wikstroemia sandwicensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Wikstroemia skottsbergiana | Listed | Endangered | | HI |
| Flowering Plants | No common name | Wikstroemia villosa | Listed | Endangered | | HI |
| Flowering Plants | No common name | Wilkstroemia bicornuta | Not Listed | Species of Concern | | HI |
| Flowering Plants | No common name | Willkommia texana | Not Listed | Resolved Taxon | | TX |
| Ferns and Allies | No common name | Woodsia abbeae | Not Listed | Resolved Taxon | | MI, MN, WI |
| Lichens | No common name | xanthoparmelia dissensa | Not Listed | Resolved Taxon | | |
| Lichens | No common name | Xanthoparmelia idahoensis | Not Listed | Resolved Taxon | | |
| Lichens | No common name | Xanthoparmelia neowyomingica | Not Listed | Resolved Taxon | | |
| Lichens | No common name | xanthoparmelia planilobata | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Xylorhiza confertifolia | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Xylorhiza cronquistii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | Xylosma crenatum | Listed | Endangered | | HI |
| Flowering Plants | No common name | Xyris isoetifolia | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Xyris scabrifolia | Not Listed | Species of Concern | | |
| Flowering Plants | No common name | Yucca angustissima toftiae | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | No common name | yucca cernua | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Zanthoxylum glandulosum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Zanthoxylum kauaense kohuana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Zanthoxylum maviense | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | No common name | Zephyranthes simpsonii | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Zephyranthes treatiae | Not Listed | Resolved Taxon | | |
| Flowering Plants | No common name | Zizia trifoliata | Not Listed | Species of Concern | | |
| Crustaceans | No Common name | Caecidotea adenta | Not Listed | Resolved Taxon | | |
| Birds | No Common Name | Coccyzus americanus ssp. occidentalis | Not Listed | Species of Concern | | CA |
| Crustaceans | No Common Name | Holsingerius samacos | Not Listed | Resolved Taxon | | |
| Crustaceans | No Common Name | Holsingerius smaragdinus | Not Listed | Resolved Taxon | | |
| Arachnids | No Common Name | Leucohya texana | Not Listed | Resolved Taxon | | |
| Arachnids | No Common Name | Pseudogarypus hypogeus | Not Listed | Resolved Taxon | | |
| Millipedes | No Common Name | Speodesmus aquiliensis | Not Listed | Resolved Taxon | | |
| Insects | [no common name] Beetle | Rhadine exilis | Listed | Endangered | | TX |
| Insects | [no common name] Beetle | Rhadine infernalis | Listed | Endangered | | TX |
| Flowering Plants | Nodding needlegrass | Nassella cernua | Not Listed | Resolved Taxon | | |
| Flowering Plants | Nodding rock-daisy | Perityle cernua | Not Listed | Species of Concern | | NM |
| Crustaceans | Noel's Amphipod | Gammarus desperatus | Listed | Endangered | | NM |
| Flowering Plants | Nohoanu | Geranium arboreum | Listed | Endangered | | HI |
| Flowering Plants | Nohoanu | Geranium hanaense | Listed | Endangered | | HI |
| Flowering Plants | Nohoanu | Geranium hillebrandii | Listed | Endangered | | HI |
| Flowering Plants | Nohoanu | Geranium kauaiense | Listed | Endangered | | HI |
| Flowering Plants | Nohoanu | Geranium multiflorum | Listed | Endangered | | HI |
| Birds | Noisy scrub-bird | Atrichornis clamosus | Listed | Endangered | | |
| Flowering Plants | None | Esenbeckia berlandieri | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Noni kuahiwi | Morinda trimera | Not Listed | Resolved Taxon | | HI |
| Snails | noonday snail | Mesodon clarki nantahala | Listed | Threatened | | NC |
| Birds | Nordmann's greenshank | Tringa guttifer | Listed | Endangered | | |
| Birds | Norfolk Island parakeet | Cyanoramphus cookii (=novaezelandiae c.) | Listed | Endangered | | |
| Birds | Norfolk Island white-eye | Zosterops albogularis | Listed | Endangered | | |
| Mammals | North American wolverine | Gulo gulo luscus | Not Listed | Resolved Taxon | | |
| Mammals | North American wolverine | Gulo gulo luscus | Listed | Threatened | | CA, ID, MT, NV, OR, UT, WA, WY |
| Mammals | North Andean huemul | Hippocamelus antisensis | Listed | Endangered | | |
| Mammals | North Atlantic Right Whale | Eubalaena glacialis | Listed | Endangered | | |
| Mammals | North China sika deer | Cervus nippon mandarinus | Listed | Endangered | | |
| Flowering Plants | Northcoast birds-beak | Cordylanthus maritimus palustris | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Northcoast phacelia | Phacelia insularis continentis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Northcoast semaphore grass | Pleuropogon hooverianus | Not Listed | Species of Concern | | CA |
| Insects | Northeastern beach tiger beetle | Habroscelimorpha dorsalis dorsalis | Listed | Threatened | | MA, MD, NJ, VA |
| Flowering Plants | Northeastern bulrush | Scirpus ancistrochaetus | Listed | Endangered | Proposed Delisting | MA, MD, NH, NY, PA, VA, VT, WV |
| Mammals | Northeastern pygmy shrew | Microsorex hoyi thompsoni | Not Listed | Resolved Taxon | | MA, ME, MI, NH, NY, OH, PA, VT, WI, WV |
| Birds | Northern Alaska Dunlin | Calidris alpina arcticola | Not Listed | Species of Concern | | |
| Birds | Northern Aplomado Falcon | Falco femoralis septentrionalis | Listed | Experimental Population, Non-Essential | | AZ, NM |
| Birds | Northern Aplomado Falcon | Falco femoralis septentrionalis | Listed | Endangered | | TX |
| Birds | Northern bald ibis | Geronticus eremita | Listed | Endangered | | |
| Birds | Northern Beardless-Tyrannulet | Camptostoma imberbe | Not Listed | Species of Concern | | |
| Mammals | northern bog lemming | Synaptomys borealis | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Northern bog lemming | Synaptomys borealis sphagnicola | | Not Listed | | ME, NH |
| Fishes | Northern Brook Lamprey | Ichthyomyzon fossor | | Not Listed | | |
| Flowering Plants | Northern California black walnut | Juglans californica hindsii | Not Listed | Species of Concern | | CA |
| Fishes | Northern cavefish | Amblyopsis spelaea | Not Listed | Resolved Taxon | | IN, KY |
| Amphibians | Northern Cricket Frog | Acris crepitans | | Not Listed | | |
| Reptiles | Northern diamondback terrapin | Malaclemys terrapin terrapin | Not Listed | Species of Concern | | CT, DE, MA, MD, NC, NJ, NY, RI, VA |
| Birds | Northern Flicker | Colaptes auratus | Not Listed | Status Undefined | | |
| Birds | Northern Fulmar | Fulmarus glacialis | Not Listed | Species of Concern | | |
| Birds | Northern Gannet | Morus bassanus | Not Listed | Species of Concern | | |
| Birds | Northern goshawk | Accipiter gentilis | Not Listed | Resolved Taxon | | |
| Birds | Northern gray hawk | Buteo nitidus maximus | Not Listed | Species of Concern | | AZ, NM, TX |
| Birds | Northern Harrier | Circus hudsonius | Not Listed | Species of Concern | | |
| Fishes | Northern Hog Sucker | Hypentelium nigricans | | Not Listed | | |
| Mammals | Northern Idaho Ground Squirrel | Urocitellus brunneus | Listed | Threatened | | ID |
| Clams | Northern Lance | Elliptio fisheriana | | Not Listed | | |
| Fishes | Northern leatherside Chub | Lepidomeda copei | Not Listed | Resolved Taxon | | ID, UT |
| Amphibians | northern leopard frog | Rana pipiens | Not Listed | Resolved Taxon | | CO |
| Amphibians | Northern Leopard Frog | Lithobates pipiens | | Not Listed | | |
| Mammals | Northern Long-Eared Bat | Myotis septentrionalis | Listed | Endangered | | AL, AR, CT, DC, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NY, OH, OK, PA, RI, SC, SD, TN, TX, VA, VT, WI, WV, WY |
| Fishes | Northern Madtom | Noturus stigmosus | | Not Listed | | |
| Reptiles | Northern Mexican gartersnake | Thamnophis eques megalops | Listed | Threatened | | AZ, NM |
| Flowering Plants | Northern (=New England) reedgrass | Calamagrostis inexpansa novae-angliae | Not Listed | Resolved Taxon | | ME, NH, VT |
| Flowering Plants | Northern Oconee Bells | Shortia galacifolia var. brevistyla | Not Listed | Species of Concern | | NC |
| Fishes | Northern Pike | Esox lucius | | Not Listed | | |
| Fishes | Northern Pikeminnow | Ptychocheilus oregonensis | | Not Listed | | |
| Reptiles | Northern pine snake | Pituophis melanoleucus melanoleucus | Not Listed | Species of Concern | | AL, DE, GA, NC, NJ, SC, TN, VA, WV |
| Birds | Northern pygmy-owl | Glaucidium gnoma | | Not Listed | | |
| Fishes | Northern Redbelly Dace | Chrosomus eos | | Not Listed | | |
| Reptiles | Northern red diamond rattlesnake | Crotalus ruber ruber | Not Listed | Species of Concern | | CA |
| Amphibians | Northern red-legged frog | Rana aurora aurora | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Clams | Northern riffleshell | Epioblasma rangiana | Listed | Endangered | | IL, IN, KY, MI, NY, OH, PA, WV |
| Fishes | Northern Roach | Hesperoleucus mitrulus | | Not Listed | | |
| Birds | northern rockhopper penguin | Eudyptes moseleyi | Not Listed | Resolved Taxon | | |
| Birds | Northern Rough winged Swallow | Stelgidopteryx serripennis | Not Listed | Status Undefined | | |
| Reptiles | Northern sagebrush lizard | Sceloporus graciosus graciosus | Not Listed | Species of Concern | | WA |
| Birds | Northern Saw-whet Owl | Aegolius acadicus | Not Listed | Species of Concern | | NC |
| Mammals | Northern Sea Otter | Enhydra lutris kenyoni | Not Listed | Status Undefined | | |
| Mammals | Northern Sea Otter | Enhydra lutris kenyoni | Not Listed | Status Undefined | | |
| Mammals | Northern Sea Otter | Enhydra lutris kenyoni | Not Listed | Status Undefined | | |
| Mammals | Northern Sea Otter | Enhydra lutris kenyoni | | Not Listed | | |
| Mammals | Northern Sea Otter | Enhydra lutris kenyoni | Listed | Threatened | | AK |
| Fishes | northern snakehead | Channa argus | Not Listed | Resolved Taxon | | |
| Birds | Northern spotted owl | Strix occidentalis caurina | Listed | Threatened | | CA, OR, WA |
| Snails | Northern Steptoe pyrg | Pyrgulopsis serrata | Petitioned for Listing, Under Review | Under Review | | NV |
| Fishes | Northern Studfish | Fundulus catenatus | | Not Listed | | |
| Mammals | Northern swift fox | Vulpes velox hebes | Listed | Endangered | | |
| Crustaceans | Northern Virginia well amphipod | Stygobromus phreaticus | Not Listed | Resolved Taxon | | VA |
| Reptiles | Northern water snake | Nerodia sipedon | Not Listed | Resolved Taxon | | |
| Mammals | Northern white rhinoceros | Ceratotherium simum cottoni | Listed | Endangered | | |
| Flowering Plants | Northern wild monkshood | Aconitum noveboracense | Listed | Threatened | | IA, NY, OH, WI |
| Flowering Plants | Northern Wormwood | Artemisia campestris var. wormskioldii | Not Listed | Resolved Taxon | | OR, WA |
| Mammals | North Pacific Right Whale | Eubalaena japonica | Listed | Endangered | | |
| Flowering Plants | North Park phacelia | Phacelia formosula | Listed | Endangered | Proposed Delisting | CO |
| Flowering Plants | North Rim primrose | Primula specuicola | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Northwestern larkspur | Delphinium xantholeucum | Not Listed | Resolved Taxon | | WA |
| Mammals | Northwestern Moose | Alces alces andersoni | Not Listed | Resolved Taxon | | MI, MN, ND, WI |
| Reptiles | Northwestern Pond Turtle | Actinemys marmorata | Proposed for Listing | Proposed Threatened | | CA, NV, OR, WA |
| Amphibians | Northwestern salamander | ambystoma gracile | Not Listed | Species of Concern | | |
| Mammals | Northwestern San Diego pocket mouse | chaetodipus fallax | Not Listed | Species of Concern | | |
| Mammals | Northwestern San Diego pocket mouse | Perognathus fallax fallax | Not Listed | Species of Concern | | CA |
| Crustaceans | Norton's cave amphipod | Stygobromus nortoni | Not Listed | Species of Concern | | TN |
| Insects | Norton's cave beetle | Pseudanophthalmus nortoni | Not Listed | Species of Concern | | TN |
| Clams | Notched Rainbow | Villosa constricta | | Not Listed | | |
| Insects | notodontid moth | afilia species | Not Listed | Resolved Taxon | | |
| Snails | Nudulose Coosa river snail | Elimia lachryma | Petitioned for Listing, Under Review | Under Review | | AL |
| Crustaceans | Nueces Crayfish | Procambarus nueces | Not Listed | Resolved Taxon | | |
| Fishes | Nueces River shiner | Cyprinella sp. | Not Listed | Resolved Taxon | | TX |
| Fishes | Nueces Roundnose Minnow | Dionda serena | | Not Listed | | |
| Snails | Nugget pebblesnail | Fluminicola seminalis | Not Listed | Resolved Taxon | | CA |
| Mammals | Numbat | Myrmecobius fasciatus | Listed | Endangered | | |
| Flowering Plants | Nutriosa milk-vetch | Astragalus nutriosensis | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Nuttall's Cornsalad | Valerianella nuttallii | | Not Listed | | |
| Flowering Plants | Nuttall's micranthemum | Micranthemum micranthemoides | Not Listed | Species of Concern | | DC, DE, MD, NJ, NY, PA, VA |
| Flowering Plants | Nuttall's scrub oak | Quercus dumosa | Not Listed | Species of Concern | | CA |
| Birds | Nuttall's Woodpecker | Dryobates nuttallii | Not Listed | Species of Concern | | |
| Snails | Nymph elimia | Elimia porrecta | Not Listed | Species of Concern | | AL |
| Snails | Nymph Trumpet | Phreatoceras taylori | Not Listed | Resolved Taxon | | |
| Snails | Oachita pebblesnail | Somatogyrus amnicoloides | Not Listed | Species of Concern | | AR |
| Insects | Oahu abutilon clavicoccus mealybug | Clavicoccus erinaceus | Not Listed | Species of Concern | | HI |
| Birds | O`ahu `alauahio | Paroreomyza maculata | Listed | Endangered | | |
| Birds | O'ahu 'Amakihi | Chlorodrepanis flava | Not Listed | Species of Concern | | |
| Insects | Oahu aulu thyrocopa moth | Thyrocopa sapindiella | Not Listed | Species of Concern | | HI |
| Insects | Oahu blackburnia ground beetle | Blackburnia insignis | Not Listed | Species of Concern | | HI |
| Insects | Oahu capper moth | Plutella capparidis | Not Listed | Species of Concern | | HI |
| Insects | Oahu deceptor bush cricket | Leptogryllus deceptor | Not Listed | Species of Concern | | HI |
| Birds | Oahu elepaio | Chasiempis ibidis | Listed | Endangered | | HI |
| Insects | Oahu hesperonmannia philodoria moth | Philodoria sp. | Not Listed | Species of Concern | | HI |
| Insects | Oahu heteramphus fern weevil | Heteramphus filicum | Not Listed | Species of Concern | | HI |
| Insects | Oahu holio gall psyllid | Paurotriozana adaptata | Not Listed | Species of Concern | | HI |
| Insects | Oahu iliahi gall mealybug | Phyllococcus antricolens | Not Listed | Species of Concern | | HI |
| Insects | Oahu kalanian leaf bug | Kalania sp. | Not Listed | Species of Concern | | HI |
| Insects | Oahu ke`oke`o clavicoccus mealybug | Clavicoccus tribulus | Not Listed | Species of Concern | | HI |
| Insects | Oahu megalagrion damselfly | Megalagrion oahuense | Not Listed | Species of Concern | | HI |
| Insects | Oahu nesiotes weevil | Deinocossonus nesiotes | Not Listed | Species of Concern | | HI |
| Insects | Oahu opuhe leaf mining moth | Philodoria ureraella | Not Listed | Species of Concern | | HI |
| Insects | Oahu super long-horned beetle | Plagithmysus superstes | Not Listed | Species of Concern | | HI |
| Insects | Oahu swamp hedyleptan moth | Hedylepta epicentra | Not Listed | Resolved Taxon | | HI |
| Snails | Oahu tree snails | Achatinella spp. | Listed | Endangered | | |
| Snails | Oak Creek Talussnail | Sonorella compar | Not Listed | Resolved Taxon | | |
| Birds | Oak Titmouse | Baeolophus inornatus | Not Listed | Species of Concern | | |
| Fishes | Oasis Valley speckled dace | Rhinichthys osculus ssp. | Not Listed | Resolved Taxon | | NV |
| Snails | Oasis Valley springsnail | Pyrgulopsis micrococcus | Not Listed | Resolved Taxon | | NV |
| Crustaceans | Obey crayfish | Cambarus obeyensis | Not Listed | Status Undefined | | TN |
| Insects | Oblivious tiger beetle | Cicindela latesignata obliviosa | Not Listed | Species of Concern | | CA |
| Snails | Oblong rocksnail | Leptoxis compacta | Proposed for Listing | Proposed Endangered | | AL |
| Insects | Obrien rhyacophilan caddisfly | Rhyacophila colonus | Not Listed | Species of Concern | | OR |
| Insects | Obscuratan yellow-faced bee | Hylaeus obscurata | Not Listed | Species of Concern | | HI |
| Flowering Plants | Obscure Indian paintbrush | Castilleja cryptantha | Not Listed | Species of Concern | | WA |
| Insects | Obscure pentarthrum weevil | Pentarthrum obscura | Not Listed | Species of Concern | | HI |
| Insects | Obsolete rhyncogonus weevil | Rhyncogonus obsoletus | Not Listed | Species of Concern | | HI |
| Insects | Obsolete viceroy butterfly | Limenitis archippus obsoletus | Not Listed | Resolved Taxon | | AZ, CA, NM, NV |
| Insects | Ocala burrowing scarab | Peltotrupes youngi | Not Listed | Species of Concern | | |
| Flowering Plants | Ocala vetch | Vicia ocalensis | Not Listed | Resolved Taxon | | |
| Mammals | Occult little brown bat | Myotis lucifugus occultus | Not Listed | Species of Concern | | AZ, CA, NM, TX |
| Snails | Occult vertigo | Vertigo occulta | Not Listed | Species of Concern | | IA, MN |
| Insects | Oceanic Hawaiian damselfly | Megalagrion oceanicum | Listed | Endangered | | HI |
| Insects | Oceanic metromenus ground beetle | Metromenus oceanicus | Not Listed | Species of Concern | | HI |
| Fishes | Oceanic whitetip shark | Carcharhinus longimanus | Listed | Threatened | | |
| Mammals | Ocelot | Leopardus (=Felis) pardalis | Listed | Endangered | | AZ, TX |
| Clams | Ochlockonee moccasinshell | Medionidus simpsonianus | Listed | Endangered | | FL, GA |
| Flowering Plants | Ochoco lomatium | Lomatium ochocense | Not Listed | Status Undefined | | OR |
| Snails | Ocmulgee marstonia | Marstonia agarhecta | | Not Listed | | GA |
| Snails | Ocmulgee marstonia | Pyrgulopsis agarhecta | Not Listed | Status Undefined | | GA |
| Fishes | Ocmulgee shiner | Cyprinella callisema | Not Listed | Species of Concern | | GA |
| Flowering Plants | Ocmulgee skullcap | Scutellaria ocmulgee | Listed | Endangered | | GA, SC |
| Crustaceans | Oconee crayfish ostracod | Cymocythere clavata | Not Listed | Species of Concern | | NC, SC |
| Flowering Plants | Ofer Hollow reedgrass | Calamagrostis porteri insperata | Not Listed | Species of Concern | | AR, IL, KY, MO, OH |
| Snails | Ofu tree snail | Samoana thurstoni | Not Listed | Species of Concern | | AS |
| Snails | Ogden Mountainsnail | Oreohelix peripherica wasatchensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Oglethorpe oak | Quercus oglethorpensis | Not Listed | Resolved Taxon | | GA, LA, MS, SC |
| Flowering Plants | Oha | Delissea subcordata | Listed | Endangered | | HI |
| Flowering Plants | Ohai | Sesbania tomentosa | Listed | Endangered | | HI |
| Flowering Plants | `Oha wai | Clermontia drepanomorpha | Listed | Endangered | | HI |
| Flowering Plants | `Oha wai | Clermontia lindseyana | Listed | Endangered | | HI |
| Flowering Plants | `Oha wai | Clermontia oblongifolia ssp. brevipes | Listed | Endangered | | HI |
| Flowering Plants | `Oha wai | Clermontia oblongifolia ssp. mauiensis | Listed | Endangered | | HI |
| Flowering Plants | `Oha wai | Clermontia peleana | Listed | Endangered | | HI |
| Flowering Plants | `Oha wai | Clermontia pyrularia | Listed | Endangered | | HI |
| Flowering Plants | `Oha wai | Clermontia samuelii | Listed | Endangered | | HI |
| Flowering Plants | `Ohe | Joinvillea ascendens ascendens | Listed | Endangered | | HI |
| Flowering Plants | `Ohe | Reynoldsia sandwicensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ohe | Tetraplasandra hawaiiensis microcarpa | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ohe | Tetraplasandra kaalae multiplex | Not Listed | Resolved Taxon | | HI |
| Insects | `Ohenaupaka oeobian moth | Oeobia dryadopa | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Ohe`ohe | Polyscias gymnocarpa | Listed | Endangered | | HI |
| Flowering Plants | `Ohe`ohe | Tetraplasandra kavaiensis grandis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ohe`ohe | Tetraplasandra kavaiensis koloana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ohe`ohe | Tetraplasandra kavaiensis occidua | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ohe`ohe ) | Tetraplasandra kavaiensis dipyrena | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | `Ohe`ohe e | Tetraplasandra kavaiensis intercedens | Not Listed | Resolved Taxon | | HI |
| Insects | `Ohe`ohe leafroller | Spheterista oheoheana | Not Listed | Species of Concern | | HI |
| Flowering Plants | `Ohe`ohe s | Tetraplasandra kavaiensis nahikuensis | Not Listed | Resolved Taxon | | HI |
| Insects | `Ohe omoides moth | Omoides asaphombra | Not Listed | Species of Concern | | HI |
| Insects | Ohi`a long-horned beetle | Plagithmysus pulvillatus | Not Listed | Species of Concern | | HI |
| Insects | Ohio cave beetle | Pseudanophthalmus ohioensis | Not Listed | Species of Concern | | OH |
| Algae | Ohio Lamprey | Ichthyomyzon bdellium | | Not Listed | | |
| Clams | Ohio Pigtoe | Pleurobema cordatum | | Not Listed | | |
| Insects | Ohlone tiger beetle | Cicindela ohlone | Listed | Endangered | | CA |
| Flowering Plants | Ojai frtillary | Fritillaria ojaiensis | Not Listed | Species of Concern | | CA |
| Fishes | Okaloosa darter | Etheostoma okaloosae | Delisted | Recovery | | FL |
| Flowering Plants | Okeechobee gourd | Cucurbita okeechobeensis ssp. okeechobeensis | Listed | Endangered | | FL |
| Insects | Okefenokee zale moth | Zale perculta | Not Listed | Species of Concern | | |
| Birds | Okinawa woodpecker | Dendrocopos noguchii | Candidate for Listing | Candidate | | |
| Crustaceans | Oklahoma cave amphipod | Allocrangonyx pellucidus | Not Listed | Species of Concern | | OK |
| Crustaceans | Oklahoma cave crayfish | Cambarus tartarus | Petitioned for Listing, Under Review | Under Review | | OK |
| Flowering Plants | Oklahoma grasspink | Calopogon oklahomensis | Not Listed | Resolved Taxon | | AR, IL, LA, MO, MS, OK, TX, WI |
| Flowering Plants | Oklahoma phlox | Phlox oklahomensis | Not Listed | Resolved Taxon | | KS, OK, TX |
| Amphibians | Oklahoma salamander | Eurycea tynerensis | Not Listed | Status Undefined | | AR, MO, OK |
| Sponges | Oklawaha sponge | Dosilia palmeri | Not Listed | Species of Concern | | |
| Crustaceans | Oktibbeha rivulet crayfish | Hobbseus orconectoides | Petitioned for Listing, Under Review | Under Review | | MS |
| Insects | Ola`a banana omoides moth | Omoides euryprora | Not Listed | Species of Concern | | HI |
| Insects | `Ola`a pepppered looper | Tritocleis microphylla | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Olaga | Opuntia borinquensis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Olanche Peak buckwheat | Eriogonum wrightii olanchense | Not Listed | Resolved Taxon | | CA |
| Lichens | Old birch spots | Arthopyrenia betulicola | Not Listed | Species of Concern | | |
| Flowering Plants | Old Blue mock pennyroyal | Hedeoma pilosum | Not Listed | Species of Concern | | TX |
| Lichens | Old gray cross-lobes | Santessoniella crossophylla | Not Listed | Species of Concern | | |
| Flowering Plants | Old man's beard | Clematis catesbyana | Not Listed | Resolved Taxon | | |
| Flowering Plants | Old Switch Panic Grass | Panicum virgatum | | Not Listed | | |
| Insects | Oliarus wild cotton planthopper | Oliarus discrepans | Not Listed | Species of Concern | | HI |
| Fishes | Olive darter | Percina squamata | Not Listed | Species of Concern | | NC |
| Snails | Olive marstonia | Pyrgulopsis olivacea | Not Listed | Species of Concern | | AL |
| Reptiles | Olive ridley sea turtle | Lepidochelys olivacea | Listed | Endangered | | |
| Reptiles | Olive ridley sea turtle | Lepidochelys olivacea | Listed | Threatened | | CA, HI, OR |
| Birds | Olive-sided Flycatcher | Contopus cooperi | Not Listed | Species of Concern | | NC |
| Birds | Olive Warbler | Peucedramus taeniatus | Not Listed | Species of Concern | | |
| Insects | Olopua rhyncogonus weevil | Rhyncogonus oleae | Not Listed | Species of Concern | | HI |
| Ferns and Allies | olua | Hypolepis hawaiiensis var. mauiensis | Listed | Endangered | | HI |
| Flowering Plants | Olulu | Brighamia insignis | Listed | Endangered | | HI |
| Mammals | Olympia pocket gopher | Thomomys mazama pugetensis | Listed | Threatened | | WA |
| Flowering Plants | Olympic harebell | Campanula piperi | Not Listed | Resolved Taxon | | WA |
| Mammals | Olympic marmot | Marmota olympus | Not Listed | Status Undefined | | WA |
| Fishes | Olympic mudminnow | Novumbra hubbsi | Not Listed | Resolved Taxon | | WA |
| Mammals | Olympic pocket gopher | Thomomys mazama melanops | Not Listed | Resolved Taxon | | WA |
| Amphibians | Olympic torrent salamander | Rhyacotriton olympicus | Not Listed | Resolved Taxon | | |
| Birds | 'Oma'o | Myadestes obscurus | Not Listed | Species of Concern | | |
| Insects | Ombrias yellow-faced bee | Hylaeus ombrias | Not Listed | Species of Concern | | HI |
| Insects | (Omus dejeanii) ground beetle | omus dejeanii | Not Listed | Species of Concern | | |
| Flowering Plants | One-awned spineflower | Chorizanthe rectispina | Not Listed | Species of Concern | | CA |
| Sponges | Oneida sponge | Spongilla heteroslerifa | Not Listed | Resolved Taxon | | NY |
| Insects | One-spot rhyacophilan caddisfly | Rhyacophila unipunctata | Not Listed | Species of Concern | | OR |
| Amphibians | One-toed Amphiuma | Amphiuma pholeter | Not Listed | Status Undefined | | GA |
| Crustaceans | Onondaga Cave amphipod | Stygobromus onondagaensis | Not Listed | Resolved Taxon | | MO |
| Insects | Onthophagus tortoise commensal scarab | Onthophagus polyphemi | Not Listed | Species of Concern | | |
| Snails | Onyx rocksnail | Leptoxis praerosa | Not Listed | Species of Concern | | KY, TN |
| Fishes | O`opu alamo`o | Lentipes concolor | Not Listed | Species of Concern | | HI |
| Crustaceans | `Opae Kala`Ole (Hawaiian Spineless Shrimp) | Atyoida bisulcata | | Not Listed | | |
| Snails | Opaque pebblesnail | Somatogyrus tennesseensis | Not Listed | Species of Concern | | AL, TN |
| Insects | Opler's longhorn moth | Adella oplerella | Not Listed | Resolved Taxon | | CA |
| Fishes | Opossum Pipefish | Microphis brachyurus | | Not Listed | | |
| Flowering Plants | Opposite-leaved lewisia | Lewisia oppositifolia | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Opuhe | Urera kaalae | Listed | Endangered | | HI |
| Insects | Opuhe gall mealybug | Phyllococcus oahuensis | Not Listed | Species of Concern | | HI |
| Birds | Orange-bellied parakeet | Neophema chrysogaster | Listed | Endangered | | |
| Fishes | Orangebelly Darter | Etheostoma radiosum | | Not Listed | | |
| Insects | Orangeblack Hawaiian damselfly | Megalagrion xanthomelas | Listed | Endangered | | HI |
| Fishes | Orangefin madtom | Noturus gilberti | Petitioned for Listing, Under Review | Under Review | | NC, VA |
| Clams | Orangefoot pimpleback (pearlymussel) | Plethobasus cooperianus | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Orangefoot pimpleback (pearlymussel) | Plethobasus cooperianus | Listed | Endangered | | IL, IN, KY, TN |
| Birds | Orange-fronted parakeet | Cyanoramphus malherbi | Candidate for Listing | Candidate | | |
| Crustaceans | Orange Lake Cave crayfish | Procambarus franzi | Petitioned for Listing, Under Review | Under Review | | FL |
| Flowering Plants | Orange lupine | Lupinus citrinus | Not Listed | Species of Concern | | CA |
| Clams | Orangenacre mucket | Hamiota perovalis | Listed | Threatened | | AL, MS |
| Fishes | Orangespotted sunfish | Lepomis humilis | | Not Listed | | |
| Fishes | Orangetail Shiner | Pteronotropis merlini | | Not Listed | | |
| Reptiles | Orange-throated whiptail | Cnemidophorus hyperythrus | Not Listed | Species of Concern | | CA |
| Mammals | Orangutan | Pongo pygmaeus | Listed | Endangered | | |
| Birds | Orchard Oriole | Icterus spurius | Not Listed | Species of Concern | | |
| Flowering Plants | Orcutt's bird's-beak | Cordylanthus orcuttianus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Orcutt's brodiaea | Brodiaea orcuttii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Orcutt's dudleya | Dudleya attentuata orcuttii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Orcutt's hazardia | Hazardia orcuttii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Orcutt's linanthus | Linanthus orcuttii | Not Listed | Species of Concern | | CA |
| Ferns and Allies | Orcutt's quillwort | Isoetes orcuttii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Orcutt's spineflower | Chorizanthe orcuttiana | Listed | Endangered | | CA |
| Flowering Plants | Oreganillo | Koanophyllon droserolepis | Not Listed | Species of Concern | | PR, VI |
| Crustaceans | Oregon cave amphipod | Stygobromus oregonensis | Not Listed | Resolved Taxon | | CA, NV, OR |
| Fishes | Oregon chub | Oregonichthys crameri | Delisted | Recovery | | OR |
| Insects | Oregon dolophilodes caddisfly | Dolophilodes oregonus | Not Listed | Resolved Taxon | | OR |
| Flowering Plants | Oregon fireweed | Epilobium oreganum | Not Listed | Species of Concern | | CA, OR |
| Clams | Oregon Floater | Anodonta oregonensis | | Not Listed | | |
| Annelid Worms | Oregon giant earthworm | Megascolides macelfreshi | Not Listed | Species of Concern | | CA, NV, OR |
| Snails | Oregon megomphix | megomphix hemphilli | Not Listed | Species of Concern | | |
| Flowering Plants | Oregon rock-cress | Arabis oregana | Not Listed | Resolved Taxon | | CA, OR |
| Flowering Plants | Oregon semaphore grass | Pleuropogon oregonus | Not Listed | Species of Concern | | OR |
| Insects | Oregon silverspot butterfly | Speyeria zerene hippolyta | Listed | Experimental Population, Non-Essential | | |
| Insects | Oregon silverspot butterfly | Speyeria zerene hippolyta | Listed | Threatened | | CA, OR |
| Amphibians | Oregon slender salamander | Batrachoseps wrighti | Not Listed | Status Undefined | | |
| Amphibians | Oregon spotted frog | Rana pretiosa | Listed | Threatened | | OR, WA |
| Birds | Oregon Vesper Sparrow | Pooecetes gramineus affinis | Petitioned for Listing, Under Review | Under Review | | CA, OR, WA |
| Ferns and Allies | Oregon woodsia | Woodsia oregana cathcartiana | Not Listed | Species of Concern | | MN, NY, WI |
| Arachnids | Organ Cave pseudoscorpion | Kleptochthonius hetricki | Not Listed | Species of Concern | | WV |
| Flowering Plants | Organ Mountain evening-primrose | Oenothera organensis | Not Listed | Species of Concern | | NM |
| Flowering Plants | Organ Mountain figwort | Scrophularia laevis | Not Listed | Species of Concern | | NM |
| Mammals | Organ Mountains Colorado chipmunk | Eutamias quadrivittatus australis | Not Listed | Species of Concern | | NM |
| Birds | Oriental white stork | Ciconia boyciana (=ciconia b.) | Listed | Endangered | | |
| Reptiles | Orinoco crocodile | Crocodylus intermedius | Listed | Endangered | | |
| Crustaceans | Orlando Cave crayfish | Procambarus acherontis | Petitioned for Listing, Under Review | Under Review | | FL |
| Snails | Ornate rocksnail | Lithasia geniculata | Not Listed | Species of Concern | | AL, KY, TN |
| Flowering Plants | Orocopia sage | Salvia greatai | Not Listed | Species of Concern | | CA |
| Arachnids | Orpheus cave pseudoscorpion | Kleptochthonius orpheus | Not Listed | Species of Concern | | WV |
| Flowering Plants | Osgood Mountains milk-vetch | Astragalus yoder-williamsii | Not Listed | Resolved Taxon | | ID, NV |
| Insects | Oso Flaco flightless moth | Areniscythris brachypteris | Not Listed | Species of Concern | | CA |
| Insects | Oso Flaco patch butterfly | Chlosyne leanira osoflaco | Not Listed | Species of Concern | | CA |
| Insects | Oso Flaco robber fly | Ablautus schlingeri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Oso manzanita | Arctostaphylos osoensis | Not Listed | Species of Concern | | CA |
| Birds | osprey | Pandion haliaetus | Not Listed | Species of Concern | | |
| Flowering Plants | Osterhout milkvetch | Astragalus osterhoutii | Listed | Endangered | | CO |
| Flowering Plants | Ostler's peppergrass | Lepidium ostleri | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Ostlund wild-buckwheat | Eriogonum ostlundii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Otay lotus | Lotus crassifolius otayensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Otay manzanita | Arctostaphylos otayensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Otay mesa-mint | Pogogyne nudiuscula | Listed | Endangered | | CA |
| Flowering Plants | Otay tarplant | Deinandra (=Hemizonia) conjugens | Listed | Threatened | | CA |
| Snails | Otter Creek Pyrg | Pyrgulopsis fusca | Not Listed | Resolved Taxon | | |
| Crustaceans | Ouachita burrowing crayfish | Fallicambarus harpi | Not Listed | Status Undefined | | AR |
| Clams | Ouachita creekshell | Villosa arkansasensis | Not Listed | Resolved Taxon | | AR, OK |
| Amphibians | Ouachita dusky salamander | Desmognathus brimleyorum | Not Listed | Species of Concern | | AR, OK |
| Clams | Ouachita fanshell | Cyprogenia sp. cf. aberti | Listed | Threatened | | |
| Clams | Ouachita kidneyshell | Ptychobranchus occidentalis | Not Listed | Species of Concern | | AR, KS, MO, OK |
| Fishes | Ouachita madtom | Noturus lachneri | Not Listed | Status Undefined | | AR |
| Snails | Ouachita Mantleslug | Pallifera tournescalis | Not Listed | Resolved Taxon | | |
| Fishes | Ouachita Mountain shiner | Lythrurus snelsoni | Not Listed | Species of Concern | | AR, OK |
| Clams | Ouachita rock pocketbook | Arcidens wheeleri | Listed | Endangered | | AR, OK, TX |
| Birds | `O`u (honeycreeper) | Psittirostra psittacea | Listed | Endangered | | |
| Flowering Plants | Oval-leaved snapdragon | Howelliella ovata | Not Listed | Resolved Taxon | | CA |
| Clams | Oval pigtoe | Pleurobema pyriforme | Listed | Endangered | | AL, FL, GA |
| Clams | Ovate clubshell | Pleurobema perovatum | Listed | Endangered | | AL, MS, TN |
| Snails | Ovate pebblesnail | Somatogyrus excavatus | Not Listed | Species of Concern | | AL |
| Snails | Ovate vertigo | Vertigo ovata | Not Listed | Species of Concern | | NM |
| Insects | Overlooked cave beetle | Pseudanophthalmus praetermissus | Not Listed | Resolved Taxon | | VA |
| Fishes | Owens Or Lahontan Speckled Dace | Rhinichthys osculus robustus | | Not Listed | | |
| Flowering Plants | Owens Peak lomatium | Lomatium shevockii | Not Listed | Species of Concern | | CA |
| Fishes | Owens pupfish | Cyprinodon radiosus | Listed | Endangered | | CA, NV |
| Fishes | Owens speckled dace | Rhinichthys osculus ssp. | Not Listed | Species of Concern | | CA |
| Snails | Owens springsnail | Pyrgulopsis owensensis | Not Listed | Species of Concern | | CA |
| Fishes | Owens Sucker | Catostomus fumeiventris | | Not Listed | | |
| Fishes | Owens Tui Chub | Gila bicolor ssp. snyderi | Listed | Endangered | | CA |
| Mammals | Owens Valley California vole | Microtus californicus vallicola | Not Listed | Species of Concern | | CA |
| Flowering Plants | Owens Valley checkermallow | Sidalcea covillei | Not Listed | Resolved Taxon | | CA |
| Amphibians | Owens Valley web-toes salamander | Hydromantes sp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Ownbey's thistle | Cirsium ownbeyi | Not Listed | Species of Concern | | UT |
| Flowering Plants | Owyhee clover | Trifolium owyheense | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Snails | Owyhee hot springsnail | Pyrgulopsis fresti | Not Listed | Status Undefined | | OR |
| Snails | Owyhee upland pyrg | Pyrgulopsis owyheensis | Not Listed | Status Undefined | | OR |
| Clams | Oyster mussel | Epioblasma capsaeformis | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Oyster mussel | Epioblasma capsaeformis | Listed | Endangered | | AL, KY, MS, TN, VA |
| Clams | Oyster mussel | Epioblasma capsaeformis | Listed | Experimental Population, Non-Essential | | TN |
| Mammals | Ozark big-eared bat | Corynorhinus (=Plecotus) townsendii ingens | Listed | Endangered | | AR, MO, OK |
| Crustaceans | Ozark cave amphipod | Stygobromus ozarkensis | Not Listed | Resolved Taxon | | AR, MO, OK |
| Fishes | Ozark cavefish | Amblyopsis rosae | Listed | Threatened | | AR, KS, MO, OK |
| Flowering Plants | Ozark chinquapin | Castanea pumila ozarkensis | Not Listed | Resolved Taxon | | AL, AR, MO, OK |
| Fishes | Ozark chub | Erimystax harryi | Not Listed | Resolved Taxon | | AR, MO |
| Insects | Ozark emerald | Somatochlora ozarkensis | Not Listed | Status Undefined | | AR, KS, MO, OK |
| Amphibians | Ozark Hellbender | Cryptobranchus alleganiensis bishopi | Listed | Endangered | | AR, MO |
| Fishes | Ozark Minnow | Notropis nubilus | | Not Listed | | |
| Clams | Ozark Pigtoe | Fusconaia ozarkensis | | Not Listed | | |
| Snails | Ozark pyrg | Pyrgulopsis ozarkensis | Not Listed | Resolved Taxon | | AR |
| Fishes | Ozark shiner | Notropis ozarcanus | Petitioned for Listing, Under Review | Under Review | | AR, MO |
| Insects | Ozark snaketail | Ophiogomphus westfalli | Not Listed | Species of Concern | | AR, KS, MO |
| Birds | Pacific Black Duck | Anas superciliosa | Not Listed | Species of Concern | | |
| Birds | Pacific Black Duck | Anas superciliosa pelewensis | Not Listed | Species of Concern | | |
| Flowering Plants | Pacific bleeding-heart | Dicentra formosa oregana | Not Listed | Resolved Taxon | | CA, OR |
| Amphibians | Pacific giant salamander | dicamptodon tenebrosus | Not Listed | Species of Concern | | |
| Birds | Pacific Golden-Plover | Pluvialis fulva | Not Listed | Species of Concern | | |
| Flowering Plants | Pacific Grove clover | Trifolium variegatum | Not Listed | Resolved Taxon | | CA |
| Insects | Pacific Hawaiian damselfly | Megalagrion pacificum | Listed | Endangered | | HI |
| Fishes | Pacific Herring | Clupea pallasii | | Not Listed | | |
| Birds | Pacific Imperial Pigeon | Ducula pacifica pacifica | Not Listed | Species of Concern | | |
| Fishes | Pacific lamprey | lampetra tridentata | Not Listed | Species of Concern | | |
| Fishes | Pacific lamprey | Lampetra tridentata ssp. | Not Listed | Resolved Taxon | | AK, CA, OR, WA |
| Fishes | Pacific Lamprey | Entosphenus tridentatus | | Not Listed | | |
| Flowering Plants | Pacific manzanita | Arctostaphylos pacifica | Not Listed | Resolved Taxon | | CA |
| Mammals | Pacific Marten, Coastal Distinct Population Segment | Martes caurina | Listed | Threatened | | CA, OR |
| Mammals | Pacific pocket mouse | Perognathus longimembris pacificus | Listed | Endangered | | CA |
| Fishes | Pacific Red Snapper | Lutjanus peru | | Not Listed | | |
| Fishes | Pacific River Goby, `O`Opu Nakea | Awaous guamensis | | Not Listed | | |
| Mammals | Pacific sheath-tailed Bat | Emballonura semicaudata rotensis | Listed | Endangered | | MP |
| Mammals | Pacific sheath-tailed Bat | Emballonura semicaudata semicaudata | Listed | Endangered | | AS |
| Snails | Pacific Sideband | Monadenia fidelis | | Not Listed | | |
| Birds | Pacific slope Flycatcher | Empidonax difficilis | Not Listed | Species of Concern | | |
| Fishes | Pacific Staghorn Sculpin | Leptocottus armatus | | Not Listed | | |
| Mammals | Pacific Townsend's big-eared bat | Plecotus townsendii townsendii | Not Listed | Species of Concern | | CA, ID, NV, OR, WA |
| Mammals | Pacific walrus | Odobenus rosmarus ssp. divergens | Not Listed | Resolved Taxon | | AK |
| Conifers and Cycads | Pacific yew | Taxus brevifolia | Not Listed | Resolved Taxon | | |
| Crustaceans | Packard's cave amphipod | Crangonyx packardi | Not Listed | Resolved Taxon | | IN, KY |
| Flowering Plants | Packard's milkvetch | Astragalus cusickii var. packardiae | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | Packard's stickleaf | Mentzelia packardiae | Not Listed | Resolved Taxon | | CA, NV, OR |
| Fishes | Paddlefish | Polyodon spathula | Not Listed | Resolved Taxon | | AL, AR, IA, IL, IN, KS, KY, LA, MN, MO, MS, MT, ND, NE, OH, OK, PA, SD, TN, TX, WI |
| Mammals | Pagan Mariana flying fox bat | Pteropus mariannus paganensis | Not Listed | Species of Concern | | MP |
| Insects | Page Spring micro caddisfly | Metrichia volada | Not Listed | Species of Concern | | AZ |
| Snails | Page springsnail | Pyrgulopsis morrisoni | Not Listed | Resolved Taxon | | AZ |
| Mammals | Pagi Island langur | Nasalis concolor | Listed | Endangered | | |
| Snails | Pagoda slitshell | Gyrotoma pagoda | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | Pagosa skyrocket | Ipomopsis polyantha | Listed | Endangered | | CO |
| Snails | Pahasapa mountainsnail | Oreohelix strigosa ssp. | Not Listed | Species of Concern | | SD, WY |
| Snails | Pahranagat pebblesnail | Pyrgulopsis merriami | Not Listed | Resolved Taxon | | NV |
| Fishes | Pahranagat roundtail chub | Gila robusta jordani | Listed | Endangered | | NV |
| Fishes | Pahranagat speckled dace | Rhinichthys osculus velifer | Not Listed | Resolved Taxon | | NV |
| Fishes | Pahranagat spinedace | Lepidomeda altivelis | Not Listed | Resolved Taxon | | NV |
| Mammals | Pahranagat Valley montane vole | Microtus montanus fucosus | Not Listed | Species of Concern | | NV |
| Fishes | Pahrump Killifish | Empetrichthys latos latos | | Not Listed | | |
| Fishes | Pahrump poolfish | Empetrichthys latos | Listed | Endangered | | NV |
| Flowering Plants | Pa`iniu | Astelia veratroides gracilis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Pa`iniu | Astelia veratroides macrosperma | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Pa`iniu | Astelia veratroides veratroides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Pa`iniu | Astelia waialealae | Listed | Endangered | | HI |
| Birds | Painted Bunting | Passerina ciris | Not Listed | Species of Concern | | |
| Clams | Painted clubshell | Pleurobema chattanoogaense | Not Listed | Resolved Taxon | | GA |
| Fishes | Painted Creekshell | Villosa taeniata | | Not Listed | | |
| Snails | Painted rocksnail | Leptoxis taeniata | Listed | Threatened | | AL |
| Snails | Painted snake coiled forest snail | Anguispira picta | Listed | Threatened | | TN |
| Mammals | Painted woolly bat | Kerivoula picta | Not Listed | Status Undefined | | |
| Fishes | Paiute cutthroat trout | Oncorhynchus clarkii seleniris | Listed | Threatened | | CA, NV |
| Conifers and Cycads | Paiute cypress | Callitropsis nevadensis | Not Listed | Resolved Taxon | | CA |
| Fishes | Paiute sculpin | Cottus beldingii | Not Listed | Status Undefined | | |
| Mammals | Pajarito southern pocket gopher | Thomomys umbrinus quercinus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Pajaroensis manzanita | Arctostaphylos pajaroensis | Not Listed | Species of Concern | | CA |
| Mammals | Pakistan sand cat | Felis margarita scheffeli | Listed | Endangered | | |
| Ferns and Allies | Palai la`au | Adenophorus periens | Listed | Endangered | | HI |
| Ferns and Allies | Palapalai aumakua | Dryopteris crinalis var. podosorus | Listed | Endangered | | HI |
| Insects | Palatka skipper | Euphyes pilatka klotsi | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Palau blue-faced parrotfinch | Erythrura trichroa pelewensis | Not Listed | Resolved Taxon | | |
| Birds | Palau fantail flycatcher | Rhipidura lepida | Delisted | Recovery | | |
| Birds | Palau ground dove | Gallicolumba canifrons | Delisted | Recovery | | |
| Birds | Palau Nicobar pigeon | Caloenas nicobarica pelewensis | Not Listed | Resolved Taxon | | |
| Birds | Palau Owl | Pyrroglaux podargina | Delisted | Recovery | | |
| Birds | Palau white-breasted wood-swallow | Artamus leucorhynchus pelewensis | Not Listed | Pre-Act Delisted Taxon | | PW |
| Birds | Palawan peacock pheasant | Polyplectron emphanum | Listed | Endangered | | |
| Fishes | Paleback darter | Etheostoma pallididorsum | | Not Listed | | AR |
| Flowering Plants | Pale blue-eyed grass | Sisyrinchium pallidum | Not Listed | Species of Concern | | CO, WY |
| Insects | Pale cave beetle | Pseudanophthalmus pallidus | Not Listed | Species of Concern | | TN |
| Clams | Pale lilliput (pearlymussel) | Toxolasma cylindrellus | Listed | Endangered | | AL, TN |
| Flowering Plants | Pale phacelia | Phacelia pallida | Not Listed | Species of Concern | | TX |
| Flowering Plants | Pale poppy | Papaver alboroseum | Not Listed | Resolved Taxon | | AK |
| Mammals | Pale Townsend's big-eared bat | Plecotus townsendii pallescens | Not Listed | Species of Concern | | AZ, CA, CO, ID, KS, MT, ND, NE, NM, OK, SD |
| Flowering Plants | Pale-yellow layia | Layia heterotricha | Not Listed | Species of Concern | | CA |
| Flowering Plants | Pale yellow lupine | Lupinus luteolus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Pale yellow stonecrop | Sedum laxum flavidum | Not Listed | Resolved Taxon | | CA |
| Fishes | Palezone shiner | Notropis albizonatus | Listed | Endangered | | AL, KY |
| Birds | Palila (honeycreeper) | Loxioides bailleui | Listed | Endangered | | HI |
| Mammals | Pallid bat | antrozous pallidus | Not Listed | Species of Concern | | |
| Flowering Plants | Pallid birds-beak | Cordylanthus tenuis pallescens | Not Listed | Species of Concern | | CA |
| Crustaceans | Pallid Cave crayfish | Procambarus pallidus | Petitioned for Listing, Under Review | Under Review | | FL |
| Flowering Plants | Pallid manzanita | Arctostaphylos pallida | Listed | Threatened | | CA |
| Snails | Pallid Mountainsnail | Oreohelix hendersoni | Not Listed | Resolved Taxon | | |
| Mammals | Pallid oldfield beach mouse | Peromyscus polionotus decoloratus | Not Listed | Resolved Taxon | | |
| Mammals | Pallid San Diego pocket mouse | Perognathus fallax pallidus | Not Listed | Species of Concern | | CA |
| Fishes | Pallid Shiner | Hybopsis amnis | | Not Listed | | |
| Fishes | Pallid sturgeon | Scaphirhynchus albus | Listed | Endangered | | AR, CO, IA, IL, KS, KY, LA, MO, MS, MT, ND, NE, SD, TN, WY |
| Insects | Pallipes eopenthes click beetle | Eopenthes pallipes | Not Listed | Species of Concern | | HI |
| Flowering Plants | Palma de manaca | Calyptronoma rivalis | Listed | Threatened | | PR |
| Flowering Plants | Palmate-bracted bird's beak | Cordylanthus palmatus | Listed | Endangered | | CA |
| Flowering Plants | Palmer's bush-mallow | Malacothamnus palmeri palmeri | Not Listed | Resolved Taxon | | CA |
| Mammals | Palmer's chipmunk | Tamias palmeri | Not Listed | Species of Concern | | NV |
| Birds | Palmer's Curve-billed Thrasher | Toxostoma curvirostre palmeri | Not Listed | Species of Concern | | |
| Flowering Plants | Palmer's goldenbush | Ericameria palmeri ssp. palmeri | Not Listed | Status Undefined | | |
| Flowering Plants | Palmer's grapplinghook | Harpagonella palmeri | Not Listed | Species of Concern | | |
| Flowering Plants | Palmer's grapplinghook | Harpagonella palmeri palmeri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Palmer's haplopappus | Haplopappus palmeri palmeri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Palmer's mariposa lily | Calochortus palmeri palmeri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Palmer's monardella | Monardella palmeri | Not Listed | Resolved Taxon | | CA |
| Snails | Palmetto pillsnail | Euchemotrema cheatumi | Not Listed | Species of Concern | | TX |
| Mammals | Palm Springs little pocket mouse | Perognathus longimembris bangsi | | Not Listed | | CA |
| Mammals | Palm Springs round-tailed ground (=Coachella Valley) Squirrel | Spermophilus tereticaudus chlorus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Palo colorado | Ternstroemia luquillensis | Listed | Endangered | | PR |
| Flowering Plants | Palo de jazmin | Styrax portoricensis | Listed | Endangered | | PR |
| Flowering Plants | Palo de nigua | Cornutia obovata | Listed | Endangered | | PR |
| Flowering Plants | Palo de ramon | Banara vanderbiltii | Listed | Endangered | | PR |
| Flowering Plants | Palo de rosa | Ottoschulzia rhodoxylon | Listed | Threatened | | PR |
| Flowering Plants | Palo de violeta | Polygala cowellii | Not Listed | Resolved Taxon | | PR, VI |
| Mammals | Palo Duro mouse | Peromyscus truei comanche | Not Listed | Species of Concern | | TX |
| Flowering Plants | Palomar monkeyflower | mimulus diffusus | Not Listed | Species of Concern | | |
| Fishes | Palomas pupfish | Cyprinodon | Not Listed | Species of Concern | | NM |
| Insects | Palos Verdes blue butterfly | Glaucopsyche lygdamus palosverdesensis | Listed | Endangered | | CA |
| Flowering Plants | Pamakani | Tetramolopium capillare | Listed | Endangered | | HI |
| Flowering Plants | Pamakani | Viola chamissoniana ssp. chamissoniana | Listed | Endangered | | HI |
| Mammals | Pampas deer | Ozotoceros bezoarticus | Listed | Endangered | | |
| Crustaceans | Panama City crayfish | Procambarus econfinae | Listed | Threatened | | FL |
| Amphibians | Panamanian golden frog | Atelopus varius zeteki | Listed | Endangered | | |
| Mammals | Panamanian jaguarundi | Herpailurus (=Felis) yagouaroundi panamensis | Listed | Endangered | | |
| Reptiles | Panamint alligator lizard | Elgaria panamintina | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Panamint daisy | Enceliopsis covillei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Panamint dudleya | Dudleya saxosa saxosa | Not Listed | Species of Concern | | CA |
| Flowering Plants | Panamint Mountains buckwheat | Eriogonum microthecum panamintense | Not Listed | Species of Concern | | CA |
| Flowering Plants | Panamint Mountains lupine | Lupinus magnificus magnificus | Not Listed | Species of Concern | | CA |
| Flowering Plants | panaunau | lobelia yuccoides | Not Listed | Species of Concern | | |
| Reptiles | Pandanus skink | Aulacoplax leptosoma | Not Listed | Resolved Taxon | | |
| Flowering Plants | Panguitch wild-buckwheat | Eriogonum panguicense alpestre | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Panhandle lily | Lilium iridollae | | Not Listed | | |
| Flowering Plants | Panhandle meadowbeauty | Rhexia salicifolia | | Not Listed | | GA |
| Snails | Panhandle pebblesnail | Somatogyrus virginicus | Not Listed | Species of Concern | | NC, VA |
| Flowering Plants | Panoche peppergrass | Lepidium jaredii album | Not Listed | Species of Concern | | CA |
| Flowering Plants | Papala | Charpentiera densiflora | Listed | Endangered | | HI |
| Flowering Plants | Paper-spined cactus | Sclerocactus papyracanthus | Not Listed | Species of Concern | | AZ, NM, TX |
| Flowering Plants | Papery whitlow-wort | Paronychia chartacea | Listed | Threatened | | FL |
| Snails | Papillose taildropper | prophysaon dubium | Not Listed | Species of Concern | | |
| Flowering Plants | Pappose spikeweed | Hemizonia parryi congdonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Parachute beardtongue | Penstemon debilis | Listed | Threatened | | CO |
| Birds | Paradise parakeet | Psephotus pulcherrimus | Listed | Endangered | | |
| Mammals | Paraguana Mustached Bat | Pteronotus paraguanensis | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Parasitic Jaeger | Stercorarius parasiticus | Not Listed | Species of Concern | | |
| Flowering Plants | Parasol clover | Trifolium bolanderi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Paria spurge | Euphorbia nephradenia | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Paria sunflower | Heliomeris soliceps | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Pariette cactus | Sclerocactus brevispinus | Listed | Threatened | | UT |
| Flowering Plants | Parish's alkali grass | Puccinellia parishii | Not Listed | Resolved Taxon | | AZ, CA, CO, NM |
| Flowering Plants | Parish's bush-mallow | Malacothamnus parishii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Parish's chaenactis | Chaenactis parishii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Parish's checkerbloom | Sidalcea hickmanii parishii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Parish's daisy | Erigeron parishii | Listed | Threatened | | CA |
| Flowering Plants | Parish's gooseberry | Ribes divaricatum parishii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Parish's meadowfoam | Limnanthes gracilis parishii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Parish's phacelia | Phacelia parishii | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Parish's rock-cress | Arabis parishii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Parker's pipewort | Eriocaulon parkeri | Not Listed | Resolved Taxon | | CT, DC, DE, MA, MD, ME, NC, NJ, NY, PA, VA |
| Insects | Parker's riffle beetle | Cylloepus parkeri | Not Listed | Resolved Taxon | | AZ |
| Crustaceans | Parkhill Prairie Crayfish | Procambarus steigmani | Not Listed | Resolved Taxon | | |
| Birds | Parkinson's black petrel | Procellaria parkinsoni | Not Listed | Resolved Taxon | | |
| Flowering Plants | Park rock-cress | Arabis vivariensis | Not Listed | Species of Concern | | CO, UT |
| Flowering Plants | Parks' jointweed | Polygonella parksii | Not Listed | Resolved Taxon | | TX |
| Mammals | Parma wallaby | Macropus parma | Listed | Endangered | | |
| Crustaceans | Parrish crayfish | Cambarus parrishi | Not Listed | Status Undefined | | GA, NC |
| Flowering Plants | Parrish's brittlescale | Atriplex parishii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Parrot pitcher-plant | Sarracenia psittacina | Not Listed | Resolved Taxon | | |
| Flowering Plants | Parry's horkelia | Horkelia parryi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Parry's spineflower | Chorizanthe parryi parryi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Parry's tetracoccus | Tetracoccus dioicus | Not Listed | Species of Concern | | CA |
| Reptiles | Pascagoula map turtle | Graptemys gibbonsi | Listed | Similarity of Appearance (Threatened) | | LA, MS |
| Flowering Plants | Passey's onion | Allium passeyi | Not Listed | Resolved Taxon | | UT |
| Insects | patagonia eyed silkmoth | Automeris patagoniensis | Not Listed | Resolved Taxon | | AZ |
| Amphibians | Patch-nosed salamander | Urspelerpes brucei | Not Listed | Status Undefined | | GA, SC |
| Insects | Patruelis oechalia stink bug | Oechalia patruelis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Paudedo | Hedyotis megalantha | Listed | Endangered | | GU |
| Ferns and Allies | Pauoa | Ctenitis squamigera | Listed | Endangered | | HI |
| Flowering Plants | Pauper milk-vetch | Astragalus misellus pauper | Not Listed | Resolved Taxon | | WA |
| Insects | Pawnee montane skipper | Hesperia leonardus montana | Listed | Threatened | | CO |
| Insects | Payne's cave beetle | Pseudanophthalmus paynei | Not Listed | Species of Concern | | TN |
| Flowering Plants | Payson beardtongue | Penstemon paysoniorum | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | Payson's jewelflower | Caulanthus simulans | Not Listed | Species of Concern | | CA |
| Flowering Plants | Peach-leaved willow | Salix amygdaloides | Not Listed | Status Undefined | | |
| Flowering Plants | Peacock larkspur | Delphinium pavonaceum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Reptiles | Peacock softshell turtle | Trionyx hurum | Listed | Endangered | | |
| Amphibians | Peaks of Otter salamander | Plethodon hubrichti | Not Listed | Resolved Taxon | | VA |
| Fishes | Peamouth | Mylocheilus caurinus | | Not Listed | | |
| Flowering Plants | Peanut sandwort | Minuartia rosei | Not Listed | Resolved Taxon | | CA |
| Fishes | Pearl Dace | Margariscus margarita | | Not Listed | | |
| Fishes | Pearl darter | Percina aurora | Listed | Threatened | | MS |
| Reptiles | Pearl River Map Turtle | Graptemys pearlensis | Listed | Threatened | | |
| Mammals | Peary caribou | Rangifer tarandus pearyi | Not Listed | Resolved Taxon | | |
| Insects | Pecatonica River mayfly | Acanthometropus pecatonica | Not Listed | Species of Concern | | IL, WI |
| Flowering Plants | Pecho manzanita | Arctostaphylos pechoensis | Not Listed | Species of Concern | | CA |
| Crustaceans | Peck's cave amphipod | Stygobromus (=Stygonectes) pecki | Listed | Endangered | | TX |
| Flowering Plants | Peck's lomatium | Lomatium peckianum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Peck's sanicle | Sanicula peckiana | Not Listed | Resolved Taxon | | CA, NV, OR |
| Crustaceans | Pecos amphipod | Gammarus pecos | Listed | Endangered | | TX |
| Snails | Pecos assiminea snail | Assiminea pecos | Listed | Endangered | | NM, TX |
| Fishes | Pecos bluntnose shiner | Notropis simus pecosensis | Listed | Threatened | | NM |
| Fishes | Pecos gambusia | Gambusia nobilis | Listed | Endangered | | NM, TX |
| Fishes | Pecos pupfish | Cyprinodon pecosensis | Proposed for Listing | Proposed Threatened | | NM |
| Flowering Plants | Pecos (=puzzle, =paradox) sunflower | Helianthus paradoxus | Listed | Threatened | | NM, TX |
| Mammals | Pecos River muskrat | Ondatra zibethicus ripensis | Not Listed | Species of Concern | | NM, TX |
| Snails | Pecos springsnail | Pyrgulopsis pecosensis | Petitioned for Listing, Under Review | Under Review | | NM |
| Birds | Pectoral Sandpiper | Calidris melanotos | Not Listed | Species of Concern | | |
| Flowering Plants | Pedate checker-mallow | Sidalcea pedata | Listed | Endangered | | CA |
| Snails | Pedernales Oval | Patera leatherwoodi | Not Listed | Resolved Taxon | | |
| Amphibians | Pedernales River Springs salamander | Eurycea species | Petitioned for Listing, Under Review | Under Review | | |
| Arachnids | Pederseni''s Tiger Spider | Poecilotheria vittata | Listed | Endangered | | |
| Flowering Plants | Peebles Navajo cactus | Pediocactus peeblesianus ssp. peeblesianus | Listed | Endangered | | AZ |
| Crustaceans | Pee Dee crayfish ostracod | Dactylocythere peedeensis | Not Listed | Species of Concern | | NC |
| Crustaceans | Pee Dee lotic crayfish | Procambarus lepidodactylus | Not Listed | Species of Concern | | NC, SC |
| Flowering Plants | Peirson's aster | Oreostemma peirsonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Peirson's lupine | Lupinus peirsonii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Peirson's milk-vetch | Astragalus magdalenae var. peirsonii | Listed | Threatened | | CA |
| Flowering Plants | Peirson's morning-glory | Calystegia peirsonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Peirson's spring beauty | Claytonia lanceolata peirsonii | Not Listed | Species of Concern | | CA |
| Birds | Pelagic Cormorant | Phalacrocorax pelagicus pelagicus | Not Listed | Species of Concern | | |
| Insects | Pele megalagrion damselfly | Megalagrion amaurodytum peles | Not Listed | Species of Concern | | HI |
| Insects | Pele yellow-faced bee | Nesoprosopis pele | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Pelos del diablo | Aristida portoricensis | Listed | Endangered | | PR |
| Mammals | Pelzeln's gazelle | Gazella dorcas pelzelni | Listed | Endangered | | |
| Mammals | Penasco least chipmunk | Tamias minimus atristriatus | Listed | Endangered | | NM |
| Flowering Plants | Pendleton button-clery | Eryngium pendletonensis | Not Listed | Status Undefined | | |
| Snails | Peninsula Coast Range shoulderband | Helminthoglypta nickliniana awania | Not Listed | Species of Concern | | CA |
| Flowering Plants | Peninsular beargrass | Nolina cismontana | Not Listed | Species of Concern | | |
| Mammals | Peninsular bighorn sheep | Ovis canadensis nelsoni | Listed | Endangered | | CA |
| Mammals | Peninsular pronghorn | Antilocapra americana peninsularis | Listed | Endangered | | |
| Snails | Peninsular Range shoulderband | Helminthoglypta traski coelata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Penland alpine fen mustard | Eutrema penlandii | Listed | Threatened | | CO |
| Flowering Plants | Penland beardtongue | Penstemon penlandii | Listed | Endangered | | CO |
| Flowering Plants | Pennell's bird's-beak | Cordylanthus tenuis ssp. capillaris | Listed | Endangered | | CA |
| Sponges | Pennsylvania sponge | Heteromeyenia longistylis | Not Listed | Resolved Taxon | | PA |
| Mammals | Penobscot meadow vole | Microtus pennsylvanicus shattucki | Not Listed | Species of Concern | | ME |
| Fishes | Peppered chub | Macrhybopsis tetranema | Listed | Endangered | | KS, NM, OK, TX |
| Fishes | Peppered shiner | Notropis perpallidus | Petitioned for Listing, Under Review | Under Review | | AR, OK |
| Mammals | Perdido Key beach mouse | Peromyscus polionotus trissyllepsis | Listed | Endangered | | AL, FL |
| Birds | Peregrine Falcon | Falco peregrinus | Not Listed | Species of Concern | | |
| Flowering Plants | Perennial caltrop | Kallstroemia perennans | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Perennial spurge | Chamaesyce perennans | Not Listed | Resolved Taxon | | TX |
| Insects | Perkin's club-palp bristletail | Machiloides perkinsi | Not Listed | Species of Concern | | HI |
| Insects | Perkins' nesomimesan sphecid wasp | Nesomimesa perkinsi | Not Listed | Species of Concern | | HI |
| Insects | Perkins' oceanides seed bug | Oceanides perkinsi | Not Listed | Species of Concern | | HI |
| Insects | Perkin's yellow-faced bee | Hylaeus perkinsianus | Not Listed | Species of Concern | | HI |
| Mammals | Persian fallow deer | Dama mesopotamica (=dama m.) | Listed | Endangered | | |
| Fishes | Persian Sturgeon | Acipenser persicus | Proposed for Listing | Proposed Endangered | | |
| Flowering Plants | Persistent trillium | Trillium persistens | Listed | Endangered | | GA, SC |
| Insects | Perspicuan yellow-faced bee | Hylaeus perspicuus | Not Listed | Resolved Taxon | | HI |
| Birds | Peruvian plantcutter | Phytotoma raimondii | Listed | Endangered | | |
| Flowering Plants | Petaluma popcornflower | Plagiobothrys mollis vestitus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Peter's Mountain mallow | Iliamna corei | Listed | Endangered | | VA |
| Flowering Plants | Petites Graines camasey | Graffenrieda ottoschulzii | Not Listed | Species of Concern | | PR, VI |
| Insects | Petrunkevitch's cave beetle | Pseudanophthalmus petrunkevitchi | Not Listed | Species of Concern | | VA |
| Birds | Phainopepla | Phainopepla nitens | Not Listed | Species of Concern | | |
| Birds | Phainopepla | Phainopepla nitens lepida | Not Listed | Species of Concern | | |
| Fishes | Phantom shiner | Notropis orca | Not Listed | Resolved Taxon | | NM, TX |
| Snails | Phantom Springsnail | Pyrgulopsis texana | Listed | Endangered | | TX |
| Snails | Phantom Tryonia | Tryonia cheatumi | Listed | Endangered | | TX |
| Clams | pheasantshell | Ortmanniana pectorosa | Not Listed | Status Undefined | | |
| Insects | Pheres blue | Icaricia icarioides pheres | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Philadelphia panic grass | Panicum philadelphicum | Not Listed | Resolved Taxon | | GA, SC |
| Birds | Philippine cockatoo | Cacatua haematuropygia | Listed | Endangered | | |
| Reptiles | Philippine crocodile | Crocodylus novaeguineae mindorensis | Listed | Endangered | | |
| Birds | Philippine eagle | Pithecophaga jefferyi | Listed | Endangered | | |
| Mammals | Philippine pangolin | Manis culionensis | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Philippine tarsier | Tarsius syrichta | Listed | Threatened | | |
| Insects | Phleophagan chestnut nepticulid moth | Ectodemia phleophaga | Not Listed | Species of Concern | | MD |
| Birds | Phoenix Petrel | Pterodroma alba | Not Listed | Species of Concern | | |
| Snails | Phoenix talussnail | Maricopella allynsmithi | Petitioned for Listing, Under Review | Under Review | | AZ |
| Insects | Phyllostegian leaf bug | Cyrtopeltis phyllostegiae | Not Listed | Resolved Taxon | | HI |
| Fishes | Pickerel Frog | Lithobates palustris | | Not Listed | | |
| Amphibians | Pickerel Frog | Lithobates palustris | | Not Listed | | |
| Flowering Plants | Pickering ivesia | Ivesia pickeringii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Pickering's morning-glory | Stylisma pickeringii | Not Listed | Species of Concern | | AL, DE, GA, MS, NC, NJ, SC |
| Crustaceans | Pickle Springs amphipod | Stygobromus heteropodus | Not Listed | Resolved Taxon | | MO |
| Fishes | Piebald Madtom | Noturus gladiator | Petitioned for Listing, Under Review | Under Review | | MS, TN |
| Birds | Pied-billed Grebe | Podilymbus podiceps | Not Listed | Species of Concern | | |
| Flowering Plants | Piedmont Aster | Eurybia mirabilis | Not Listed | Species of Concern | | NC |
| Flowering Plants | Piedmont barren strawberry | Waldsteinia lobata | Not Listed | Status Undefined | | GA, SC |
| Crustaceans | Piedmont Blue burrower | Cambarus harti | Not Listed | Status Undefined | | GA |
| Crustaceans | Piedmont Blue Burrower | Cambarus hartii | | Not Listed | | |
| Flowering Plants | piedmont false pimpernel | Lindernia monticola | Not Listed | Resolved Taxon | | AL, GA, NC |
| Flowering Plants | Piedmont meadow-rue | Thalictrum macrostylum | Not Listed | Species of Concern | | NC |
| Flowering Plants | Piedmont ragwort | Packera millefolia | Not Listed | Species of Concern | | GA, NC, SC |
| Mammals | Pied tamarin | Saguinus bicolor | Listed | Endangered | | |
| Flowering Plants | Pierpoint Springs liveforever | Dudleya cymosa costifolia | Not Listed | Species of Concern | | CA |
| Amphibians | Pigeon Mountain salamander | Plethodon petraeus | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | Pigeon wings | Clitoria fragrans | Listed | Threatened | | FL |
| Mammals | Pig-footed bandicoot | Chaeropus ecaudatus | Listed | Endangered | | |
| Flowering Plants | Pikes Peak Spring parsley | Oreoxis humilis | Not Listed | Resolved Taxon | | |
| Insects | Piko anobiid beetle | Holcobius pikoensis | Not Listed | Species of Concern | | HI |
| Birds | Pileated woodpecker | dryocopus pileatus | Not Listed | Species of Concern | | |
| Corals | Pillar Coral | Dendrogyra cylindrus | Listed | Threatened | | |
| Flowering Plants | pilo | Kadua laxiflora | Listed | Endangered | | HI |
| Flowering Plants | Pilo kea lau li`i | Melicope rostrata | Listed | Endangered | | HI |
| Insects | Pilo kea long-horned beetle | Plagithmysus platydesmae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Pima pineapple cactus | Coryphantha scheeri var. robustispina | Listed | Endangered | | AZ |
| Clams | Pimpleback | Cyclonaias pustulosa | | Not Listed | | |
| Mammals | Pinacate cactus mouse | Peromyscus eremicus papagensis | Not Listed | Species of Concern | | AZ |
| Insects | Pinaleno monkey grasshopper | Eumorsea pinaleno | Not Listed | Species of Concern | | AZ |
| Snails | Pinaleno mountainsnail | Oreohelix grahamensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Pinalenos fleabane | Erigeron heligraphicus | Not Listed | Species of Concern | | AZ |
| Snails | Pinaleno talussnail | Sonorella grahamensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Pine barren gentian | Gentiana autumnalis | Not Listed | Resolved Taxon | | DE, NC, NJ, SC, VA |
| Flowering Plants | Pine barrens boneset | Eupatorium resinosum | Not Listed | Species of Concern | | DE, NC, NJ, NY, SC |
| Amphibians | Pine barrens treefrog | Hyla andersonii | Delisted | Original Data in Error - New Information Discovered | | |
| Flowering Plants | Pine City stonecrop | Sedum pinetorum | Not Listed | Species of Concern | | CA |
| Snails | Pinecone Holospira | Holospira pityis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Pine Hill ceanothus | Ceanothus roderickii | Listed | Endangered | | CA |
| Flowering Plants | Pine Hill flannelbush | Fremontodendron californicum ssp. decumbens | Listed | Endangered | | CA |
| Mammals | Pine Island rice rat | Oryzomys palustris planirostris | | Not Listed | | |
| Flowering Plants | Pineland hoary-pea | Tephrosia mohrii | Not Listed | Species of Concern | | |
| Flowering Plants | Pineland jacquemontia | Jacquemontia curtissii | Not Listed | Species of Concern | | |
| Flowering Plants | Pineland plantain | Plantago sparsiflora | Not Listed | Species of Concern | | |
| Flowering Plants | Pineland sandmat | Chamaesyce deltoidea pinetorum | Listed | Threatened | | FL |
| Flowering Plants | Pine Nut Mountains ivesia | Ivesia pityocharis | Not Listed | Species of Concern | | NV |
| Birds | Pine Siskin | Carduelis pinus | Not Listed | Species of Concern | | |
| Fishes | Pinewoods darter | Etheostoma mariae | Not Listed | Resolved Taxon | | NC, SC |
| Fishes | pinewoods shiner | Lythrurus matutinus | Not Listed | Species of Concern | | NC |
| Mammals | Pink fairy armadillo | Chlamyphorus truncatus | Listed | Endangered | | |
| Birds | Pink-footed Shearwater | Ardenna creatopus | Not Listed | Species of Concern | | |
| Birds | Pink-headed duck | Rhodonessa caryophyllacea | Listed | Endangered | | |
| Clams | Pink Heelsplitter | Potamilus alatus | | Not Listed | | |
| Clams | Pink mucket (pearlymussel) | Lampsilis abrupta | Listed | Endangered | | AL, AR, IL, IN, KY, LA, MO, MS, OH, TN, VA, WV |
| Clams | Pink Papershell | Potamilus ohiensis | | Not Listed | | |
| Birds | Pink pigeon | Columba mayeri | Listed | Endangered | | |
| Fishes | Pink Salmon | Oncorhynchus gorbuscha | | Not Listed | | |
| Flowering Plants | Pink sand-verbena | Abronia umbellata breviflora | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Pink-shell azalea | Rhododendron vaseyi | Not Listed | Resolved Taxon | | NC |
| Flowering Plants | Pinnacles buckwheat | Eriogonum nortonii | Not Listed | Resolved Taxon | | CA |
| Insects | Pinnacles optioservus riffle beetle | Optioservus canus | Not Listed | Species of Concern | | CA |
| Insects | Pinnacles shield-back katydid | Idiostatus kathleenae | Not Listed | Species of Concern | | CA |
| Flowering Plants | pinnately-lobed brown-eyed susan | Rudbeckia triloba var. pinnatiloba | Not Listed | Species of Concern | | |
| Flowering Plants | Pinnate spring-parsley | Cymopterus beckii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Pinninerve peperomia | Peperomia macraeana | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Pinon | Tillandsia lineatispica | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Pinon espinoso or cockspur | Erythrina eggersii | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | Pinos Altos fameflower | Talinum humile | Not Listed | Species of Concern | | AZ, NM |
| Snails | Pinos Altos Mountainsnail | Oreohelix confragosa | Not Listed | Resolved Taxon | | |
| Birds | Pinyon Jay | Gymnorhinus cyanocephalus | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Piper's bluegrass | Poa piperi | Not Listed | Resolved Taxon | | CA, NV, OR |
| Birds | Piping Plover | Charadrius melodus | Listed | Threatened | | AL, AR, CO, CT, DE, FL, GA, IA, IL, KS, LA, MA, MD, ME, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NY, OK, RI, SC, SD, TN, TX, VA, WY |
| Birds | Piping Plover | Charadrius melodus | Listed | Endangered | | IL, IN, MI, MN, NY, OH, PA, WI |
| Mammals | Pipistrelles (Bats) | Pipistrellus sp. | | Not Listed | | |
| Flowering Plants | Piratebush | Buckleya distichophylla | Not Listed | Species of Concern | | NC, VA |
| Fishes | Pirate Perch | Aphredoderus sayanus | | Not Listed | | |
| Flowering Plants | Pismo clarkia | Clarkia speciosa ssp. immaculata | Listed | Endangered | | CA |
| Clams | Pistolgrip | Quadrula verrucosa | | Not Listed | | |
| Mammals | Pistol River pocket gopher | Thomomys umbrinus detumidus | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Pitcher's thistle | Cirsium pitcheri | Listed | Threatened | | IL, IN, MI, WI |
| Flowering Plants | Pitkin Marsh lily | Lilium pardalinum ssp. pitkinense | Listed | Endangered | | CA |
| Flowering Plants | Pitkin Marsh paintbrush | Castilleja uliginosa | Not Listed | Species of Concern | | CA |
| Fishes | Pit-Klamath Brook Lamprey | Entosphenus lethophagus | | Not Listed | | |
| Fishes | Pit roach | Lavinia symmetricus mitrulus | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Pit Sculpin | Cottus perplexus | | Not Listed | | |
| Fishes | Pit Sculpin | Cottus pitensis | | Not Listed | | |
| Ferns and Allies | Pitted quillwort | Isoetes foveolata | Not Listed | Resolved Taxon | | CT, MA, NH |
| Flowering Plants | Piute buckwheat | Eriogonum breedlovei breedlovei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Piute Mountains jewelflower | Streptanthus cordatus piutensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Piute Mountains navarretia | Navarretia setiloba | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Pizzini's amphipod | Stygobromus pizzinii | Not Listed | Species of Concern | | DC, MD, PA, VA |
| Clams | Plain Pocketbook | Lampsilis cardium | | Not Listed | | |
| Mammals | Plains bison | Bison bison bison | Petitioned for Listing, Under Review | Under Review | | CO, IA, MT, OK, SD, UT, WY |
| Flowering Plants | Plains gumweed | Grindelia oolepis | Not Listed | Resolved Taxon | | TX |
| Algae | Plains Killifish | Fundulus zebrinus | | Not Listed | | |
| Fishes | Plains minnow | Hybognathus placitus | Not Listed | Species of Concern | | AR, CO, IA, IL, KS, KY, LA, MO, MT, ND, NE, NM, OK, SD, TX, WY |
| Fishes | Plains Orangethroat Darter | Etheostoma spectabile | | Not Listed | | |
| Amphibians | Plains Spadefoot | Spea bombifrons | | Not Listed | | |
| Mammals | Plains Spotted Skunk | Spilogale interrupta | Not Listed | Resolved Taxon | | AR, IA, KS, MN, MO, MT, ND, NE, OK, SD, TX, WY |
| Fishes | Plains topminnow | Fundulus sciadicus | Not Listed | Resolved Taxon | | CO, IA, KS, MN, MO, NE, OK, SD, WY |
| Birds | Plains wanderer (=collared-hemipode) | Pedionomus torquatus | Listed | Endangered | | |
| Flowering Plants | Plank's catchfly | Silene plankii | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | Plaskett Meadows linanthus | Linanthus harknessii condensatus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Plateau catchfly | Silene petersonii | Not Listed | Species of Concern | | UT |
| Flowering Plants | Plateau milkvine | Matelea edwardsensis | Not Listed | Resolved Taxon | | TX |
| Fishes | Plateau shiner | Cyprinella lepida | Not Listed | Resolved Taxon | | TX |
| Reptiles | Plateau spot-tailed earless lizard | Holbrookia lacerata | Not Listed | Resolved Taxon | | TX |
| Insects | Platte River caddisfly | Ironoquia plattensis | Not Listed | Resolved Taxon | | NE |
| Flowering Plants | Pleasant Valley mariposa lily | Calochortus clavatus avius | Not Listed | Species of Concern | | CA |
| Fishes | Pleasant Valley tui chub | Siphateles bicolor ssp. | Not Listed | Species of Concern | | NV |
| Snails | Plicate rocksnail | Leptoxis plicata | Listed | Endangered | | AL |
| Flowering Plants | Plumas ivesia | Ivesia sericoleuca | Not Listed | Species of Concern | | CA |
| Flowering Plants | Plumas lupine | Lupinus onustus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Birds | Plumbeous Vireo | Vireo plumbeus | Not Listed | Species of Concern | | |
| Flowering Plants | Plumleaf azalea | Rhododendron prunifolium | Not Listed | Resolved Taxon | | AL, GA |
| Flowering Plants | Plummer's mariposa lily | Calochortus plummerae | Not Listed | Species of Concern | | CA |
| Reptiles | Plymouth Redbelly Turtle = Plymouth Redbelly Cooter | Pseudemys rubriventris bangsi | Listed | Endangered | | MA |
| Crustaceans | Pocahontas cave amphipod | Stygobromus nanus | Not Listed | Species of Concern | | WV |
| Clams | Pocketbook | Lampsilis ovata | | Not Listed | | |
| Mammals | Pocketed free-tailed bat | nyctinomops femorosaccus | Not Listed | Species of Concern | | |
| Crustaceans | Pocket-Pouch Fairy Shrimp | Branchinecta campestris | | Not Listed | | |
| Flowering Plants | Podunk Groundsel | Packera malmstenii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Po`e | Portulaca sclerocarpa | Listed | Endangered | | HI |
| Mammals | Point Arena mountain beaver | Aplodontia rufa nigra | Listed | Endangered | | CA |
| Insects | Point Conception jerusalem cricket | Ammopelmatus muwu | Not Listed | Species of Concern | | CA |
| Flowering Plants | Point Lobos buckwheat | Eriogonum parvifolium lucidum | Not Listed | Resolved Taxon | | CA |
| Snails | Point of Rocks tryonia | Tryonia elata | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Point Reyes bentgrass | Agrostis clivicola punta-reyesensis | Not Listed | Resolved Taxon | | CA |
| Insects | Point Reyes blue | Icaricia icariodes ssp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Point Reyes horkelia | Horkelia marinensis | Not Listed | Species of Concern | | CA |
| Mammals | Point Reyes jumping mouse | Zapus trinotatus orarius | Not Listed | Species of Concern | | CA |
| Flowering Plants | Point Reyes manzanita | Arctostaphylos uva-ursi marinensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Point Reyes meadowfoam | Limnanthes douglasii sulphurea | Not Listed | Species of Concern | | CA |
| Mammals | Point Reyes mountain beaver | Aplodontia rufa phaea | Not Listed | Species of Concern | | CA |
| Flowering Plants | Point Reyes paintbrush | Castilleja chrymactis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Point Reyes stickyseed | Blennosperma nanum robustum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Poison Canyon stickseed | Hackelia brevicula | Not Listed | Species of Concern | | CA |
| Insects | 'Poko' noctuid moth | Agrotis crinigera | Not Listed | Resolved Taxon | | HI |
| Mammals | Polar bear | Ursus maritimus | Listed | Threatened | | AK |
| Insects | Politus eopenthes click beetle | Eopenthes politus | Not Listed | Species of Concern | | HI |
| Birds | Pollen's vanga | Xenopirostris polleni | Listed | Threatened | | |
| Birds | Polynesian Starling | Aplonis tabuensis | Not Listed | Species of Concern | | |
| Birds | Polynesian Storm Petrel | Nesofregetta fuliginosa | Not Listed | Species of Concern | | |
| Birds | Pomarine Jaeger | Stercorarius pomarinus | Not Listed | Species of Concern | | |
| Snails | Pomo bronze shoulderband | Helminthoglypta arrosa pomoensis | Not Listed | Species of Concern | | CA |
| Birds | Ponape greater white-eye | Rukia longirostra | Listed | Endangered | | |
| Birds | Ponape mountain starling | Aplonis pelzelni | Listed | Endangered | | |
| Birds | Ponape short-eared owl | Asio flammeus ponapensis | Not Listed | Pre-Act Delisted Taxon | | FM |
| Flowering Plants | Pondberry | Lindera melissifolia | Listed | Endangered | | AL, AR, GA, MO, MS, NC, SC, TN |
| Conifers and Cycads | Ponderosa Pine | Pinus ponderosa | Not Listed | Resolved Taxon | | |
| Snails | Ponderous siltsnail | Cincinnatia ponderosa | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Pondspice | Litsea aestivalis | Not Listed | Species of Concern | | |
| Flowering Plants | Po`ola | Claoxylon sandwicense sandwicense | Not Listed | Resolved Taxon | | HI |
| Insects | Po'olanui gall fly | Phaeogramma sp. | Not Listed | Resolved Taxon | | HI |
| Birds | Po`ouli (honeycreeper) | Melamprosops phaeosoma | Delisted | Extinction | | |
| Fishes | Popeye shiner | Notropis ariommus | | Not Listed | | GA, KY, OH, TN, VA, WV |
| Flowering Plants | Poplar-leaved bidens | Bidens populifolia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Popolo | Cyanea solanacea | Listed | Endangered | | HI |
| Flowering Plants | Popolo | Solanum nelsonii | Listed | Endangered | | HI |
| Flowering Plants | Popolo ku mai | Solanum incompletum | Listed | Endangered | | HI |
| Flowering Plants | Porsild's Starwort | Stellaria porsildii | Not Listed | Resolved Taxon | | |
| Snails | Portal Talussnail | Sonorella neglecta | Not Listed | Resolved Taxon | | |
| Flowering Plants | Porter sagebrush | Artemisia porteri | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | Porter's Feathergrass | Ptilagrostis porteri | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Porter's goldenrod | Solidago porteri | Not Listed | Species of Concern | | GA |
| Flowering Plants | Porter's groundsel | Packera porteri | Not Listed | Resolved Taxon | | CA, CO, NV, OR |
| Flowering Plants | Porter's, Key spurge | Chamaesyce porteriana keyensis | Not Listed | Species of Concern | | |
| Flowering Plants | Porter's reedgrass | Calamagrostis porteri | Not Listed | Resolved Taxon | | KY, MD, NC, NY, PA, TN, VA, WV |
| Flowering Plants | Porter's, spurge | Chamaesyce porteriana scoparia | Not Listed | Species of Concern | | |
| Snails | Potem Creek pebblesnail | Fluminicola potemicus | Not Listed | Resolved Taxon | | CA |
| Mammals | Potholes meadow vole | Microtus pennsylvanicus kincaidi | Not Listed | Species of Concern | | WA |
| Crustaceans | Potomac groundwater amphipod | Stygobromus tenuis potomacus | Not Listed | Resolved Taxon | | DC, MD, PA, VA |
| Insects | Potophila agrotis noctuid moth | Agrotis potophila | Not Listed | Species of Concern | | HI |
| Insects | Poweshiek skipperling | Oarisma poweshiek | Listed | Endangered | | MI, WI |
| Flowering Plants | Prairie bush-clover | Lespedeza leptostachya | Listed | Threatened | | IA, IL, MN, WI |
| Fishes | prairie chub | Macrhybopsis australis | Petitioned for Listing, Under Review | Under Review | | OK, TX |
| Birds | Prairie Falcon | Falco mexicanus | Not Listed | Species of Concern | | |
| Mammals | Prairie gray fox | Urocyon cinereoargenteus ssp. ocythous | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Prairie Loggerhead Shrike | Lanius ludovicianus excubitorides | Not Listed | Species of Concern | | |
| Insects | Prairie mole cricket | Gryllotalpa major | Not Listed | Species of Concern | | AR, IL, KS, MO, MS, OK |
| Ferns and Allies | Prairie moonwort | Botrychium gallicomontanum | Not Listed | Species of Concern | | MI |
| Birds | Prairie Warbler | Setophaga discolor | Not Listed | Species of Concern | | |
| Mammals | Preble's meadow jumping mouse | Zapus hudsonius preblei | Listed | Threatened | | CO, WY |
| Mammals | Preble's shrew | Sorex preblei | Not Listed | Species of Concern | | WA |
| Insects | Precious underwing | Catocala pretiosa pretiosa | Not Listed | Species of Concern | | CT, DE, MA, MD, NH, NJ, NY, OH, PA, VA |
| Flowering Plants | Presidio clarkia | Clarkia franciscana | Listed | Endangered | | CA |
| Snails | Presidio County springsnail | Fontelicella metcalfi | Not Listed | Species of Concern | | TX |
| Flowering Plants | Presidio Manzanita | Arctostaphylos hookeri var. ravenii | Listed | Endangered | | CA |
| Mammals | Presidio mole | Scalopus aquaticus texanus | Not Listed | Species of Concern | | TX |
| Flowering Plants | Preston Peak rock-cress | Arabis macdonaldiana | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Preston White River springfish | Crenichthys baileyi albivallis | Not Listed | Resolved Taxon | | NV |
| Mammals | Preuss' red colobus monkey | Procolobus (=Colobus) preussi (=badius p.) | Listed | Endangered | | |
| Mammals | Pribilof Islands shrew | Sorex hydrodromus | Not Listed | Species of Concern | | AK |
| Flowering Plants | Price''s potato-bean | Apios priceana | Listed | Threatened | | AL, KY, MS, TN |
| Snails | Pricklypear islandsnail | Micrarionta opuntia | Not Listed | Species of Concern | | CA |
| Fishes | Prickly Sculpin | Cottus asper | | Not Listed | | |
| Flowering Plants | Prieto tortugo | Ravenia urbanii | Not Listed | Resolved Taxon | | PR, VI |
| Mammals | Prince of Wales flying squirrel | Glaucomys sabrinus griseifrons | Not Listed | Resolved Taxon | | AK |
| Snails | Princess elimia | Elimia bellacrenata | Petitioned for Listing, Under Review | Under Review | | AL |
| Flowering Plants | Pringle hawkweed | Hieracium pringlei | Not Listed | Species of Concern | | AZ |
| Ferns and Allies | Pringle lip fern | Cheilanthes pringlei insulare | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Pringle monardella | Monardella pringlei | Not Listed | Species of Concern | | CA |
| Insects | Priolan oliarus planthopper | Oliarus priola | Not Listed | Species of Concern | | HI |
| Crustaceans | Pristine crayfish | Cambarus pristinus | Not Listed | Resolved Taxon | | TN |
| Mammals | Proboscis monkey | Nasalis larvatus | Listed | Endangered | | |
| Insects | Procellaris agrotis noctuid moth | Agrotis procellaris | Not Listed | Resolved Taxon | | HI |
| Mammals | Pronghorn | Antilocapra americana | | Not Listed | | |
| Arachnids | Proserpina cave pseudoscorpion | Kleptochthonius proserpinae | Not Listed | Species of Concern | | WV |
| Fishes | Proserpine shiner | Cyprinella proserpina | Not Listed | Species of Concern | | TX |
| Mammals | Prospect Valley pocket gopher | Thomomys umbrinus muralis | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Prostrate buckwheat | Eriogonum prociduum | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Prostrate hosackia | Lotus nuttallianus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Prostrate milkweed | Asclepias prostrata | Listed | Endangered | | TX |
| Flowering Plants | prostrate pincushionplant | Navarretia prostrata | Not Listed | Species of Concern | | |
| Flowering Plants | Prostrate spineflower | chorizanthe procumbens | Not Listed | Species of Concern | | |
| Birds | Prothonotary Warbler | Protonotaria citrea | Not Listed | Species of Concern | | |
| Insects | Provost's ochrotrichian micro caddisfly | Ochrotrichia provosti | Not Listed | Species of Concern | | |
| Snails | Prune elimia | Elimia chiltonensis | Not Listed | Status Undefined | | AL |
| Flowering Plants | Pryor Mountains Bladderpod | Lesquerella lesicii | Not Listed | Resolved Taxon | | |
| Mammals | Przewalski's horse | Equus przewalskii | Listed | Endangered | | |
| Insects | Psammobian yellow-faced bee | Hylaeus psammobia | Not Listed | Resolved Taxon | | HI |
| Arachnids | Pseudoscorpion | Kleptochthonius magnus | Not Listed | Status Undefined | | |
| Arachnids | Pseudoscorpion | Kleptochthonius tantalus | Not Listed | Status Undefined | | |
| Insects | (Pterostichus johnsoni) ground beetle | pterostichus johnsoni | Not Listed | Species of Concern | | |
| Flowering Plants | Pua `ala | Brighamia rockii | Listed | Endangered | | HI |
| Flowering Plants | Pua-hekili | Lysimachia hillebrandii | Not Listed | Resolved Taxon | | HI |
| Birds | Puaiohi | Myadestes palmeri | Listed | Endangered | | HI |
| Flowering Plants | Puakauhi | Canavalia hawaiiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Pualoalo | Hibiscus kokio | Not Listed | Species of Concern | | HI |
| Flowering Plants | Pua pilo | Capparis sandwichiana | Not Listed | Species of Concern | | HI |
| Mammals | Pudu | Pudu pudu | Listed | Endangered | | |
| Reptiles | Puerto Rican boa | Chilabothrus inornatus | Listed | Endangered | Proposed Delisting | PR |
| Birds | Puerto Rican broad-winged hawk | Buteo platypterus brunnescens | Listed | Endangered | | PR |
| Amphibians | Puerto Rican crested toad | Peltophryne lemur | Listed | Threatened | | PR |
| Insects | Puerto Rican harlequin butterfly | Atlantea tulita | Listed | Threatened | | PR |
| Birds | Puerto Rican nightjar | Antrostomus noctitherus | Listed | Endangered | | PR |
| Birds | Puerto Rican Oriole | Icterus portoricensis | Not Listed | Species of Concern | | |
| Birds | Puerto Rican parrot | Amazona vittata | Listed | Endangered | | PR |
| Birds | Puerto Rican plain Pigeon | Patagioenas inornata wetmorei | Listed | Endangered | | PR |
| Reptiles | Puerto Rican pygmy anole | Anolis occultus | Not Listed | Species of Concern | | PR, VI |
| Birds | Puerto Rican Screech-Owl | Megascops nudipes newtoni | Not Listed | Species of Concern | | |
| Birds | Puerto Rican sharp-shinned hawk | Accipiter striatus venator | Listed | Endangered | | PR |
| Reptiles | Puerto Rican Skink | Spondylurus nitidus | Proposed for Listing | Proposed Endangered | | PR, VI |
| Birds | Puerto Rican Vireo | Vireo latimeri | Not Listed | Species of Concern | | |
| Snails | Puget oregonian | Cryptomastix devia | Not Listed | Resolved Taxon | | OR, WA |
| Fishes | Pugnose minnow | Opsopoeodus emiliae | Not Listed | Status Undefined | | |
| Fishes | Pugnose Shiner | Notropis anogenus | | Not Listed | | |
| Insects | Pulchrus thread bug | Empicoris pulchrus | Not Listed | Species of Concern | | HI |
| Mammals | Puma (=mountain lion) | Puma (=Felis) concolor (all subsp. except coryi) | Listed | Similarity of Appearance (Threatened) | | FL |
| Insects | Puna deinomimesan sphecid wasp | Deinomimesa punae | Not Listed | Species of Concern | | HI |
| Flowering Plants | Pungent dwarf greasebush | Glossopetalon pungens var. pungens | | Not Listed | | |
| Mammals | Pungo white-footed mouse | Peromyscus leucopus easti | Not Listed | Resolved Taxon | | VA |
| Snails | Pupa elimia | Elimia pupaeformis | Not Listed | Resolved Taxon | | AL |
| Crustaceans | Purgatory cave shrimp | Palaemonetes holthuisi | Not Listed | Resolved Taxon | | |
| Insects | Puritan tiger beetle | Ellipsoptera puritana | Listed | Threatened | | CT, MA, MD |
| Flowering Plants | Purple amole | Chlorogalum purpureum | Listed | Threatened | | CA |
| Clams | Purple bankclimber (mussel) | Elliptoideus sloatianus | Listed | Threatened | | AL, FL, GA |
| Clams | Purple bean | Villosa perpurpurea | Listed | Endangered | | AL, NC, TN, VA, WV |
| Clams | Purple Cat's paw (=Purple Cat's paw pearlymussel) | Epioblasma obliquata | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Purple Cat's paw (=Purple Cat's paw pearlymussel) | Epioblasma obliquata | Listed | Endangered | | KY, OH, TN, WV |
| Flowering Plants | Purpledisk honeycombhead | Balduina atropurpurea | Not Listed | Resolved Taxon | | GA, SC |
| Mammals | Purple-faced langur | Presbytis senex | Listed | Threatened | | |
| Flowering Plants | Purple false-foxglove | Tomanthera skinneriana | Not Listed | Species of Concern | | IA, IL, IN, KS, KY, LA, MI, MO, OH, WI |
| Birds | Purple Finch | Carpodacus purpureus | Not Listed | Species of Concern | | |
| Flowering Plants | Purple fringeless orchid | Platanthera peramoena | Not Listed | Resolved Taxon | | AL, AR, DE, GA, IL, IN, KY, MD, MO, MS, NC, NJ, NY, OH, PA, SC, TN, VA, WV |
| Flowering Plants | Purple gay-mallow | Batesimalva violacea | Not Listed | Resolved Taxon | | TX |
| Clams | purple lilliput | Toxolasma lividum | Not Listed | Resolved Taxon | | AL, AR, GA, IL, IN, KS, KY, MO, MS, NC, OH, OK, TN |
| Birds | Purple martin | progne subis | Not Listed | Species of Concern | | |
| Flowering Plants | Purple monkey-flower | Mimulus purpureus purpureus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Purple mountain parsley | Oreonana purpurascens | Not Listed | Resolved Taxon | | CA |
| Birds | Purple Sandpiper | Calidris maritima | Not Listed | Species of Concern | | |
| Insects | Purple skimmer | Libellula jesseana | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Purple-spined Hedgehog cactus | Echinocereus engelmannii var. purpureus | Delisted | Original Data in Error - Taxonomic Revision | | UT |
| Birds | Purple Swamphen | Porphyrio porphyrio | Not Listed | Species of Concern | | |
| Flowering Plants | Purple, Texas spike | Hexalectris warnockii | Not Listed | Species of Concern | | AZ, NM, TX |
| Clams | Purple Wartyback | Cyclonaias tuberculata | | Not Listed | | |
| Flowering Plants | Pussytoes ragwort | Packera antennariifolia | Not Listed | Resolved Taxon | | MD, PA, VA, WV |
| Crustaceans | Putnam County Cave crayfish | Procambarus morrisi | Petitioned for Listing, Under Review | Under Review | | FL |
| Insects | Putnam minute moss beetle | Ochthebius putnamensis | Not Listed | Species of Concern | | IN |
| Flowering Plants | Pu`uka`a | Cyperus trachysanthos | Listed | Endangered | | HI |
| Snails | Puzzle elimia | Elimia varians | Not Listed | Species of Concern | | AL |
| Mammals | Pygmy chimpanzee | Pan paniscus | Listed | Endangered | | |
| Snails | Pygmy elimia | Elimia pygmaea | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | Pygmy fringe-tree | Chionanthus pygmaeus | Listed | Endangered | | FL |
| Mammals | Pygmy hog | Sus salvanius | Listed | Endangered | | |
| Fishes | Pygmy madtom | Noturus stanauli | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Pygmy madtom | Noturus stanauli | Listed | Endangered | | TN |
| Snails | Pygmy Mountainsnail | Oreohelix pygmaea | Not Listed | Resolved Taxon | | |
| Snails | Pygmy pebblesnail | Somatogyrus pygmaeus | Not Listed | Species of Concern | | AL |
| Flowering Plants | Pygmypipes | Monotropsis odorata | Not Listed | Species of Concern | | NC |
| Ferns and Allies | Pygmy quillwort | Isoetes bolanderi pygmaea | Not Listed | Resolved Taxon | | CA |
| Mammals | Pygmy Rabbit | Brachylagus idahoensis | Petitioned for Listing, Under Review | Under Review | | CA, CO, ID, MT, NV, OR, UT, WY |
| Mammals | Pygmy Rabbit | Brachylagus idahoensis | Listed | Endangered | | WA |
| Flowering Plants | Pygmy rock-cress | Arabis pygmaea | Not Listed | Resolved Taxon | | CA |
| Amphibians | Pygmy salamander | Desmognathus wrighti | Not Listed | Species of Concern | | |
| Fishes | Pygmy Sculpin | Cottus paulus (=pygmaeus) | Listed | Threatened | | AL |
| Snails | Pygmy siltsnail | Cincinnatia parva | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Pygmy siltsnail | Floridobia parva | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Pygmy Talussnail | Sonorella micra | Not Listed | Resolved Taxon | | |
| Mammals | Pygmy Three-toed Sloth | Bradypus pygmaeus | Proposed for Listing | Proposed Threatened | | |
| Fishes | Pygmy whitefish | prosopium coulterii | Not Listed | Species of Concern | | |
| Mammals | Pymatuning red-backed vole | Clethrionomys gapperi paludicola | Not Listed | Resolved Taxon | | OH, PA |
| Clams | pyramid pigtoe | Pleurobema rubrum | Not Listed | Resolved Taxon | | AL, KY, TN |
| Snails | Pyramid slitshell | Gyrotoma pyramidata | Not Listed | Resolved Taxon | | AL |
| Mammals | Pyrenean ibex | Capra pyrenaica pyrenaica | Listed | Endangered | | |
| Birds | Pyrrhuloxia | Cardinalis sinuatus | Not Listed | Species of Concern | | |
| Snails | Quadrate pebblesnail | Somatogyrus quadratus | Not Listed | Species of Concern | | AL |
| Snails | Quartzite Hill Talussnail | Sonorella bowiensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | quayle's ragwort | senecio quaylei | Not Listed | Resolved Taxon | | |
| Insects | Queen Alexandra's birdwing butterfly | Troides alexandrae | Listed | Endangered | | |
| Birds | Queen Charlotte goshawk | Accipiter gentilis laingi | Not Listed | Resolved Taxon | | AK |
| Birds | Queen Charlotte goshawk | Accipiter gentilis laingi | Listed | Threatened | | |
| Snails | Queen Conch | Aliger gigas | Listed | Threatened | | |
| Flowering Plants | Queen-of-the-forest | Filipendula occidentalis | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Mammals | Queensland hairy-nosed wombat (incl. Barnard's) | Lasiorhinus krefftii (formerly L. barnardi and L. gillespiei) | Listed | Endangered | | |
| Mammals | Queensland rat-kangaroo | Bettongia tropica | Listed | Endangered | | |
| Reptiles | Queen snake | Regina septemvittata | Not Listed | Species of Concern | | AR, MO |
| Flowering Plants | Quina | Antirhea portoricensis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Quincy lupine | Lupinus dalesiae | Not Listed | Resolved Taxon | | CA |
| Insects | Quino checkerspot butterfly | Euphydryas editha quino (=E. e. wrighti) | Listed | Endangered | | CA |
| Snails | Quitobaquito tryonia | Tryonia quitobaquitae | Proposed for Listing | Proposed Endangered | | AZ |
| Mammals | Quokka | Setonix brachyurus | Listed | Endangered | | |
| Mammals | Rabbit bandicoot | Macrotis lagotis | Listed | Endangered | | |
| Clams | Rabbitsfoot | Quadrula cylindrica cylindrica | Listed | Threatened | | AL, AR, IL, IN, KS, KY, LA, MO, MS, OH, OK, PA, TN |
| Birds | Radak Micronesian pigeon | Ducula oceanica ratakensis | Not Listed | Status Undefined | | MH |
| Flowering Plants | Radford's sedge | Carex radfordii | Not Listed | Species of Concern | | NC |
| Flowering Plants | Radford's St. John's Wort | Hypericum radfordiorum | Not Listed | Species of Concern | | NC |
| Flowering Plants | Radford's St. John's Wort | Hypericum sp. 1 | Not Listed | Resolved Taxon | | AL, GA, KY, TN |
| Insects | Radulan odynerus vespid wasp | Odynerus radula | Not Listed | Species of Concern | | HI |
| Mammals | Rafinesque's big-eared bat | Plecotus rafinesquii | Not Listed | Species of Concern | | GA, SC |
| Flowering Plants | Raiches manzanita | Arctostaphylos stanfordiana raichei | Not Listed | Species of Concern | | CA |
| Insects | Railroad Valley skipper | Hesperia uncas fulvapalla | Not Listed | Resolved Taxon | | NV |
| Insects | Railroad Valley Skipper | Hesperia uncas reeseorum | Not Listed | Resolved Taxon | | NV |
| Fishes | Railroad Valley springfish | Crenichthys nevadae | Listed | Threatened | | NV |
| Amphibians | Railroad Valley toad | Anaxyrus nevadensis | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Railroad Valley tui chub | Siphateles bicolor ssp. 7 | Not Listed | Resolved Taxon | | NV |
| Clams | Rainbow | Cambarunio iris | | Not Listed | | |
| Flowering Plants | Rainbow manzanita | arctostaphylos rainbowensis | Not Listed | Species of Concern | | |
| Fishes | Rainbow smelt | Osmerus mordax | Not Listed | Species of Concern | | ME |
| Arachnids | Rameshwaram Parachute Spider | Poecilotheria hanumavilasumica | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Ramona cinquuefoil | Horkelia truncata | Not Listed | Resolved Taxon | | CA |
| Mammals | Ramona grasshopper mouse | Onychomys torridus | | Not Listed | | |
| Flowering Plants | Ramona spineflower | Chorizanthe leptotheca | Not Listed | Species of Concern | | |
| Snails | Rampart Talussnail | Sonorella reederi | Not Listed | Resolved Taxon | | |
| Amphibians | Ramsey Canyon leopard frog | Rana subaquavocalis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Ramshaw Meadows sand-verbena | Abronia alpina | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Ram's-head lady's-slipper | Cypripedium arietinum | Not Listed | Resolved Taxon | | CT, MA, ME, MI, MN, NH, NY, VT, WI |
| Insects | Rapids Clubtail Dragonfly | Gomphus quadricolor | | Not Listed | | |
| Insects | Rare skipper | Problema bulenta | | Not Listed | | GA, MD, NC, SC, VA |
| Birds | Raso lark | Alauda razae | Listed | Endangered | | |
| Insects | Rattlesnake-master borer moth | Papaipema eryngii | Not Listed | Resolved Taxon | | AR, IL, KS, KY, NC, OK |
| Flowering Plants | Ravendale skullcap | Scutellaria nana | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Raven's milk-vetch | Astragalus monoensis ravenii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Raven's seedbox | Ludwigia ravenii | Petitioned for Listing, Under Review | Under Review | | SC |
| Flowering Plants | Ravine sedge | Carex impressinervia | Petitioned for Listing, Under Review | Under Review | | AL, MS, NC, SC |
| Flowering Plants | Rawhide Hill onion | Allium tuolumnense | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Rawson's flaming trumpet | Collomia rawsoniana | Not Listed | Resolved Taxon | | CA |
| Clams | Rayed Bean | Villosa fabalis | Listed | Endangered | | IN, KY, MI, NY, OH, PA, TN, WV |
| Clams | Rayed creekshell | Anodontoides radiatus | | Not Listed | | AL, FL, GA |
| Flowering Plants | Rayless layia | Layia discoidea | Not Listed | Species of Concern | | CA |
| Flowering Plants | Raynor's huckleberry | Vaccinium crassifolium | Not Listed | Species of Concern | | SC |
| Fishes | Razorback sucker | Xyrauchen texanus | Listed | Endangered | Proposed Reclassification to Threatened | AZ, CA, CO, NM, NV, UT |
| Birds | Razorbill | Alca torda | Not Listed | Species of Concern | | |
| Birds | Razor-billed curassow | Mitu mitu mitu | Listed | Endangered | | |
| Insects | Reakirt's blue butterfly | Echinargus isola | Not Listed | Resolved Taxon | | AR, AZ, CA, CO, IA, KS, LA, MN, MO, MT, NM, NV, OK, SD, TX, UT, WY |
| Flowering Plants | Reclining bulrush | Scirpus flaccidifolius | Not Listed | Species of Concern | | VA |
| Flowering Plants | Recurved larkspur | calochortus pulchellus | Not Listed | Species of Concern | | |
| Flowering Plants | Recurved larkspur | Delphinium recurvatum | Not Listed | Species of Concern | | CA |
| Crustaceans | Redacted cave amphipod | Stygobromus redactus | Not Listed | Species of Concern | | WV |
| Insects | Red anomis noctuid moth | Anomis vulpicolor | Not Listed | Species of Concern | | HI |
| Mammals | Red-backed squirrel monkey | Saimiri oerstedii | Listed | Endangered | | |
| Mammals | Red-bellied monkey | Cercopithecus erythrogaster | Listed | Endangered | | |
| Birds | Red-billed curassow | Crax blumenbachii | Listed | Endangered | | |
| Birds | Red-billed Pigeon | Patagioenas flavirostris | Not Listed | Species of Concern | | |
| Birds | Red-billed Tropicbird | Phaethon aethereus mesonauta | Not Listed | Species of Concern | | |
| Flowering Plants | Red Bluff rush | Juncus leiospermus leiospermus | Not Listed | Resolved Taxon | | CA |
| Birds | Red-breasted Merganser | Mergus serrator | Not Listed | Species of Concern | | |
| Birds | red-breasted sapsucker | Sphyrapicus ruber | Not Listed | Status Undefined | | |
| Fishes | Redbreast Sunfish | Lepomis auritus | | Not Listed | | |
| Birds | Red-browed parrot | Amazona rhodocorytha | Listed | Endangered | | |
| Flowering Plants | Red Canyon beardtongue | Penstemon bracteatus | Not Listed | Species of Concern | | UT |
| Flowering Plants | Red Canyon catchfly | Silene petersonii minor | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Red Canyon phlox | Phlox gladiformis | Not Listed | Resolved Taxon | | NV, UT |
| Birds | Red-capped parrot | Pionopsitta pileata | Listed | Endangered | | |
| Reptiles | Red coachwhip | masticophis flagellum ssp. piceus | Not Listed | Species of Concern | | |
| Birds | Red-cockaded woodpecker | Dryobates borealis | Listed | Threatened | | AL, AR, FL, GA, LA, MS, NC, OK, SC, TX, VA |
| Birds | Red crossbill | Loxia curvirostra | Not Listed | Species of Concern | | NC |
| Birds | Red-crowned parrot | Amazona viridigenalis | Not Listed | Resolved Taxon | | TX |
| Birds | Reddish Egret | Egretta rufescens | Not Listed | Species of Concern | | |
| Fishes | Red Drum | Sciaenops ocellatus | | Not Listed | | |
| Mammals | Red-eared nose-spotted monkey | Cercopithecus erythrotis | Listed | Endangered | | |
| Reptiles | Red-Eared Slider | Trachemys scripta elegans | | Not Listed | | |
| Fishes | Redear Sunfish | Lepomis microlophus | | Not Listed | | |
| Crustaceans | Redell's cave amphipod | Stygobromus reddelli | Not Listed | Resolved Taxon | | TX |
| Fishes | Redeye Bass | Micropterus coosae | | Not Listed | | |
| Birds | Red-faced Cormorant | Urile urile | Not Listed | Species of Concern | | |
| Birds | Red-faced malkoha (cuckoo) | Phaenicophaeus pyrrhocephalus | Listed | Endangered | | |
| Birds | Red-faced Warbler | Cardellina rubrifrons | Not Listed | Species of Concern | | |
| Fishes | Redfin Darter | Etheostoma whipplei | | Not Listed | | |
| Flowering Plants | Red fir catchfly | Silene invisa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Red-flowered lotus | Lotus rubriflorus | Not Listed | Species of Concern | | CA |
| Birds | Red-footed Booby | Sula sula | Not Listed | Species of Concern | | |
| Birds | Red-footed Booby | Sula sula sula | Not Listed | Species of Concern | | |
| Flowering Plants | Red-fruited desert-parsley | Lomatium erythrocarpum | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Redheaded sphecid wasp | Eucerceris ruficeps | Not Listed | Species of Concern | | CA, NV |
| Birds | Red-headed Woodpecker | Melanerpes erythrocephalus | Not Listed | Species of Concern | | |
| Flowering Plants | Red Hills butterweed | Senecio clevelandii heterophyllus | Not Listed | Resolved Taxon | | CA |
| Fishes | Red Hills roach | Lavinia symmetricus ssp. | Not Listed | Species of Concern | | CA |
| Amphibians | Red Hills salamander | Phaeognathus hubrichti | Listed | Threatened | | AL |
| Flowering Plants | Red Hills soaproot | Chlorogalum grandiflorum | Not Listed | Species of Concern | | CA |
| Insects | Red Hills unique whirligig | Spanglerogyrus albiventris | Not Listed | Species of Concern | | AL |
| Flowering Plants | Red Hills vervain | Verbena californica | Listed | Threatened | | CA |
| Mammals | Red kangaroo | Macropus rufus | Delisted | Recovery | | |
| Birds | Red Knot | Calidris canutus roselaari | Not Listed | Resolved Taxon | | |
| Mammals | Red lechwe | Kobus leche | Listed | Threatened | | |
| Birds | Red-legged Kittiwake | Rissa brevirostris | Not Listed | Species of Concern | | AK |
| Fishes | Redline Darter | Nothonotus rufilineatus | | Not Listed | | |
| Fishes | redlips darter | Etheostoma maydeni | Not Listed | Resolved Taxon | | |
| Flowering Plants | Red Mountain buckwheat | Eriogonum kelloggii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Red Mountain catchfly | Silene campanulata campanulata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Red Mountain stonecrop | Sedum eastwoodiae | Not Listed | Resolved Taxon | | CA |
| Birds | Red-necked parrot | Amazona arausiaca | Listed | Endangered | | |
| Birds | Red-necked Phalarope | Phalaropus lobatus | Not Listed | Species of Concern | | |
| Arachnids | Red Parachute Spider | Poecilotheria miranda | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Red Phalarope | Phalaropus fulicarius | Not Listed | Species of Concern | | |
| Fishes | Red River Pupfish | Cyprinodon rubrofluviatilis | | Not Listed | | |
| Flowering Plants | Red Rock Canyon aster | ionactis caelestis | Not Listed | Species of Concern | | |
| Insects | Redrock stonefly | Anacroneuria wipukupa | Petitioned for Listing, Under Review | Under Review | | AZ |
| Flowering Plants | Red Rock tarweed | Hemizonia arida | Not Listed | Species of Concern | | CA |
| Flowering Plants | Red-root yampah | Perideridia erythrorhiza | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Red Shiner | Cyprinella lutrensis | | Not Listed | | |
| Birds | Red-shouldered hawk | buteo lineatus | Not Listed | Species of Concern | | |
| Fishes | Redside Dace | Clinostomus elongatus | | Not Listed | | |
| Fishes | Redside Shiner | Richardsonius balteatus | | Not Listed | | |
| Birds | Red siskin | Carduelis cucullata | Listed | Endangered | | |
| Arachnids | Redslate Ornamental Tarantula | Poecilotheria rufilata | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Red-spectacled parrot | Amazona pretrei pretrei | Listed | Endangered | | |
| Fishes | Redspot Chub | Nocomis asper | | Not Listed | | |
| Fishes | Redspotted Sunfish | Lepomis miniatus | | Not Listed | | |
| Fishes | Red Swamp Crayfish | Procambarus clarkii | | Not Listed | | |
| Birds | Red-tailed Hawk | Buteo jamaicensis | | Not Listed | | |
| Birds | Red-tailed parrot | Amazona brasiliensis | Listed | Endangered | | |
| Birds | Red-tailed Tropicbird | Phaethon rubricauda | Not Listed | Species of Concern | | |
| Birds | Red-tailed Tropicbird | Phaethon rubricauda melanorhynchos | Not Listed | Species of Concern | | |
| Insects | Redtail sphecid wasp | Ectemnius rubrocaudatus | Not Listed | Species of Concern | | HI |
| Birds | Red-throated Loon | Gavia stellata | Not Listed | Species of Concern | | |
| Mammals | red tree vole | Arborimus longicaudus | Not Listed | Resolved Taxon | | OR |
| Insects | Redveined prairie leafhopper | Aflexia rubranura | Not Listed | Species of Concern | | IL, WI |
| Mammals | Red wolf | Canis rufus | Listed | Endangered | | NC |
| Mammals | Red wolf | Canis rufus | Listed | Experimental Population, Non-Essential | | NC |
| Snails | Redwood shoulderband | Helminthoglypta sequoicola consors | Not Listed | Species of Concern | | CA |
| Snails | Reed's Mountain woodlandsnail | Ashmunella ferrissi | Not Listed | Resolved Taxon | | |
| Flatworms and Roundworms | Refton Cave planarian | Sphalloplana pricei | Not Listed | Species of Concern | | PA |
| Flowering Plants | Refugio manzanita | Arctostaphylos refugioensis | Not Listed | Species of Concern | | CA |
| Crustaceans | Regal Burrowing crayfish | Procambarus regalis | Not Listed | Status Undefined | | AR |
| Insects | Regal fritillary | Speyeria idalia | Not Listed | Resolved Taxon | | AR, CO, IA, IL, IN, KS, MN, MO, MT, ND, NE, OK, PA, SD, WI, WY |
| Flowering Plants | Reid's stonecrop | Sedum moranii | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Reisen's hydropsyche caddisfly | Hydropsyche reiseni | Not Listed | Species of Concern | | OK |
| Fishes | Relict dace | Relictus solitarius | Petitioned for Listing, Under Review | Under Review | | NV |
| Fishes | Relict darter | Etheostoma chienense | Listed | Threatened | | KY |
| Birds | Relict gull | Larus relictus | Listed | Endangered | | |
| Amphibians | Relict leopard Frog | Lithobates onca | Not Listed | Resolved Taxon | | AZ, NV |
| Flowering Plants | Relict trillium | Trillium reliquum | Listed | Endangered | | AL, GA, SC |
| Amphibians | Relictual slender salamander | Batrachoseps relictus | Proposed for Listing | Proposed Endangered | | CA |
| Insects | Remote conehead katydid | Conocephaloides remotus | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Remy's `anaunau | Lepidium bidentatum remyi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Remy's nehe | Lipochaeta remyi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Repand Twinpod | Physaria repanda | Not Listed | Resolved Taxon | | |
| Birds | Resplendent quetzel | Pharomachrus mocinno ssp. mocinno | Listed | Endangered | | |
| Reptiles | Reticulate collared lizard | Crotaphytus reticulatus | Not Listed | Resolved Taxon | | TX |
| Amphibians | Reticulated flatwoods salamander | Ambystoma bishopi | Listed | Endangered | | FL, GA |
| Reptiles | Reticulated gecko | Coleonyx reticulatus | Not Listed | Resolved Taxon | | TX |
| Birds | Reunion cuckoo-shrike | Coquus newtoni | Listed | Endangered | | |
| Flowering Plants | Reveal indian paintbrush | Castilleja revealii | Not Listed | Species of Concern | | UT |
| Flowering Plants | Reveal's buckwheat | Eriogonum contiguum | Not Listed | Resolved Taxon | | CA, NV |
| Snails | Reverse pepplesnail | Somatogyrus alcoviensis | Petitioned for Listing, Under Review | Under Review | | GA |
| Snails | Ribbed elimia | Elimia laeta | Not Listed | Resolved Taxon | | AL |
| Snails | Ribbed slitshell | Gyrotoma pumila | Not Listed | Resolved Taxon | | AL |
| Mammals | Richardson's ground squirrel | Spermophilus richardsoni nevadensis | Not Listed | Resolved Taxon | | ID, NV, OR |
| Insects | Rich Mountain cave beetle | Pseudanophthalmus krekeleri | Not Listed | Species of Concern | | WV |
| Amphibians | Rich Mountain salamander | Plethodon ouachitae | Not Listed | Resolved Taxon | | AR, OK |
| Snails | Rich Mt. slitmouth | Stenotrema pilsbryi | Not Listed | Species of Concern | | AR, OK |
| Insects | Ricksecker's water scavenger beetle | Hydrochara rickseckeri | Not Listed | Species of Concern | | CA |
| Reptiles | Ricord's rock iguana | Cyclura ricordi | Not Listed | Resolved Taxon | | |
| Birds | Ridgeway's hawk | Buteo ridgwayi | Petitioned for Listing, Under Review | Under Review | | |
| Insects | Riffle beetle | Microcylloepus sp | Not Listed | Status Undefined | | |
| Reptiles | rim rock crowned snake | Tantilla oolitica | Proposed for Listing | Proposed Endangered | | FL |
| Flowering Plants | Rincon ceanothus | Ceanothus confusus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Rincon Mountain Rockcress | Pennellia tricornuta | Not Listed | Resolved Taxon | | |
| Snails | Rincon Talussnail | Sonorella bagnarai | Not Listed | Resolved Taxon | | |
| Birds | Ring-billed Gull | Larus delawarensis | Not Listed | Species of Concern | | |
| Snails | Ringed hornsnail | Pleurocera annulifera | Not Listed | Species of Concern | | AL |
| Reptiles | Ringed map turtle | Graptemys oculifera | Listed | Threatened | | LA, MS |
| Mammals | Ringed seal | Phoca (=Pusa) hispida ladogensis | Listed | Endangered | | |
| Mammals | Ringed Seal | Phoca (=Pusa) hispida botnica | Listed | Threatened | | |
| Mammals | Ringed Seal | Phoca (=Pusa) hispida hispida | Listed | Threatened | | |
| Mammals | Ringed Seal | Phoca (=Pusa) hispida ochotensis | Listed | Threatened | | |
| Reptiles | Ringneck snake | diadophis punctatus | Not Listed | Species of Concern | | |
| Clams | Ring Pink | Obovaria retusa | Listed | Endangered | | IL, IN, KY, TN |
| Clams | Ring Pink | Obovaria retusa | Listed | Experimental Population, Non-Essential | | TN |
| Mammals | Ringtail | bassariscus astutus | Not Listed | Species of Concern | | |
| Mammals | Rio de Oro Dama gazelle | Gazella dama lozanoi | Listed | Endangered | | |
| Fishes | Rio Grande bluntnose shiner | Notropis simus simus | Not Listed | Resolved Taxon | | NM |
| Fishes | Rio Grande chub | Gila pandora | Not Listed | Resolved Taxon | | CO, NM |
| Reptiles | Rio Grande cooter | Pseudemys gorzugi | Not Listed | Resolved Taxon | | NM, TX |
| Fishes | Rio Grande cutthroat trout | Oncorhynchus clarkii virginalis | | Not Listed | | CO, NM |
| Fishes | Rio Grande darter | Etheostoma grahami | Not Listed | Species of Concern | | TX |
| Amphibians | Rio Grande lesser siren | Siren intermedia texana | Not Listed | Species of Concern | | TX |
| Fishes | Rio Grande shiner | Notropis jemezanus | Petitioned for Listing, Under Review | Under Review | | NM, TX |
| Fishes | Rio Grande Silvery Minnow | Hybognathus amarus | Listed | Endangered | | NM |
| Fishes | Rio Grande Sucker | Catostomus plebeius | Not Listed | Resolved Taxon | | CO, NM, TX |
| Snails | Rio Grand Holospira | Holospira riograndensis | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Riparian brush rabbit | Sylvilagus bachmani riparius | Listed | Endangered | | CA |
| Mammals | Riparian woodrat (=San Joaquin Valley) | Neotoma fuscipes riparia | Listed | Endangered | | CA |
| Flowering Plants | Ripley milk-vetch | Astragalus ripleyi | Not Listed | Species of Concern | | CO, NM |
| Flowering Plants | Ripley's senna | Senna ripleyana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Ripley wild-buckwheat | Eriogonum ripleyi | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Riverbank vervain | Verbena riparia | Not Listed | Species of Concern | | NC, VA |
| Fishes | River Carpsucker | Carpiodes carpio | | Not Listed | | |
| Fishes | River Chub | Nocomis micropogon | | Not Listed | | |
| Fishes | River Darter | Percina shumardi | | Not Listed | | |
| Fishes | River Goby | Awaous banana | | Not Listed | | |
| Fishes | Riverine Clingfish | Gobiesox nudus | | Not Listed | | |
| Insects | Riverine Clubtail | Stylurus amnicola | | Not Listed | | |
| Fishes | River lamprey | Lampetra ayresii | Not Listed | Resolved Taxon | | AK, CA, OR, WA |
| Mammals | River otter | Lontra canadensis | Not Listed | Resolved Taxon | | |
| Fishes | River Redhorse | Moxostoma carinatum | Not Listed | Status Undefined | | |
| Flowering Plants | River rock-daisy | Perityle warnockii | Not Listed | Resolved Taxon | | TX |
| Fishes | River Shiner | Notropis blennius | | Not Listed | | |
| Insects | Riverside cuckoo bee | Holcopasites ruthae | Not Listed | Resolved Taxon | | |
| Crustaceans | Riverside fairy shrimp | Streptocephalus woottoni | Listed | Endangered | | CA |
| Reptiles | River terrapin | Batagur baska | Listed | Endangered | | |
| Flowering Plants | Roan Mountain bluet | Hedyotis purpurea var. montana | Listed | Endangered | | NC, TN, VA |
| Flowering Plants | Roan Mountain false goats beard | Astilbe crenatiloba | Not Listed | Species of Concern | | TN |
| Fishes | Roanoke Bass | Ambloplites cavifrons | | Not Listed | | |
| Fishes | Roanoke logperch | Percina rex | Listed | Endangered | Proposed Delisting | NC, VA |
| Clams | Roanoke Slabshell | Elliptio roanokensis | | Not Listed | | |
| Snails | Roan supercoil | Paravitrea varidens | Not Listed | Species of Concern | | NC, TN |
| Arachnids | Robber Baron Cave Meshweaver | Cicurina baronia | Listed | Endangered | | TX |
| Insects | Robber fly | Proctacanthus species | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Robbins' cinquefoil | Potentilla robbinsiana | Delisted | Recovery | | NH |
| Flowering Plants | Robbins, milk-vetch | Astragalus robbinsii alpiniformis | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Robbins, milk-vetch | Astragalus robbinsii robbinsii | Not Listed | Resolved Taxon | | VT |
| Flowering Plants | Robbins, western ssp. milk-vetch | Astragalus robbinsii occidentalis | Not Listed | Species of Concern | | NV |
| Insects | Robert's alloperlan stonefly | Alloperla roberti | Not Listed | Resolved Taxon | | IL |
| Flowering Plants | Robert's stonecrop | Sedum robertsianum | Not Listed | Species of Concern | | TX |
| Insects | Robert's wingless thread bug | Nesidiolestes roberti | Not Listed | Species of Concern | | HI |
| Flowering Plants | Robinson's pepper-grass | lepidium virginicum var. robinsonii | Not Listed | Species of Concern | | |
| Insects | Robinson's rain scarab beetle | Phoebetus robinsoni | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Robison's monardella | Monardella robisonii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Robust bidens | Bidens valida | Not Listed | Resolved Taxon | | HI |
| Insects | Robust dubiraphian riffle beetle | Dubiraphia robusta | Not Listed | Species of Concern | | WI |
| Flowering Plants | Robust Hoffmann's buckwheat | Eriogonum hoffmannii robustius | Not Listed | Resolved Taxon | | CA |
| Snails | Robust Holospira | Holospira pasonis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Robust monardella | monardella villosa ssp. globosa | Not Listed | Species of Concern | | |
| Flowering Plants | Robust Oak | Quercus robusta | Not Listed | Resolved Taxon | | |
| Insects | Robust pentagenian burrowing mayfly | Pentagenia robusta | Not Listed | Resolved Taxon | | OH |
| Flowering Plants | Robust prickly-poppy | Argemone munita robusta | Not Listed | Resolved Taxon | | CA |
| Fishes | Robust redhorse | Moxostoma robustum | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC |
| Flowering Plants | Robust spineflower | Chorizanthe robusta var. robusta | Listed | Endangered | | CA |
| Snails | Robust tryonia | Tryonia robusta | Not Listed | Species of Concern | | CA |
| Fishes | Rock Bass | Ambloplites rupestris | | Not Listed | | |
| Flowering Plants | Rockcastle aster | Eurybia saxicastellii | | Not Listed | | KY, TN |
| Flowering Plants | Rock Creek broomrape | Orobanche valida valida | Not Listed | Species of Concern | | CA |
| Fishes | Rock darter | Etheostoma rupestre | Not Listed | Resolved Taxon | | AL, GA, MS |
| Lichens | Rock gnome lichen | Gymnoderma lineare | Listed | Endangered | | GA, NC, SC, TN, VA |
| Flowering Plants | Rock lady | Holmgrenanthe petrophila | Not Listed | Species of Concern | | CA |
| Flowering Plants | Rock monardella | Monardella viridis saxicola | Not Listed | Resolved Taxon | | CA |
| Clams | Rock Pocketbook | Arcidens confragosus | | Not Listed | | |
| Ferns and Allies | Rock quillwort | Isoetes lithophila | Not Listed | Species of Concern | | TX |
| Birds | Rock Sandpiper | Calidris ptilocnemis ptilocnemis | Not Listed | Species of Concern | | |
| Flowering Plants | Rock sanicle | Sanicula saxatilis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Rock's nehe | Lipochaeta rockii | Not Listed | Resolved Taxon | | HI |
| Snails | Rocky coast Pacific sideband | Monadenia fidelis pronotis | Not Listed | Resolved Taxon | | CA |
| Snails | Rocky Mountain capshell | Acroloxus coloradensis | Not Listed | Resolved Taxon | | CO, MT |
| Flowering Plants | Rocky Mountain monkeyflower | Mimulus gemmiparus | Not Listed | Resolved Taxon | | CO |
| Amphibians | Rocky Mountain Tailed Frog | Ascaphus montanus | | Not Listed | | |
| Fishes | Rocky shiner | Notropis suttkusi | Petitioned for Listing, Under Review | Under Review | | AR, OK |
| Flowering Plants | Roderick's fritillary | Fritillaria grayana | Not Listed | Resolved Taxon | | CA |
| Birds | Rodrigues fody | Foudia flavicans | Listed | Endangered | | |
| Mammals | Rodrigues fruit bat (=flying fox) | Pteropus rodricensis | Listed | Endangered | | |
| Birds | Rodrigues warbler (old world warbler) | Bebrornis rodericanus | Listed | Endangered | | |
| Insects | Rogers' cave beetle | Pseudanophthalmus rogersae | Not Listed | Species of Concern | | KY |
| Insects | Rogue Creek hydroptila caddisfly | Hydroptila okaloosa | Not Listed | Resolved Taxon | | |
| Snails | Rolling pebblesnail | Somatogyrus strengi | Not Listed | Species of Concern | | AL |
| Birds | Roseate Spoonbill | Platalea ajaja | Not Listed | Species of Concern | | |
| Birds | Roseate tern | Sterna dougallii dougallii | Listed | Endangered | | CT, DE, MA, MD, ME, NC, NH, NJ, NY, RI, SC, VA |
| Birds | Roseate tern | Sterna dougallii dougallii | Listed | Threatened | | FL, PR, VI |
| Birds | Roseate Tern | Sterna dougallii | Not Listed | Species of Concern | | |
| Birds | Rose-breasted Grosbeak | Pheucticus ludovicianus | Not Listed | Species of Concern | | |
| Flowering Plants | Rose-flowered foxtail cactus | Escobaria vivipara rosea | Not Listed | Resolved Taxon | | AZ, CA, NV, UT |
| Flowering Plants | Rosemary-mint | Poliomintha glabrescens | Not Listed | Resolved Taxon | | TX |
| Arachnids | Rosemary wolf spider | Lycosa ericeticola | Not Listed | Resolved Taxon | | |
| Snails | Rosemont talussnail | Sonorella rosemontensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Rose-purple sand-verbena | Abronia umbellata acutalata | Not Listed | Species of Concern | | WA |
| Birds | Rose-throated Becard | Pachyramphus aglaiae | Not Listed | Species of Concern | | |
| Flowering Plants | Ross bentgrass | Agrostis rossiae | Not Listed | Resolved Taxon | | WY |
| Arachnids | Ross micro-blind harvestman | Microcina sp | Not Listed | Resolved Taxon | | |
| Insects | Ross's apatalestes tabanid fly | Apatalestes rossi | Not Listed | Resolved Taxon | | CA |
| Birds | Ross's Gull | Rhodostethia rosea | Not Listed | Species of Concern | | |
| Flowering Plants | Ross' Woodfern | Dryopteris rossii | Not Listed | Resolved Taxon | | |
| Snails | Roswell springsnail | Pyrgulopsis roswellensis | Listed | Endangered | | NM |
| Reptiles | Rosy boa | Charina trivirgata | Not Listed | Species of Concern | | AZ, CA |
| Flowering Plants | Rosy-pink spurge | Euphorbia rosescens | Not Listed | Status Undefined | | |
| Fishes | Rosyside Dace | Clinostomus funduloides | | Not Listed | | |
| Insects | Rota blue damselfly | Ischnura luta | Listed | Endangered | | MP |
| Birds | Rota bridled white-eye | Zosterops rotensis | Listed | Endangered | | MP |
| Insects | Roth's blind ground beetle | Pterostichus rothi | Not Listed | Species of Concern | | OR |
| Birds | Rothschild's starling (myna) | Leucopsar rothschildi | Listed | Endangered | | |
| Insects | Roth's dune weevil | Trigonoscuta rothi algodones | Not Listed | Resolved Taxon | | |
| Insects | Roth's dune weevil | Trigonoscuta rothi imperialis | Not Listed | Resolved Taxon | | |
| Insects | Roth's dune weevil | Trigonoscuta rothi punctata | Not Listed | Resolved Taxon | | |
| Insects | Roth's dune weevil | Trigonoscuta rothi rothi | Not Listed | Resolved Taxon | | |
| Snails | Rotund rocksnail | Leptoxis ligata | Not Listed | Resolved Taxon | | AL |
| Snails | Rotund Vertigo | Vertigo berryi | Not Listed | Resolved Taxon | | |
| Corals | Rough Cactus Coral | Mycetophyllia ferox | Listed | Threatened | | |
| Clams | Rough Fatmucket | Lampsilis straminea | | Not Listed | | |
| Insects | Rough-headed oceanides seed bug | Oceanides rugosiceps | Not Listed | Species of Concern | | HI |
| Fishes | Roughhead shiner | Notropis semperasper | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Rough hornsnail | Pleurocera foremani | Listed | Endangered | | AL |
| Flowering Plants | Rough-leaved loosestrife | Lysimachia asperulaefolia | Listed | Endangered | | NC, SC |
| Birds | Rough-legged hawk | buteo lagopus | Not Listed | Species of Concern | | |
| Snails | Rough-lined elimia | Elimia pilsbryi | Not Listed | Resolved Taxon | | AL |
| Clams | Rough pigtoe | Pleurobema plenum | Listed | Endangered | | IL, IN, KY, TN, VA |
| Clams | Rough pigtoe | Pleurobema plenum | Listed | Experimental Population, Non-Essential | | TN |
| Flowering Plants | rough popcornflower | Plagiobothrys hirtus | Listed | Endangered | | OR |
| Clams | Rough rabbitsfoot | Quadrula cylindrica strigillata | Listed | Endangered | | TN, VA, WV |
| Fishes | Rough sculpin | Cottus asperrimus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Rough-seeded fameflower | Talinum rugospermum | Not Listed | Species of Concern | | IA, IL, IN, KS, MN, NE, TX, WI |
| Flowering Plants | Roughseed sea-purslane | Sesuvium trianthemoides | Not Listed | Species of Concern | | TX |
| Amphibians | Rough-skinned newt | taricha granulosa | Not Listed | Species of Concern | | |
| Flowering Plants | rough-stemmed aster | Symphyotrichum puniceum var. scabricaule | | Not Listed | | TX |
| Clams | Round combshell | Epioblasma personata | Not Listed | Resolved Taxon | | AL, TN |
| Clams | Round Ebonyshell | Reginaia rotulata | Listed | Endangered | | AL, FL |
| Clams | Round hickorynut | Obovaria subrotunda | Listed | Threatened | | AL, IN, KY, MI, MS, OH, PA, TN, WV |
| Reptiles | Round Island bolyeria boa | Bolyeria multocarinata | Listed | Endangered | | |
| Reptiles | Round Island casarea boa | Casarea dussumieri | Listed | Endangered | | |
| Reptiles | Round Island day gecko | Phelsuma guentheri | Listed | Endangered | | |
| Reptiles | Round Island skink | Leiolopisma telfairi | Listed | Threatened | | |
| Flowering Plants | Round leaf, Death Valley phacelia | Phacelia mustelina | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Roundleaf four-o'clock | Mirabilis rotundifolia | Not Listed | Species of Concern | | CO |
| Flowering Plants | Roundleaf Liverwort | Cephaloziella obtusilobula | Not Listed | Species of Concern | | GA, NC |
| Flowering Plants | Round-leaf willow | Salix ovalifolia glacialis | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | Round-leaved chaff-flower | Achyranthes splendens var. rotundata | Listed | Endangered | | HI |
| Fishes | Roundnose Minnow | Dionda episcopa | | Not Listed | | |
| Clams | Round Pigtoe | Pleurobema sintoxia | | Not Listed | | |
| Snails | Round-rib elimia | Elimia nassula | Petitioned for Listing, Under Review | Under Review | | AL |
| Snails | Round rocksnail | Leptoxis ampla | Listed | Threatened | | AL |
| Snails | Round slitshell | Gyrotoma walkeri | Not Listed | Resolved Taxon | | AL |
| Fishes | Roundtail chub | Gila robusta | Not Listed | Resolved Taxon | | AZ, NM |
| Fishes | Roundtail chub | Gila robusta | | Not Listed | | |
| Mammals | Round-tailed muskrat | Neofiber alleni | Not Listed | Species of Concern | | |
| Fishes | Round Whitefish | Prosopium cylindraceum | | Not Listed | | |
| Flowering Plants | Royal catchfly | Silene regia | Not Listed | Resolved Taxon | | AL, AR, GA, IL, IN, KS, KY, MO, OH, OK |
| Birds | Royal cinclodes | Cinclodes aricomae | Listed | Endangered | | |
| Flowering Plants | Royal, Florida palm | Roystonea elata | Not Listed | Resolved Taxon | | |
| Flowering Plants | Royal Gorge stickleaf | Mentzelia densa | Not Listed | Resolved Taxon | | CO |
| Snails | Royal marstonia (snail) | Marstonia ogmorhaphe | Listed | Endangered | | TN |
| Insects | Royal Moth | sphingicampa blanchardi | Not Listed | Resolved Taxon | | TX |
| Birds | royal penguin | Eudyptes schlegeli | Not Listed | Resolved Taxon | | |
| Arachnids | Royal syarinid pseudoscorpion | Chitrella regina | Not Listed | Species of Concern | | WV |
| Birds | Royal Tern | Thalasseus maximus | Not Listed | Species of Concern | | |
| Mammals | Roy Prairie pocket gopher | Thomomys mazama glacialis | Listed | Threatened | | WA |
| Crustaceans | Rubious Cave amphipod | Stygobromus lucifugus | Not Listed | Resolved Taxon | | IL |
| Flowering Plants | Ruby bundleflower | Desmanthus bicornutus | Not Listed | Resolved Taxon | | AZ |
| Birds | Ruddy Duck | Oxyura jamaicensis | Not Listed | Species of Concern | | |
| Birds | Ruddy Duck | Oxyura jamaicensis jamaicensis | Not Listed | Species of Concern | | PR, VI |
| Birds | Ruddy Turnstone | Arenaria interpres morinella | Not Listed | Species of Concern | | |
| Insects | Rude's long-horned beetle | Necydalis rudei | Not Listed | Species of Concern | | CA |
| Birds | rufa red knot | Calidris canutus rufa | Listed | Threatened | | AL, AR, CO, CT, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NY, OH, OK, PA, RI, SC, SD, TN, TX, VA, WI, WV, WY |
| Birds | Ruffed Grouse | Bonasa umbellus | Not Listed | Species of Concern | | |
| Crustaceans | Ruffo's Cave Amphipod | Paramexiweckelia ruffoi | Not Listed | Resolved Taxon | | |
| Birds | Rufous-crowned Sparrow | Aimophila ruficeps | Not Listed | Species of Concern | | |
| Birds | Rufous-crowned Sparrow | Aimophila ruficeps eremoeca | Not Listed | Species of Concern | | |
| Birds | Rufous Fantail | Rhipidura rufifrons mariae | Not Listed | Species of Concern | | |
| Birds | Rufous Fantail | Rhipidura rufifrons saipanensis | Not Listed | Species of Concern | | |
| Birds | Rufous Hummingbird | Selasphorus rufus | Not Listed | Species of Concern | | |
| Flowering Plants | Rugel's pawpaw | Deeringothamnus rugelii | Listed | Endangered | | FL |
| Flowering Plants | Rugel''s Ragwort | Rugelia nudicaulis | Not Listed | Species of Concern | | NC |
| Snails | Rugged hornsnail | Pleurocera alveare | Not Listed | Species of Concern | | AL, AR, KY, MO, TN |
| Snails | Rugose rocksnail | Lithasia jayana | Not Listed | Species of Concern | | TN |
| Insects | Rugulose yellow-faced bee | Nesoprosopis rugulosa | Not Listed | Resolved Taxon | | HI |
| Snails | Ruidoso Snaggletooth | Gastrocopta ruidosensis | Not Listed | Resolved Taxon | | |
| Insects | Rulien's miloderes weevil | Miloderes rulieni | Not Listed | Species of Concern | | NV |
| Flowering Plants | Running buffalo clover | Trifolium stoloniferum | Delisted | Recovery | | AR, IN, KY, MO, OH, PA, WV |
| Flowering Plants | Runyon huaco | Manfreda longiflora | Not Listed | Species of Concern | | TX |
| Flowering Plants | Runyon's water-willow | Justicia runyonii | Not Listed | Species of Concern | | TX |
| Flowering Plants | Rusby's desert-mallow | Sphaeralcea rusbyi eremicola | Not Listed | Species of Concern | | CA |
| Flowering Plants | Rusby's fetid-marigold | Pectis rusbyi | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Rusby's Thistle | Cirsium rusbyi | Not Listed | Resolved Taxon | | |
| Fishes | Rush Darter | Etheostoma phytophilum | Listed | Endangered | | AL |
| Fishes | Russian River tule perch | Hysterocarpus traskii pomo | Not Listed | Species of Concern | | CA |
| Fishes | Russian Sturgeon | Acipenser gueldenstaedtii | Proposed for Listing | Proposed Endangered | | |
| Birds | Rusty Blackbird | Euphagus carolinus | Not Listed | Species of Concern | | |
| Flowering Plants | Rusty hedgehog cactus | Echinocereus russanthus | Not Listed | Resolved Taxon | | TX |
| Insects | Rusty patched bumble bee | Bombus affinis | Listed | Endangered | | IA, IL, IN, MA, MD, ME, MN, OH, VA, WI, WV |
| Fishes | Rustyside sucker | Thoburnia hamiltoni | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | Ruth milkweed | Asclepias ruthiae | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Ruth's golden aster | Pityopsis ruthii | Listed | Endangered | | TN |
| Flowering Plants | Rydberg milk-vetch | Astragalus perianus | Delisted | Original Data in Error - New Information Discovered | | UT |
| Flowering Plants | Rydberg parrya | Parrya rydbergii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Rydberg's scurf-pea | Pediomelum humile | Not Listed | Resolved Taxon | | TX |
| Crustaceans | Rye Cove Cave isopod | Lirceus culveri | Not Listed | Resolved Taxon | | VA |
| Mammals | Ryukyu rabbit | Pentalagus furnessi | Listed | Endangered | | |
| Mammals | Ryukyu sika deer | Cervus nippon keramae | Listed | Endangered | | |
| Flowering Plants | Sabinal prairie-clover | Dalea sabinalis | Not Listed | Species of Concern | | TX |
| Reptiles | Sabine Map Turtle | Graptemys ouachitensis sabinensis | Not Listed | Resolved Taxon | | LA, TX |
| Fishes | Sabine Shiner | Notropis sabinae | | Not Listed | | |
| Insects | Sabino Canyon damselfly | Argia sabino | Petitioned for Listing, Under Review | Under Review | | AZ |
| Fishes | Sablefish | Anoplopoma fimbria | | Not Listed | | |
| Insects | Sacramento anthicid | Anthicus sacramento | Not Listed | Species of Concern | | CA |
| Amphibians | Sacramento mountain salamander | Aneides hardii | Not Listed | Species of Concern | | NM |
| Insects | Sacramento Mountains checkerspot Butterfly | Euphydryas anicia cloudcrofti | Listed | Endangered | | NM |
| Flowering Plants | Sacramento Mountains thistle | Cirsium vinaceum | Listed | Threatened | | NM |
| Flowering Plants | Sacramento Orcutt grass | Orcuttia viscida | Listed | Endangered | | CA |
| Fishes | Sacramento perch | Archoplites interruptus | Not Listed | Species of Concern | | CA |
| Fishes | Sacramento Pikeminnow | Ptychocheilus grandis | | Not Listed | | |
| Flowering Plants | Sacramento prickly poppy | Argemone pleiacantha ssp. pinnatisecta | Listed | Endangered | | NM |
| Flowering Plants | Sacramento saltbush | Atriplex persistens | Not Listed | Status Undefined | | |
| Fishes | Sacramento splittail | Pogonichthys macrolepidotus | Not Listed | Resolved Taxon | | CA |
| Fishes | Sacramento Sucker | Catostomus occidentalis | | Not Listed | | |
| Insects | Sacramento Valley tiger beetle | Cicindela hirticollis abrupta | Not Listed | Resolved Taxon | | CA |
| Fishes | Saddleback Darter | Percina vigil | | Not Listed | | |
| Fishes | Saddled madtom | Noturus fasciatus | | Not Listed | | TN |
| Flowering Plants | Saddle Mountain bittercress | Cardamine pattersonii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Saddle Mountain saxifrage | Micranthes hitchcockiana | Not Listed | Species of Concern | | CA, NV, OR |
| Birds | Sagebrush Sparrow | Artemisiospiza nevadensis | Not Listed | Species of Concern | | |
| Insects | Sagehen Creek goeracean caddisfly | Goeracea oregona | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sage-like loeflingia | Loeflingia squarrosa artemisiarum | Not Listed | Resolved Taxon | | CA |
| Birds | Sage Thrasher | Oreoscoptes montanus | Not Listed | Species of Concern | | |
| Mammals | Saimaa seal | Phoca hispida saimensis | Listed | Endangered | | |
| Insects | Saint Francis' satyr butterfly | Neonympha mitchellii francisci | Listed | Endangered | | NC |
| Insects | Saint Paul cave beetle | Pseudanophthalmus sanctipauli | | Not Listed | | VA |
| Flowering Plants | Saiya | Amoreuxia gonzalezii | Petitioned for Listing, Under Review | Under Review | | AZ |
| Fishes | Sakhalin sturgeon | Acipenser mikadoi | Listed | Endangered | | |
| Amphibians | Salado Salamander | Eurycea chisholmensis | Listed | Threatened | | TX |
| Clams | Salamander mussel | Simpsonaias ambigua | Proposed for Listing | Proposed Endangered | | AR, IA, IL, IN, KY, MI, MO, NY, OH, PA, TN, WI, WV |
| Clams | salina mucket | Potamilus metnecktayi | Proposed for Listing | Proposed Endangered | | TX |
| Snails | Salinas Peak Woodlandsnail | Ashmunella salinasensis | Not Listed | Resolved Taxon | | |
| Mammals | Salinas pocket mouse | Perognathus inornatus psammophilus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Salinas Valley baeria | Lasthenia leptalea | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Salinas Valley popcornflower | Plagiobothrys uncinatus | Not Listed | Species of Concern | | CA |
| Crustaceans | Saline Burrowing crayfish | Fallicambarus strawni | Not Listed | Status Undefined | | AR |
| Flowering Plants | Saline Valley phacelia | Phacelia amabilis | Not Listed | Species of Concern | | CA |
| Insects | Saline Valley snow-front june beetle | Polyphylla anteronivea | Not Listed | Species of Concern | | CA |
| Birds | Salmon-crested cockatoo | Cacatua moluccensis | Listed | Threatened | | |
| Flowering Plants | Salmon Mountains wake robin | Trillium ovatum oettingeri | Not Listed | Resolved Taxon | | CA |
| Fishes | Salt Creek Pupfish | Cyprinodon salinus | | Not Listed | | |
| Insects | Salt Creek Tiger beetle | Cicindela nevadica lincolniana | Listed | Endangered | | NE |
| Mammals | Salt Gulch pocket gopher | Thomomys umbrinus powelli | Not Listed | Species of Concern | | UT |
| Flowering Plants | Salt marsh bird's-beak | Cordylanthus maritimus ssp. maritimus | Listed | Endangered | | CA |
| Flowering Plants | Saltmarsh Cordgrass | Spartina alterniflora | | Not Listed | | |
| Mammals | Salt marsh harvest mouse | Reithrodontomys raviventris | Listed | Endangered | | CA |
| Mammals | Salt marsh ornate shrew | Sorex ornatus salicornicus | Not Listed | Species of Concern | | CA |
| Birds | Saltmarsh Sparrow | Ammospiza caudacuta | Not Listed | Species of Concern | | SC |
| Fishes | Saltmarsh topminnow | Fundulus jenkinsi | | Not Listed | | AL, FL, LA, MS, TX |
| Mammals | Salt marsh vagrant shrew | Sorex vagrans halicoetes | Not Listed | Species of Concern | | CA |
| Reptiles | Saltwater crocodile | Crocodylus porosus | Listed | Endangered | | |
| Reptiles | Saltwater crocodile | Crocodylus porosus | Listed | Threatened | | |
| Crustaceans | Saluda crayfish | Distocambarus youngineri | Petitioned for Listing, Under Review | Under Review | | SC |
| Snails | Samoana tree snail | Samoana conica | Not Listed | Species of Concern | | AS |
| Mammals | Samoan fruit bat | Pteropus samoensis samoensis | Not Listed | Resolved Taxon | | AS |
| Clams | Sampson's pearlymussel | Epioblasma sampsoni | Delisted | Extinction | | IL, IN |
| Insects | Samwell Cave cricket | Pristoceuthophilus sp. | Not Listed | Species of Concern | | CA |
| Snails | San Agustin Mountainsnail | Oreohelix litoralis | Not Listed | Resolved Taxon | | |
| Snails | san andreas woodlandsnail | Ashmunella kochii | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | San Antonio Hills monardella | Monardella antonina | Not Listed | Resolved Taxon | | CA |
| Mammals | San Antonio pocket gopher | Thomomys umbrinus curtatus | Not Listed | Species of Concern | | NV |
| Flowering Plants | San Benito evening-primrose | Camissonia benitensis | Delisted | Recovery | | CA |
| Flowering Plants | San Benito fritillary | Fritillaria viridea | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Benito monardella | Monardella antonina ssp. benitensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Benito spineflower | Chorizanthe biloba immemora | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Benito thornmint | Acanthomintha obovata obovata | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Bernardino birds-beak | Cordylanthus eremicus bernardinus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Bernardino bluegrass | Poa atropurpurea | Listed | Endangered | | CA |
| Flowering Plants | San Bernardino butterweed | Packera bernardina | Not Listed | Species of Concern | | CA |
| Mammals | San Bernardino dusky shrew | Sorex monticolus parvidens | Not Listed | Resolved Taxon | | CA |
| Mammals | San Bernardino Merriam's kangaroo rat | Dipodomys merriami parvus | Listed | Endangered | | CA |
| Reptiles | San Bernardino mountain king snake | Lampropeltis zonata parvirubra | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Bernardino Mountains bladderpod | Lesquerella kingii ssp. bernardina | Listed | Endangered | | CA |
| Flowering Plants | San Bernardino Mountains dudleya | Dudleya abramsii affinis | Not Listed | Species of Concern | | CA |
| Insects | San Bernardino Mountains grasshopper | Trimerotropis bernardi | Not Listed | Resolved Taxon | | |
| Flowering Plants | San Bernardino Mountains monkey-flower | Mimulus exiguus | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Bernardino Mountains orthocarpus | Castilleja lasiorhyncha | Not Listed | Species of Concern | | CA |
| Mammals | San Bernardino northern flying squirrel | Glaucomys sabrinus californicus | Not Listed | Resolved Taxon | | CA |
| Reptiles | San Bernardino ringneck snake | Diadophis punctatus modestus | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Bernardino rock-cress | Arabis breweri pecuniaria | Not Listed | Species of Concern | | CA |
| Snails | San Bernardino springsnail | Pyrgulopsis bernardina | Listed | Threatened | | AZ |
| Crustaceans | Sanborn Crayfish | Faxonius sanbornii | | Not Listed | | |
| Insects | San Bruno elfin butterfly | Callophrys mossii bayensis | Listed | Endangered | | CA |
| Flowering Plants | San Bruno Mountain manzanita | Arctostaphylos imbricata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Carlos wild-buckwheat | Eriogonum capillare | Not Listed | Species of Concern | | AZ |
| Birds | San Clemente Bewick's wren | Thryomanes bewickii leucophrys | Not Listed | Resolved Taxon | | CA |
| Mammals | San Clemente deer mouse | Peromyscus maniculatus clementis | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente island bedstraw | Galium catalinense acrispum | Not Listed | Species of Concern | | CA |
| Snails | San Clemente Island blunt-top snail | Sterkia clementina | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Clemente Island brodiaea | Brodiaea kinkiensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente Island brodiaea | Triteleia clementina | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente Island buckwheat | Eriogonum giganteum formosum | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente Island bush-mallow | Malacothamnus clementinus | Delisted | Recovery | | CA |
| Insects | San Clemente Island coenonycha beetle | Coenonycha clementina | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente Island evening-primrose | Camissonia guadalupensis clementina | Not Listed | Species of Concern | | CA |
| Mammals | San Clemente Island fox | Urocyon littoralis clementae | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente Island larkspur | Delphinium variegatum ssp. kinkiense | Delisted | Recovery | | CA |
| Flowering Plants | San Clemente Island lotus (=broom) | Acmispon dendroideus var. traskiae | Delisted | Recovery | | CA |
| Flowering Plants | San Clemente Island milk-vetch | Astragalus nevinii | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente Island Paintbrush | Castilleja grisea | Delisted | Recovery | | CA |
| Snails | San Clemente islandsnail | Micrarionta gabbii | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Clemente Island woodland-star | Lithophragma maximum | Listed | Endangered | | CA |
| Birds | San Clemente loggerhead shrike | Lanius ludovicianus mearnsi | Listed | Endangered | | CA |
| Birds | San Clemente sage sparrow | Amphispiza belli clementeae | Delisted | Recovery | | CA |
| Clams | Sandbank Pocketbook | Lampsilis satura | | Not Listed | | |
| Flowering Plants | Sandbar, inside-outside willow | Salix interior exterior | Not Listed | Resolved Taxon | | ME, PA |
| Flowering Plants | Sand cholla | Opuntia pulchella | Not Listed | Resolved Taxon | | AZ, CA, NV, UT |
| Flowering Plants | Sand dune phacelia | Phacelia argentea | Listed | Threatened | | CA, OR |
| Flowering Plants | Sanderson's Cheesebush | Hymenoclea sandersonii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Sand flax | Linum arenicola | Listed | Endangered | | FL |
| Flowering Plants | Sandfood | Pholisma sonorae | Not Listed | Species of Concern | | AZ, CA |
| Mammals | Sand gazelle | Gazella subgutturosa marica | Listed | Endangered | | |
| Flowering Plants | Sandhill four-o'clock | Mirabilis nyctaginea | Not Listed | Species of Concern | | TX |
| Flowering Plants | Sandhill goosefoot | Chenopodium cycloides | Not Listed | Species of Concern | | CO, KS, NM, TX |
| Fishes | Sandhills chub | Semotilus lumbee | Not Listed | Resolved Taxon | | NC, SC |
| Insects | Sandhills clubtail | Gomphus parvidens carolinus | Not Listed | Species of Concern | | NC, SC |
| Flowering Plants | Sandhills milk-vetch | Astragalus michauxii | Not Listed | Species of Concern | | GA, NC, SC |
| Flowering Plants | San Diego ambrosia | Ambrosia pumila | Listed | Endangered | | CA |
| Reptiles | San Diego banded gecko | Coleonyx variegatus abbotti | Not Listed | Species of Concern | | CA |
| Mammals | San Diego black-tailed jackrabbit | Lepus californicus bennettii | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Diego button-celery | Eryngium aristulatum var. parishii | Listed | Endangered | | CA |
| Birds | San Diego cactus wren | Campylorhynchus brunneicapillus couesi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Diego County viguiera | viguiera laciniata | Not Listed | Species of Concern | | |
| Mammals | San Diego desert woodrat | Neotoma lepida intermedia | Not Listed | Species of Concern | | CA |
| Crustaceans | San Diego fairy shrimp | Branchinecta sandiegonensis | Listed | Endangered | | CA |
| Flowering Plants | San Diego goldenstar | Muilla clevelandii | Not Listed | Species of Concern | | CA |
| Reptiles | San Diego horned lizard | Phrynosoma coronatum blainvillii | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Diego marsh elder | Iva hayesiana | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Diego mesa-mint | Pogogyne abramsii | Listed | Endangered | | CA |
| Reptiles | San Diego Mountain king snake | Lampropeltis zonata pulchra | Not Listed | Species of Concern | | CA |
| Reptiles | San Diego ringneck snake | Diadophis punctatus similis | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Diego sagewort | artemisia palmeri | Not Listed | Species of Concern | | |
| Flowering Plants | San Diego thornmint | Acanthomintha ilicifolia | Listed | Threatened | | CA |
| Flowering Plants | Sandlace | Polygonella myriophylla | Listed | Endangered | | FL |
| Flowering Plants | Sand linanthus | Linanthus arenicola | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Sand-loving wild-buckwheat | Eriogonum ammophilum | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Sandmat manzanita | Arctostaphylos pumila | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sand mesa manzanita | Arctostaphylos rudis | Not Listed | Species of Concern | | CA |
| Insects | Sand Mountain aphodius scarab | Aphodius sp. | Not Listed | Species of Concern | | NV |
| Insects | Sand Mountain blue | Euphilotes rita ssp. | Not Listed | Species of Concern | | NV |
| Insects | Sand Mountain blue butterfly | Euphilotes pallescens arenamontana | Not Listed | Resolved Taxon | | |
| Insects | Sand Mountain serican scarab | Serica psammobunus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Sandplain gerardia | Agalinis acuta | Listed | Endangered | | CT, MA, MD, NY, RI |
| Flowering Plants | Sand prickly-pear | Opuntia arenaria | Not Listed | Species of Concern | | NM, TX |
| Fishes | Sand Roller | Percopsis transmontana | | Not Listed | | |
| Flowering Plants | Sand sacahuista | Nolina arenicola | Not Listed | Species of Concern | | TX |
| Fishes | Sand Shiner | Notropis stramineus | | Not Listed | | |
| Reptiles | Sand skink | Neoseps reynoldsi | Listed | Threatened | | FL |
| Reptiles | Sandstone night lizard | Xantusia gracilis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Sandstone wild-buckwheat | Eriogonum jamesii rupicola | Not Listed | Resolved Taxon | | UT |
| Insects | Sand-verbena moth | Copablepharon fuscum | Not Listed | Resolved Taxon | | WA |
| Insects | Sand wasp | Microbembex elegans | Not Listed | Resolved Taxon | | |
| Insects | Sand wasp | Stictiella villegasi | Not Listed | Resolved Taxon | | |
| Birds | Sandwich Tern | Thalasseus sandvicensis | Not Listed | Species of Concern | | |
| Insects | Sandy beach tiger beetle | Cicindela hirticollis gravida | Not Listed | Species of Concern | | CA |
| Insects | San Emigdio blue | Plebulina emigdionis | Not Listed | Species of Concern | | CA |
| Reptiles | San Esteban Island chuckwalla | Sauromalus varius | Listed | Endangered | | |
| Fishes | San Felipe gambusia | Gambusia clarkhubbsi | Not Listed | Resolved Taxon | | |
| Flowering Plants | San Felipe monardella | Monardella nana leptosiphon | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Fernando Valley Spineflower | Chorizanthe parryi var. fernandina | Not Listed | Resolved Taxon | | CA |
| Snails | Sanford Talussnail | Sonorella tryoniana | Not Listed | Resolved Taxon | | |
| Flowering Plants | San Francisco Bay spineflower | Chorizanthe cuspidata cuspidata | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Francisco collinsia | collinsia multicolor | Not Listed | Species of Concern | | |
| Mammals | San Francisco dusky-footed woodrat | Neotoma fuscipes annectens | Not Listed | Species of Concern | | CA |
| Insects | San Francisco forktail damselfly | Ischnura gemina | Not Listed | Resolved Taxon | | CA |
| Reptiles | San Francisco garter snake | Thamnophis sirtalis tetrataenia | Listed | Endangered | | CA |
| Flowering Plants | San Francisco gumplant | Grindelia hirsuta maritima | Not Listed | Species of Concern | | CA |
| Insects | San Francisco lacewing | Nothochrysa californica | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Francisco lessingia | Lessingia germanorum (=L.g. var. germanorum) | Listed | Endangered | | CA |
| Flowering Plants | San Francisco owl's-clover | Triphysaria floribunda | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Francisco Peaks ragwort | Packera franciscana | Listed | Threatened | | AZ |
| Flowering Plants | San Francisco popcornflower | Plagiobothrys torreyi var. diffusus | Not Listed | Species of Concern | | CA |
| Insects | San Francisco tree lupine moth | Grapholita edwardsiana | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Francisco wallflower | Erysimum franciscanum | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Gabriel bedstraw | Galium grande | Not Listed | Species of Concern | | CA |
| Snails | San Gabriel chestnut snail | Glyptostoma gabrielense | Not Listed | Status Undefined | | |
| Flowering Plants | San Gabriel manzanita | Arctostaphylos gabrielensis | Not Listed | Species of Concern | | CA |
| Insects | San Gabriel Mountains blue | Plejebus saepiolus ssp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Gabriel Mountains dudleya | Dudleya densiflora | Not Listed | Resolved Taxon | | CA |
| Insects | San Gabriel Mountains elfin | Incisalia mossii ssp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Gabriel River dudleya | Dudleya cymosa crebrifolia | Not Listed | Species of Concern | | CA |
| Clams | Sangre de Cristo peaclam | Pisidium sanguinichristi | Petitioned for Listing, Under Review | Under Review | | NM |
| Mammals | Sanibel Island rice rat | Oryzomys palustris sanibeli | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Sanibel love grass | Eragrostis pectinacea | Not Listed | Species of Concern | | |
| Flowering Plants | San Jacinto bedstraw | Galium californicum primum | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Jacinto Mountains bedstraw | galium angustifolium ssp. jacinticum | Not Listed | Species of Concern | | |
| Flowering Plants | San Jacinto Mountains chia | Salvia columbariae ziegleri | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Jacinto prickly-phlox | Leptodactylon jaegeri | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Jacinto Valley crownscale | Atriplex coronata var. notatior | Listed | Endangered | | CA |
| Flowering Plants | San Joaquin adobe sunburst | Pseudobahia peirsonii | Listed | Threatened | | CA |
| Insects | San Joaquin dune beetle | Coelus gracilis | Not Listed | Resolved Taxon | | CA |
| Mammals | San Joaquin kit fox | Vulpes macrotis mutica | Listed | Endangered | | CA |
| Birds | San Joaquin LeConte's thrasher | Toxostoma lecontei macmillanorum | Not Listed | Species of Concern | | CA |
| Mammals | San Joaquin pocket mouse | Perognathus inornatus | Not Listed | Species of Concern | | CA |
| Mammals | San Joaquin pocket mouse | Perognathus inornatus inornatus | Not Listed | Resolved Taxon | | CA |
| Insects | San Joaquin tiger beetle | Cicindela tranquebarica ssp. | Not Listed | Species of Concern | | CA |
| Insects | San Joaquin Valley giant flower-loving fly | Rhaphiomidas trochilus | Petitioned for Listing, Under Review | Under Review | | CA |
| Flowering Plants | San Joaquin Valley Orcutt grass | Orcuttia inaequalis | Listed | Threatened | | CA |
| Reptiles | San Joaquin whipsnake | Masticophis flagellum ruddocki | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Joaquin wooly-threads | Monolopia (=Lembertia) congdonii | Listed | Endangered | | CA |
| Flowering Plants | San Juan milkweed | Asclepias sanjuanensis | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | San Luis lupine | Lupinus ludovicianus | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Luis mariposa | Calochortus obispoensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Luis Obispo monardella | Monardella frutescens | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Luis sedge | Carex obispoensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Luis serpentine dudleya | Dudleya abramsii bettinae | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Luis watercress | Rorippa coloradensis | Not Listed | Species of Concern | | CO |
| Fishes | San Marcos gambusia | Gambusia georgei | Delisted | Extinction | | TX |
| Insects | San Marcos saddle-case caddisfly | Protoptila arca | Not Listed | Resolved Taxon | | TX |
| Amphibians | San Marcos salamander | Eurycea nana | Listed | Threatened | | TX |
| Flowering Plants | San Mateo thornmint | Acanthomintha obovata ssp. duttonii | Listed | Endangered | | CA |
| Flowering Plants | San Mateo woolly sunflower | Eriophyllum latilobum | Listed | Endangered | | CA |
| Flowering Plants | San Miguel Island bedstraw | Galium californicum miguelense | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Miguel Island buckwheat | Eriogonum grande dunklei | Not Listed | Resolved Taxon | | CA |
| Mammals | San Miguel Island Fox | Urocyon littoralis littoralis | Delisted | Recovery | | CA |
| Flowering Plants | San Miguel savory | Clinopodium chandleri | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | San Nicolas Island buckwheat | Eriogonum grande timorum | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Nicolas Island desert-thorn | Lycium verrucosum | Not Listed | Resolved Taxon | | CA |
| Mammals | San Nicolas Island fox | Urocyon littoralis dickeyi | Not Listed | Species of Concern | | CA |
| Flowering Plants | San Nicolas Island lomatium | Lomatium insulare | Not Listed | Species of Concern | | CA |
| Snails | San Nicolas islandsnail | Micrarionta feralis | Not Listed | Species of Concern | | CA |
| Mammals | San Pablo California vole | Microtus californicus sanpabloensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | san pedro river wild buckwheat | eriogonum terrenatum | Not Listed | Resolved Taxon | | |
| Flowering Plants | San Pitch Valley milk-vetch | Astragalus lentiginosus chartaceus | Not Listed | Resolved Taxon | | CA, CO, ID, NV, OR, UT |
| Flowering Plants | San Rafael cactus | Pediocactus despainii | Listed | Endangered | | UT |
| Flowering Plants | San Rafael milk-vetch | Astragalus rafaelensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Santa Ana River woolly-star | Eriastrum densifolium ssp. sanctorum | Listed | Endangered | | CA |
| Fishes | Santa Ana speckled dace | Rhinichthys gabrielino | Proposed for Listing | Proposed Threatened | | CA |
| Fishes | Santa Ana sucker | Catostomus santaanae | Listed | Threatened | | CA |
| Fishes | Santa Ana threespine stickleback | Gasterosteus aculeatus santaannae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Santa Barbara false-lupine | Thermopsis macrophylla agnina | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Barbara Island buckwheat | Eriogonum giganteum compactum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Barbara Island cream cups | Platystemon californicus ciliatus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Barbara Island liveforever | Dudleya traskiae | Listed | Endangered | | CA |
| Snails | Santa Barbara islandsnail | Micrarionta facta | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Barbara jewelflower | Caulanthus amplexicaulis barbarae | Not Listed | Resolved Taxon | | CA |
| Snails | Santa Barbara shelled slug | Binneya notabilis | Not Listed | Species of Concern | | CA |
| Birds | Santa Barbara Song Sparrow | Melospiza melodia graminea | Delisted | Extinction | | CA |
| Flowering Plants | Santa Catalina figwort | Scrophularia villosa | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Catalina Island desert-thorn | Lycium hassei | Not Listed | Species of Concern | | CA |
| Mammals | Santa Catalina Island Fox | Urocyon littoralis catalinae | Listed | Threatened | | CA |
| Flowering Plants | Santa Catalina Island manzanita | Arctostaphylos catalinae | Not Listed | Species of Concern | | CA |
| Insects | Santa Catalina Island trigonscuta weevil | Trigonoscuta catalina | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Catalina monkey-flower | Mimulus traskiae | Not Listed | Species of Concern | | CA |
| Mammals | Santa Catalina Mountains squirrel | Sciurus arizonensis catalinae | Not Listed | Species of Concern | | AZ |
| Mammals | Santa Catalina Mountains woodrat | Neotoma mexicana bullata | Not Listed | Species of Concern | | AZ |
| Mammals | Santa Catalina ornate shrew | Sorex ornatus willetti | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Clara Valley dudleya | Dudleya setchellii | Listed | Endangered | | CA |
| Flowering Plants | Santa Cruz beehive cactus | Coryphantha recurvata | Not Listed | Species of Concern | | AZ |
| Conifers and Cycads | Santa Cruz cypress | Cupressus abramsiana | Listed | Threatened | | CA |
| Flowering Plants | Santa Cruz gooseberry | Ribes thacherianum | Not Listed | Species of Concern | | CA |
| Mammals | Santa Cruz harvest mouse | Reithrodontomys megalotis santacruzae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Santa Cruz Island bush-mallow | Malacothamnus fasciculatus var. nesioticus | Listed | Endangered | | CA |
| Flowering Plants | Santa Cruz Island dudleya | Dudleya nesiotica | Delisted | Recovery | | CA |
| Mammals | Santa Cruz Island Fox | Urocyon littoralis santacruzae | Delisted | Recovery | | CA |
| Flowering Plants | Santa Cruz Island fringepod | Thysanocarpus conchuliferus | Listed | Endangered | | CA |
| Reptiles | Santa Cruz Island gopher snake | Pituophis melanoleucus pumilis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Cruz Island malacothrix | Malacothrix indecora | Listed | Endangered | | CA |
| Flowering Plants | Santa Cruz Island monkey-flower | Mimulus brandegeei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Cruz Island oak | Quercus parvula | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Santa Cruz Island rockcress | Sibara filifolia | Listed | Endangered | | CA |
| Insects | Santa Cruz Island shore weevil | Trigonoscuta stantoni | Not Listed | Species of Concern | | CA |
| Amphibians | Santa Cruz long-toed salamander | Ambystoma macrodactylum croceum | Listed | Endangered | | CA |
| Flowering Plants | Santa Cruz manzanita | Arctostaphylos andersonii | Not Listed | Species of Concern | | CA |
| Insects | Santa Cruz rain beetle | Pleocoma conjugens conjugens | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Santa Cruz silverpuffs | Stebbinsoseris decipiens | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Cruz star leaf | Choisya mollis | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Santa Cruz striped agave | Agave parviflora parviflora | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Santa Cruz tarplant | Holocarpha macradenia | Listed | Threatened | | CA |
| Arachnids | Santa Cruz telemid spider | Telema sp. | Not Listed | Species of Concern | | CA |
| Crustaceans | Santa Fe Cave crayfish | Procambarus erythrops | Petitioned for Listing, Under Review | Under Review | | FL |
| Flowering Plants | Santa Fe cholla | Opuntia viridiflora | Not Listed | Species of Concern | | NM |
| Flowering Plants | Santa Lucia bedstraw | Galium clementis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Santa Lucia lupine | Lupinus cervinus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Santa Lucia manzanita | Arctostaphylos luciana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Lucia pogogyne | Pogogyne clareana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Margarita manzanita | Arctostaphylos pilosula pilosula | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Monica Mountains dudleyea | Dudleya cymosa ssp. ovatifolia | Listed | Threatened | | CA |
| Insects | Santa Monica Mountains grasshopper | Trimerotropis occidentiloides | Not Listed | Resolved Taxon | | |
| Insects | Santa Monica Mountains hairstreak | Satyrium auretorum fumosum | Not Listed | Resolved Taxon | | CA |
| Insects | Santa Monica shieldback katydid | Neduba longipennis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santa Paula buckwheat | Eriogonum parvifolium paynei | Not Listed | Resolved Taxon | | CA |
| Insects | Santa Rita Mountains chlorochroan bug | Chlorochroa rita | Not Listed | Species of Concern | | AZ |
| Snails | Santa Rita rabdotus | Naesiotus christenseni | Not Listed | Resolved Taxon | | |
| Mammals | Santa Rosa beach mouse | Peromyscus polionotus leucocephalus | Not Listed | Species of Concern | | |
| Flowering Plants | Santa Rosa Island dudleya | Dudleya blochmaniae insularis | Not Listed | Resolved Taxon | | CA |
| Mammals | Santa Rosa Island Fox | Urocyon littoralis santarosae | Delisted | Recovery | | CA |
| Flowering Plants | Santa Rosa Island manzanita | Arctostaphylos confertiflora | Listed | Endangered | | CA |
| Crustaceans | Santa Rosa linderiella | Linderiella santarosae | Not Listed | Species of Concern | | |
| Flowering Plants | Santa Susana tarweed | Hemizonia minthornii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Santiago Peak phacelia | Phacelia suaveolens keckii | Not Listed | Species of Concern | | CA |
| Snails | San Xavier talussnail | Sonorella eremita | Not Listed | Resolved Taxon | | AZ |
| Birds | Sao Miguel bullfinch (finch) | Pyrrhula pyrrhula murina | Listed | Endangered | | |
| Flowering Plants | Sapphire Mt. rock-cress | Arabis fecunda | Not Listed | Species of Concern | | MT |
| Insects | Sarah's hydroptila caddisfly | Hydroptila sarahae | Not Listed | Resolved Taxon | | |
| Insects | Saratoga Springs belostoman bug | Belostoma saratogae | Not Listed | Species of Concern | | CA |
| Fishes | Saratogoa Springs Pupfish | Cyprinodon nevadensis nevadensis | | Not Listed | | |
| Insects | Satellus yellow-faced bee | Hylaeus satellus | Not Listed | Species of Concern | | HI |
| Mammals | Saudi Arabian gazelle | Gazella dorcas saudiya | Listed | Endangered | | |
| Fishes | Sauger | Sander canadensis | | Not Listed | | |
| Flowering Plants | Savannah campylopus | Campylopus carolinae | Not Listed | Species of Concern | | GA, NC |
| Clams | Savannah lilliput | Toxolasma pullus | Not Listed | Status Undefined | | GA, NC |
| Snails | Savannah pebblesnail | Somatogyrus tenax | Not Listed | Species of Concern | | GA |
| Fishes | Sawback angelshark | Squatina aculeata | Listed | Endangered | | |
| Insects | Sawmill Hollow cave beetle | Pseudanophthalmus scholasticus | Not Listed | Species of Concern | | KY |
| Flowering Plants | Saw-toothed lewisia | Lewisia serrata | Not Listed | Species of Concern | | CA |
| Snails | Sawtooth Mountain woodlandsnail | Ashmunella mudgei | Not Listed | Resolved Taxon | | |
| Flowering Plants | Saxicola rock catfoot | Gnaphalium obtusifolium saxicola | Not Listed | Species of Concern | | WI |
| Insects | Say's spiketail | Cordulegaster sayi | Not Listed | Status Undefined | | GA |
| Flowering Plants | Scabrid railardella | Anisocarpus scabridus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Scadden Flat checkerbloom | Sidalcea stipularis | Not Listed | Species of Concern | | CA |
| Birds | Scaled Quail | Callipepla squamata | Not Listed | Species of Concern | | |
| Clams | Scaleshell mussel | Leptodea leptodon | Listed | Endangered | | AR, MO, NE, OK, SD |
| Fishes | Scalloped Hammerhead Shark | Sphyrna lewini | Listed | Endangered | | |
| Fishes | Scalloped Hammerhead Shark | Sphyrna lewini | Listed | Endangered | | |
| Fishes | Scalloped Hammerhead Shark | Sphyrna lewini | Listed | Threatened | | |
| Fishes | Scalloped Hammerhead Shark | Sphyrna lewini | Listed | Threatened | | |
| Insects | Scaly rhyncogonus weevil | Rhyncogonus squamiger | Not Listed | Species of Concern | | HI |
| Mammals | Scaly-tailed possum | Wyulda squamicaudata | Listed | Endangered | | |
| Birds | Scarlet-breasted robin (flycatcher) | Petroica multicolor multicolor | Listed | Endangered | | |
| Flowering Plants | Scarlet catchfly | Silene subciliata | Not Listed | Species of Concern | | LA, TX |
| Birds | Scarlet-chested parakeet | Neophema splendida | Delisted | Recovery | | |
| Birds | Scarlet macaw | Ara macao ssp. cyanopterus | Listed | Endangered | | |
| Birds | Scarlet macaw | Ara macao ssp. macao | Listed | Threatened | | |
| Birds | Scarlet macaw | Ara macao ssp. macao | Listed | Similarity of Appearance (Threatened) | | |
| Birds | Scarlet Tanager | Piranga olivacea | Not Listed | Species of Concern | | |
| Insects | Schauinsland's bush cricket | Caconemobius schauinslandi | Not Listed | Species of Concern | | HI |
| Insects | Schaum's Blue Ridge ground beetle | Sphaeroderus schaumi | Not Listed | Species of Concern | | VA |
| Insects | Schaus swallowtail butterfly | Heraclides aristodemus ponceanus | Listed | Endangered | | FL |
| Snails | Schell Creek mountainsnail | Oreohelix nevadensis | Not Listed | Species of Concern | | NV |
| Flowering Plants | Schleser's fishhook cactus | Sclerocactus schleseri | Not Listed | Species of Concern | | NV |
| Flowering Plants | Schoolcraft's cryptantha | Cryptantha sobolifera | Not Listed | Species of Concern | | NV |
| Insects | Schoolhouse Springs leuctran stonefly | Leuctra szczytkoi | Petitioned for Listing, Under Review | Under Review | | LA |
| Flowering Plants | Schott's wire-lettuce | Stephanomeria schottii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Schreiber's manzanita | Arabis oxylobula | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Schreiber's manzanita | Arctostaphylos glutinosa | Not Listed | Species of Concern | | CA |
| Insects | Schuh's homoplectran caddisfly | Homoplectra schuhi | Not Listed | Species of Concern | | OR |
| Insects | Schwarz' diving beetle | Laccophilus schwarzi | Not Listed | Resolved Taxon | | AL, DC, MD, VA |
| Flowering Plants | Schweinitz's sunflower | Helianthus schweinitzii | Listed | Endangered | | NC, SC |
| Flowering Plants | Schweinitz's waterweed | Elodea schweinitzii | Not Listed | Species of Concern | | NY, PA |
| Mammals | Scimitar-horned oryx | Oryx dammah | Listed | Endangered | | |
| Fishes | Scioto madtom | Noturus trautmani | Delisted | Extinction | | OH |
| Birds | Scissor-tailed Flycatcher | Tyrannus forficatus | Not Listed | Species of Concern | | |
| Birds | Sclater's monal pheasant | Lophophorus sclateri | Listed | Endangered | | |
| Amphibians | Scott Bar salamander | Plethodon asupak | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Scott Mountains bedstraw | Galium serpenticum scotticum | Not Listed | Resolved Taxon | | CA |
| Insects | Scott optioservus riffle beetle | Optioservus phaeus | Not Listed | Resolved Taxon | | KS |
| Birds | Scott's Oriole | Icterus parisorum | Not Listed | Species of Concern | | |
| Ferns and Allies | Scott's spleenwort | Asplenium ebenoides | Not Listed | Resolved Taxon | | AL, AR, CT, DE, GA, IL, MA, MO, NC, NJ, OH, PA, TN, VA, WV |
| Flowering Plants | Scotts Valley Polygonum | Polygonum hickmanii | Listed | Endangered | | CA |
| Flowering Plants | Scotts Valley spineflower | Chorizanthe robusta var. hartwegii | Listed | Endangered | | CA |
| Flowering Plants | Scott Valley phacelia | Phacelia greenei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Scribe allocarya | Plagiobothrys scriptus | Not Listed | Resolved Taxon | | CA |
| Birds | Scripp's Murrelet | Synthliboramphus hypoleucus scrippsi | Not Listed | Resolved Taxon | | |
| Birds | Scripps's Murrelet | Synthliboramphus scrippsi | Not Listed | Species of Concern | | |
| Flowering Plants | Scrub blazingstar | Liatris ohlingerae | Listed | Endangered | | FL |
| Flowering Plants | Scrub buckwheat | Eriogonum longifolium var. gnaphalifolium | Listed | Threatened | | FL |
| Insects | Scrub golden aster noctuid moth | Schinia rufipenna | Not Listed | Species of Concern | | |
| Insects | Scrub Island burrowing scarab | Mycotrupes pedester | Not Listed | Species of Concern | | |
| Flowering Plants | Scrub lupine | Lupinus aridorum | Listed | Endangered | | FL |
| Flowering Plants | Scrub mint | Dicerandra frutescens | Listed | Endangered | | FL |
| Flowering Plants | Scrub oak | Quercus berberidifolia | Not Listed | Species of Concern | | |
| Insects | Scrub palmetto flower scarab | Trigonopelastes floridana | Not Listed | Species of Concern | | |
| Flowering Plants | Scrub plum | Prunus geniculata | Listed | Endangered | | FL |
| Snails | Sculpin snail | Stiobia nana | Not Listed | Species of Concern | | AL |
| Snails | Sculpted supercoil | Paravitrea ternaria | Not Listed | Species of Concern | | NC |
| Flowering Plants | Sculptured popcornflower | Plagiobothrys glyptocarpus var. glyptocarpus | Not Listed | Species of Concern | | |
| Fishes | Scup | Stenotomus chrysops | | Not Listed | | |
| Flowering Plants | Seabeach amaranth | Amaranthus pumilus | Listed | Threatened | | DE, MA, MD, NC, NJ, NY, SC, VA |
| Flowering Plants | sea bean | Mucuna persericea | Listed | Endangered | | HI |
| Flowering Plants | Sea cliff bluegrass | Poa unilateralis | Not Listed | Resolved Taxon | | WA |
| Fishes | Sea Lamprey | Petromyzon marinus | Not Listed | Species of Concern | | |
| Mammals | Sea Otter | Enhydra lutris | | Not Listed | | |
| Mammals | Searchlight southern pocket gopher | Thomomys umbrinus suboles | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Seashore cactus | Opuntia martiniana | Not Listed | Resolved Taxon | | |
| Flowering Plants | Seaside alder | Alnus maritima | Not Listed | Resolved Taxon | | DE, GA, MD, OK |
| Flowering Plants | Seaside birds-beak | Cordylanthus rigidus littoralis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Seaside, Coulter's daisy | Lasthenia glabrata coulteri | Not Listed | Species of Concern | | CA |
| Flowering Plants | Seaside goldfields | Lasthenia maritima | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Birds | Seaside Sparrow | Ammospiza maritima fisheri | Not Listed | Species of Concern | | |
| Birds | Seaside Sparrow | Ammospiza maritima maritima | Not Listed | Species of Concern | | |
| Birds | Seaside Sparrow | Ammospiza maritima peninsulae | Not Listed | Species of Concern | | |
| Birds | Seaside Sparrow | Ammospiza maritima sennetti | Not Listed | Species of Concern | | |
| Flowering Plants | Seaside tarweed | Hemizonia multicaulis multicaulis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sebastopol meadowfoam | Limnanthes vinculans | Listed | Endangered | | CA |
| Insects | Seclusive water scavenger beetle | Paracymus seclusus | Not Listed | Resolved Taxon | | MS |
| Flowering Plants | Secund jewelflower | Streptanthus glandulosus hoffmanii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sedge fescue | Festuca dasyclada | Not Listed | Resolved Taxon | | CO, UT |
| Birds | Sedge Wren | Cistothorus platensis | Not Listed | Species of Concern | | |
| Amphibians | Seepage salamander | Desmognathus aeneus | | Not Listed | | NC |
| Mammals | Sei whale | Balaenoptera borealis | Listed | Endangered | | |
| Mammals | Seledang | Bos gaurus | Listed | Endangered | | |
| Insects | Selium wingless thread bug | Nesidiolestes selium | Not Listed | Species of Concern | | HI |
| Snails | Seminole siltsnail | Cincinnatia vanhyningi | Not Listed | Species of Concern | | |
| Birds | Semipalmated Sandpiper | Calidris pusilla | Not Listed | Species of Concern | | |
| Birds | Semper's warbler (=wood) | Leucopeza semperi | Listed | Endangered | | |
| Insects | Seneca cave beetle | Pseudanophthalmus potomaca senecae | Not Listed | Species of Concern | | WV |
| Birds | Sennett's hooded oriole | Icterus cucullatus sennetti | Not Listed | Species of Concern | | TX |
| Insects | Sensabush cave beetle | Pseudanophthalmus paradoxus | Not Listed | Species of Concern | | TN |
| Flowering Plants | Sensitive joint-vetch | Aeschynomene virginica | Listed | Threatened | | DE, MD, NC, NJ, VA |
| Flowering Plants | Sentry milk-vetch | Astragalus cremnophylax var. cremnophylax | Listed | Endangered | | AZ |
| Flowering Plants | september 11 stickleaf | mentzelia memorabalis | Not Listed | Resolved Taxon | | |
| Insects | Septima's clubtail | Gomphus septima | Petitioned for Listing, Under Review | Under Review | | AL, NC, SC |
| Insects | Sequatchie caddisfly | Glyphopsyche sequatchie | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | Sequoia gooseberry | Ribes tularensis | Not Listed | Species of Concern | | CA |
| Insects | Sequoyah Caverns cave beetle | Pseudanophthalmus sequoyah | Not Listed | Species of Concern | | AL |
| Mammals | Serow | Naemorhedus (=Capricornis) sumatraensis | Listed | Endangered | | |
| Flowering Plants | Serpentine aster | Symphyotrichum depauperatum | Not Listed | Species of Concern | | DE, MD, NC, PA |
| Flowering Plants | Serpentine haplopappus | Ericameria ophitidis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Serpentine sunflower | Helianthus exilis | Not Listed | Resolved Taxon | | CA |
| Reptiles | Serpent Island gecko | Cyrtodactylus serpensinsula | Listed | Threatened | | |
| Flowering Plants | Sessile-leaved warea | Warea sessilifolia | Not Listed | Resolved Taxon | | |
| Insects | Seth Forest water scavenger beetle | Hydrochus sp. | Not Listed | Species of Concern | | MD |
| Insects | Setose Cream and Brown Mottle microcaddisfly | Oxyethira setosa | Not Listed | Status Undefined | | |
| Insects | Sevier snowfly | Allocapnia brooksi | Petitioned for Listing, Under Review | Under Review | | TN |
| Birds | Seychelles fody (weaver-finch) | Foudia sechellarum | Listed | Endangered | | |
| Birds | Seychelles kestrel | Falco araea | Listed | Endangered | | |
| Birds | Seychelles lesser vasa parrot | Coracopsis nigra barklyi | Listed | Endangered | | |
| Birds | Seychelles magpie-robin (thrush) | Copsychus sechellarum | Listed | Endangered | | |
| Birds | Seychelles paradise flycatcher | Terpsiphone corvina | Listed | Endangered | | |
| Birds | Seychelles scops owl | Otus magicus (=insularis) insularis | Listed | Endangered | | |
| Birds | Seychelles turtle dove | Streptopelia picturata rostrata | Listed | Endangered | | |
| Birds | Seychelles warbler (old world warbler) | Bebrornis sechellensis | Listed | Endangered | | |
| Birds | Seychelles white-eye | Zosterops modesta | Listed | Endangered | | |
| Insects | Shade-winged nesomimesan sphecid wasp | Nesomimesa sciopteryx | Not Listed | Species of Concern | | HI |
| Snails | Shaggy coil | Helicodiscus diadema | Not Listed | Species of Concern | | VA |
| Flowering Plants | shaggyhair alumroot | Heuchera hirsutissima | Not Listed | Species of Concern | | |
| Flowering Plants | Shaggy-hair lupine | Lupinus spectabilis | Not Listed | Species of Concern | | CA |
| Flowering Plants | shaggy horkelia | Horkelia congesta ssp. congesta | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Shale barren rock cress | Boechera serotina | Listed | Endangered | | VA, WV |
| Mammals | Shansi sika deer | Cervus nippon grassianus | Listed | Endangered | | |
| Mammals | Shapo | Ovis vignei vignei | Listed | Endangered | | |
| Mammals | Shark Bay mouse | Pseudomys praeconis | Listed | Endangered | | |
| Fishes | Sharphead darter | Etheostoma acuticeps | Not Listed | Resolved Taxon | | NC |
| Snails | Sharp Hornsnail | Pleurocera acuta | | Not Listed | | |
| Fishes | Sharpnose Shiner | Notropis oxyrhynchus | Listed | Endangered | | TX |
| Birds | Sharp shinned hawk | Accipiter striatus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sharp's leafy liverwort | Plagiochila sharpii | Not Listed | Status Undefined | | NC |
| Insects | Sharp's rhyncogonus weevil | Rhyncogonus sharpi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Sharsmth's stickseed | Hackelia sharsmithii | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Shasta arnica | Arnica viscosa | Not Listed | Resolved Taxon | | CA, NV, OR |
| Snails | Shasta chaparral | Trilobopsis roperi | Petitioned for Listing, Under Review | Under Review | | CA |
| Crustaceans | Shasta crayfish | Pacifastacus fortis | Listed | Endangered | | CA |
| Flowering Plants | Shasta eupatorium | Ageratina shastensis | Not Listed | Resolved Taxon | | CA |
| Snails | Shasta hesperian | Vespericola shasta | Petitioned for Listing, Under Review | Under Review | | CA |
| Flowering Plants | Shasta orthocarpus | Orthocarpus pachystachyus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Shasta panic grass | Dichanthelium acuminatum var. acuminatum | Not Listed | Resolved Taxon | | CA |
| Snails | Shasta pebblesnail | Fluminicola multifarius | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Shasta River mariposa lily | Calochortus monanthus | Not Listed | Species of Concern | | CA |
| Amphibians | Shasta salamander | Hydromantes shastae | Not Listed | Resolved Taxon | | CA |
| Snails | Shasta sideband | Monadenia troglodytes troglodytes | Petitioned for Listing, Under Review | Under Review | | CA |
| Snails | Shasta Sideband | Monadenia troglodytes | | Not Listed | | |
| Flowering Plants | Shasta snow-wreath | Neviusia cliftonii | Petitioned for Listing, Under Review | Under Review | | CA |
| Mammals | Shaw Island Townsend's vole | Microtus townsendii pugeti | Not Listed | Resolved Taxon | | WA |
| Fishes | Shawnee darter | Etheostoma tecumsehi | Petitioned for Listing, Under Review | Under Review | | KY |
| Flowering Plants | Shaw's agave | Agave shawii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sheathed deathcamus | Zigadenus vaginatus | Not Listed | Resolved Taxon | | NV, UT |
| Mammals | Sheath-tailed Bat | Emballonura semicaudata semicaudata | Not Listed | Species of Concern | | GU, MP, PW |
| Clams | Sheepnose Mussel | Plethobasus cyphyus | Not Listed | Status Undefined | | |
| Clams | Sheepnose Mussel | Plethobasus cyphyus | Listed | Endangered | | AL, IA, IL, IN, KY, MN, MO, MS, OH, PA, TN, VA, WI, WV |
| Clams | Sheepnose Mussel | Plethobasus cyphyus | Not Listed | Status Undefined | | |
| Fishes | Sheepshead | Archosargus probatocephalus | | Not Listed | | |
| Fishes | Sheldon tui chub | Siphateles bicolor eurysoma | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Shelled cave springtail | Pseudosinella testa | Not Listed | Species of Concern | | WV |
| Crustaceans | Shelta Cave crayfish | Orconectes sheltae | Petitioned for Listing, Under Review | Under Review | | AL |
| Mammals | Shelton pocket gopher | Thomomys mazama couchi | Not Listed | Resolved Taxon | | WA |
| Insects | Shenandoah cave beetle | Pseudanophthalmus limicola | Not Listed | Resolved Taxon | | VA |
| Amphibians | Shenandoah salamander | Plethodon shenandoah | Listed | Endangered | | VA |
| Crustaceans | Shenandoah Valley cave amphipod | Stygobromus gracilipes | Not Listed | Resolved Taxon | | MD, PA, VA, WV |
| Flowering Plants | Sherff railliardia | Dubautia sherffiana | Not Listed | Species of Concern | | HI |
| Mammals | Sherman's fox squirrel | Sciurus niger shermani | Not Listed | Species of Concern | | |
| Mammals | Sherman's southeastern pocket gopher | Geomys pinetis fontanelus | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | Shevock's milk-vetch | Astragalus shevockii | Not Listed | Resolved Taxon | | CA |
| Fishes | Shiner Perch | Cymatogaster aggregata | | Not Listed | | |
| Flowering Plants | Shining milk-vetch | Astragalus lentiginosus micans | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Shinner's false-foxglove | Tomanthera pseudaphylla | Not Listed | Species of Concern | | AL, MS, TN |
| Flowering Plants | Shinner's sunflower | Helianthus occidentalis ssp. plantagineus | Not Listed | Status Undefined | | AR, LA, TX |
| Flowering Plants | Shinner's tickle-tongue | Zanthoxylum parvum | Not Listed | Resolved Taxon | | TX |
| Clams | Shiny pigtoe | Fusconaia cor | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Shiny pigtoe | Fusconaia cor | Listed | Experimental Population, Non-Essential | | TN |
| Clams | Shiny pigtoe | Fusconaia cor | Listed | Endangered | | AL, KY, TN, VA |
| Clams | Shinyrayed pocketbook | Hamiota subangulata | Listed | Endangered | | AL, FL, GA |
| Fishes | Ship Sturgeon | Acipenser nudiventris | Proposed for Listing | Proposed Endangered | | |
| Flowering Plants | Shirley Meadows mariposa lily | Calochortus westonii | Not Listed | Species of Concern | | CA |
| Insects | Shirttail Creek stonefly | Megaleuctra sierra | Not Listed | Species of Concern | | CA |
| Flowering Plants | Shivwits milk-vetch | Astragalus ampullarioides | Listed | Endangered | | UT |
| Fishes | Shoal Bass | Micropterus cataractae | | Not Listed | | |
| Fishes | Shoal Chub | Macrhybopsis hyostoma | | Not Listed | | |
| Fishes | Shoal Chub | Macrhybopsis hyostoma | | Not Listed | | |
| Snails | Shoal sprite | Amphigyra alabamensis | Not Listed | Species of Concern | | AL |
| Flowering Plants | Shoals spider-lily | Hymenocallis coronaria | Not Listed | Species of Concern | | AL, GA, SC |
| Flowering Plants | Shockley's rock-cress | Arabis shockleyi | Not Listed | Resolved Taxon | | CA, NV, UT |
| Birds | Short-billed Dowitcher | Limnodromus griseus | Not Listed | Species of Concern | | |
| Birds | Short-eared Owl | Asio flammeus | Not Listed | Species of Concern | | |
| Birds | Short-eared Owl | Asio flammeus flammeus | Not Listed | Species of Concern | | |
| Snails | Shortface lanx | Fisherola nuttalli | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Insects | Short-foot ectemnius sphecid wasp | Ectemnius curtipes | Not Listed | Species of Concern | | HI |
| Flowering Plants | Short-fruited spikerush | Eleocharis brachycarpa | Not Listed | Resolved Taxon | | TX |
| Reptiles | Short-headed garter snake | Thamnophis brachystoma | Not Listed | Species of Concern | | NY, PA |
| Fishes | Shorthead Redhorse | Moxostoma macrolepidotum | | Not Listed | | |
| Fishes | Shorthead Sculpin | Cottus confusus | | Not Listed | | |
| Fishes | Shortjaw cisco | Coregonus zenithicus | Not Listed | Species of Concern | | IL, IN, MI, MN, WI |
| Flowering Plants | Short-jointed beavertail cactus | Opuntia basilaris brachyclada | Not Listed | Species of Concern | | CA |
| Flowering Plants | Short-leaved dudleya | Dudleya blochmaniae blochmaniae | Not Listed | Species of Concern | | CA |
| Flowering Plants | Short-leaved dudleya | Dudleya blochmaniae brevifolia | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Short-leaved rosemary | Conradina brevifolia | Listed | Endangered | | FL |
| Flowering Plants | Short-lobed broomrape | Orobanche parishii brachyloba | Not Listed | Species of Concern | | CA |
| Flowering Plants | Short-lobed paintbrush | Castilleja brevilobata | Not Listed | Resolved Taxon | | CA, NV, OR |
| Reptiles | Short-necked or western swamp turtle | Pseudemydura umbrina | Listed | Endangered | | |
| Snails | Shortneck snaggletooth | Gastrocopta dalliana dalliana | Not Listed | Species of Concern | | NM |
| Fishes | Shortnose cisco | Coregonus reighardi | Not Listed | Species of Concern | | IL, IN, MI, NY, WI |
| Mammals | Short-nosed kangaroo rat | Dipodomys nitratoides brevinasus | Not Listed | Species of Concern | | CA |
| Fishes | Shortnose Gar | Lepisosteus platostomus | | Not Listed | | |
| Fishes | Shortnose sturgeon | Acipenser brevirostrum | Listed | Endangered | | NC |
| Fishes | Shortnose Sucker | Chasmistes brevirostris | Listed | Endangered | | CA, OR |
| Flowering Plants | Short-podded thelypody | Thelypodium brachycarpum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Mammals | Shortridge's mouse | Pseudomys shortridgei | Listed | Endangered | | |
| Snails | Short Samoan tree snail | Somoana abbreviata | Not Listed | Species of Concern | | AS |
| Flowering Plants | Short's bladderpod | Physaria globosa | Listed | Endangered | | IN, KY, TN |
| Flowering Plants | Short's goldenrod | Solidago shortii | Listed | Endangered | | IN, KY |
| Snails | Short-spire elimia | Elimia brevis | Not Listed | Resolved Taxon | | AL |
| Snails | Shortspire hornsnail | Pleurocera curta | | Not Listed | | AL, TN |
| Birds | Short-tailed albatross | Phoebastria (=Diomedea) albatrus | Listed | Endangered | | AK, CA, GU, HI, MP, OR, UM, WA |
| Mammals | short-tailed chinchilla | Chinchilla chinchilla | | Not Listed | | |
| Birds | short-tailed hawk | Buteo brachyurus | Not Listed | Species of Concern | | |
| Birds | short-tailed hawk | Buteo brachyurus | Not Listed | Status Undefined | | |
| Reptiles | Short-tailed snake | Stilosoma extenuatum | Proposed for Listing | Proposed Threatened | Proposed Listing | FL |
| Fishes | Shoshone pupfish | Cyprinodon nevadensis shoshone | Not Listed | Species of Concern | | CA |
| Fishes | Shoshone sculpin | Cottus greenei | Not Listed | Resolved Taxon | | ID |
| Mammals | Shou | Cervus elaphus wallichi | Listed | Endangered | | |
| Fishes | Shovelnose Sturgeon | Scaphirhynchus platorynchus | Listed | Similarity of Appearance (Threatened) | | |
| Flowering Plants | Showy Indian clover | Trifolium amoenum | Listed | Endangered | | CA |
| Flowering Plants | Showy madia | madia radiata | Not Listed | Species of Concern | | |
| Flowering Plants | Showy raillardella | Raillardella pringlei | Not Listed | Species of Concern | | CA |
| Flowering Plants | Showy stickseed | Hackelia venusta | Listed | Endangered | | WA |
| Flowering Plants | Shriver's Purple Fringed Orchid | Platanthera shriveri | Not Listed | Species of Concern | | |
| Flowering Plants | Shrubby reed-mustard | Schoenocrambe suffrutescens | Listed | Endangered | | UT |
| Crustaceans | Shutispear crayfish | Procambarus lylei | Not Listed | Status Undefined | | MS |
| Mammals | Siamang | Symphalangus syndactylus | Listed | Endangered | | |
| Reptiles | Siamese crocodile | Crocodylus siamensis | Listed | Endangered | | |
| Fishes | Siberian sturgeon | Acipenser baerii | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Siberian white Crane | Grus leucogeranus | Listed | Endangered | | |
| Mammals | Sichuan snub-nosed monkey | Rhinopithecus roxellana | Listed | Endangered | | |
| Fishes | Sickle darter | Percina williamsi | Listed | Threatened | | TN, VA |
| Fishes | Sicklefin chub | Macrhybopsis meeki | Not Listed | Resolved Taxon | | AR, IA, IL, KS, KY, LA, MO, MS, MT, ND, NE, SD, TN |
| Fishes | Sicklefin redhorse | Moxostoma sp. | | Not Listed | | GA, NC, TN |
| Snails | Sidelong supercoil | Paravitrea ceres | Not Listed | Species of Concern | | WV |
| Reptiles | sidewinder | Crotalus cerastes | Not Listed | Species of Concern | | |
| Snails | Sierra Ancha Talussnail | Sonorella anchana | Not Listed | Resolved Taxon | | |
| Snails | Sierra Blanca Woodlandsnail | Ashmunella rhyssa | Not Listed | Resolved Taxon | | |
| Flowering Plants | Sierra corydalis | Corydalis caseana caseana | Not Listed | Resolved Taxon | | CA |
| Mammals | Sierra Nevada bighorn sheep | Ovis canadensis sierrae | Listed | Endangered | | CA |
| Flowering Plants | Sierra Nevada bleeding-heart | Dicentra nevadensis | Not Listed | Resolved Taxon | | CA |
| Mammals | Sierra Nevada red fox | Vulpes vulpes necator | Not Listed | Resolved Taxon | | CA, OR |
| Mammals | Sierra Nevada red fox | Vulpes vulpes necator | Listed | Endangered | | CA, NV |
| Mammals | Sierra Nevada red fox | Vulpes vulpes necator | Not Listed | Resolved Taxon | | |
| Mammals | Sierra Nevada red fox | Vulpes vulpes ssp. necator | Not Listed | Status Undefined | | |
| Mammals | Sierra Nevada snowshoe hare | Lepus americanus tahoensis | Not Listed | Species of Concern | | CA, NV |
| Amphibians | Sierra Nevada Yellow-legged Frog | Rana sierrae | Listed | Endangered | | CA, NV |
| Reptiles | Sierra night lizard | Xantusia vigilis sierrae | Not Listed | Species of Concern | | CA |
| Insects | Sierra pygmy grasshopper | Tetrix sierrana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sierra sedge | Carex mariposana | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Sierra sweet-bay | Myrica hartwegii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Sierra Valley evening-primrose | Camissonia tanacetifolia quadriperforata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Sierra Valley ivesia | Ivesia aperta aperta | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sierra Vieja brickellia | Brickellia viejensis | Not Listed | Species of Concern | | TX |
| Mammals | Sifakas | Propithecus spp. | Listed | Endangered | | |
| Crustaceans | signal crayfish | Pacifastacus leniusculus | | Not Listed | | |
| Flowering Plants | Siler pincushion cactus | Pediocactus (=Echinocactus,=Utahia) sileri | Listed | Threatened | | AZ, UT |
| Flowering Plants | Siler's Fishhook Cactus | Sclerocactus sileri | Not Listed | Resolved Taxon | | |
| Insects | Silken cave beetle | Pseudanophthalmus sericus | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | Silky cryptantha | Cryptantha crinita | Not Listed | Species of Concern | | CA |
| Mammals | Silky pocket mouse | Perognathus flavus goodpasteri | Not Listed | Species of Concern | | AZ |
| Snails | Silt elimia | Elimia haysiana | Not Listed | Species of Concern | | AL |
| Fishes | Silverband Shiner | Notropis shumardi | | Not Listed | | |
| Flowering Plants | Silver cholla | Opuntia imbricata argentea | Not Listed | Species of Concern | | TX |
| Fishes | Silver Chub | Macrhybopsis storeriana | | Not Listed | | |
| Arachnids | Silver Creek blind harvestman | Calicina jungi | Not Listed | Resolved Taxon | | |
| Snails | Silver Creek Holospira | Holospira sherbrookei | Not Listed | Resolved Taxon | | |
| Snails | Silver Creek Woodlandsnail | Ashmunella binneyi | Not Listed | Resolved Taxon | | |
| Crustaceans | Silver Glen Springs crayfish | Procambarus attiguus | Petitioned for Listing, Under Review | Under Review | | FL |
| Mammals | Silver-haired bat | lasionycteris noctivagans | Not Listed | Species of Concern | | |
| Flowering Plants | Silver-haired ivesia | Ivesia argyrocoma | Not Listed | Species of Concern | | CA |
| Flowering Plants | Silverling | Paronychia argyrocoma | Not Listed | Resolved Taxon | | MA, ME, NH |
| Fishes | Silver Redhorse | Moxostoma anisurum | | Not Listed | | |
| Mammals | Silver rice rat | Oryzomys palustris natator | Listed | Endangered | | FL |
| Flowering Plants | Silver, San Clemente Island hosackia | Lotus argophyllus adsurgens | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Silver, Santa Cruz Island hosackia | Lotus argophyllus niveus | Not Listed | Species of Concern | | CA |
| Insects | Silverspot | Speyeria nokomis nokomis | Listed | Threatened | | CO, NM, UT |
| Fishes | Silver trout | Salvelinus agassizii | Not Listed | Resolved Taxon | | NH |
| Flowering Plants | Silver wolfberry | Lycium puberulum berberioides | Not Listed | Resolved Taxon | | TX |
| Reptiles | Silvery legless lizard | Anniella pulchra pulchra | Not Listed | Species of Concern | | CA |
| Flowering Plants | Silvery nailwort | Paronychia virginica var. virginica | Not Listed | Species of Concern | | DC, MD, VA, WV |
| Mammals | Simien fox | Canis simensis | Listed | Endangered | | |
| Crustaceans | Simple Amphipod | Stygobromus simplex | Not Listed | Resolved Taxon | | |
| Insects | Simple hydroporus diving beetle | Hydroporus simplex | Not Listed | Species of Concern | | CA |
| Insects | Simple-necked long-horned beetle | Plagithmysus simplicicollis | Not Listed | Species of Concern | | HI |
| Insects | Simple rhyncogonus weevil | Rhyncogonus simplex | Not Listed | Species of Concern | | HI |
| Insects | Simple yellow-faced bee | Hylaeus simplex | Not Listed | Species of Concern | | HI |
| Flowering Plants | Simpson's prickly-apple | Cereus gracilis simpsonii | Not Listed | Species of Concern | | |
| Flowering Plants | Simpson stopper | Myrcianthes fragrans simpsonii | Not Listed | Species of Concern | | |
| Mammals | Sinaloan jaguarundi | Puma yagouaroundi tolteca | Listed | Endangered | | |
| Mammals | Singapore roundleaf horseshoe bat | Hipposideros ridleyi | Listed | Endangered | | |
| Birds | Sira curassow | Pauxi koepckeae | Listed | Endangered | | |
| Fishes | Sirajo Goby | Sicydium plumieri | | Not Listed | | |
| Flowering Plants | Siskiyou buckwheat | Eriogonum siskiyouense | Not Listed | Resolved Taxon | | CA |
| Insects | Siskiyou caddisfly | Neothremma siskiyou | Not Listed | Species of Concern | | CA |
| Insects | Siskiyou caddisfly | Tinodes siskiyou | Not Listed | Species of Concern | | OR |
| Insects | Siskiyou chloealtis grasshopper | Chloealtis aspasma | Not Listed | Species of Concern | | OR |
| Insects | Siskiyou ground beetle | Nebria gebleri siskiyouensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Siskiyou inside-out flower | Vancouveria chrysantha | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Siskiyou Mariposa lily | Calochortus persistens | Not Listed | Resolved Taxon | | CA, OR |
| Flowering Plants | Siskiyou monardella | Monardella purpurea | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Siskiyou Mountains bilberry | Vaccinium membranaceum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Amphibians | Siskiyou Mountains salamander | Plethodon stormi | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Siskiyou onion | Allium tribracteatum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Siskiyou paintbrush | Castilleja elata | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Siskiyou rock-fringe | Epilobium siskiyouense | Not Listed | Resolved Taxon | | CA, NV, OR |
| Snails | Siskiyou sideband | Monadenia chaceana | Not Listed | Resolved Taxon | | CA, OR |
| Insects | Siuslaw hairy-necked tiger beetle | Cicindela hirticollis siuslawensis | Petitioned for Listing, Under Review | Under Review | | |
| Insects | Sixbanded long-horned beetle | Dryobius sexnotatus | Not Listed | Species of Concern | | AL, AR, IN, KS, KY, LA, MD, MI, MO, MS, OH, PA, TN, VA, WV |
| Flowering Plants | Skiff milkvetch | Astragalus microcymbus | Not Listed | Resolved Taxon | | CO |
| Algae | Skipjack Herring | Alosa chrysochloris | | Not Listed | | |
| Snails | Skirted hornsnail | Pleurocera pyrenella | Not Listed | Status Undefined | | AL, GA |
| Mammals | Skull Valley pocket gopher | Thomomys umbrinus robustus | Not Listed | Species of Concern | | UT |
| Clams | Slabside Pearlymussel | Pleuronaia dolabelloides | Listed | Endangered | | AL, MS, TN, VA |
| Fishes | Slackwater darter | Etheostoma boschungi | Listed | Threatened | | AL, TN |
| Flowering Plants | Sleeping Ute milkvetch | Astragalus tortipes | Not Listed | Resolved Taxon | | CO |
| Birds | Slender-billed curlew | Numenius tenuirostris | Listed | Endangered | | |
| Birds | Slender-billed Grackle | Quisicalus palustris | Listed | Endangered | | |
| Snails | Slender campeloma | Campeloma decampi | Listed | Endangered | | AL |
| Fishes | Slender chub | Erimystax cahni | Listed | Threatened | | TN, VA |
| Fishes | Slender chub | Erimystax cahni | Listed | Experimental Population, Non-Essential | | TN |
| Crustaceans | Slenderclaw crayfish | Cambarus cracens | Listed | Endangered | | AL |
| Flowering Plants | Slender dodder | Cuscuta attenuata | Not Listed | Species of Concern | | KS, OK, TX |
| Flowering Plants | Slender gay-feather | Liatris tenuis | Not Listed | Species of Concern | | LA, TX |
| Fishes | Slenderhead Darter | Percina phoxocephala | | Not Listed | | |
| Mammals | Slender-horned gazelle | Gazella leptoceros | Listed | Endangered | | |
| Flowering Plants | Slender-horned spineflower | Dodecahema leptoceras | Listed | Endangered | | CA |
| Flowering Plants | Slender mariposa lily | Calochortus clavatus gracilis | Not Listed | Species of Concern | | CA |
| Flowering Plants | slender meadowfoam | Limnanthes gracilis ssp. gracilis | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Slender meadowfoam | Lasthenia macrantha prisca | Not Listed | Species of Concern | | CA, NV, OR |
| Ferns and Allies | Slender Moonwort | Botrychium lineare | Not Listed | Resolved Taxon | | CO, WA |
| Flowering Plants | Slender oak | Quercus graciliformis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Slender Orcutt grass | Orcuttia tenuis | Listed | Threatened | | CA, OR |
| Flowering Plants | Slender pentachaeta | Pentachaeta exilis aeolica | Not Listed | Species of Concern | | CA |
| Flowering Plants | Slender-petaled mustard | Thelypodium stenopetalum | Listed | Endangered | | CA |
| Flowering Plants | Slender-pod jewelflower | Caulanthus heterophyllus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Slender rush-pea | Hoffmannseggia tenella | Listed | Endangered | | TX |
| Fishes | Slender sculpin | Cottus tenuis | Not Listed | Species of Concern | | OR |
| Flowering Plants | Slender spiderflower | Cleome multicaulis | Not Listed | Species of Concern | | AZ, CO, NM, TX, WY |
| Crustaceans | Slenderwrist burrowing crayfish | Fallicambarus petilicarpus | Petitioned for Listing, Under Review | Under Review | | AR |
| Reptiles | Slevin's skink | Emoia slevini | Listed | Endangered | | GU, MP |
| Flowering Plants | Slickrock desert-parsley | Lomatium latilobum | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | Slickspot peppergrass | Lepidium papilliferum | Listed | Threatened | | ID, OR |
| Fishes | Slimy Sculpin | Cottus cognatus | | Not Listed | | |
| Clams | Slippershell Mussel | Pressodonta viridis | | Not Listed | | |
| Fishes | Slough Darter | Etheostoma gracile | | Not Listed | | |
| Flowering Plants | Slough thistle | Cirsium crassicaule | Not Listed | Species of Concern | | CA |
| Insects | Slow rhyncogonus weevil | Rhyncogonus segnis segnis | Not Listed | Species of Concern | | HI |
| Snails | Slowwater elimia | Elimia interveniens | Not Listed | Species of Concern | | AL |
| Flowering Plants | Small-anthered bittercress | Cardamine micranthera | Listed | Endangered | | NC, VA |
| Flowering Plants | Small beardtongue | Penstemon parvus | Not Listed | Species of Concern | | UT |
| Fishes | Smalleye Shiner | Notropis buccula | Listed | Endangered | | TX |
| Flowering Plants | Small-flowered, Douglas' pogogyne | Pogogyne douglasii parviflora | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Small-flowered microseris | microseris douglasii ssp. platycarpha | Not Listed | Species of Concern | | |
| Flowering Plants | Small-flowered morning-glory | Convolvulus equitans | Not Listed | Species of Concern | | CA |
| Flowering Plants | Small fryxell wort | Fryxellia pygmaea | Not Listed | Resolved Taxon | | TX |
| Snails | Small geniculate river snail | Lithasia pinguis | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | Small-headed goldenweed | Lorandersonia microcephala | Not Listed | Species of Concern | | CO, NM |
| Flowering Plants | Small-headed pipewort | Eriocaulon kornickianum | Petitioned for Listing, Under Review | Under Review | | AR, GA, OK, TX |
| Flowering Plants | Smallheaded Townsend Daisy | Townsendia microcephala | Not Listed | Resolved Taxon | | |
| Flowering Plants | Small-leaved agastache | Agastache parvifolia | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Small-leaved nehe | Lipochaeta degeneri | Not Listed | Species of Concern | | HI |
| Flowering Plants | Small-leaved rose | Rosa minutifolia | Not Listed | Species of Concern | | CA |
| Flowering Plants | Small-living, thick-nerved sedge | Carex microptera crassinervia | Not Listed | Resolved Taxon | | CO, MT, NV, WY |
| Fishes | Smallmouth bass | Micropterus dolomieu | Not Listed | Status Undefined | | |
| Fishes | Smallmouth Buffalo | Ictiobus bubalus | | Not Listed | | |
| Flowering Plants | Small papillosus | Echinocereus papillosus angusticeps | Not Listed | Species of Concern | | TX |
| Fishes | Smallscale darter | Etheostoma microlepidum | Not Listed | Resolved Taxon | | KY, TN |
| Flowering Plants | Small Shasta lily | Lilium washingtonianum minus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Small's milkpea | Galactia smallii | Listed | Endangered | | FL |
| Flowering Plants | Small's Rainlily | Cooperia smallii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Small's southern clarkia | Clarkia australis | Not Listed | Resolved Taxon | | CA |
| Fishes | Smalltooth sawfish | Pristis pectinata | Listed | Endangered | | |
| Fishes | Smalltooth sawfish | Pristis pectinata | Listed | Endangered | | |
| Flowering Plants | Small white lady's-slipper | Cypripedium candidum | Not Listed | Resolved Taxon | | AL, DE, IA, IL, IN, KY, MD, MI, MN, MO, ND, NE, NJ, NY, OH, PA, SD, WI |
| Flowering Plants | Small whorled pogonia | Isotria medeoloides | Listed | Threatened | | CT, DE, GA, KY, MA, MD, ME, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, WV |
| Insects | Smith's blue butterfly | Euphilotes enoptes smithi | Listed | Endangered | | CA |
| Mammals | Smiths Island cottontail rabbit | Sylvilagus floridanus hitchensi | Not Listed | Species of Concern | | VA |
| Birds | Smith's Longspur | Calcarius pictus | Not Listed | Species of Concern | | |
| Insects | Smith's siacellan reduviid | Saicella smithi | Not Listed | Species of Concern | | HI |
| Flowering Plants | Smith wild-buckwheat | Eriogonum smithii | Not Listed | Resolved Taxon | | UT |
| Insects | Smokies needlefly | Megaleuctra williamsae | Petitioned for Listing, Under Review | Under Review | | NC, SC, TN, VA |
| Insects | Smokies snowfly | Allocapnia fumosa | Not Listed | Status Undefined | | NC, TN, VA |
| Insects | Smoky eyed brown butterfly | Satyrodes eurydice fumosa | Not Listed | Resolved Taxon | | CO, IA, IL, NE |
| Fishes | Smoky madtom | Noturus baileyi | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Smoky madtom | Noturus baileyi | Listed | Endangered | | TN |
| Flowering Plants | Smoky Mountains manna grass | Glyceria nubigena | Not Listed | Species of Concern | | NC |
| Mammals | Smoky mouse | Pseudomys fumeus | Listed | Endangered | | |
| Fishes | Smoothback angelshark | Squatina oculata | Listed | Endangered | | |
| Flowering Plants | Smooth barked St. JohnÂ’s wort | Hypericum lissophloeus | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Smooth-billed ani | Crotophaga ani | Not Listed | Resolved Taxon | | |
| Flowering Plants | Smooth blue-star | Amsonia glaberrima | Not Listed | Resolved Taxon | | LA, TX |
| Flowering Plants | Smooth bog-asphodel | Tofieldia glabra | Not Listed | Species of Concern | | GA, NC, SC |
| Flowering Plants | Smooth catseye | Cryptantha semiglabra | Petitioned for Listing, Under Review | Under Review | | AZ, UT |
| Flowering Plants | Smooth coneflower | Echinacea laevigata | Listed | Threatened | | GA, NC, SC, VA |
| Snails | Smooth Glenwood Pyrg | Pyrgulopsis chamberlini | Not Listed | Resolved Taxon | | |
| Flowering Plants | Smooth-leaf bluebells | Mertensia viridis dilatata | Not Listed | Resolved Taxon | | CO, UT, WY |
| Flowering Plants | smooth lessingia | Lessingia micradenia var. glabrata | Not Listed | Species of Concern | | CA |
| Clams | Smooth pimpleback | Cyclonaias houstonensis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Smooth pungent forsellesia | Glossopetalon pungens glabra | Not Listed | Species of Concern | | CA, NV |
| Snails | Smooth rocksnail | Leptoxis virgata | Not Listed | Status Undefined | | AL, NC, TN |
| Reptiles | Smooth Softshell Turtle | Apalone mutica | | Not Listed | | |
| Flowering Plants | Smooth-stem skullcap | Scutellaria laevis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Smooth stickleaf | Mentzelia mollis | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | Smooth tarplant | Hemizonia pungens laevis | Not Listed | Species of Concern | | CA |
| Birds | Smyrna seaside sparrow | Ammodramus maritimus pelonotus | Not Listed | Resolved Taxon | | |
| Insects | Smyth's apamea moth | Apamea smythi | Not Listed | Species of Concern | | IL, VA |
| Insects | Smyth's tiger beetle | Cicindela chlorocephala smythi | Not Listed | Species of Concern | | TX |
| Fishes | Snail Bullhead | Ameiurus brunneus | | Not Listed | | |
| Fishes | Snail darter | Percina tanasi | Delisted | Recovery | | AL, GA, MS, TN |
| Snails | Snail [no common name] | Eua zebrina | Listed | Endangered | | AS |
| Snails | Snail [no common name] | Ostodes strigatus | Listed | Endangered | | AS |
| Insects | Snail shell cave beetle | Pseudanophthalmus acherontis | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | Snake cholla | Opuntia parryi serpentina | Not Listed | Species of Concern | | CA |
| Snails | Snake River physa snail | Physella natricina | Listed | Endangered | | ID, OR |
| Fishes | Snake River sucker | Chasmistes muriei | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | Snakeroot | Eryngium cuneifolium | Listed | Endangered | | FL |
| Reptiles | Snapping Turtle | Chelydra serpentine | | Not Listed | | |
| Birds | snares crested penguin | Eudyptes robustus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Sneed pincushion cactus | Coryphantha sneedii var. sneedii | Listed | Endangered | | NM, TX |
| Mammals | Snow leopard | Uncia (=Panthera) uncia | Listed | Endangered | | |
| Flowering Plants | Snow, little draba | Draba nivalis brevicula | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | Snow Mountain buckwheat | Eriogonum nervulosum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Snow Mountain willowherb | Epilobium nivium | Not Listed | Resolved Taxon | | CA |
| Birds | Snowy Egret | Egretta thula | Not Listed | Species of Concern | | |
| Birds | Snowy Owl | Bubo scandiacus | Not Listed | Species of Concern | | |
| Birds | Snowy Plover | Charadrius alexandrinus | Not Listed | Species of Concern | | |
| Birds | Snowy Plover | Charadrius nivosus tenuirostris | Not Listed | Species of Concern | | |
| Insects | Snowy yellow-faced bee | Nesoprosopis nivalis | Not Listed | Resolved Taxon | | HI |
| Clams | Snuffbox mussel | Epioblasma triquetra | Listed | Endangered | | AL, AR, IL, IN, KY, MI, MN, MO, NY, OH, PA, TN, VA, WI, WV |
| Fishes | Sockeye salmon | Oncorhynchus (=Salmo) nerka | Not Listed | Status Undefined | | |
| Fishes | Sockeye salmon | Oncorhynchus (=Salmo) nerka | Not Listed | Resolved Taxon | | |
| Fishes | Sockeye salmon | Oncorhynchus (=Salmo) nerka | Listed | Threatened | | |
| Fishes | Sockeye salmon | Oncorhynchus (=Salmo) nerka | Listed | Endangered | | |
| Fishes | Sockeye Salmon | Oncorhynchus nerka | | Not Listed | | |
| Crustaceans | Socorro isopod | Thermosphaeroma thermophilus | Listed | Endangered | | NM |
| Birds | Socorro mockingbird | Mimus graysoni | Listed | Endangered | | |
| Snails | Socorro springsnail | Pyrgulopsis neomexicana | Listed | Endangered | | NM |
| Flowering Plants | Sodaville milk-vetch | Astragalus lentiginosus sesquimetralis | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Soft bird's-beak | Cordylanthus mollis ssp. mollis | Listed | Endangered | | CA |
| Flowering Plants | Soft-leaved paintbrush | Castilleja mollis | Listed | Endangered | | CA |
| Flowering Plants | Solano grass | Tuctoria mucronata | Listed | Endangered | | CA |
| Flowering Plants | Soldier Meadows Cinquefoil | Potentilla basaltica | Not Listed | Resolved Taxon | | CA, NV |
| Birds | Solitary Sandpiper | Tringa solitaria | Not Listed | Species of Concern | | |
| Birds | Solitary Sandpiper | Tringa solitaria cinnamomea | Not Listed | Species of Concern | | |
| Birds | Solitary tinamou | Tinamus solitarius | Listed | Endangered | | |
| Birds | Song Sparrow | Melospiza melodia | Not Listed | Species of Concern | | |
| Birds | Song Sparrow | Melospiza melodia maxillaris | Not Listed | Species of Concern | | CA |
| Birds | Song Sparrow | Melospiza melodia pusillula | Not Listed | Species of Concern | | CA |
| Birds | Song Sparrow | Melospiza melodia samuelis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sonoma alopecurus | Alopecurus aequalis var. sonomensis | Listed | Endangered | | CA |
| Insects | Sonoma arctic skipper | Carterocephalus palaemon ssp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sonoma ceanothus | Ceanothus sonomensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sonoma spineflower | Chorizanthe valida | Listed | Endangered | | CA |
| Flowering Plants | Sonoma sunshine | Blennosperma bakeri | Listed | Endangered | | CA |
| Fishes | Sonora chub | Gila ditaenia | Listed | Threatened | | AZ |
| Flowering Plants | Sonora fleabane | Erigeron versicolor | Not Listed | Species of Concern | | TX |
| Reptiles | Sonoran desert tortoise | Gopherus morafkai | Not Listed | Resolved Taxon | | AZ |
| Amphibians | Sonoran green toad | Bufo retiformis | Not Listed | Resolved Taxon | | AZ |
| Reptiles | Sonoran lyre snake | trimorphodon biscutatus ssp. lambda | Not Listed | Species of Concern | | |
| Flowering Plants | Sonoran panic grass | Panicum sonoran | Not Listed | Status Undefined | | |
| Mammals | Sonoran pronghorn | Antilocapra americana sonoriensis | Listed | Experimental Population, Non-Essential | | AZ, CA |
| Mammals | Sonoran pronghorn | Antilocapra americana sonoriensis | Listed | Endangered | | AZ |
| Snails | Sonoran Snaggletooth | Gastrocopta prototypus | Not Listed | Resolved Taxon | | |
| Snails | Sonoran talussnail | Sonorella magdalenensis | Petitioned for Listing, Under Review | Under Review | | AZ |
| Amphibians | Sonoran tiger salamander | Ambystoma mavortium stebbinsi | Listed | Endangered | | AZ |
| Birds | Sonoran Yellow Warbler | Dendroica petechia ssp. sonorana | Not Listed | Species of Concern | | |
| Fishes | Sonora sucker | Catostomus insignis | Not Listed | Species of Concern | | AZ, NM |
| Reptiles | Sonoyta mud turtle | Kinosternon sonoriense longifemorale | Listed | Endangered | | AZ |
| Birds | Sooty Shearwater | Ardenna grisea | Not Listed | Species of Concern | | |
| Birds | Sooty Tern | Onychoprion fuscatus | Not Listed | Species of Concern | | |
| Insects | Soror odynerus vespid wasp | Odynerus soror | Not Listed | Species of Concern | | HI |
| Mammals | South American (=Brazilian) tapir | Tapirus terrestris | Listed | Endangered | | |
| Reptiles | South American red-lined turtle | Trachemys scripta callirostris | Listed | Endangered | | |
| Mammals | South Andean huemul | Hippocamelus bisulcus | Listed | Endangered | | |
| Mammals | South Asian River dolphin | Platanista gangetica minor | Listed | Endangered | | |
| Insects | South Branch Valley cave beetle | Pseudanophthalmus potomaca potomaca | | Not Listed | | VA, WV |
| Mammals | South China sika deer | Cervus nippon kopschi | Listed | Endangered | | |
| Reptiles | South coast garter snake | Thamnophis sirtalis ssp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | South Coast Range morning-glory | Calystegia collina venusta | Not Listed | Species of Concern | | CA |
| Flowering Plants | South coast saltbush | Atriplex pacifica | Not Listed | Species of Concern | | CA |
| Birds | Southeastern American Kestrel | Falco sparverius paulus | Not Listed | Species of Concern | | |
| Mammals | Southeastern beach mouse | Peromyscus polionotus niveiventris | Listed | Threatened | | FL |
| Mammals | Southeastern myotis | Myotis austroriparius | Not Listed | Species of Concern | | |
| Birds | Southeastern rufous-vented ground cuckoo | Neomorphus geoffroyi dulcis | Listed | Endangered | | |
| Fishes | Southeastern walleye | Stizostedion vitreum vitreum | Not Listed | Resolved Taxon | | |
| Clams | Southern acornshell | Epioblasma othcaloogensis | Delisted | Extinction | | AL, GA, TN |
| Birds | Southern Appalachian black-capped chickadee | Poecile atricapillus ssp. practica | Not Listed | Species of Concern | | NC |
| Mammals | Southern Appalachian eastern woodrat | Neotoma floridana haematoreia | Not Listed | Species of Concern | | GA, NC, SC |
| Mammals | Southern bearded saki | Chiropotes satanas satanas | Listed | Endangered | | |
| Fishes | Southern Brook Lamprey | Ichthyomyzon gagei | | Not Listed | | |
| Birds | Southern California rufous-crowned sparrow | Aimophila ruficeps canescens | Not Listed | Species of Concern | | CA |
| Fishes | Southern cave crayfish | orconectes australis ssp. australis | Not Listed | Species of Concern | | |
| Fishes | Southern cavefish | typhlichthys subterraneus | Not Listed | Species of Concern | | |
| Clams | Southern clubshell | Pleurobema decisum | Listed | Endangered | | AL, GA, MS, TN |
| Clams | Southern combshell | Epioblasma penita | Listed | Endangered | | AL, MS |
| Snails | Southern Duckwater pyrg | Pyrgulopsis anatina | Not Listed | Resolved Taxon | | NV |
| Amphibians | Southern Dusky Salamander | Desmognathus auriculatus | Not Listed | Resolved Taxon | | |
| Clams | Southern elktoe | Alasmidonta triangulata | Proposed for Listing | Proposed Endangered | | AL, FL, GA |
| Clams | Southern Fatmucket | Lampsilis straminea | | Not Listed | | |
| Fishes | Southern Flounder | Paralichthys lethostigma | | Not Listed | | |
| Mammals | Southern grasshopper mouse | Onychomys torridus ramona | Not Listed | Species of Concern | | CA |
| Birds | Southern-helmeted curassow | Pauxi unicornis | Listed | Endangered | | |
| Clams | Southern hickorynut | Obovaria jacksoniana | Not Listed | Resolved Taxon | | AL, AR, LA, MO, MS, OK, TN, TX |
| Reptiles | Southern hognose snake | Heterodon simus | Not Listed | Resolved Taxon | | GA, SC |
| Mammals | Southern Idaho ground Squirrel | Urocitellus endemicus | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | Southern island phacelia | Phacelia floribunda | Not Listed | Species of Concern | | CA |
| Clams | Southern kidneyshell | Ptychobranchus jonesi | Listed | Endangered | | AL, FL |
| Clams | Southern lance | Elliptio ahenea | Not Listed | Status Undefined | | GA |
| Mammals | Southern marsh harvest mouse | Reithrodontomys megalotis limicola | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Southern meadowrue | Thalictrum debile | Not Listed | Status Undefined | | AL, GA, MS |
| Mammals | Southern Mountain Caribou DPS | Rangifer tarandus ssp. caribou | Listed | Endangered | | ID, WA |
| Flowering Plants | Southern mountain wild-buckwheat | Eriogonum kennedyi var. austromontanum | Listed | Threatened | | CA |
| Mammals | southern mule deer | Odocoileus hemionus spp. fuliginatus | Not Listed | Status Undefined | | |
| Flowering Plants | Southern Oconee Bells | Shortia galacifolia var. galacifolia | Not Listed | Species of Concern | | GA, NC, SC |
| Mammals | Southern pig-tailed macaque | Macaca nemestrina | | Not Listed | | |
| Clams | Southern pigtoe | Pleurobema georgianum | Listed | Endangered | | AL, GA, TN |
| Insects | Southern Plains Bumblebee | Bombus fraternus | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Southern planigale | Planigale tenuirostris | Listed | Endangered | | |
| Clams | Southern Pocketbook | Lampsilis ornata | | Not Listed | | |
| Clams | Southern Purple Lilliput | Toxolasma corvunculus | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Southern pygmy shrew | Sorex hoyi winnemana | Not Listed | Resolved Taxon | | IL, IN, KY, MD, NC, OH, TN, VA |
| Flowering Plants | Southern Racemose goldenrod | Solidago arenicola | Not Listed | Status Undefined | | AL, TN |
| Fishes | Southern Rainbow | Villosa vibex | | Not Listed | | |
| Fishes | Southern Redbelly Dace | Chrosomus erythrogaster | | Not Listed | | |
| Flowering Plants | Southern rein-orchid | Platanthera flava | Not Listed | Resolved Taxon | | |
| Mammals | Southern Right Whale | Eubalaena australis | Listed | Endangered | | |
| Mammals | Southern river otter | Lontra (=Lutra) provocax | Listed | Endangered | | |
| Birds | southern rockhopper penguin | Eudyptes chrysocome | Listed | Threatened | | |
| Mammals | Southern rock vole | Microtus chrotorrhinus carolinensis | Not Listed | Species of Concern | | NC, TN, VA, WV |
| Reptiles | Southern rubber boa | Charina bottae umbratica | Not Listed | Resolved Taxon | | CA |
| Birds | Southern Ryukyu robin | Erithacus komadori subrufa | Not Listed | Resolved Taxon | | |
| Reptiles | Southern sagebrush lizard | Sceloporus graciosus vandenburgianus | Not Listed | Resolved Taxon | | CA |
| Clams | Southern Sandshell | Hamiota australis | Listed | Threatened | | AL, FL |
| Mammals | Southern sea otter | Enhydra lutris nereis | Listed | Threatened | | CA |
| Insects | Southern snaketail | Ophiogomphus australis | Petitioned for Listing, Under Review | Under Review | | FL |
| Snails | Southern Steptoe pyrg | Pyrgulopsis sulcata | Petitioned for Listing, Under Review | Under Review | | NV |
| Flowering Plants | Southern tarplant | Hemizonia parryi australis | Not Listed | Species of Concern | | CA |
| Insects | Southern tawny crescent | Phyciodes batesii maconensis | Not Listed | Species of Concern | | NC |
| Flowering Plants | Southern three-awned grass | Aristida simpliciflora | Not Listed | Species of Concern | | |
| Snails | Southern Tightcoil | Ogaridiscus subrupicola | Not Listed | Resolved Taxon | | |
| Amphibians | Southern torrent salamander | Rhyacotriton variegatus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Mammals | Southern water shrew | Sorex palustris punctulatus | Not Listed | Species of Concern | | MD, NC, PA, TN, VA, WV |
| Mammals | Southern white rhinoceros | Ceratotherium simum ssp. simum | Listed | Similarity of Appearance (Threatened) | | |
| Birds | southern white-tailed ptarmigan | Lagopus leucura altipetens | Not Listed | Resolved Taxon | | CO |
| Mammals | Southern Yellow Bat | Dasypterus ega | | Not Listed | | |
| Mammals | Southern Yellow Bat | Lasiurus ega | Not Listed | Species of Concern | | |
| Reptiles | South Florida rainbow snake | Farancia erytrogramma seminola | Not Listed | Resolved Taxon | | |
| Insects | South Forks ground beetle | Nebria darlingtoni | Not Listed | Species of Concern | | CA |
| Mammals | South Island Hector's dolphin | Cephalorhynchus hectori hectori | Listed | Threatened | | |
| Lichens | South Llano Springs moss | Donrichardsia macroneuron | Listed | Endangered | | |
| Amphibians | South Mountain gray-cheeked salamander | Plethodon meridianus | Not Listed | Resolved Taxon | | NC |
| Birds | South Polar Skua | Stercorarius maccormicki | Not Listed | Species of Concern | | |
| Flowering Plants | South Texas ambrosia | Ambrosia cheiranthifolia | Listed | Endangered | | TX |
| Mammals | Southwestern otter | Lutra canadensis sonora | Not Listed | Species of Concern | | CO |
| Reptiles | Southwestern pond turtle | Actinemys pallida | Proposed for Listing | Proposed Threatened | | CA |
| Crustaceans | Southwestern Virginia cave amphipod | Stygobromus mackini | Not Listed | Resolved Taxon | | TN, VA |
| Birds | Southwestern willow flycatcher | Empidonax traillii extimus | Listed | Endangered | | AZ, CA, CO, NM, NV, TX, UT |
| Snails | Southwest Nevada pyrg | Pyrgulopsis turbatrix | Not Listed | Resolved Taxon | | NV |
| Insects | Southwest spring firefly | Bicellonycha wickershamorum | Petitioned for Listing, Under Review | Under Review | | AZ |
| Flowering Plants | Spalding's Catchfly | Silene spaldingii | Listed | Threatened | | ID, MT, OR, WA |
| Insects | Spangler's hydroporus diving beetle | Hydroporus spangleri | Not Listed | Species of Concern | | UT |
| Birds | Spanish imperial eagle | Aquila heliaca adalberti | Listed | Endangered | | |
| Mammals | Spanish lynx | Felis pardina | Listed | Endangered | | |
| Fishes | Spanish Mackerel | Scomberomorus maculatus | | Not Listed | | |
| Flowering Plants | Spanish needle onion | Allium shevockii | Not Listed | Species of Concern | | CA |
| Snails | Sparrow pebblesnail | Somatogyrus parvulus | Not Listed | Species of Concern | | TN |
| Flowering Plants | Spathulate seedbox | Ludwigia spathulata | Not Listed | Status Undefined | | GA, SC |
| Crustaceans | Speckled burrowing crayfish | Fallicambarus danielae | Petitioned for Listing, Under Review | Under Review | | AL, MS |
| Fishes | Speckled chub | Macrhybopsis aestivalis | Not Listed | Status Undefined | | |
| Fishes | Speckled dace | Rhinichthys osculus ssp. | Not Listed | Species of Concern | | AZ |
| Fishes | Speckled Dace | Rhinichthys osculus | | Not Listed | | |
| Fishes | Speckled Darter | Etheostoma stigmaeum | | Not Listed | | |
| Fishes | Speckled Madtom | Noturus leptacanthus | | Not Listed | | |
| Clams | Speckled pocketbook | Lampsilis streckeri | Listed | Endangered | | AR |
| Reptiles | Speckled rattlesnake | Crotalus mitchellii | Not Listed | Species of Concern | | |
| Clams | Spectaclecase (mussel) | Cumberlandia monodonta | Listed | Endangered | | AL, AR, IA, IL, KY, MN, MO, TN, VA, WI, WV |
| Birds | Spectacled eider | Somateria fischeri | Listed | Threatened | | AK |
| Insects | Specular yellow-faced bee | Hylaeus specularis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Spellenberg's groundsel | Packera spellenbergii | Not Listed | Species of Concern | | NM |
| Millipedes | (Speodesmus) millipede | speodesmus | Not Listed | Species of Concern | | |
| Mammals | Sperm whale | Physeter catodon (=macrocephalus) | Listed | Endangered | | |
| Flatworms and Roundworms | (Sphalloplana mohri) flatworm | sphalloplana mohri | Not Listed | Species of Concern | | |
| Insects | Sphecodoid yellow-faced bee | Hylaeus sphecodoides | Not Listed | Species of Concern | | HI |
| Flowering Plants | Sphinx date palm | Phoenix dactylifera | Not Listed | Resolved Taxon | | AZ |
| Insects | Sphinx moth | Sphinx smithi | Not Listed | Resolved Taxon | | |
| Insects | Spiculose serratellan mayfly | Serratella serrata | Not Listed | Species of Concern | | NC |
| Crustaceans | Spider Cave crayfish | Troglocambarus maclanei | Petitioned for Listing, Under Review | Under Review | | FL |
| Snails | Spider elimia | Elimia arachnoidea | Petitioned for Listing, Under Review | Under Review | | TN, VA |
| Mammals | Spider monkey | Ateles geoffroyi frontatus | Listed | Endangered | | |
| Mammals | Spider monkey | Ateles geoffroyl panamensis | Listed | Endangered | | |
| Reptiles | Spider Tortoise | Pyxis arachnoides | Petitioned for Listing, Under Review | Under Review | | |
| Clams | Spike | Eurynia dilatata | | Not Listed | | |
| Fishes | Spikedace | Meda fulgida | Listed | Endangered | | AZ, NM |
| Snails | Spindle elimia | Elimia capillaris | Not Listed | Species of Concern | | AL, GA |
| Flowering Plants | Spineless hedgehog Cactus | Echinocereus triglochidiatus var. inermis | Delisted | Original Data in Error - Not a listable entity | | CO, UT |
| Fishes | Spiny angelshark | Squatina guggenheim | Listed | Endangered | | |
| Fishes | Spinycheek Sleeper | Eleotris pisonis | | Not Listed | | |
| Fishes | Spiny Dogfish | Squalus acanthias | | Not Listed | | |
| Insects | Spiny Florida sandhill scarab | Gronocarus multispinosus | Not Listed | Species of Concern | | |
| Insects | Spiny rhyacophilan caddisfly | Rhyacophila spinata | Not Listed | Species of Concern | | CA |
| Snails | Spiny riversnail | Io fluvialis | Petitioned for Listing, Under Review | Under Review | | VA |
| Crustaceans | Spiny Scale crayfish | Cambarus jezerinaci | Petitioned for Listing, Under Review | Under Review | | TN, VA |
| Flowering Plants | Spinysepaled eryngo | Eryngium spinosepalum | Not Listed | Species of Concern | | CA |
| Reptiles | Spiny Softshell Turtle | Apalone spinifera | | Not Listed | | |
| Crustaceans | Spinytail crayfish | Procambarus fitzpatricki | Not Listed | Resolved Taxon | | MS |
| Snails | Spiral hornsnail | Pleurocera brumbyi | Not Listed | Species of Concern | | AL |
| Fishes | Splendid Darter | Etheostoma barrenense | | Not Listed | | |
| Insects | Splendid shield-backed katydid | Ateloplus splendidus | Not Listed | Resolved Taxon | | |
| Lichens | Splitting yarn lichen | Sulcaria isidiisera | Not Listed | Species of Concern | | CA |
| Ferns and Allies | Sp. nov. ined. (Appalachian) oak fern | Gymnocarpium sp. | Not Listed | Species of Concern | | NC |
| Flowering Plants | Sp. nov. ined. artemisia | Artemisia | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Sp. nov. ined. blue curls | Trichostema sp. | Not Listed | Species of Concern | | NC, SC |
| Flowering Plants | Sp. nov. ined. browallia | Browallia sp. | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Sp. nov. ined. (chaparral) beargrass | Nolina sp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sp. nov. ined. cirsium | Cirsium sp. | Not Listed | Species of Concern | | WY |
| Flowering Plants | Sp. nov. ined. (Del Norte) rock-cress | Arabis sp. | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Sp. nov. ined. erigeron | Erigeron sp. | Not Listed | Species of Concern | | WY |
| Flowering Plants | Sp. nov. ined. (Gray Knolls) rock-cress | Arabis sp. | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Sp. nov. ined. (gypsum) townsendia | Townsendia sp. | Not Listed | Species of Concern | | NM |
| Flowering Plants | Sp. nov. ined. leptodactylon | Leptodactylon sp. | Not Listed | Species of Concern | | CO |
| Flowering Plants | Sp. nov. ined. lysimachia | Lysimachia sp. | Not Listed | Species of Concern | | HI |
| Flowering Plants | Sp. nov. ined. (munchkin) dudleya | Dudleya sp. | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Sp. nov. ined. (Nye Co.) townsendia | Townsendia sp. | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | Sp. nov. ined. (Pit River) jewelflower | Streptanthus sp. | Not Listed | Species of Concern | | CA |
| Flowering Plants | Sp. nov. ined. sclerocactus | Sclerocactus sp. | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Sp. nov. ined. (Tonto Basin) agave | Agave sp. | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Sp. nov. ined. (Waihoi Valley) lysimachia | Lysimachia sp. nov. ined. | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Sp. nov. ined. (WY) townsendia | Townsendia sp. | Not Listed | Species of Concern | | WY |
| Sponges | Spongy sponge | Spongilla sponginosa | Not Listed | Resolved Taxon | | SC |
| Fishes | Spoonhead Sculpin | Cottus ricei | | Not Listed | | |
| Snails | Sportinggoods tryonia | Tryonia angulata | Not Listed | Resolved Taxon | | NV |
| Fishes | Spot | Leiostomus xanthurus | | Not Listed | | |
| Fishes | Spotfin Chub | Erimonax monachus | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Spotfin Chub | Erimonax monachus | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Spotfin Chub | Erimonax monachus | Listed | Threatened | | NC, TN, VA |
| Fishes | Spotfin Chub | Erimonax monachus | Listed | Experimental Population, Non-Essential | | AL, TN |
| Fishes | Spotfin Gambusia | Gambusia krumholzi | | Not Listed | | |
| Fishes | Spotfin Shiner | Cyprinella spiloptera | | Not Listed | | |
| Birds | Spotless Crake | Porzana tabuensis | Not Listed | Resolved Taxon | | AS |
| Birds | Spotless Crake | Porzana tabuensis tabuensis | Not Listed | Species of Concern | | |
| Fishes | Spottail Darter | Etheostoma squamiceps | | Not Listed | | |
| Fishes | Spotted Algae-Eating Goby | Sicydium punctatum | | Not Listed | | |
| Fishes | Spotted Bass | Micropterus punctulatus | | Not Listed | | |
| Mammals | Spotted bat | Euderma maculatum | Not Listed | Species of Concern | | AZ, CA, CO, ID, MT, NM, NV, OR, TX, UT, WY |
| Insects | Spotted cave beetle | Pseudanophthalmus punctatus | Not Listed | Species of Concern | | VA |
| Fishes | Spotted darter | Etheostoma maculatum | Not Listed | Resolved Taxon | | NY |
| Fishes | Spotted Darter | Nothonotus maculatus | | Not Listed | | |
| Reptiles | Spotted Leaf-nosed Snake | Phyllorhynchus decurtatus | | Not Listed | | |
| Mammals | Spotted linsang | Prionodon pardicolor | Listed | Endangered | | |
| Fishes | Spotted madtom | Noturus insignis ssp. | Not Listed | Species of Concern | | NC, VA |
| Reptiles | Spotted pond turtle | Geoclemys hamiltonii | Listed | Endangered | | |
| Snails | Spotted rocksnail | Leptoxis picta | Petitioned for Listing, Under Review | Under Review | | AL |
| Amphibians | Spotted Salamander | Ambystoma maculatum | Not Listed | Status Undefined | | |
| Mammals | Spotted Seal | Phoca largha | Listed | Threatened | | |
| Fishes | Spotted Seatrout | Cynoscion nebulosus | | Not Listed | | |
| Mammals | Spotted skunk | Spilogale putorius | Not Listed | Status Undefined | | |
| Fishes | Spotted Sucker | Minytrema melanops | | Not Listed | | |
| Fishes | Spotted Sunfish | Lepomis punctatus | | Not Listed | | |
| Birds | Spotted Towhee | Pipilo maculatus | Not Listed | Species of Concern | | |
| Birds | Spotted Towhee | Pipilo maculatus clementae | Not Listed | Species of Concern | | CA |
| Reptiles | Spotted turtle | Clemmys guttata | Petitioned for Listing, Under Review | Under Review | | GA, SC |
| Insects | Spotted Warner Valley Dunes june beetle | Polyphylla avittata | Not Listed | Species of Concern | | UT |
| Snails | Spp. (ca 12) carelia | Carelia spp. (ca 12) | Not Listed | Species of Concern | | HI |
| Birds | Sprague's pipit | Anthus spragueii | Not Listed | Resolved Taxon | | AR, AZ, KS, LA, MN, MS, MT, ND, NM, OK, SD, TX |
| Flowering Plants | Spreading avens | Geum radiatum | Listed | Endangered | | NC, TN, VA |
| Flowering Plants | Spreading navarretia | Navarretia fossalis | Listed | Threatened | | CA |
| Flowering Plants | Spreading wild-buckwheat | Eriogonum lonchophyllum | Not Listed | Resolved Taxon | | UT |
| Crustaceans | Spring amphipod | Stygobromus fontinalis | Not Listed | Resolved Taxon | | |
| Crustaceans | Spring Cave amphipod | Stygobromus spinatus | Not Listed | Species of Concern | | WV |
| Fishes | Spring Cavefish | Forbesichthys agassizii | | Not Listed | | |
| Flowering Plants | Spring Creek bladderpod | Lesquerella perforata | Listed | Endangered | | TN |
| Snails | Spring Creek pyrg | Pyrgulopsis sp. | Not Listed | Species of Concern | | AL |
| Snails | Spring elimia | Elimia pybasi | Not Listed | Species of Concern | | AL |
| Flowering Plants | Spring-flowering goldenrod | Solidago verna | Not Listed | Species of Concern | | NC, SC |
| Flowering Plants | Spring-loving centaury | Centaurium namophilum | Listed | Threatened | | CA, NV |
| Insects | Spring Mountain comma skipper | Hesperia comma ssp. | Not Listed | Species of Concern | | NV |
| Flowering Plants | Spring Mountain milk-vetch | Astragalus remotus | Not Listed | Species of Concern | | NV |
| Insects | Spring Mountains acastus checkerspot butterfly | Chlosyne acastus robusta | Not Listed | Resolved Taxon | | NV |
| Insects | Spring Mountains blue | Plejebus shasta charlestonensis | Not Listed | Species of Concern | | NV |
| Insects | Spring Mountains comma skipper butterfly | hesperia comma ssp. mojavensis | Not Listed | Species of Concern | | |
| Insects | Spring Mountains dark blue butterfly | Euphilotes ancilla cryptica | Not Listed | Resolved Taxon | | NV |
| Insects | Spring Mountains dark blue butterfly | Euphilotes ancilla purpura | Not Listed | Resolved Taxon | | NV |
| Insects | Spring Mountains icarioides blue | Plejebus icarioides ssp. | Not Listed | Species of Concern | | CA, NV |
| Insects | Spring Mountains icarioides blue butterfly | Plebejus icarioides austinorum | Not Listed | Resolved Taxon | | NV |
| Snails | Spring Mountains pyrg | Pyrgulopsis deaconi | Not Listed | Resolved Taxon | | NV |
| Amphibians | Spring Peeper | Pseudacris crucifer | | Not Listed | | |
| Fishes | Spring pygmy sunfish | Elassoma alabamae | Listed | Threatened | | AL |
| Crustaceans | Spring River crayfish | Faxonius roberti | Not Listed | Resolved Taxon | | |
| Amphibians | Spring Salamander | Gyrinophilus porphyriticus | | Not Listed | | |
| Flowering Plants | Springville clarkia | Clarkia springvillensis | Listed | Threatened | | CA |
| Snails | Spruce Creek snail | Melongena sprucecreekensis | Not Listed | Resolved Taxon | | |
| Arachnids | Spruce-fir moss spider | Microhexura montivaga | Listed | Endangered | | NC, TN, VA |
| Flowering Plants | Square-stemmed monkey-flower | Mimulus ringens colpophilus | Not Listed | Species of Concern | | ME |
| Snails | Squat elimia | Elimia variata | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | Squaw carpet | Ceanothus prostratus laxus | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Squirrel Chimney Cave shrimp | Palaemonetes cummingi | Listed | Threatened | | FL |
| Arachnids | Sri Lankan Ornamental Tarantula | Poecilotheria fasciata | Listed | Endangered | | |
| Flowering Plants | stage station milkvetch | Astragalus vehiculus | | Not Listed | | |
| Corals | Staghorn coral | Acropora cervicornis | Listed | Threatened | | |
| Flowering Plants | Stairstep two-bristle rock-daisy | Perityle bisetosa scalaris | Not Listed | Species of Concern | | TX |
| Ferns and Allies | Stalked moonwort | Botrychium pedunculosum | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Stalk-leaved monkey-flower | Mimulus patulus | Not Listed | Species of Concern | | CA, ID, NV, OR, WA |
| Flowering Plants | Standley whitlow-grass | Draba standleyi | Not Listed | Species of Concern | | AZ, NM, TX |
| Mammals | St. Andrew beach mouse | Peromyscus polionotus peninsularis | Listed | Endangered | | FL |
| Flowering Plants | Stanley whitlow-grass | Draba trichocarpa | Not Listed | Species of Concern | | ID |
| Insects | Stannard's agarodes caddisfly | Agarodes stannardi | Not Listed | Species of Concern | | MS, TN |
| Mammals | Stansbury Island harvest mouse | Reithrodontomys megalotis ravus | Not Listed | Species of Concern | | UT |
| Mammals | Stansbury Island pocket gopher | Thomomys umbrinus minimus | Not Listed | Species of Concern | | UT |
| Flowering Plants | Star cactus | Astrophytum asterias | Listed | Endangered | | TX |
| Corals | Star coral | Montastraea franksi | Not Listed | Status Undefined | | |
| Flowering Plants | Star-fruited, small stonecrop | Sedum radiatum depauperatum | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Stargazing darter | Percina uranidea | Not Listed | Species of Concern | | AR, IL, IN, LA, MO |
| Fishes | Stargazing Minnow | Phenacobius uranops | | Not Listed | | |
| Insects | Stark's false water penny | Alabameubria starki | Not Listed | Species of Concern | | AL |
| Mammals | Star-nosed mole | Condylura cristata parva | Not Listed | Resolved Taxon | | GA, MD, NC, SC, TN, VA, WV |
| Fishes | Starry Flounder | Platichthys stellatus | | Not Listed | | |
| Reptiles | St. Croix ground lizard | Ameiva polops | Listed | Endangered | | VI |
| Reptiles | St. Croix racer | Alsophis sancticrucis | Not Listed | Resolved Taxon | | VI |
| Insects | St. Croix snaketail | Ophiogomphus sp. | Not Listed | Species of Concern | | MN, WI |
| Flowering Plants | Steamboat buckwheat | Eriogonum ovalifolium var. williamsiae | Listed | Endangered | | NV |
| Flowering Plants | Stebbins lewisia | Lewisia stebbinsii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Stebbins' lomatium | Lomatium stebbinsii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Stebbins' madia | Madia stebbinsii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Stebbins' morning-glory | Calystegia stebbinsii | Listed | Endangered | | CA |
| Flowering Plants | Stebbins' phacelia | Phacelia stebbinsii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Steele's meadowrue | Thalictrum coriaceum | Not Listed | Resolved Taxon | | DC, MD, PA, VA, WV |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Endangered | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Threatened | | |
| Fishes | Steelhead (Rainbow Trout) | Oncorhynchus (=Salmo) mykiss | Listed | Experimental Population, Non-Essential | | |
| Flowering Plants | Steen's mountain paintbrush | Castilleja pilosa steenensis | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Stellate Sturgeon | Acipenser stellatus | Proposed for Listing | Proposed Endangered | | |
| Mammals | Steller sea lion | Eumetopias jubatus | Listed | Endangered | | |
| Mammals | Steller sea lion | Eumetopias jubatus | Delisted | Recovery | | |
| Birds | Steller's Eider | Polysticta stelleri | Listed | Threatened | | AK |
| Crustaceans | Stellmack's cave amphipod | Stygobromus stellmacki | Not Listed | Species of Concern | | PA |
| Flowering Plants | Stemless beardtongue | Penstemon acaulis | Not Listed | Species of Concern | | UT, WY |
| Insects | Stephan's Riffle beetle | Heterelmis stephani | Not Listed | Resolved Taxon | | AZ |
| Amphibians | Stephen Island frog | Leiopelma hamiltoni | Listed | Endangered | | |
| Flowering Plants | Stephens' beardtongue | Penstemon stephensii | Not Listed | Species of Concern | | CA |
| Mammals | Stephens' California vole | Microtus californicus stephensi | Not Listed | Species of Concern | | CA |
| Mammals | Stephens' kangaroo rat | Dipodomys stephensi (incl. D. cascus) | Listed | Threatened | | CA |
| Insects | Steptoe Valley crescentspot | Phyciodes cocyta arenacolor | Not Listed | Resolved Taxon | | NV |
| Snails | Sterile Basin pyrg | Pyrgulopsis sterilis | Petitioned for Listing, Under Review | Under Review | | NV |
| Flowering Plants | Sterile milk-vetch | Astragalus sterilis | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Lichens | Sterlings lips | Graphis sterlingiana | Not Listed | Species of Concern | | NC |
| Insects | Stevens' tortricid moth | Decodes stevensi | Not Listed | Species of Concern | | CO |
| Crustaceans | St. Francis River Crayfish | Faxonius quadruncus | Listed | Threatened | | MO |
| Insects | Sthenele wood nymph | Cercyonis sthenele sthenele | Not Listed | Resolved Taxon | | CA |
| Mammals | Stick-nest rat | Leporillus conditor | Listed | Endangered | | |
| Flowering Plants | Sticky-leaved liveforever | Dudleya viscida | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Sticky phacelia | Phacelia lenta | Not Listed | Species of Concern | | WA |
| Flowering Plants | Sticky ringstem | anulocaulis leiosolenus | Not Listed | Species of Concern | | |
| Fishes | Stimpson'S Goby, `O`Opu Nopili | Sicyopterus stimpsoni | | Not Listed | | |
| Flowering Plants | Stingingbush | Malpighia infestissima | Not Listed | Species of Concern | | VI |
| Flowering Plants | Stink bells | Fritillaria agrestis | Not Listed | Resolved Taxon | | CA |
| Fishes | Stippled Darter | Etheostoma punctulatum | | Not Listed | | |
| Fishes | Stippled studfish | Fundulus bifax | Not Listed | Status Undefined | | AL |
| Clams | Stirrupshell | Quadrula stapes | Delisted | Extinction | | AL, MS |
| Clams | St. Johns elephantear | Elliptio monroensis | Not Listed | Status Undefined | | GA |
| Birds | St. Lucia Forest thrush | Cichlherminia iherminieri santaeluciae | Listed | Endangered | | |
| Birds | St. Lucia house wren | Troglodytes aedon mesoleucus | Listed | Endangered | | |
| Birds | St. Lucia parrot | Amazona versicolor | Listed | Endangered | | |
| Fishes | St. Maarten Pejerry | Melanorhinus boekei | | Not Listed | | |
| Mammals | St. Mathew vole | Microtus abbreviatus | Not Listed | Status Undefined | | AK |
| Snails | Stock Island tree snail | Orthalicus reses (not incl. nesodryas) | Listed | Threatened | | FL |
| Snails | Stocky pebblesnail | Somatogyrus crassus | Not Listed | Species of Concern | | AL |
| Birds | Stoddard's yellow-throated warbler | Dendroica dominica stoddardi | Not Listed | Species of Concern | | |
| Flowering Plants | Stolon whitlow-grass | Draba sobolifera | Not Listed | Species of Concern | | UT |
| Fishes | Stonecat | Noturus flavus | | Not Listed | | |
| Flowering Plants | Stone Corral Canyon monardella | Monardella scelerata | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Stonecrop Gily flower | Gilia sedifolia | Not Listed | Resolved Taxon | | |
| Insects | Stone-dwelling cave beetle | Pseudanophthalmus hypolithos | Not Listed | Species of Concern | | KY |
| Crustaceans | Stone Mountain fairy shrimp | Branchinella lithaca | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | Stones River bladderpod | Paysonia stonensis | Not Listed | Resolved Taxon | | TN |
| Mammals | straight-horned markhor | Capra falconeri megaceros | Listed | Endangered | | |
| Mammals | straight-horned markhor | Capra falconeri megaceros | Listed | Endangered | | |
| Insects | Straight snowfly | Capnia lineata | Not Listed | Resolved Taxon | | ID |
| Insects | Straley's cave beetle | Pseudanophthalmus quadratus | Not Listed | Species of Concern | | VA |
| Insects | Strange itodacnus click beetle | Itodacnus paradoxus | Not Listed | Species of Concern | | HI |
| Birds | Streaked Horned lark | Eremophila alpestris strigata | Listed | Threatened | | OR, WA |
| Amphibians | Streamside Salamander | Ambystoma barbouri | Petitioned for Listing, Under Review | Under Review | | IN, KY, OH, TN, WV |
| Amphibians | Strecker's Chorus Frog | Pseudacris streckeri | | Not Listed | | |
| Mammals | strecker's pocket gopher | geomys streckeri | Not Listed | Status Undefined | | |
| Birds | Stresemann's bristlefront | Merulaxis stresemanni | Not Listed | Status Undefined | | |
| Fishes | Striated darter | Etheostoma striatulum | Petitioned for Listing, Under Review | Under Review | | TN |
| Snails | Striated Hydrobe | Texapyrgus longleyi | Not Listed | Resolved Taxon | | |
| Snails | Striate slitshell | Gyrotoma lewisii | Not Listed | Resolved Taxon | | AL |
| Fishes | Striped Bass | Morone saxatilis | Not Listed | Status Undefined | | |
| Fishes | Striped Bass | Morone saxatilis | Not Listed | Status Undefined | | |
| Fishes | Striped Bass | Morone saxatilis | | Not Listed | | |
| Amphibians | Striped newt | Notophthalmus perstriatus | Not Listed | Resolved Taxon | | GA |
| Insects | Striped rhyncogonus weevil | Rhyncogonus vittatus | Not Listed | Species of Concern | | HI |
| Snails | Striped rocksnail | Leptoxis vittata | Not Listed | Resolved Taxon | | AL |
| Fishes | Striped smoothhound shark | Mustelus fasciatus | Listed | Endangered | | |
| Insects | Strohbeen's parnassian | Parnassius clodius strohbeeni | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Strong bladder-pod | Lesquerella valida | Not Listed | Resolved Taxon | | NM, TX |
| Snails | Stronghold Canyon Talussnail | Sonorella dragoonensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | St. Thomas lidpod | Operculina turpethum var. turpethum | Not Listed | Species of Concern | | VI |
| Flowering Plants | St. Thomas prickly-ash | Zanthoxylum thomasianum | Listed | Endangered | | PR, VI |
| Mammals | Stump-tailed macaque | Macaca arctoides | Listed | Threatened | | |
| Fishes | Sturgeon chub | Macrhybopsis gelida | Not Listed | Resolved Taxon | | AR, IA, IL, KS, KY, LA, MO, MS, MT, ND, NE, SD, TN, WY |
| Birds | St Vincent parrot | Amazona guildingii | Listed | Endangered | | |
| Snails | Subcarinate mountain snail | Oreohelix specieseleven | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Sub-globose Snake pyrg | Pyrgulopsis saxatilis | Not Listed | Resolved Taxon | | UT |
| Snails | Sub-globose Steptoe Ranch pyrg | Pyrgulopsis orbiculata | Petitioned for Listing, Under Review | Under Review | | NV |
| Crustaceans | Subtle cave amphipod | Stygobromus subtilis | Not Listed | Species of Concern | | IL, MO |
| Insects | Subtropical blue-black tiger beetle | Cicindela nigrocoerulea subtropica | Not Listed | Species of Concern | | TX |
| Crustaceans | Sucarnoochee River crayfish | Orconectes jonesi | Not Listed | Status Undefined | | AL, MS |
| Fishes | Suckermouth Minnow | Phenacobius mirabilis | | Not Listed | | |
| Insects | Suckley's cuckoo bumble bee | Bombus suckleyi | Proposed for Listing | Proposed Endangered | | AZ, CA, CO, IA, ID, KS, MI, MN, MO, MT, ND, NE, NM, NV, OR, SD, UT, WA, WI, WY |
| Insects | Sugarfoot moth fly | Nemopalpus nearcticus | Not Listed | Species of Concern | | |
| Clams | Sugarspoon | Epioblasma arcaeformis | Not Listed | Resolved Taxon | | AL, TN |
| Flowering Plants | Suisun aster | Aster chilensis lentus | Not Listed | Species of Concern | | CA |
| Mammals | Suisun ornate shrew | Sorex ornatus sinuosus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Suisun thistle | Cirsium hydrophilum var. hydrophilum | Listed | Endangered | | CA |
| Flowering Plants | Suksdorf's desert-parsley | Lomatium suksdorfii | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Reptiles | Sulawesi forest turtle | Leucocephalon yuwonoi | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Sulfur-flowered, alpine buckwheat | Eriogonum umbellatum minus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Sulphur Springs buckwheat | Eriogonum argophyllum | Not Listed | Resolved Taxon | | NV |
| Insects | Sulphur Springs hydroporus diving beetle | Hydroporus sulphurius | Not Listed | Species of Concern | | AR |
| Mammals | Sumatran rhinoceros | Dicerorhinus sumatrensis | Listed | Endangered | | |
| Fishes | Summer Basin tui chub | Gila bicolor ssp. | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Summer Flounder | Paralichthys dentatus | | Not Listed | | |
| Flowering Plants | Summer-holly | Comarostaphylis diversifolia diversifolia | Not Listed | Species of Concern | | CA |
| Birds | Summer tanager | piranga rubra | Not Listed | Species of Concern | | |
| Mammals | Sunda pangolin | Manis javanica | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Sunfacing coneflower | Rudbeckia heliopsidis | Petitioned for Listing, Under Review | Under Review | | GA, SC, VA |
| Insects | Superb grasshopper | Eximacris superbum | Not Listed | Species of Concern | | TX |
| Flowering Plants | Supine bean | Phaseolus supinus | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Supple daisy | Erigeron supplex | Not Listed | Species of Concern | | CA |
| Birds | Surf Scoter | Melanitta perspicillata | Not Listed | Species of Concern | | |
| Flowering Plants | Surf thistle | Cirsium rhothophilum | Not Listed | Resolved Taxon | | CA |
| Insects | Surprising Cave beetle | Pseudanophthalmus inexpectatus | Not Listed | Resolved Taxon | | KY |
| Insects | Susan's purse-making microcaddisfly | Ochrotrichia susanae | Not Listed | Resolved Taxon | | |
| Reptiles | Suwanee cooter | Pseudemys concinna suwaniensis | Not Listed | Resolved Taxon | | |
| Reptiles | Suwannee alligator snapping turtle | Macrochelys suwanniensis | Listed | Threatened | | FL, GA |
| Clams | Suwannee moccasinshell | Medionidus walkeri | Listed | Threatened | | FL, GA |
| Clams | Suwannee Pigtoe | Quincuncina kleiniana | Not Listed | Status Undefined | | |
| Birds | Swainson's hawk | Buteo swainsoni | Not Listed | Species of Concern | | CO |
| Birds | Swainson's Warbler | Limnothlypis swainsonii | Not Listed | Species of Concern | | |
| Flowering Plants | swale paintbrush | Castilleja ornata | Listed | Endangered | | NM |
| Flowering Plants | Swallow spurge | Chamaesyce golondrina | Not Listed | Species of Concern | | TX |
| Insects | Swallowtail butterfly | Battus zetides | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Eurytides iphitas | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Graphium levassori | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Graphium sandawanum | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio benguetanus | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio carolinensis | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio desmondi teita | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio himeros | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio leucotaenia | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio maraho | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio moerneri | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio morondavana | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio neumoegeni | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio osmana | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Papilio phorbanta | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Parides burchellanus | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Parides jophon | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Parides schadenberqi | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Troides croesus | Not Listed | Status Undefined | | |
| Insects | Swallowtail butterfly | Troides dohertyi | Not Listed | Status Undefined | | |
| Birds | Swallow-tailed Kite | Elanoides forficatus | Not Listed | Species of Concern | | |
| Fishes | Swamp Darter | Etheostoma fusiforme | | Not Listed | | |
| Mammals | Swamp deer | Cervus duvauceli | Listed | Endangered | | |
| Fishes | Swampfish | Chologaster cornuta | | Not Listed | | |
| Flowering Plants | Swamp harebell | Campanula californica | Not Listed | Species of Concern | | CA |
| Flowering Plants | Swamp justiceweed | Eupatorium paludicola | Not Listed | Status Undefined | | NC, SC |
| Flowering Plants | swamp milkweed | Asclepias incarnata | | Not Listed | | |
| Flowering Plants | Swamp pink | Helonias bullata | Listed | Threatened | | DE, GA, MD, NC, NJ, PA, SC, VA, WV |
| Flowering Plants | Swamp smartweed | Persicaria hydropiperoides | Not Listed | Resolved Taxon | | |
| Mammals | Swasey Spring pocket gopher | Thomomys umbrinus sevieri | Not Listed | Species of Concern | | UT |
| Mammals | Swayne's hartebeest | Alcelaphus buselaphus swaynei | Listed | Endangered | | |
| Insects | Sweadner's olive hairstreak | Mitoura gryneus sweadneri | Not Listed | Species of Concern | | |
| Flowering Plants | Sweet pinesap | Monotropsis odorata | Not Listed | Species of Concern | | |
| Flowering Plants | Sweet, red-flowered pitcher-plant | Sarracenia rubra rubra | Not Listed | Resolved Taxon | | |
| Flowering Plants | Sweetwater Mountains draba | Draba lemmonii incrassata | Not Listed | Resolved Taxon | | CA |
| Insects | Swezey's brown lacewing | Micromus swezeyi | Not Listed | Species of Concern | | HI |
| Insects | Swezey's long-horned beetle | Plagithmysus swezeyi | Not Listed | Species of Concern | | HI |
| Insects | Swezey's zoroapteran | Zorotypus swezeyi | Not Listed | Species of Concern | | HI |
| Mammals | Swift fox | Vulpes velox | Not Listed | Resolved Taxon | | CA, CO |
| Birds | Swinhoe's pheasant | Lophura swinhoii | Listed | Endangered | | |
| Flowering Plants | Sword townsendia | Townsendia spathulata | Not Listed | Resolved Taxon | | WY |
| Insects | Sykora's Hydroptila caddisfly | Hydroptila sykorai | Petitioned for Listing, Under Review | Under Review | | FL |
| Insects | Sylvan hygrotus diving beetle | Hygrotus sylvanus | Not Listed | Species of Concern | | MA, MN, NY |
| Fishes | Syr Darya Sturgeon | Pseudoscaphirhynchus fedtschenkoi | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Tacoma western pocket gopher | Thomomys mazama tacomensis | Not Listed | Resolved Taxon | | |
| Fishes | Tadpole Madtom | Noturus gyrinus | | Not Listed | | |
| Birds | Tahiti flycatcher | Pomarea nigra | Listed | Endangered | | |
| Birds | Tahiti Petrel | Pseudobulweria rostrata | Not Listed | Species of Concern | | |
| Flowering Plants | Tahoe draba | Draba asterophora asterophora | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Tahoe haplopappus | Tonestus eximius | Not Listed | Resolved Taxon | | CA, NV |
| Fishes | Tahoe Sucker | Catostomus tahoensis | | Not Listed | | |
| Flowering Plants | Tahoe yellow cress | Rorippa subumbellata | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | Tahquitz ivesia | Ivesia callida | Not Listed | Species of Concern | | CA |
| Amphibians | Tailed frog | Ascaphus truei | Not Listed | Species of Concern | | CA, ID, MT, OR, WA |
| Fishes | Taillight Shiner | Notropis maculatus | | Not Listed | | |
| Birds | Taita thrush | Turdus olivaceus helleri | Listed | Endangered | | |
| Mammals | Taiwanese humpback dolphin | Sousa chinensis taiwanensis | Proposed for Listing | Proposed Endangered | | |
| Birds | Takahe | Porphyrio hochstetteri | Candidate for Listing | Candidate | | |
| Birds | Takahe | Porphyrio mantelli | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Tallahassee hedge-nettle | Stachys hyssopifolia lythroides | Not Listed | Species of Concern | | |
| Clams | Tallapoosa orb | Quadrula asperata ssp. archeri | Petitioned for Listing, Under Review | Under Review | | AL |
| Snails | Tallapoosa pebblesnail | Somatogyrus pilsbryanus | Not Listed | Species of Concern | | AL |
| Crustaceans | Tallapoosa River crayfish | Cambarus englishi | Not Listed | Species of Concern | | AL, GA |
| Flowering Plants | Tall bugbane | Cimicifuga elata | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | Tall larkspur | Delphinium exaltatum | Not Listed | Species of Concern | | NC |
| Flowering Plants | Tall paintbrush | Castilleja elongata | Not Listed | Resolved Taxon | | TX |
| Snails | Tall pebblesnail | Fluminicola spk | Not Listed | Resolved Taxon | | OR |
| Flowering Plants | Tall western penstemon | Penstemon hesperius | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Talus collomia | Collomia debilis var. larsenii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | Talus fritillary | Fritillaria falcata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tamalpais jewelflower | Streptanthus batrachopus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tamalpais manzanita | Arctostaphylos hookeri montana | Not Listed | Species of Concern | | CA |
| Mammals | Tamaraw | Bubalus mindorensis | Listed | Endangered | | |
| Insects | Tamaulipan Agapema | agapema galbina | Not Listed | Resolved Taxon | | TX |
| Reptiles | Tamaulipan spot-tailed earless lizard | Holbrookia subcaudalis | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Tamaulipas Shiner | Notropis braytoni | | Not Listed | | |
| Clams | Tampico pearlymussel | Cyrtonaias tampicoensis tecomatensis | Listed | Endangered | | |
| Mammals | Tana River mangabey | Cercocebus galeritus galeritus | Listed | Endangered | | |
| Mammals | Tana River red colobus monkey | Procolobus (=Colobus) rufomitratus (=badius r.) | Listed | Endangered | | |
| Insects | Tanner's black camel cricket | Utabaenetes tanneri | Not Listed | Species of Concern | | UT |
| Clams | Tan riffleshell | Epioblasma florentina walkeri (=E. walkeri) | Listed | Endangered | | KY, TN, VA, WV |
| Insects | Tantula serican scarab | Serica tantula | Not Listed | Species of Concern | | |
| Insects | Tapered cave beetle | Pseudanophthalmus fastigatus | Not Listed | Species of Concern | | GA |
| Snails | Tapered cavesnail | Fontigens holsingeri | Not Listed | Species of Concern | | WV |
| Clams | Tapered pigtoe | Fusconaia burkei | Listed | Threatened | | AL, FL |
| Amphibians | Tarahumara frog | Rana tarahumarae | Not Listed | Species of Concern | | AZ |
| Fishes | Tarpon | Megalops atlanticus | | Not Listed | | |
| Clams | Tar River spinymussel | Parvaspina steinstansana | Listed | Endangered | | NC |
| Insects | Tarsalis eopenthes click beetle | Eopenthes tarsalis | Not Listed | Species of Concern | | HI |
| Arachnids | (Tartarocreagris) pseudoscorpion | tartarocreagris | Not Listed | Species of Concern | | |
| Reptiles | Tartaruga | Podocnemis expansa | Listed | Endangered | | |
| Mammals | Tasmanian forester kangaroo | Macropus giganteus tasmaniensis | Listed | Endangered | | |
| Mammals | Tasmanian tiger | Thylacinus cynocephalus | Listed | Endangered | | |
| Insects | Tatum Cave beetle | Pseudanophthalmus parvus | Not Listed | Resolved Taxon | | KY |
| Insects | Tawny crescent | Phyciodes batesii | Not Listed | Species of Concern | | DE, GA, MI, MN, NC, ND, NJ, NY, PA, SD, VA, WI, WV |
| Insects | Taylor's (=whulge) Checkerspot | Euphydryas editha taylori | Listed | Endangered | | OR, WA |
| Snails | Teasing Holospira | Holospira tantalus | Not Listed | Resolved Taxon | | |
| Conifers and Cycads | Tecate cypress | Cupressus forbesii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tecate tarweed | Hemizonia floribunda | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tecopa bird's beak | Chloropyron tecopense | Petitioned for Listing, Under Review | Under Review | | CA, NV |
| Fishes | Tecopa pupfish | Cyprinodon nevadensis calidae | Delisted | Extinction | | CA |
| Insects | Tehachapi Mountain silverspot | Speyeria egleis tehachapina | Not Listed | Species of Concern | | CA |
| Amphibians | Tehachapi slender salamander | Batrachoseps stebbinsi | Not Listed | Resolved Taxon | | CA |
| Mammals | Tehachapi white-eared pocket mouse | Perognathus alticola inexpectatus | Not Listed | Species of Concern | | CA |
| Snails | Tehama chaparral | Trilobopsis tehamana | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Tehama dwarf-flax | Hesperolinon tehamense | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tehama pincushionplant | Navarretia heterandra | Not Listed | Species of Concern | | |
| Flowering Plants | Tehipite Valley jewelflower | Streptanthus fenestratus | Not Listed | Resolved Taxon | | CA |
| Insects | Telegraphic hedyleptan moth | Hedylepta telegrapha | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Telephus spurge | Euphorbia telephioides | Listed | Threatened | | FL |
| Snails | Telescope hornsnail | Pleurocera walkeri | Not Listed | Species of Concern | | AL, TN |
| Flowering Plants | Telescope Peak bedstraw | Galium hypotrichium tomentellum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Temblor buckwheat | Eriogonum temblorense | Not Listed | Species of Concern | | CA |
| Reptiles | Temblor legless lizard | Anniella alexanderae | Petitioned for Listing, Under Review | Under Review | | |
| Mammals | Temnick''s ground Pangolin | Manis temminckii | Listed | Endangered | | |
| Mammals | Tenino pocket gopher | Thomomys mazama tumuli | Listed | Threatened | | WA |
| Crustaceans | Tennessee bottlebrush crayfish | Barbicambarus simmonsi | Petitioned for Listing, Under Review | Under Review | | AL, TN |
| Crustaceans | Tennessee Cave crayfish | Orconectes incomptus | Not Listed | Status Undefined | | TN |
| Amphibians | Tennessee cave salamander | Gyrinophilus palleucus | Not Listed | Resolved Taxon | | AL, GA, TN |
| Clams | Tennessee clubshell | Pleurobema oviforme | Proposed for Listing | Proposed Endangered | | AL, GA, KY, NC, TN, VA |
| Insects | Tennessee clubtail | Gomphus sandrius | Petitioned for Listing, Under Review | Under Review | | TN |
| Insects | Tennessee forestfly | Amphinemura mockfordi | Petitioned for Listing, Under Review | Under Review | | AL, TN |
| Clams | Tennessee heelsplitter | Lasmigona holstonia | Not Listed | Resolved Taxon | | AL, GA, IL, IN, KY, TN, VA |
| Snails | Tennessee pebblesnail | Somatogyrus currierianus | Not Listed | Species of Concern | | AL |
| Clams | Tennessee pigtoe | Pleuronaia barnesiana | Proposed for Listing | Proposed Endangered | | AL, GA, KY, MS, NC, TN, VA, WV |
| Flowering Plants | Tennessee pondweed | Potamogeton tennesseensis | Petitioned for Listing, Under Review | Under Review | | OH |
| Flowering Plants | Tennessee purple coneflower | Echinacea tennesseensis | Delisted | Recovery | | TN |
| Clams | Tennessee riffleshell | Epioblasma propinqua | Not Listed | Resolved Taxon | | AL, TN |
| Flowering Plants | Tennessee yellow-eyed grass | Xyris tennesseensis | Listed | Endangered | | AL, GA, TN |
| Flowering Plants | Tepic fameflower | Talinum marginatum | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Terciopelo | Abutilon hulseanum | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | Terlingua bricklebush | Brickellia brachyphylla terlinguensis | Not Listed | Species of Concern | | TX |
| Flowering Plants | Terlingua Creek cat's-eye | Cryptantha crassipes | Listed | Endangered | | TX |
| Snails | terrestrial snail | sonorella species | Not Listed | Status Undefined | | |
| Fishes | Tessellated Darter | Etheostoma olmstedi | | Not Listed | | |
| Flowering Plants | Texas amorpha | Amorpha roemeriana | Not Listed | Resolved Taxon | | TX |
| Insects | Texas asaphomyian tabanid fly | Asaphomyia texanus | Not Listed | Species of Concern | | TX |
| Insects | Texas austrotinodes caddisfly | Austrotinodes sp. | Not Listed | Species of Concern | | TX |
| Flowering Plants | Texas ayenia | Ayenia limitaris | Listed | Endangered | | TX |
| Amphibians | Texas blind salamander | Eurycea rathbuni | Listed | Endangered | | TX |
| Birds | Texas Botteri's sparrow | Aimophila botterii texana | Not Listed | Species of Concern | | TX |
| Crustaceans | Texas cave shrimp | Palaemonetes antrorum | Not Listed | Species of Concern | | TX |
| Reptiles | Texas diamondback terrapin | Malaclemys terrapin littoralis | Not Listed | Species of Concern | | LA, TX |
| Insects | Texas emerald | Somatochlora margarita | Not Listed | Status Undefined | | LA, OK, TX |
| Clams | Texas fatmucket | Lampsilis bracteata | Listed | Endangered | | TX |
| Clams | Texas fawnsfoot | Truncilla macrodon | Listed | Threatened | | TX |
| Reptiles | Texas garter snake | Thamnophis sirtalis annectens | Not Listed | Species of Concern | | KS, OK, TX |
| Flowering Plants | Texas golden Gladecress | Leavenworthia texana | Listed | Endangered | | TX |
| Flowering Plants | Texas greasebush | Glossopetalon texense | | Not Listed | | TX |
| Clams | Texas heelsplitter | Potamilus amphichaenus | Proposed for Listing | Proposed Endangered | | LA, TX |
| Birds | Texas Henslow's sparrow | Ammodramus henslowii houstonensis | Not Listed | Resolved Taxon | | TX |
| Reptiles | Texas horned lizard | Phrynosoma cornutum | Not Listed | Species of Concern | | CO |
| Clams | Texas Hornshell | Popenaias popeii | Listed | Endangered | | NM, TX |
| Mammals | Texas kangaroo rat | Dipodomys elator | Proposed for Listing | Proposed Endangered | | OK, TX |
| Reptiles | Texas map turtle | Graptemys versa | Not Listed | Resolved Taxon | | TX |
| Mammals | Texas margay | Leopardus wiedii cooperi | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Texas milkvine | Matelea texensis | Not Listed | Resolved Taxon | | TX |
| Insects | Texas minute moss beetle | Limnebius texanus | Not Listed | Species of Concern | | TX |
| Birds | Texas olive sparrow | Arremonops rufivirgatus rufivirgatus | Not Listed | Species of Concern | | TX |
| Clams | Texas Pigtoe | Fusconaia askewi | | Not Listed | | |
| Clams | Texas pimpleback | Cyclonaias petrina | Listed | Endangered | | TX |
| Fishes | Texas Pipefish | Syngnathus affinis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Texas poppy-mallow | Callirhoe scabriuscula | Listed | Endangered | | TX |
| Flowering Plants | Texas prairie dawn-flower | Hymenoxys texana | Listed | Endangered | | TX |
| Amphibians | Texas salamander | Eurycea neotenes | Petitioned for Listing, Under Review | Under Review | | TX |
| Flowering Plants | Texas screwstem | Bartonia texana | Not Listed | Resolved Taxon | | LA, TX |
| Fishes | Texas Shiner | Notropis amabilis | | Not Listed | | |
| Fishes | Texas silverside | Menidia clarkhubbsi | Not Listed | Resolved Taxon | | |
| Fishes | Texas Silverside | Menidia clarkhubbsi | | Not Listed | | |
| Flowering Plants | Texas snowbells | Styrax platanifolius ssp. texanus | Listed | Endangered | | TX |
| Crustaceans | Texas Spring Amphipod | Hyalella muerta | | Not Listed | | |
| Flowering Plants | Texas stonecrop | Lenophyllum texanum | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Texas sunnybell | Schoenolirion wrightii | Not Listed | Resolved Taxon | | AL, AR, LA, TX |
| Flowering Plants | Texas trailing phlox | Phlox nivalis ssp. texensis | Listed | Endangered | | TX |
| Flowering Plants | Texas trillium | Trillium pusillum texanum | Petitioned for Listing, Under Review | Under Review | | AR, LA, TX |
| Crustaceans | Texas Troglobitic Water Slater | Lirceolus smithii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Texas trumpets | Acleisanthes crassifolia | Not Listed | Species of Concern | | TX |
| Flowering Plants | Texas wild-rice | Zizania texana | Listed | Endangered | | TX |
| Flowering Plants | Texas windmill grass | Chloris texensis | Not Listed | Species of Concern | | TX |
| Flowering Plants | Texas wolfberry | Lycium texanum | Not Listed | Species of Concern | | TX |
| Fishes | Tex-Mex Gambusia | Gambusia speciosa | | Not Listed | | |
| Fishes | Thailand giant catfish | Pangasianodon gigas | Listed | Endangered | | |
| Flowering Plants | Tharp''s bluestar | Amsonia tharpii | Petitioned for Listing, Under Review | Under Review | | NM, TX |
| Flowering Plants | The Cedars globe-lily | Calochortus raichei | Not Listed | Species of Concern | | CA |
| Flowering Plants | The Geysers panic grass | Dichanthelium acuminatum acuminatum | Not Listed | Species of Concern | | CA |
| Flowering Plants | The Lassics sandwort | Minuartia decumbens | Not Listed | Species of Concern | | CA |
| Flowering Plants | The Needles buckwheat | Eriogonum breedlovei shevockii | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Thermophilic ostracod | Potamocypris hunteri | Not Listed | Resolved Taxon | | OR |
| Birds | Thick-billed Longspur | Rhynchophanes mccownii | Not Listed | Species of Concern | | |
| Birds | Thick-billed Murre | Uria lomvia | Not Listed | Species of Concern | | |
| Birds | Thick-billed parrot | Rhynchopsitta pachyrhyncha | Listed | Endangered | | |
| Flowering Plants | thick-leaf bladderpod | Physaria pachyphylla | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Thickleaf Pepperwort | Lepidium integrifolium | Not Listed | Resolved Taxon | | |
| Flowering Plants | Thick-leaved water-willow | Justicia crassifolia | Not Listed | Species of Concern | | |
| Snails | Thick-lipped pebblesnail | Somatogyrus crassilabris | Not Listed | Species of Concern | | AR |
| Snails | Thickshell pondsnail | Stagnicola utahensis | Not Listed | Resolved Taxon | | UT |
| Fishes | Thicktail chub | Gila crassicauda | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Thieret's skullcap | Scutellaria thieretii | Not Listed | Species of Concern | | LA, TX |
| Flowering Plants | thin-leaved peavine | Lathyrus holochlorus | | Not Listed | | OR, WA |
| Insects | Thin-neck cave beetle | Pseudanophthalmus parvicollis | Not Listed | Species of Concern | | VA |
| Mammals | Thin-spined porcupine | Chaetomys subspinosus | Listed | Endangered | | |
| Ferns and Allies | Thin-wall quillwort | Isoetes microvela | Petitioned for Listing, Under Review | Under Review | | NC |
| Flowering Plants | Thistle | Cirsium brevifolium | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | Thistle, Douglas' milk-vetch | Astragalus kentrophyta douglasii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Insects | Thomas' cave beetle | Pseudanophthalmus thomasi | | Not Listed | | VA |
| Flowering Plants | Thompkins' sedge | Carex tompkinsii | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Thompson, Atwood's wild-buckwheat | Eriogonum thompsonae atwoodii | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Thompson's clover | Trifolium thompsonii | Not Listed | Species of Concern | | WA |
| Flowering Plants | Thompson's dalea | Psorothamnus thompsoniae var. thompsoniae | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Thompson, white-flow wild-buckwheat | Eriogonum thompsonae albiflorum | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Thompson wild-buckwheat | Eriogonum thompsonae thompsonae | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | Thorne's beaked-rush | Rhynchospora thornei | Not Listed | Status Undefined | | GA, SC |
| Flowering Plants | Thorne's buckwheat | Eriogonum ericifolium thornei | Not Listed | Species of Concern | | CA |
| Insects | Thorne's hairstreak | Mitoura thornei | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Thorne's royal larkspur | Delphinium variegatum thornei | Not Listed | Resolved Taxon | | CA |
| Snails | Thousand Palms desertsnail | Eremarionta millepalmarum | Not Listed | Species of Concern | | CA |
| Fishes | Threadfin Shad | Dorosoma petenense | | Not Listed | | |
| Flowering Plants | Thread-leaved bladder-pod | Lesquerella angustifolia | Not Listed | Resolved Taxon | | OK, TX |
| Flowering Plants | Thread-leaved brodiaea | Brodiaea filifolia | Listed | Threatened | | CA |
| Flowering Plants | Thread-leaved penstemon | Penstemon filiformis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Threecorner milkvetch | Astragalus geyeri triquetrus | Petitioned for Listing, Under Review | Under Review | | AZ, NV |
| Snails | Three Forks Springsnail | Pyrgulopsis trivialis | Listed | Endangered | | AZ |
| Clams | Threehorn Wartyback | Obliquaria reflexa | | Not Listed | | |
| Reptiles | Three-keeled Asian turtle | Melanochelys tricarinata | Listed | Endangered | | |
| Flowering Plants | Three Peaks jewelflower | Streptanthus morrisonii elatus | Not Listed | Species of Concern | | CA |
| Clams | Threeridge Mussel | Amblema plicata | | Not Listed | | |
| Fishes | Threespine Stickleback | Gasterosteus aculeatus | | Not Listed | | |
| Amphibians | Three-toed Amphiuma | Amphiuma tridactylum | | Not Listed | | |
| Reptiles | Three-toed Box Turtle | Terrapene triunguis | | Not Listed | | |
| Birds | Three-toed woodpecker | picoides tridactylus | Not Listed | Species of Concern | | |
| Flowering Plants | Three-tongued spurge | Chamaesyce chaetocalyx triligulata | Not Listed | Species of Concern | | TX |
| Insects | Three-tooth long-horned caddisfly | Triaenodes tridontus | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Thurber's pilostyles | Pilostyles thurberi | Not Listed | Resolved Taxon | | AZ, CA, NV |
| Flowering Plants | Thurber's reedgrass | Calamagrostis crassiglumis | Not Listed | Species of Concern | | AK, CA, WA |
| Birds | Thyolo alethe | Alethe choloensis | Listed | Endangered | | |
| Mammals | Tibetan antelope | Panthalops hodgsonii | Listed | Endangered | | |
| Insects | Tibial scarab | Anomala tibialis | Not Listed | Species of Concern | | TX |
| Flowering Plants | Tiburon buckwheat | Eriogonum caninum | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Tiburon jewelflower | Streptanthus niger | Listed | Endangered | | CA |
| Flowering Plants | Tiburon mariposa lily | Calochortus tiburonensis | Listed | Threatened | | CA |
| Arachnids | Tiburon micro-blind harvestman | Microcina tiburona | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tiburon paintbrush | Castilleja affinis ssp. neglecta | Listed | Endangered | | CA |
| Flowering Plants | Tiburon tarweed | Hemizonia multicaulis vernalis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tidestrom beardtongue | Penstemon tidestromii | Not Listed | Species of Concern | | UT |
| Crustaceans | Tidewater amphipod | Stygobromus indentatus | Not Listed | Resolved Taxon | | MD, NC, VA |
| Fishes | Tidewater goby | Eucyclogobius newberryi | Listed | Endangered | Proposed Reclassification to Threatened | CA, OR |
| Crustaceans | Tidewater interstitial amphipod | Stygobromus araeus | Not Listed | Species of Concern | | VA |
| Clams | Tidewater Mucket | Leptodea ochracea | | Not Listed | | |
| Flowering Plants | Tiehm's buckwheat | Eriogonum tiehmii | Listed | Endangered | | NV |
| Flowering Plants | Tiehm's milk-vetch | Astragalus tiehmii | Not Listed | Species of Concern | | NV |
| Flowering Plants | Tiehm's rock-cress | Arabis tiehmii | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | Tiehm's stroganowia | Stroganowia tiehmii | Not Listed | Species of Concern | | NV |
| Mammals | Tiger | Panthera tigris | Listed | Endangered | | |
| Flowering Plants | Tiger beardtongue | Penstemon mensarum | Not Listed | Species of Concern | | CO |
| Mammals | Tiger cat | Leopardus (=Felis) tigrinus | Listed | Endangered | | |
| Flowering Plants | Tigna Potato | Solanum leptosepalum | Not Listed | Resolved Taxon | | |
| Flowering Plants | Timber bluegrass | Poa rhizomata | Not Listed | Resolved Taxon | | CA |
| Reptiles | Timber rattlesnake | Crotalus horridus | Not Listed | Resolved Taxon | | OH |
| Insects | Tinged eopenthes click beetle | Eopenthes tinctus | Not Listed | Species of Concern | | HI |
| Birds | Tinian Monarch (old world flycatcher) | Monarcha takatsukasae | Delisted | Recovery | | MP |
| Flowering Plants | Tiny bog buttons | Lachnocaulon digynum | Not Listed | Species of Concern | | |
| Flowering Plants | tiny mousetail | Myosurus minimus | Not Listed | Species of Concern | | |
| Flowering Plants | Tiny orchid | Lepanthopsis melanantha | Not Listed | Species of Concern | | |
| Flowering Plants | Tiny polygala | Polygala smallii | Listed | Endangered | | FL |
| Fishes | Tippecanoe darter | Nothonotus tippecanoe | Not Listed | Resolved Taxon | | IN, KY, OH, PA, TN, WV |
| Mammals | Tipton kangaroo rat | Dipodomys nitratoides nitratoides | Listed | Endangered | | CA |
| Flowering Plants | Tissue sedge | Carex hyalina | Not Listed | Species of Concern | | AR, OK, TX |
| Flowering Plants | Tobusch fishhook cactus | Sclerocactus brevihamatus ssp. tobuschii | Listed | Threatened | | TX |
| Flowering Plants | Todsen's pennyroyal | Hedeoma todsenii | Listed | Endangered | | NM |
| Snails | Tollhouse Canyon talussnail | Sonorella delicata | Not Listed | Resolved Taxon | | |
| Insects | Tomah mayfly | Siphlonisca aerodromia | Not Listed | Species of Concern | | ME, NY |
| Flowering Plants | Tomales clarkia | Clarkia concinna raichei | Not Listed | Species of Concern | | CA |
| Fishes | Tombigbee Darter | Etheostoma lachneri | | Not Listed | | |
| Crustaceans | Tombigbee Riverlet crayfish | Hobbseus petilus | Petitioned for Listing, Under Review | Under Review | | MS |
| Insects | Tombstone Prairie farulan caddisfly | Farula reapiri | Not Listed | Species of Concern | | OR |
| Insects | Tombstone Prairie oligophlebodes caddisfly | Oligophlebodes mostbento | Not Listed | Species of Concern | | OR |
| Reptiles | Tomistoma | Tomistoma schlegelii | Listed | Endangered | | |
| Fishes | Tonguetied Minnow | Exoglossum laurae | | Not Listed | | |
| Mammals | Tonkin snub-nosed monkey | Rhinopithecus avunculus | Listed | Endangered | | |
| Flowering Plants | Tonopah milk-vetch | Astragalus iodanthus pseudoiodanthus | Not Listed | Resolved Taxon | | CA, NV |
| Insects | Tooth Cave blind rove beetle | Cylindropsis sp. | Not Listed | Resolved Taxon | | TX |
| Insects | Tooth Cave ground beetle | Rhadine persephone | Listed | Endangered | | TX |
| Arachnids | Tooth Cave pseudoscorpion | Tartarocreagris texana | Listed | Endangered | | TX |
| Arachnids | Tooth Cave spider | Tayshaneta myopica | Listed | Endangered | | TX |
| Fishes | Toothless blindcat | Trogloglanis pattersoni | Proposed for Listing | Proposed Endangered | | TX |
| Snails | Toothy coil | Helicodiscus hexodon | Not Listed | Species of Concern | | TN |
| Fishes | Topeka shiner | Notropis topeka (=tristis) | Listed | Experimental Population, Non-Essential | | MO |
| Fishes | Topeka shiner | Notropis topeka (=tristis) | Listed | Endangered | | IA, KS, MN, MO, NE, SD |
| Mammals | Toque macaque | Macaca sinica | Listed | Threatened | | |
| Mammals | Tora hartebeest | Alcelaphus buselaphus tora | Listed | Endangered | | |
| Fishes | Torrent Sculpin | Cottus rhotheus | | Not Listed | | |
| Insects | Torreya pygmy grasshopper | Tettigidea empedonepia | Not Listed | Species of Concern | | |
| Arachnids | Torreya trap-door spider | Cyclocosmia torreya | Not Listed | Species of Concern | | |
| Conifers and Cycads | Torrey, Del Mar pine | Pinus torreyana torreyana | Not Listed | Species of Concern | | CA |
| Conifers and Cycads | Torrey Island pine | Pinus torreyana insularis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Torrey's mountainmint | Pycnanthemum torrei | Not Listed | Species of Concern | | NC |
| Flowering Plants | Torrey's muhly | Muhlenbergia torreyana | Not Listed | Resolved Taxon | | DE, GA, MD, NC, NJ, NY, TN |
| Flowering Plants | Torrey's pea | Lathyrus torreyi | Not Listed | Species of Concern | | |
| Insects | Tortoise commensal noctuid moth | Idia gopheri | Not Listed | Species of Concern | | |
| Snails | Total Wreck Talussnail | Sonorella imperatrix | Not Listed | Resolved Taxon | | |
| Fishes | Totoaba (seatrout or weakfish) | Cynoscion macdonaldi | Listed | Endangered | | |
| Mammals | Townsend's western big-eared bat | plecotus townsendii ssp. pallescens | Not Listed | Species of Concern | | |
| Mammals | Townsend's western big-eared bat | plecotus townsendii ssp. townsendii | Not Listed | Species of Concern | | |
| Reptiles | Tracaja | Podocnemis unifilis | Listed | Endangered | | |
| Flowering Plants | Tracy beardtongue | Penstemon tracyi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Tracy's lupine | Lupinus tracyi | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Tracy's sanicle | Sanicula tracyi | Not Listed | Species of Concern | | CA |
| Insects | Transient atelothrus ground beetle | Atelothrus transiens | Not Listed | Species of Concern | | HI |
| Flowering Plants | Trans-Pecos maidenbush | Phyllanthopsis arida | Not Listed | Species of Concern | | TX |
| Flowering Plants | Trask's cryptantha | Cryptantha traskiae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Trask's milk-vetch | Astragalus traskiae | Not Listed | Species of Concern | | CA |
| Insects | Travertine band-thigh diving beetle | Hygrotus fontinalis | Not Listed | Species of Concern | | CA |
| Ferns and Allies | Tree-fern (Tsatsa) | Cyathea lunulata | Not Listed | Status Undefined | | |
| Mammals | Tree pangolin | Manis tricuspis | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Tree swallow | tachycineta bicolor | Not Listed | Species of Concern | | |
| Clams | Triangle Floater | Alasmidonta undulata | | Not Listed | | |
| Ferns and Allies | Trianglelobe moonwort | Botrychium ascendens | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Clams | Triangle Pigtoe | Fusconaia lananensis | Not Listed | Resolved Taxon | | |
| Clams | Triangular Kidneyshell | Ptychobranchus greenii | Listed | Endangered | | AL, GA, TN |
| Crustaceans | Trichoniscidae isopod | trichoniscoides | Not Listed | Species of Concern | | |
| Snails | Tricolia Mussel | Tricolia pullus | | Not Listed | | |
| Mammals | Tricolored bat | Perimyotis subflavus | Proposed for Listing | Proposed Endangered | | AL, AR, CO, CT, DC, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, NC, NE, NH, NJ, NM, NY, OH, OK, PA, RI, SC, SD, TN, TX, VA, VT, WI, WV, WY |
| Birds | Tricolored Blackbird | Agelaius tricolor | Not Listed | Resolved Taxon | | CA, NV, OR |
| Birds | Trinidad white-headed curassow | Pipile pipile pipile | Listed | Endangered | | |
| Flowering Plants | Trinity Alps daisy | Erigeron flexuosus | Not Listed | Resolved Taxon | | CA |
| Insects | Trinity Alps ground beetle | Nebria sahlbergii triad | Not Listed | Species of Concern | | CA |
| Snails | Trinity bristlesnail | Monadenia setosa | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Trinity buckwheat | Eriogonum alpinum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Trinity phacelia | Phacelia dalesiana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Triple-ribbed milk-vetch | Astragalus tricarinatus | Listed | Endangered | | CA |
| Fishes | Trispot darter | Etheostoma trisella | Listed | Threatened | | AL, GA, TN |
| Birds | Tristam's woodpecker | Dryocopus javensis richardsi | Listed | Endangered | | |
| Birds | Tristram's Storm Petrel | Hydrobates tristrami | Not Listed | Species of Concern | | |
| Crustaceans | Troglobitic groundwater shrimp | Typhlatya monae | Not Listed | Resolved Taxon | | PR, VI |
| Birds | Tropical parula | Parula pitiayumi nigrilora | Not Listed | Species of Concern | | TX |
| Birds | Tropical Parula | Parula pitiayumi | Not Listed | Species of Concern | | |
| Fishes | Trout-Perch | Percopsis omiscomaycus | | Not Listed | | |
| Flowering Plants | Truckee Barberry | Berberis (=Mahonia) sonnei | Delisted | Original Data in Error - Taxonomic Revision | | CA |
| Flowering Plants | Truckee waterweed | Elodea brandegeae | Not Listed | Resolved Taxon | | CA |
| Clams | True pigtoe | Pleurobema verum | Not Listed | Species of Concern | | AL |
| Birds | Truk greater white-eye | Rukia ruki | Not Listed | Pre-Act Delisted Taxon | | FM |
| Birds | Truk Micronesian pigeon | Ducula oceanica teraoki | Not Listed | Status Undefined | | FM |
| Birds | Truk monarch | Metabolus rugensis | Not Listed | Resolved Taxon | | |
| Birds | Trumpeter swan | Cygnus buccinator | Not Listed | Resolved Taxon | | |
| Birds | Trumpeter swan | Cygnus buccinator | Not Listed | Species of Concern | | |
| Birds | Trumpeter swan | Cygnus buccinator | Not Listed | Resolved Taxon | | |
| Reptiles | Tuatara | Sphenodon punctatus | Listed | Endangered | | |
| Clams | Tubercled blossom (pearlymussel) | Epioblasma torulosa torulosa | Delisted | Extinction | | GA, TN, WV |
| Clams | Tubercled blossom (pearlymussel) | Epioblasma torulosa torulosa | Not Listed | Resolved Taxon | | AL |
| Insects | Tubercled rhyncogonus weevil | Rhyncogonus tuberculatus | Not Listed | Species of Concern | | HI |
| Mammals | Tuckahoe masked shrew | Sorex cinereus nigriculus | Not Listed | Species of Concern | | DE, NJ |
| Fishes | Tuckaseegee darter | Etheostoma blenniodes guttseli | Not Listed | Status Undefined | | |
| Reptiles | Tucson shovel-nosed Snake | Chionactis occipitalis klauberi | Not Listed | Resolved Taxon | | AZ |
| Birds | Tufted Puffin | Fratercula cirrhata | Not Listed | Resolved Taxon | | AK, CA, NV, OR, WA |
| Crustaceans | Tug Valley Crayfish | Cambarus hatfieldi | | Not Listed | | |
| Algae | Tui Chub | Siphateles bicolor | | Not Listed | | |
| Mammals | Tulare grasshopper mouse | Onychomys torridus tularensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tulare horkelia | Horkelia tularensis | Not Listed | Species of Concern | | CA |
| Clams | tularosa juturnia | juturnia tularosae | Not Listed | Resolved Taxon | | |
| Birds | Tule white-fronted goose | Anser albifrons elgasi | Not Listed | Resolved Taxon | | AK, CA, OR |
| Snails | Tulotoma snail | Tulotoma magnifica | Listed | Threatened | | AL |
| Snails | Tulsa Whitelip | Neohelix lioderma | Not Listed | Resolved Taxon | | |
| Birds | Tumaco seedeater | Sporophila insulata | Not Listed | Status Undefined | | |
| Flowering Plants | Tumamoc globeberry | Tumamoca macdougalii | Delisted | Original Data in Error - New Information Discovered | | AZ |
| Snails | Tumbling Creek cavesnail | Antrobia culveri | Listed | Endangered | | MO |
| Insects | Tuna Cave roach | Aspiduchus cavernicola | Not Listed | Species of Concern | | PR, VI |
| Ferns and Allies | Tunbridge fern | Hymenophyllum tunbrigense | Not Listed | Species of Concern | | SC |
| Flowering Plants | Tundra shootingstar | Dodecatheon austrofrigidum | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | Tunnel Springs beardtongue | Penstemon concinnus | Not Listed | Species of Concern | | NV, UT |
| Flowering Plants | Tuolumne coyote-thistle | Eryngium pinnatisectum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Tuolumne fawn-lily | Erythronium tuolumnense | Not Listed | Species of Concern | | CA |
| Clams | Turgid blossom (pearlymussel) | Epioblasma turgidula | Delisted | Extinction | | AR, TN |
| Clams | Turgid blossom (pearlymussel) | Epioblasma turgidula | Not Listed | Resolved Taxon | | AL |
| Birds | Turkey vulture | cathartes aura | Not Listed | Species of Concern | | |
| Flowering Plants | Turkish rugging | Chorizanthe staticoides chrysacantha | Not Listed | Resolved Taxon | | CA |
| Reptiles | Turks and Caicos iguana | Cyclura carinata carinata | Listed | Threatened | | |
| Birds | Turquoise parakeet | Neophema pulchella | Delisted | Recovery | | |
| Insects | Turtle Mound firefly | Photuris sp. | Not Listed | Species of Concern | | |
| Flowering Plants | Tusayan fameflower | Talinum validulum | Not Listed | Species of Concern | | AZ |
| Fishes | Tuscumbia darter | Etheostoma tuscumbia | Petitioned for Listing, Under Review | Under Review | | AL, TN |
| Flowering Plants | Tushar indian paintbrush | Castilleja parvula | Not Listed | Species of Concern | | UT |
| Flowering Plants | Tushar Mountain Whitlow grass | Draba ramulosa | Not Listed | Resolved Taxon | | |
| Fishes | Tuskaloosa darter | Etheostoma douglasi | Not Listed | Species of Concern | | AL |
| Flowering Plants | Tussock panic grass | Dichanthelium cynodon | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Tweedy's pussypaws | Cistanthe tweedyi | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | Twisselmann's buckwheat | Eriogonum twisselmannii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Twisselmann's nemacladus | Nemacladus twisselmannii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Two-bristle rock-daisy | Perityle bisetosa bisetosa | Not Listed | Species of Concern | | TX |
| Flowering Plants | Two carpeled dwarf-flax | Hesperolinon bicarpellatum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Two-flowered lathyrus | Lathyrus biflorus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Two-flowered stick-pea | Calliandra biflora | Not Listed | Resolved Taxon | | TX |
| Reptiles | Two-striped garter snake | Thamnophis hammondii | Not Listed | Species of Concern | | CA |
| Amphibians | Two-toed Amphiuma | Amphiuma means | | Not Listed | | |
| Mammals | Uakari (all species) | Cacajao spp. | Listed | Endangered | | |
| Arachnids | Ubick''s gnaphosid spider | Talanites ubicki | Not Listed | Resolved Taxon | | |
| Flowering Plants | Ufa-halomtano | Heritiera longipetiolata | Listed | Endangered | | GU, MP |
| Flowering Plants | Uhiuhi | Mezoneuron kavaiense | Listed | Endangered | | HI |
| Flowering Plants | Uinta Basin hookless cactus | Sclerocactus wetlandicus | Listed | Threatened | | UT |
| Flowering Plants | Uintah beardtongue | Penstemon uintahensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Uinta Mountains draba | Draba inexpectata | Not Listed | Resolved Taxon | | |
| Snails | Uinta mountainsnail | Oreohelix eurekensis uinta | Not Listed | Resolved Taxon | | UT |
| Birds | Ulugura bush-shrike | Malaconotus alius | Listed | Threatened | | |
| Flowering Plants | Ulunahele | Cyrtandra kauaiensis | Not Listed | Resolved Taxon | | HI |
| Snails | Umbilicate river snail | Leptoxis subglubosa umbilicata | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | Umbrella sedge | Cyperus grayoides | Not Listed | Species of Concern | | IL, LA, MO, TX |
| Flowering Plants | Umpqua green-gentian | Frasera fastigiata | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Umpqua mariposa Lily | Calochortus umpquaensis | Not Listed | Resolved Taxon | | CA, NV, OR |
| Fishes | Umpqua Oregon Chub | Oregonichthys kalawatseti | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Umtanum desert buckwheat | Eriogonum codium | Listed | Threatened | | WA |
| Fishes | Unarmored threespine stickleback | Gasterosteus aculeatus williamsoni | Listed | Endangered | | CA |
| Insects | Uncompahgre fritillary butterfly | Boloria acrocnema | Listed | Endangered | | CO |
| Mammals | Underwood's mastiff-bat | Eumops underwoodi | Not Listed | Species of Concern | | AZ |
| Crustaceans | Undescribed amphipod | Crangonyx sp | Not Listed | Status Undefined | | |
| Conifers and Cycads | Undescribed pine | Pinus | Not Listed | Status Undefined | | |
| Flowering Plants | Unexpected larkspur | Delphinium inopinum | Not Listed | Resolved Taxon | | CA |
| Insects | Unicolored eopenthes click beetle | Eopenthes unicolor | Not Listed | Species of Concern | | HI |
| Insects | Union County cave beetle | Pseudanophthalmus unionis | Not Listed | Species of Concern | | TN |
| Insects | Unique yellow-faced bee | Hylaeus unica | Not Listed | Species of Concern | | HI |
| Ferns and Allies | [Unnamed] adder's-tongue | Ophioglossum concinnum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | [Unnamed] adobe-lily | Fritillaria pluriflora | Not Listed | Species of Concern | | CA |
| Flowering Plants | [Unnamed] alkali grass | Puccinellia nutkaensis | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | [Unnamed] alumroot | Heuchera americana hispida | Not Listed | Resolved Taxon | | VA, WV |
| Flowering Plants | [Unnamed] ambrosia | Ambrosia linearis | Not Listed | Species of Concern | | CO |
| Crustaceans | [Unnamed] amphipod | Stygobromus hoffmani | Not Listed | Species of Concern | | VA |
| Flowering Plants | [Unnamed] anemone | Anemone edwardsiana edwardsiana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] anemone | Anemone minima | Not Listed | Resolved Taxon | | VA, WV |
| Flowering Plants | [Unnamed] anemone | Anemone oregana felix | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] anglepod | Matelea alabamensis | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] anglepod | Matelea baldwyniana | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] arrowwood | Viburnum bracteatum | Not Listed | Species of Concern | | AL, GA, TN |
| Flowering Plants | [Unnamed] ash | Fraxinus anomala lowellii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] aster | Aster greatai | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] aster | Aster kingii kingii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] aster | Eucephalus glaucescens | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | [Unnamed] aster | Eurybia furcata | Not Listed | Species of Concern | | AR, IA, IL, IN, MO, WI |
| Flowering Plants | [Unnamed] aster | Eurybia hemispherica | Not Listed | Resolved Taxon | | MS |
| Flowering Plants | [Unnamed] aster | Eurybia schreberi | Not Listed | Resolved Taxon | | IL |
| Flowering Plants | [Unnamed] aster | Eurybia spinulosa | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] aster | Symphyotrichum dumosum | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] aster | Symphyotrichum hallii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] aster | Symphyotrichum kralii | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] aster | Symphyotrichum molle | Not Listed | Species of Concern | | WY |
| Flowering Plants | [Unnamed] aster | Symphyotrichum plumosum | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] aster | Symphyotrichum potosinum | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] aster | Symphyotrichum X schistosum | Not Listed | Species of Concern | | VA |
| Flowering Plants | [Unnamed] barberry | Berberis swaseyi | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] beaked-rush | Rhynchospora culixa | Not Listed | Species of Concern | | GA |
| Flowering Plants | [Unnamed] beaked-rush | Rhynchospora decurrens | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] beaked-rush | Rhynchospora globularis saxicola | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | [Unnamed] beaked-rush | Rhynchospora punctata | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] beard grass | Andropogon arctatus | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] beardtongue | Penstemon abietinus | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | [Unnamed] beardtongue | Penstemon angustifolius dulcis | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] beardtongue | Penstemon caespitosus suffruticosus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] beardtongue | Penstemon clutei | Not Listed | Species of Concern | | AZ |
| Flowering Plants | [Unnamed] beardtongue | Penstemon deamii | Not Listed | Species of Concern | | IN |
| Flowering Plants | [Unnamed] beardtongue | Penstemon glaucinus | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | [Unnamed] beardtongue | Penstemon leiophyllus | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | [Unnamed] beardtongue | Penstemon pahutensis | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] beardtongue | Penstemon pinorum | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] beardtongue | Penstemon retrorsus | Not Listed | Species of Concern | | CO |
| Flowering Plants | [Unnamed] beardtongue | Penstemon rubicundus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] beargrass | Nolina atopocarpa | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] bedstraw | Galium andrewsii gatense | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] bedstraw | Galium collomae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] birch | Betula murrayana | Not Listed | Species of Concern | | MI |
| Flowering Plants | [Unnamed] bittercress | Cardamine rupicola | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | [Unnamed] bladderpod | Lesquerella humilis | Not Listed | Species of Concern | | MT |
| Flowering Plants | [Unnamed] bladderpod | Lesquerella paysonii | Not Listed | Species of Concern | | WY |
| Flowering Plants | [Unnamed] bladder-pod | Lesquerella hitchcockii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] bladder-pod | Lesquerella kingii diversifolia | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] bladder-pod | Lesquerella lescurii | Not Listed | Resolved Taxon | | KY, TN |
| Flowering Plants | [Unnamed] bladder-pod | Lesquerella mcvaughiana | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] bladder-pod | Lesquerella parviflora | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | [Unnamed] bladder-pod | Lesquerella pruinosa | Not Listed | Species of Concern | | CO |
| Flowering Plants | [Unnamed] blazingstar | Liatris borealis | Not Listed | Species of Concern | | CT, DE, MA, ME, NH, NJ, NY, PA, RI |
| Flowering Plants | [Unnamed] bluebells | Mertensia toyabensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] blue-star | Amsonia grandiflora | Not Listed | Species of Concern | | AZ |
| Flowering Plants | [Unnamed] blue-star | Amsonia palmeri | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] blue-star | Amsonia peeblesii | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] blue-star | Amsonia repens | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [unnamed] brush-pea | Genistidium dumosum | Petitioned for Listing, Under Review | Under Review | | TX |
| Flowering Plants | [Unnamed] buckwheat | Eriogonum anemophilum | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] buckwheat | Eriogonum lemmonii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] buckwheat | Eriogonum meledonum | Not Listed | Species of Concern | | ID |
| Flowering Plants | [Unnamed] buckwheat | Eriogonum viscidulum | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] bur-marigold | Bidens bidentoides bidentoides | Not Listed | Species of Concern | | DE, NJ, NY, PA |
| Flowering Plants | [Unnamed] buttercup | Ranunculus inamoenus subaffinis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] butterfly-pea | Centrosema arenicola | Not Listed | Resolved Taxon | | |
| Insects | [Unnamed] caddisfly | Agapetus jocassee | Not Listed | Species of Concern | | NC, SC |
| Insects | [Unnamed] caddisfly | Agarodes alabamensis | Not Listed | Species of Concern | | AL |
| Insects | [Unnamed] caddisfly | Ceraclea enodis | Not Listed | Resolved Taxon | | AL, NC |
| Insects | [Unnamed] caddisfly | Chimarra holzenthali | Not Listed | Resolved Taxon | | LA |
| Insects | [Unnamed] caddisfly | Diplectrona rossi | Not Listed | Species of Concern | | LA |
| Insects | [Unnamed] caddisfly | Helicopsyche paralimnella | Not Listed | Species of Concern | | NC, SC |
| Insects | [Unnamed] caddisfly | Hydroptila chelops | Not Listed | Species of Concern | | AL |
| Insects | [Unnamed] caddisfly | Hydroptila englishi | Not Listed | Species of Concern | | NC, SC |
| Insects | [Unnamed] caddisfly | Hydroptila lagoi | Not Listed | Species of Concern | | AL |
| Insects | [Unnamed] caddisfly | Hydroptila ouachita | Not Listed | Resolved Taxon | | LA |
| Insects | [Unnamed] caddisfly | Lepidostoma etnieri | Not Listed | Species of Concern | | TN |
| Insects | [Unnamed] caddisfly | Ochotrichia elongiralla | Not Listed | Species of Concern | | AL |
| Insects | [Unnamed] caddisfly | Polycentropus harrisi | Not Listed | Species of Concern | | AL |
| Insects | [Unnamed] caddisfly | Psilotreta frontalis | Not Listed | Resolved Taxon | | MA |
| Insects | [Unnamed] caddisfly | Setodes epicampes | Not Listed | Resolved Taxon | | AL, TN |
| Insects | [Unnamed] caddisfly | Stactiobiella cahaba | Not Listed | Species of Concern | | AL |
| Insects | [Unnamed] caddisfly | Theliopsyche tallapoosa | Not Listed | Species of Concern | | AL |
| Insects | [Unnamed] caddisfly | Wormaldia oconee | Not Listed | Species of Concern | | SC |
| Flowering Plants | [Unnamed] carpenteria | Carpenteria californica | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] catchfly | Silene virginica robusta | Not Listed | Species of Concern | | WV |
| Flowering Plants | [Unnamed] catseye | Cryptantha breviflora | Not Listed | Resolved Taxon | | ID, UT |
| Flowering Plants | [Unnamed] catseye | Cryptantha insolita | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] catseye | Cryptantha shackletteana | Not Listed | Species of Concern | | AK |
| Flowering Plants | [Unnamed] catseye | Cryptantha sobolifera | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | [Unnamed] catseye | Cryptantha stricta | Not Listed | Resolved Taxon | | CO, UT, WY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus audax | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus conditus | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus exoticus | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus globiceps | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus horni | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus puteanus | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus simulans | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanophthalmus tenebrosus | Not Listed | Species of Concern | | KY |
| Insects | [Unnamed] cave beetle | Pseudanopthalmus gracilis | Not Listed | Species of Concern | | VA |
| Insects | [Unnamed] cave beetle | Pseudanopthalmus sylvaticus | Not Listed | Species of Concern | | WV |
| Insects | [Unnamed] cave beetle | Pseudanopthalmus vicarius | Not Listed | Species of Concern | | VA |
| Flowering Plants | [Unnamed] ceanothus | Ceanothus arboreus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] checkermallow | Sidalcea malvaeflora patula | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | [Unnamed] clarkia | Clarkia amoena pacifica | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] clarkia | Clarkia amoena whitneyi | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] clover | Trifolium barnebyi | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | [Unnamed] clover | Trifolium calcaricum | Not Listed | Species of Concern | | VA |
| Flowering Plants | [Unnamed] clover | Trifolium leibergii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | [Unnamed] clover | Trifolium macilentum rollinsii | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] clover | Trifolium neurophyllum | Not Listed | Species of Concern | | AZ, NM |
| Flowering Plants | [Unnamed] clover | Trifolium plumosum amplifolium | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] clover | Trifolium plumosum plumosum | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Ferns and Allies | [Unnamed] clubmoss | Huperzia acerosa | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | [Unnamed] columbine | Aquilegia chrysantha chaplinei | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | [Unnamed] columbine | Aquilegia chrysantha rydbergii | Not Listed | Resolved Taxon | | AZ, CO, NM |
| Flowering Plants | [Unnamed] cory cactus | Coryphantha scheeri uncinata | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] cory cactus | Escobaria missouriensis var. marstonii | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | [Unnamed] cory cactus | Escobaria vivipara var. buoflama | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] coyote-thistle | Eryngium petiolatum | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Crustaceans | [Unnamed] crayfish | Cambarus batchi | Not Listed | Resolved Taxon | | KY |
| Crustaceans | [Unnamed] crayfish | Cambarus miltus | Not Listed | Species of Concern | | AL |
| Crustaceans | [Unnamed] crayfish | Fallicambarus jeanae | Not Listed | Species of Concern | | AR |
| Crustaceans | [Unnamed] crayfish | Orconectes williamsi | Not Listed | Species of Concern | | AR, MO |
| Crustaceans | [Unnamed] crayfish | Procambarus ferrugineus | Not Listed | Species of Concern | | AR |
| Crustaceans | [Unnamed] crayfish | Procambarus liberorum | Not Listed | Resolved Taxon | | MS |
| Flowering Plants | [Unnamed] croomia | Croomia pauciflora | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] desert-parsley | Lomatium graveolens clarkii | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] dewberry | Rubus trivialis | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] diamondflowers | Hedyotis nigricans pulvinata | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] dropseed | Sporobolus pyramidatus | Not Listed | Resolved Taxon | | AZ |
| Clams | [Unnamed] elktoe | Alasmidonta marginata | Not Listed | Species of Concern | | AL, IN, KS, MD, MI, MN, MO, ND, NY, OH, OK, PA, SD, TN, VA, WI, WV |
| Flowering Plants | [Unnamed] evening-primrose | Camissonia confertiflora | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] evening-primrose | Camissonia megalantha | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] evening-primrose | Camissonia nevadensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] evening-primrose | Camissonia parryi | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | [Unnamed] evening-primrose | Camissonia specuicola hesperia | Not Listed | Species of Concern | | AZ |
| Flowering Plants | [Unnamed] evening-primrose | Camissonia specuicola specuicola | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] evening-primrose | Oenothera pilosella sessilis | Not Listed | Species of Concern | | AR, LA, TX |
| Flowering Plants | [Unnamed] evening-primrose | Oenothera psammophila | Not Listed | Species of Concern | | ID |
| Flowering Plants | [Unnamed] false foxglove | Agalinis setacea | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] false indigo | Amorpha ouachitensis | Not Listed | Species of Concern | | AR, OK |
| Flowering Plants | [Unnamed] fameflower | Phemeranthus parviflorus | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | [Unnamed] fameflower | Phemeranthus sediformis | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | [Unnamed] fameflower | Talinum mengesii | Not Listed | Resolved Taxon | | AL, GA, TN |
| Flowering Plants | [Unnamed] fameflower | Talinum thompsonii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] feverfew | Parthenium ligulatum | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | [Unnamed] figwort | Scrophularia macrantha | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] flax | Linum carteri smallii | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] flax | Linum macrocarpum | Not Listed | Species of Concern | | AL, MS |
| Flowering Plants | [Unnamed] fleabane | Erigeron calvus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] fleabane | Erigeron latus | Not Listed | Species of Concern | | ID, NV |
| Flowering Plants | [Unnamed] fleabane | Laennecia eriophylla | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] four-o'clock | Mirabilis pudica | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] gama grass | Tripsacum floridanum | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] gentian | Gentiana villosa | Not Listed | Resolved Taxon | | GA |
| Flowering Plants | [Unnamed] geranium | Geranium caespitosum | Not Listed | Resolved Taxon | | NV |
| Insects | [Unnamed] ghost moth | Hepialus sciophanes | Not Listed | Species of Concern | | NC, VA |
| Flowering Plants | [Unnamed] glade cress | Leavenworthia alabamica brachystyla | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | [Unnamed] glade cress | Leavenworthia crassa elongata | Not Listed | Species of Concern | | AL |
| Flowering Plants | [Unnamed] glade cress | Leavenworthia exigua lutea | Not Listed | Species of Concern | | AL, TN |
| Flowering Plants | [Unnamed] globe-mallow | Sphaeralcea fendleri albescens | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] goldenweed | Haplopappus fremontii monocephalus | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | [Unnamed] goldenweed | Lorandersonia salicina | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] goldenweed | Pyrrocoma radiata | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Flowering Plants | [Unnamed] goldenweed | Pyrrocoma uniflora var. uniflora | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | [Unnamed] green-gentian | Frasera gypsicola | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | [Unnamed] green-gentian | Frasera pahutensis | Not Listed | Species of Concern | | NV |
| Insects | [Unnamed] ground beetle | Rhadine ozarkensis | Not Listed | Species of Concern | | AR |
| Insects | [Unnamed] ground beetle | Scaphinotus behrensi | Not Listed | Species of Concern | | CA |
| Insects | [Unnamed] ground beetle | Scaphinotus inflectus | Not Listed | Species of Concern | | AR |
| Insects | [Unnamed] ground beetle | Scaphinotus parisiana | Not Listed | Species of Concern | | AR |
| Flowering Plants | [Unnamed] groundsel | Senecio hallii discoidea | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | [Unnamed] halapepe | Pleomele aurea | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | [Unnamed] haw | Crataegus harbisonii | Not Listed | Species of Concern | | AL, GA, TN |
| Flowering Plants | [Unnamed] hawkweed | Hieracium robinsonii | Not Listed | Species of Concern | | ME, NH |
| Flowering Plants | [Unnamed] heartleaf | Hexastylis lewisii | Not Listed | Resolved Taxon | | NC, VA |
| Flowering Plants | [Unnamed] holly | Ilex amelanchier | Not Listed | Resolved Taxon | | |
| Snails | [Unnamed] hornsnail | Pleurocera viridulum | Not Listed | Species of Concern | | GA |
| Flowering Plants | [Unnamed] horse-mint | Monarda fistulosa brevis | Not Listed | Species of Concern | | WV |
| Flowering Plants | [Unnamed] horse-mint | Monarda stipitatoglandulosa | Not Listed | Resolved Taxon | | AR, OK |
| Flowering Plants | [Unnamed] horse-nettle | Solanum carolinense hirsutum | Not Listed | Species of Concern | | GA |
| Hydroids | [Unnamed] hydroid | Ostroumovia horii | Not Listed | Species of Concern | | HI |
| Flowering Plants | [Unnamed] indian paintbrush | Castilleja scabrida | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] indian paintbrush | Castilleja wootonii | Not Listed | Species of Concern | | TX |
| Flowering Plants | [Unnamed] iris | Iris missouriensis | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] iris | Iris tenax gormanii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Snails | [Unnamed] islandsnail | Micrarionta rowelli bakerensis | Not Listed | Species of Concern | | CA |
| Crustaceans | [Unnamed] isopod | Caecidotea filicispeluncae | Not Listed | Species of Concern | | OH |
| Crustaceans | [Unnamed] isopod | Caecidotea simonini | Not Listed | Species of Concern | | WV |
| Crustaceans | [Unnamed] isopod | Caecidotea sinuncus | Not Listed | Species of Concern | | WV |
| Crustaceans | [Unnamed] isopod | Caecidotea tomalensis | Not Listed | Species of Concern | | CA |
| Crustaceans | Unnamed isopod | Caecidotea acuticarpa | Not Listed | Status Undefined | | |
| Flowering Plants | [Unnamed] jack-bean | Canavalia kauaiensis | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | [Unnamed] jacob's ladder | Polemonium occidentale lacustre | Not Listed | Species of Concern | | MN, WI |
| Flowering Plants | [Unnamed] jacob's ladder | Polemonium reptans villosum | Not Listed | Resolved Taxon | | KY, OH |
| Flowering Plants | [Unnamed] jacob's ladder | Polemonium vanbruntiae | Not Listed | Resolved Taxon | | CT, DE, MD, ME, NJ, NY, PA, VT, WV |
| Flowering Plants | [Unnamed] jewelflower | Streptanthus squamiformis | Not Listed | Species of Concern | | AR, OK |
| Flowering Plants | [Unnamed] kittentails | Synthyris ranunculina | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] knotweed | Polygonum striatulum | Not Listed | Resolved Taxon | | TX |
| Insects | [Unnamed] lace bug | Acalyptera susanae | Not Listed | Species of Concern | | AR |
| Flowering Plants | [Unnamed] ladies'-tresses | Mesadenus polyanthus | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] ladies'-tresses | Spiranthes lanceolata paludicola | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] lady's-slipper | Cypripedium kentuckiense | Not Listed | Species of Concern | | AL, AR, KY, LA, MS, OK, TN, TX |
| Flowering Plants | [Unnamed] larkspur | Delphinium multiplex | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | [Unnamed] larkspur | Delphinium newtonianum | Not Listed | Resolved Taxon | | AR |
| Flowering Plants | [Unnamed] larkspur | Delphinium nuttallianum lineapetalum | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | [Unnamed] larkspur | Delphinium treleasei | Not Listed | Resolved Taxon | | AR, MO |
| Flowering Plants | [Unnamed] leather flower | Clematis occidentalis dissecta | Not Listed | Resolved Taxon | | WA |
| Lichens | [Unnamed] lichen | Texosporium sancti-jacobi | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Flowering Plants | [Unnamed] linanthus | Linanthus concinnus | Not Listed | Species of Concern | | CA |
| Flowering Plants | [Unnamed] liverwort | Cylindrocolea andersonii | Not Listed | Species of Concern | | NC |
| Flowering Plants | [Unnamed] liverwort | Plagiochila sullivantii var. spinigera | Not Listed | Species of Concern | | NC, SC, TN, VA, WV |
| Flowering Plants | [Unnamed] liverwort | Plagiochila sullivantii var. sullivantii | Not Listed | Species of Concern | | NC |
| Flowering Plants | [Unnamed] liverwort | Plagiochila virginica var. caroliniana | Not Listed | Species of Concern | | NC, SC, TN, VA |
| Flowering Plants | [Unnamed] liverwort | Sphenolobopsis pearsoni | Not Listed | Species of Concern | | NC, TN |
| Flowering Plants | [Unnamed] Liverwort | Plagiochila virginica var. virginica | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] Liverwort | Porella pinnata | Not Listed | Species of Concern | | |
| Insects | [Unnamed] looper moth | Euchlaena milnei | Not Listed | Species of Concern | | IL, NC, OH, VA, WI, WV |
| Insects | [Unnamed] looper moth | Lambdina canitiaria | Not Listed | Species of Concern | | NY |
| Insects | [Unnamed] looper moth | Lytrosis permagnaria | Not Listed | Species of Concern | | GA, KY, MO, MS, TN |
| Flowering Plants | [Unnamed] manzanita | Arctostaphylos hispidula | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] manzanita | Arctostaphylos intricata oblongifolia | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] maple | Acer grandidentatum sinuosum | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] mariposa lily | Calochortus indecorus | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | [Unnamed] mayfly | Paraleptophlebia calcarica | Not Listed | Resolved Taxon | | AR |
| Flowering Plants | [Unnamed] milkpea | Galactia pinetorum | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus accumbens | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus ackermanii | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus aequalis | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus altus | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus alvordensis | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus amnis-amissi | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus atratus inseptus | Not Listed | Species of Concern | | ID |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus barrii | Not Listed | Resolved Taxon | | MT, NE, SD, WY |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus brandegeei | Not Listed | Species of Concern | | CO |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus calycosus monophyllidius | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus camptopus | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus ceramicus apus | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus cimae sufflatus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus consobrinus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus convallarius finitimus | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus drabelliformis | Not Listed | Species of Concern | | WY |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus ensiformis | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus eurylobus | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus gilmanii | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus harrisonii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus henrimontanensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus hoodianus | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus howellii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus knightii | Not Listed | Species of Concern | | NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus lancearius | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus lentiformis | Not Listed | Species of Concern | | CA |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus lentiginosus latus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus lentiginosus maricopae | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus lentiginosus pohlii | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus lentiginosus scorpionis | Not Listed | Species of Concern | | NV, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus loanus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus lutosus | Not Listed | Resolved Taxon | | CO, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus minthorniae gracilior | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus molybdenus | Not Listed | Species of Concern | | CO, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus monumentalis | Not Listed | Resolved Taxon | | AZ, CO, NM, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus neglectus | Not Listed | Species of Concern | | MI, MN, OH, WI |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus nidularius | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus nyensis | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus oniciformis | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus oocalycis | Not Listed | Resolved Taxon | | CO, NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus panamintensis | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus pardalinus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus pauperculus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus paysonii | Not Listed | Species of Concern | | ID, WY |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus peckii | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus porrectus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus preussii cutleri | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus proimanthus | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus proximus | Not Listed | Species of Concern | | CO, NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus pterocarpus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus puniceus gertrudis | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus purshii ophiogenes | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus scaphoides | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus serenoi sordescens | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus serpens | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus shultziorum | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus siliceus | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus subvestitus | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus tegetarioides | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus tennesseensis | Not Listed | Resolved Taxon | | AL, IL, IN, TN |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus titanophilus | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus toquimanus | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus troglodytus | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus tweedyi | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus tyghensis | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus uncialis | Not Listed | Species of Concern | | NV, UT |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus wittmannii | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] milk-vetch | Astragalus woodruffii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] milkweed | Asclepias uncialis | Not Listed | Species of Concern | | CO, KS, NM |
| Flowering Plants | [Unnamed] milkweed | Asclepias viridula | Not Listed | Species of Concern | | |
| Millipedes | [Unnamed] millipede | Toltecus chihuanus | Not Listed | Species of Concern | | NM |
| Flowering Plants | [Unnamed] mint | Dicerandra odoratissima | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] mint | Dicerandra radfordiana | Not Listed | Species of Concern | | GA |
| Flowering Plants | [Unnamed] monkeyflower | Mimulus guttatus arenicola | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | [Unnamed] morning-glory | Ipomoea plummerae | Not Listed | Resolved Taxon | | AZ, NM |
| Flowering Plants | [Unnamed] mountain-mint | Pycnanthemum monotrichum | Not Listed | Resolved Taxon | | VA |
| Snails | [Unnamed] mountainsnail | Oreohelix haydeni corugata | Not Listed | Species of Concern | | UT |
| Snails | [Unnamed] mountainsnail | Oreohelix parowanensis | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] muhly | Muhlenbergia curtisetosa | Not Listed | Resolved Taxon | | IL, MO, OH, PA |
| Flowering Plants | [Unnamed] nehe | Lipochaeta alata alata | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | [Unnamed] nightshade | Solanum bahamense rugelii | Not Listed | Resolved Taxon | | |
| Insects | [Unnamed] noctuid moth | Luperina trigona | Not Listed | Species of Concern | | TN |
| Insects | [Unnamed] noctuid moth | Papaipema aerata | Not Listed | Species of Concern | | DE, IL, MI, NH, NJ, NY, PA |
| Insects | [Unnamed] noctuid moth | Papaipema aweme | Not Listed | Species of Concern | | MI, NY |
| Insects | [Unnamed] noctuid moth | Schinia indiana | Not Listed | Species of Concern | | AR, IL, IN, MI, MN, NC, NE, TX, WI |
| Flowering Plants | [Unnamed] nodding-caps | Triphora latifolia | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] nodding-caps | Triphora yucatanensis | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] oak | Quercus arkansana | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] oak | Quercus georgiana | Not Listed | Resolved Taxon | | AL, GA, SC |
| Flowering Plants | [Unnamed] olapa | Cheirodendron trigynum rockii | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | [Unnamed] olapa | Cheirodendron trigynum subcordatum | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | [Unnamed] onion | Allium constrictum | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | [Unnamed] onion | Allium madidum | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Flowering Plants | [Unnamed] onion | Allium oxyphilum | Not Listed | Resolved Taxon | | VA, WV |
| Flowering Plants | [Unnamed] onion | Allium perdulce sperryi | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] onion | Allium robinsonii | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] onion | Allium scilloides | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | [Unnamed] onion | Allium speculae | Not Listed | Species of Concern | | AL, GA |
| Flowering Plants | [Unnamed] onion | Allium tolmiei persimile | Not Listed | Resolved Taxon | | ID |
| Crustaceans | [Unnamed] ostracod | Dactylocythere isabelae | Not Listed | Species of Concern | | NC |
| Crustaceans | [Unnamed] ostracod | Waltoncythere acuta | Not Listed | Species of Concern | | NC |
| Flowering Plants | [Unnamed] phacelia | Phacelia capitata | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] phacelia | Phacelia demissa heterotricha | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] phacelia | Phacelia filiformis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] phacelia | Phacelia minutissima | Not Listed | Species of Concern | | CA, ID, NV, OR |
| Flowering Plants | [Unnamed] phacelia | Phacelia rafaelensis | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | [Unnamed] phlox | Phlox caryophylla | Not Listed | Resolved Taxon | | CO, NM |
| Flowering Plants | [Unnamed] phlox | Phlox jonesii | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] phlox | Phlox missoulensis | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | [Unnamed] phlox | Phlox mollis | Not Listed | Resolved Taxon | | CA, ID, NV, OR, WA |
| Flowering Plants | [Unnamed] phlox | Phlox pulchra | Not Listed | Resolved Taxon | | AL |
| Flowering Plants | [Unnamed] phlox | Phlox pungens | Not Listed | Species of Concern | | WY |
| Flowering Plants | [Unnamed] pinkroot | Spigelia loganioides | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] pitcher-plant | Sarracenia leucophylla | Not Listed | Species of Concern | | |
| Flatworms and Roundworms | [Unnamed] planarian | Kenkia glandulosa | Not Listed | Species of Concern | | IA, MO |
| Flatworms and Roundworms | [Unnamed] planarian | Kenkia rhynchida | Not Listed | Species of Concern | | CA, NV, OR |
| Flatworms and Roundworms | [Unnamed] planarian | Procotyla typhlops | Not Listed | Species of Concern | | VA |
| Flatworms and Roundworms | [Unnamed] planarian | Sphalloplana virginiana | Not Listed | Species of Concern | | VA |
| Flowering Plants | [Unnamed] pondweed | Potamogeton confervoides | Not Listed | Species of Concern | | DE, MA, ME, MI, NC, NH, NJ, NY, PA, SC, VT, WI |
| Flowering Plants | [Unnamed] pondweed | Potamogeton ogdenii | Not Listed | Resolved Taxon | | MA, NY, VT |
| Flowering Plants | [Unnamed] popcornflower | Plagiobothrys lamprocarpus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] poppy-mallow | Callirhoe bushii | Not Listed | Resolved Taxon | | AR, IA, KS, MO, OK |
| Flowering Plants | [Unnamed] prairie-clover | Dalea scariosa | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] primrose | Primula alcalina | Not Listed | Species of Concern | | ID, MT |
| Flowering Plants | [Unnamed] primrose | Primula capillaris | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] primrose | Primula domensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] primrose | Primula nevadensis | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] primrose | Primula tschuktschorum | Not Listed | Species of Concern | | AK |
| Flowering Plants | [Unnamed] primrose | Primula wilcoxiana | Not Listed | Resolved Taxon | | ID |
| Ferns and Allies | [Unnamed] quillwort | Isoetes flaccida | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] reedgrass | Calamagrostis nubila | Not Listed | Resolved Taxon | | NH |
| Flowering Plants | [Unnamed] reedgrass | Calamagrostis tweedyi | Not Listed | Resolved Taxon | | ID, MT, WA |
| Flowering Plants | [Unnamed] rhododendron | Rhododendron austrinum | Not Listed | Resolved Taxon | | |
| Insects | [Unnamed] riffle beetle | Microcylleopus fomicoideus | Not Listed | Species of Concern | | CA |
| Insects | [Unnamed] riffle beetle | Microcylleopus similis | Not Listed | Species of Concern | | CA |
| Flowering Plants | [Unnamed] rock-cress | Arabis crandallii | Not Listed | Resolved Taxon | | CO, WY |
| Flowering Plants | [Unnamed] rock-cress | Arabis dispar | Not Listed | Resolved Taxon | | CA, NV |
| Flowering Plants | [Unnamed] rock-cress | Arabis falcatoria | Not Listed | Resolved Taxon | | NV, UT |
| Flowering Plants | [Unnamed] rock-cress | Arabis falcifructa | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] rock-cress | Arabis gracilipes | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] rock-cress | Arabis gunnisoniana | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | [Unnamed] rock-cress | Arabis koehleri stipitata | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] rock-cress | Arabis ophira | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] rock-cress | Arabis petiolaris | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] rock-cress | Arabis williamsii | Not Listed | Resolved Taxon | | WY |
| Flowering Plants | [Unnamed] rock-daisy | Perityle gilensis salensis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] rock-daisy | Perityle lindheimeri halimifolia | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] rock-daisy | Perityle lindheimeri lindheimeri | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] rosemary | Conradina grandiflora | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] rosinweed | Silphium brachiatum | Not Listed | Species of Concern | | AL, TN |
| Flowering Plants | [Unnamed] rosinweed | Silphium integrifolium gattingeri | Not Listed | Resolved Taxon | | TN |
| Flowering Plants | [Unnamed] rush | Juncus gymnocarpus | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] rush | Juncus oronensis | Not Listed | Resolved Taxon | | ME |
| Flowering Plants | [Unnamed] sand grass | Calamovilfa brevipilis | Not Listed | Resolved Taxon | | DE, NC, NJ, SC, VA |
| Flowering Plants | [Unnamed] sand grass | Calamovilfa brevipilis calvipes | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | [Unnamed] sand grass | Calamovilfa curtissii | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] sand-verbena | Abronia ammphila | Not Listed | Species of Concern | | WY |
| Flowering Plants | [Unnamed] sand-verbena | Abronia bigelovii | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | [Unnamed] sand-verbena | Abronia turbinata | Not Listed | Resolved Taxon | | NV |
| Flowering Plants | [Unnamed] saxifrage | Saxifraga careyana | Not Listed | Resolved Taxon | | AL, GA, NC, TN, VA |
| Flowering Plants | [Unnamed] scurf-pea | Pediomelum castoreum | Not Listed | Species of Concern | | AZ, CA, NV, UT |
| Flowering Plants | [Unnamed] scurf-pea | Pediomelum epipsilum | Not Listed | Species of Concern | | AZ, UT |
| Flowering Plants | [Unnamed] sea-lavender | Limonium carolinianum angustatum | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] sebucan | Leptocereus quadricostatus | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | [Unnamed] sedge | Carex arapahoensis | Not Listed | Resolved Taxon | | CO, MT, UT |
| Flowering Plants | [Unnamed] sedge | Carex austrocaroliniana | Not Listed | Resolved Taxon | | AL, GA, KY, NC, SC, TN |
| Flowering Plants | [Unnamed] sedge | Carex baltzellii | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] sedge | Carex bicknellii opaca | Not Listed | Species of Concern | | AR |
| Flowering Plants | [Unnamed] sedge | Carex decomposita | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] sedge | Carex fissa | Not Listed | Species of Concern | | KS, OK |
| Flowering Plants | [Unnamed] sedge | Carex formosa | Not Listed | Species of Concern | | MI, MN, ND, NY, OH, WI |
| Flowering Plants | [Unnamed] sedge | Carex haysii | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] sedge | Carex interrupta | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] sedge | Carex lenticularis dolia | Not Listed | Species of Concern | | AK, MT |
| Flowering Plants | [Unnamed] sedge | Carex misera | Not Listed | Resolved Taxon | | GA, NC, TN |
| Flowering Plants | [Unnamed] sedge | Carex onusta | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] sedge | Carex oronensis | Not Listed | Species of Concern | | ME |
| Flowering Plants | [Unnamed] sedge | Carex parryana idahoa | Not Listed | Resolved Taxon | | ID, MT |
| Flowering Plants | [Unnamed] sedge | Carex purpurifera | Not Listed | Resolved Taxon | | AL, GA, KY, OH, TN, VA |
| Flowering Plants | [Unnamed] sedge | Carex roanensis | Not Listed | Species of Concern | | NC |
| Flowering Plants | [Unnamed] sedge | Carex schweinitzii | Not Listed | Species of Concern | | CT, DE, MA, MO, NC, NJ, NY, PA, VA, VT, WI |
| Flowering Plants | [Unnamed] sedge | Carex scirpoidea curatorum | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | [Unnamed] sedge | Carex socialis | Not Listed | Resolved Taxon | | AR, IL, IN, KY, MO, TN |
| Flowering Plants | [Unnamed] sedge | Cyperus louisianensis | Not Listed | Species of Concern | | LA |
| Flowering Plants | [Unnamed] service-berry | Amelanchier nantucketensis | Not Listed | Species of Concern | | MA, NY |
| Crustaceans | [Unnamed] shrimp | Halocaridina palahemo | Not Listed | Species of Concern | | HI |
| Flowering Plants | [Unnamed] silverbells | Styrax platanifolia stellata | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] skullcap | Scutellaria saxatilis | Not Listed | Resolved Taxon | | DE, GA, IN, KY, MO, NC, OH, PA, TN, VA, WV |
| Snails | [Unnamed] snail | Diastole schmeltziana | Not Listed | Species of Concern | | AS |
| Snails | [Unnamed] snail | Laminella sanguinea | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Leptachatina lepida | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Mesodon clausus trossulus | Not Listed | Species of Concern | | AL |
| Snails | [Unnamed] snail | Neoplanorbis carinatus | Not Listed | Species of Concern | | AL |
| Snails | [Unnamed] snail | Neoplanorbis smithi | Not Listed | Species of Concern | | AL |
| Snails | [Unnamed] snail | Neoplanorbis tantillus | Not Listed | Species of Concern | | AL |
| Snails | [Unnamed] snail | Neoplanorbis umbilicatus | Not Listed | Species of Concern | | AL |
| Snails | [Unnamed] snail | Paravitrea aulacogyra | Not Listed | Species of Concern | | AR |
| Snails | [Unnamed] snail | Perdicella carinella | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella fulgurans | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella helena | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella kuhnsi | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella mauiensis | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella ornata | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella thwingii | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella zebra | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Perdicella zebrina | Not Listed | Species of Concern | | HI |
| Snails | [Unnamed] snail | Succinea guamensis | Not Listed | Species of Concern | | GU |
| Snails | [Unnamed] snail | Succinea piratarum | Not Listed | Species of Concern | | GU |
| Snails | [Unnamed] snail | Succinea quadrasi | Not Listed | Species of Concern | | GU |
| Snails | [Unnamed] snail | Trochomorpha apia | Not Listed | Species of Concern | | AS |
| Snails | [Unnamed] snail | Valvata virens | Not Listed | Species of Concern | | CA |
| Flowering Plants | [Unnamed] sorrel | Rumex krausei | Not Listed | Species of Concern | | AK |
| Arachnids | [Unnamed] spider | Cicurina cueva | Not Listed | Resolved Taxon | | TX |
| Ferns and Allies | [Unnamed] spleenwort | Asplenium adiantum-nigrum | Not Listed | Resolved Taxon | | AZ, CO, UT |
| Ferns and Allies | [Unnamed] spleenwort | Asplenium heteroresiliens | Not Listed | Species of Concern | | |
| Ferns and Allies | [Unnamed] spleenwort | Asplenium kentuckiense | Not Listed | Resolved Taxon | | AR, IL, IN, KY, OH, VA |
| Ferns and Allies | [Unnamed] spleenwort | Asplenium leucostegioides | Not Listed | Resolved Taxon | | HI |
| Ferns and Allies | [Unnamed] spleenwort | Asplenium plenum | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] spring-beauty | Claytonia virginica hammondiae | Not Listed | Species of Concern | | DE, NJ |
| Flowering Plants | [Unnamed] star-grass | Hypoxis sessilis | Not Listed | Resolved Taxon | | AR, LA, OK, TX, VA |
| Flowering Plants | [Unnamed] stickleaf | Mentzelia nitens leptocaulis | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] stickseed | Hackelia ibapensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] stickseed | Hackelia ophiobia | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | [Unnamed] stolon | Draba sphaerocarpa | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] stonecrop | Sedum pusillum | Not Listed | Resolved Taxon | | GA, NC, SC |
| Flowering Plants | [Unnamed] stonecrop | Sedum rosea roanensis | Not Listed | Resolved Taxon | | NC, TN |
| Flowering Plants | [Unnamed] sullivantia | Sullivantia sullivantii | Not Listed | Resolved Taxon | | IA, IN, KY, MN, MO, OH, VA, WI |
| Flowering Plants | [Unnamed] sumac | Rhus trilobata arenaria | Not Listed | Species of Concern | | IL, IN, OH |
| Flowering Plants | [Unnamed] synandra | Synandra hispidula | Not Listed | Resolved Taxon | | AL, IL, IN, KY, NC, OH, TN, VA, WV |
| Flowering Plants | [Unnamed] tamarindillo | Cassia exunguis | Not Listed | Resolved Taxon | | PR, VI |
| Flowering Plants | [Unnamed] tansy | Sphaeromeria compacta | Not Listed | Species of Concern | | NV |
| Flowering Plants | [Unnamed] thelypody | Thelypodium texanum | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] thistle | Cirsium davisii | Not Listed | Resolved Taxon | | ID |
| Flowering Plants | [Unnamed] thistle | Cirsium hallii | Not Listed | Resolved Taxon | | CA, NV, OR, UT |
| Flowering Plants | [Unnamed] thistle | Cirsium hillii | Not Listed | Species of Concern | | IA, IL, IN, MI, MN, OH, PA, WI |
| Flowering Plants | [Unnamed] thistle | Cirsium longistylum | Not Listed | Species of Concern | | MT |
| Flowering Plants | [Unnamed] thistle | Cirsium rydbergii | Not Listed | Resolved Taxon | | AZ, UT |
| Flowering Plants | [Unnamed] thistle | Cirsium turneri | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | [Unnamed] thoroughwort | Eupatorium resinosum kentuckiense | Not Listed | Resolved Taxon | | KY |
| Flowering Plants | [Unnamed] three-awned grass | Aristida floridana | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] townsendia | Townsendia jonesii lutea | Not Listed | Species of Concern | | UT |
| Flowering Plants | [Unnamed] townsendia | Townsendia mensana | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] townsendia | Townsendia rothrockii | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | [Unnamed] twinpod | Physaria integrifolia monticola | Not Listed | Species of Concern | | WY |
| Flowering Plants | [Unnamed] twinpod | Physaria saximontana saximontana | Not Listed | Species of Concern | | WY |
| Flowering Plants | [Unnamed] vervain | Glandularia tampensis | Not Listed | Species of Concern | | |
| Flowering Plants | [Unnamed] virgin's bower | Clematis viorna | Not Listed | Resolved Taxon | | AL, TN |
| Flowering Plants | [Unnamed] wallflower | Erysimum asperum angustatum | Not Listed | Resolved Taxon | | AK |
| Flowering Plants | [Unnamed] water-willow | Justicia americana | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | [Unnamed] whitlow-grass | Draba subalpina | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | [Unnamed] whitlow-wort | Draba exunguiculata | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | [Unnamed] whitlow-wort | Paronychia rugelii interior | Not Listed | Resolved Taxon | | |
| Flowering Plants | [Unnamed] wild-buckwheat | Eriogonum ericifolium ericifolium | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | [Unnamed] wild-buckwheat | Eriogonum flavum aquilinum | Not Listed | Species of Concern | | AK |
| Flowering Plants | [Unnamed] willow | Salix fluviatilis | Not Listed | Resolved Taxon | | CA, NV, OR, WA |
| Flowering Plants | [Unnamed] wormwood | Artemisia globularia lutea | Not Listed | Species of Concern | | AK |
| Flowering Plants | [Unnamed] wormwood | Artemisia glomerata subglabra | Not Listed | Species of Concern | | AK |
| Insects | Unsilvered fritillary | Speyeria adiaste | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Upland Burrowing Crayfish | Cambarus dubius | | Not Listed | | |
| Clams | Upland combshell | Epioblasma metastriata | Delisted | Extinction | | AL, TN |
| Snails | Upland hornsnail | Pleurocera showalteri | Not Listed | Species of Concern | | AL, GA |
| Birds | Upland Sandpiper | Bartramia longicauda | Not Listed | Species of Concern | | |
| Flowering Plants | Urban's flatsedge | Cyperus urbanii | Not Listed | Species of Concern | | PR, VI |
| Mammals | Urial | Ovis musimon ophion | Listed | Endangered | | |
| Insects | Usinger's brown lacewing | Pseudopsectra usingeri | Not Listed | Species of Concern | | HI |
| Crustaceans | Utah Amphipod | Stygobromus utahensis | Not Listed | Resolved Taxon | | |
| Insects | Utah chaetarthrian water scavenger beetle | Chaetarthria utahensis | Not Listed | Resolved Taxon | | UT |
| Fishes | Utah Chub | Gila atraria | | Not Listed | | |
| Insects | Utah hydroporus diving beetle | Hydroporus utahensis | Not Listed | Species of Concern | | UT |
| Insects | Utah minute moss beetle | Limnebius utahensis | Not Listed | Species of Concern | | UT |
| Flowering Plants | Utah phacelia | Phacelia utahensis | Not Listed | Species of Concern | | UT |
| Snails | Utah physa | Physella utahensis | Not Listed | Species of Concern | | UT |
| Mammals | Utah prairie dog | Cynomys parvidens | Listed | Threatened | | UT |
| Fishes | Utah Sucker | Catostomus ardens | | Not Listed | | |
| Snails | Utah valvata snail | Valvata utahensis | Delisted | Original Data in Error - New Information Discovered | | ID, UT |
| Flowering Plants | Ute ladies'-tresses | Spiranthes diluvialis | Listed | Threatened | Proposed Delisting | AZ, CO, ID, MT, NE, NV, SD, UT, WA, WY |
| Birds | Utila chachalaca | Ortalis vetula | Not Listed | Resolved Taxon | | |
| Birds | Uvea parakeet | Eunymphicus uveaensis | Not Listed | Resolved Taxon | | |
| Flowering Plants | Uvillo | Eugenia haematocarpa | Listed | Endangered | | PR |
| Flowering Plants | Vahl's boxwood | Buxus vahlii | Listed | Endangered | | PR, VI |
| Flowering Plants | Vail Lake ceanothus | Ceanothus ophiochilus | Listed | Threatened | | CA |
| Amphibians | Valdina Farms salamander | Eurycea troglodytes | Not Listed | Resolved Taxon | | TX |
| Arachnids | Valentine's cave spider | Nesticus valentinei | Not Listed | Species of Concern | | TN |
| Insects | Valley elderberry longhorn beetle | Desmocerus californicus dimorphus | Listed | Threatened | | CA |
| Reptiles | Valley Form ground snake | sonora semiannulata | Not Listed | Species of Concern | | |
| Insects | Valley mydas fly | Drosophila alsophila | Not Listed | Resolved Taxon | | HI |
| Insects | Valley mydas fly | Drosophila psilotarsalis | Not Listed | Resolved Taxon | | HI |
| Insects | Valley mydas fly | Drosophila toxochaeta | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Valley Oak | Quercus lobata | Not Listed | Resolved Taxon | | |
| Insects | Valley oak ant | Proceratium californicum | Petitioned for Listing, Under Review | Under Review | | CA |
| Flowering Plants | Valley peperomia | Peperomia remyi | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Valley sagittaria | Sagittaria sanfordii | Not Listed | Species of Concern | | CA |
| Flowering Plants | Valley spearscale | Atriplex joaquiniana | Not Listed | Species of Concern | | CA |
| Mammals | Vancouver Island marmot | Marmota vancouverensis | Listed | Endangered | | |
| Birds | Van Dam's vanga | Xenopirostris damii | Listed | Threatened | | |
| Flowering Plants | Vandenberg monkeyflower | Diplacus vandenbergensis | Listed | Endangered | | CA |
| Amphibians | Van Dyke's salamander | plethodon vandykei | Not Listed | Species of Concern | | |
| Insects | Vannote's net-spinning caddisfly | Cheumatopsyche vannotei | Not Listed | Species of Concern | | PA |
| Birds | Van Rossem's gull-billed tern | Sterna nilotica vanrossemi | Not Listed | Resolved Taxon | | CA |
| Insects | Variable Cuckoo Bumble Bee | Bombus variabilis | Petitioned for Listing, Under Review | Under Review | | AL, AR, AZ, CO, FL, GA, IA, IL, IN, KS, LA, MD, MI, MO, MS, NC, ND, NE, NH, NM, OH, OK, SC, SD, TN, TX, VA |
| Flowering Plants | Variable leaf Indian plaintain | Arnoglossum diversifolium | Not Listed | Status Undefined | | |
| Flowering Plants | Variable sedge | Carex polymorpha | Not Listed | Species of Concern | | CT, DE, MA, MD, ME, NH, NJ, NY, PA, RI, VA, WV |
| Clams | Variable Spike | Elliptio icterina | | Not Listed | | |
| Snails | Variable Vertigo | Vertigo gouldi | | Not Listed | | |
| Snails | Varicose rocksnail | Lithasia verrucosa | Not Listed | Species of Concern | | AL, KY, OH, TN |
| Birds | Varied Bunting | Passerina versicolor | Not Listed | Species of Concern | | |
| Birds | Varied Thrush | Ixoreus naevius | Not Listed | Species of Concern | | |
| Birds | Varied Thrush | Ixoreus naevius naevius | Not Listed | Species of Concern | | |
| Fishes | Variegate Darter | Etheostoma variatum | | Not Listed | | |
| Insects | Variegated clubtail | Progomphus bellei | Not Listed | Species of Concern | | |
| Flowering Plants | Variegated dudleya | Dudleya variegata | Not Listed | Species of Concern | | CA |
| Insects | Variegated false water penny | Dicranopselaphus variegatus | Not Listed | Species of Concern | | IL |
| Birds | Vaux's swift | Chaetura vauxi | Not Listed | Species of Concern | | |
| Birds | Vaux's Swift | Chaetura vauxi vauxi | Not Listed | Species of Concern | | |
| Birds | Veery | Catharus fuscescens | Not Listed | Species of Concern | | |
| Birds | Veery | Catharus fuscescens fuscescens | Not Listed | Species of Concern | | |
| Birds | Veery | Catharus fuscescens salicicola | Not Listed | Species of Concern | | |
| Birds | Veery | Catharus fuscescens subpallidus | Not Listed | Species of Concern | | |
| Amphibians | Vegas Valley leopard frog | Rana fisheri | Not Listed | Resolved Taxon | | AZ, NV, UT |
| Flowering Plants | Veiny monardella | Monardella douglasii venosa | Not Listed | Species of Concern | | CA |
| Insects | Velvet ant | Dasymutilla imperialis | Not Listed | Resolved Taxon | | |
| Insects | Velvet ant | Dasymutilla nocturna | Not Listed | Resolved Taxon | | |
| Flowering Plants | Velvety false-lupine | Thermopsis macrophylla semota | Not Listed | Species of Concern | | CA |
| Flowering Plants | Venator Canyon, Shelly's ivesia | Ivesia rhypara shellyi | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Ventura Marsh Milk-vetch | Astragalus pycnostachyus var. lanosissimus | Listed | Endangered | | CA |
| Flowering Plants | Venus flytrap | Dionaea muscipula | Not Listed | Resolved Taxon | | |
| Insects | Venus flytrap noctuid | Hemipachnolia subporphyria subporphyria | Not Listed | Species of Concern | | NC |
| Flowering Plants | Verde four-nerve daisy | Tetraneuris verdiensis | Not Listed | Resolved Taxon | | AZ |
| Snails | Verde Rim springsnail | Pyrgulopsis glandulosa | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Verde Valley sage | Salvia dorrii mearnsii | Not Listed | Species of Concern | | AZ |
| Birds | Verdin | Auriparus flaviceps | Not Listed | Species of Concern | | |
| Birds | Verdin | Auriparus flaviceps acaciarum | Not Listed | Species of Concern | | |
| Flowering Plants | Verity's dudleya | Dudleya verityi | Listed | Threatened | | CA |
| Fishes | Vermilion darter | Etheostoma chermocki | Listed | Endangered | | AL |
| Birds | Vermillion flycatcher | pyrocephalus rubinus | Not Listed | Species of Concern | | |
| Flowering Plants | Vernal barley | hordeum intercedens | Not Listed | Species of Concern | | |
| Flowering Plants | Vernal pool brodiaea | Dichelostemma lacuna-vernalis | Not Listed | Resolved Taxon | | CA |
| Crustaceans | Vernal pool fairy shrimp | Branchinecta lynchi | Listed | Threatened | | CA, OR |
| Crustaceans | Vernal pool tadpole shrimp | Lepidurus packardi | Listed | Endangered | | CA, OR |
| Insects | Vertrees's ceraclean caddisfly | Ceraclea vertreesi | Not Listed | Species of Concern | | OR |
| Insects | Vertrees's ochrotrichian micro caddisfly | Ochrotrichia vertreesi | Not Listed | Species of Concern | | OR |
| Insects | Very yellow-faced bee | Hylaeus flavifrons | Not Listed | Species of Concern | | HI |
| Insects | Vespid | Euparagia | Not Listed | Resolved Taxon | | |
| Insects | Vicinan yellow-faced bee | Hylaeus vicina | Not Listed | Species of Concern | | HI |
| Snails | Victorville shoulderband | Helminthoglypta mohaveana | Not Listed | Species of Concern | | CA |
| Mammals | Vicuna | Vicugna vicugna | Listed | Endangered | | |
| Mammals | Vicuna | Vicugna vicugna | Listed | Threatened | | |
| Flowering Plants | Villard's pincushion cactus | Escobaria villardii | Not Listed | Species of Concern | | NM |
| Insects | Villosan flightless seed bug | Nesocryptias villosa | Not Listed | Species of Concern | | HI |
| Flowering Plants | Villous muhly | Muhlenbergia villiflora var. villosa | Not Listed | Resolved Taxon | | NM, TX |
| Birds | Vinaceous-breasted parrot | Amazona vinacea | Listed | Endangered | | |
| Flowering Plants | Vine Hill ceanothus | Ceanothus foliosus vineatus | Not Listed | Species of Concern | | CA |
| Flowering Plants | Vine Hill clarkia | Clarkia imbricata | Listed | Endangered | | CA |
| Flowering Plants | Vine Hill manzanita | Arctostaphylos densiflora | Not Listed | Species of Concern | | CA |
| Flowering Plants | Virgate halimolobus | Halimolobos virgata | Not Listed | Resolved Taxon | | CA |
| Mammals | Virginia big-eared bat | Corynorhinus (=Plecotus) townsendii virginianus | Listed | Endangered | | KY, NC, TN, VA, WV |
| Snails | Virginia fringed mountain snail | Polygyriscus virginianus | Listed | Endangered | | VA |
| Flowering Plants | Virginia mallow | Sida hermaphrodita | Not Listed | Resolved Taxon | | DC, IN, KY, MD, MI, OH, PA, TN, VA, WV |
| Mammals | Virginia northern flying Squirrel | Glaucomys sabrinus fuscus | Delisted | Recovery | | VA, WV |
| Ferns and Allies | Virginia quillwort | Isoetes virginica | Not Listed | Species of Concern | | NC, VA |
| Birds | Virginia Rail | Rallus limicola | Not Listed | Status Undefined | | |
| Flowering Plants | Virginia round-leaf birch | Betula uber | Listed | Threatened | | VA |
| Flowering Plants | Virginia saltmarsh mallow | Kosteletzkya pentacarpos | Not Listed | Resolved Taxon | | |
| Flowering Plants | Virginia sneezeweed | Helenium virginicum | Listed | Threatened | | IN, MO, VA |
| Flowering Plants | Virginia spiraea | Spiraea virginiana | Listed | Threatened | | GA, KY, NC, OH, TN, VA, WV |
| Insects | Virginia stone | Acroneuria kosztarabi | Petitioned for Listing, Under Review | Under Review | | KY, VA |
| Birds | Virginia's Warbler | Leiothlypis virginiae | Not Listed | Species of Concern | | |
| Reptiles | Virgin Islands Bronze Skink | Spondylurus sloanii | Proposed for Listing | Proposed Endangered | | VI |
| Amphibians | Virgin Islands coqui | Eleutherodactylus schwartzi | Not Listed | Resolved Taxon | | |
| Birds | Virgin Islands screech owl | Otus nudipes newtoni | Not Listed | Species of Concern | | PR, VI |
| Reptiles | Virgin Islands tree boa | Chilabothrus granti | Listed | Endangered | | PR, VI |
| Mammals | Virgin Merriam's kangaroo rat | Dipodomys merriami frenatus | Not Listed | Species of Concern | | UT |
| Flowering Plants | Virgin phacelia | Phacelia cephalotes | Not Listed | Resolved Taxon | | AZ, UT |
| Fishes | Virgin River Chub | Gila seminuda (=robusta) | Listed | Endangered | | AZ, NV, UT |
| Mammals | Virgin River montane vole | Microtus montanus rivularis | Not Listed | Species of Concern | | UT |
| Fishes | Virgin River spinedace | Lepidomeda mollispinis mollispinis | Not Listed | Resolved Taxon | | AZ, NV, UT |
| Fishes | Virgin Spinedace | Lepidomeda mollispinis | | Not Listed | | |
| Fishes | Virgin Spinedace | Lepidomeda mollispinis | | Not Listed | | |
| Flowering Plants | Virgin thistle | Cirsium mohavense | Not Listed | Species of Concern | | AZ, UT |
| Snails | Virile Amargosa snail | Undescribed sp. | Not Listed | Resolved Taxon | | |
| Mammals | Visayan deer | Cervus alfredi | Listed | Endangered | | |
| Flowering Plants | Viznaga | Ferocactus acanthodes acanthodes | Not Listed | Resolved Taxon | | AZ, CA |
| Insects | Volatile yellow-faced bee | Hylaeus volatilis | Not Listed | Species of Concern | | HI |
| Flowering Plants | Volcanic melicope | Melicope volcanica | Not Listed | Resolved Taxon | | HI |
| Insects | Volcanoes cave cricket | Thaumatogryllus cavicola | Not Listed | Species of Concern | | HI |
| Mammals | Volcano rabbit | Romerolagus diazi | Listed | Endangered | | |
| Flowering Plants | Vollmer's lily | Lilium pardalinum ssp. vollmeri | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Volutine stonemyian tabanid fly | Stonemyia volutina | Not Listed | Resolved Taxon | | CA |
| Fishes | Voodoo Whiff | Citharichthys uhleri | | Not Listed | | |
| Insects | Wabash belted skimmer | Macromia taeniolata | Not Listed | Species of Concern | | IN, OH, TX |
| Clams | Wabash Pigtoe | Fusconaia flava | | Not Listed | | |
| Fishes | Waccamaw darter | Etheostoma perlongum | Not Listed | Resolved Taxon | | NC |
| Clams | Waccamaw fatmucket | Lampsilis fullerkati | Not Listed | Status Undefined | | NC |
| Fishes | Waccamaw killifish | Fundulus waccamensis | Not Listed | Species of Concern | | NC |
| Clams | Waccamaw lance | Elliptio sp. | Not Listed | Species of Concern | | NC |
| Fishes | Waccamaw silverside | Menidia extensa | Listed | Threatened | | NC |
| Clams | Waccamaw spike | Elliptio waccamawensis | Not Listed | Species of Concern | | NC |
| Flowering Plants | Wahaula heiau | Rauvolfia remotiflora | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | wahine noho Kula | Isodendrion pyrifolium | Listed | Endangered | | HI |
| Insects | Wahkeena Falls flightless stonefly | Zapada wahkeena | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Waianae megalagrion damselfly | Megalagrion amaurodytum waianaeanum | Not Listed | Species of Concern | | HI |
| Flowering Plants | Wai`anae tetraplasandra | Tetraplasandra waianensis | Not Listed | Resolved Taxon | | HI |
| Snails | Waianae tree snail | Partulina dubia | Not Listed | Species of Concern | | HI |
| Insects | Wailupe leafroller | Spheterista reynoldsiana | Not Listed | Species of Concern | | HI |
| Birds | Wakulla seaside sparrow | Ammodramus maritimus juncicola | Not Listed | Resolved Taxon | | |
| Flowering Plants | Waldo buckwheat | Eriogonum pendulum | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Waldo daisy | Erigeron bloomeri nudatus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Waldo rock-cress | Arabis aculeolata | Not Listed | Resolved Taxon | | CA, NV, OR |
| Mammals | Walia ibex | Capra walie | Listed | Endangered | | |
| Flowering Plants | Walker's manioc | Manihot walkerae | Listed | Endangered | | TX |
| Insects | Wallace's cave beetle | Pseudanophthalmus wallacei | Not Listed | Species of Concern | | TN |
| Insects | Wallace's deepwater mayfly | Spinadis simplex | Not Listed | Species of Concern | | GA, IN, MS, WI |
| Fishes | Wall Canyon sucker | Catostomus sp. | Petitioned for Listing, Under Review | Under Review | | NV |
| Fishes | Walleye | Sander vitreus | | Not Listed | | |
| Flowering Plants | Wallowa beardtongue | Penstemon spatulatus | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Wallowa primrose | Primula cusickiana | Not Listed | Resolved Taxon | | CA, ID, NV, OR |
| Snails | Walnut Canyon Talussnail | Sonorella coltoniana | Not Listed | Resolved Taxon | | |
| Snails | Walnut elimia | Elimia bellula | Not Listed | Status Undefined | | AL |
| Flowering Plants | Walpole poppy | Papaver walpolei | Not Listed | Resolved Taxon | | AK |
| Mammals | Walrus | Odobenus rosmarus | | Not Listed | | |
| Insects | Wandering oodemas weevil | Oodemas erro | Not Listed | Species of Concern | | HI |
| Insects | Wandering skipper | Panoquina errans | Not Listed | Species of Concern | | CA |
| Birds | Wandering Tattler | Tringa incana | Not Listed | Species of Concern | | |
| Flowering Plants | Ward beardtongue | Penstemon wardii | Not Listed | Species of Concern | | UT |
| Crustaceans | Ward's Amphipod | Stygobromus wardi | Not Listed | Resolved Taxon | | |
| Fishes | Warm Springs pupfish | Cyprinodon nevadensis pectoralis | Listed | Endangered | | NV |
| Insects | Warm Springs Zaitzevian riffle beetle | Zaitzevia posthonia | Not Listed | Resolved Taxon | | MT |
| Flowering Plants | Warner hawthorn | Crataegus warneri | Not Listed | Species of Concern | | TX |
| Flowering Plants | Warner Mountains bedstraw | Galium serpenticum warnerense | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Warner's dodder | Cuscuta warneri | Not Listed | Species of Concern | | AZ, UT |
| Flowering Plants | Warner Springs lessingia | Lessingia glandulifera tomentosa | Not Listed | Species of Concern | | CA |
| Fishes | Warner sucker | Catostomus warnerensis | Listed | Threatened | | CA, NV, OR |
| Fishes | Warner Valley redband trout | Oncorhynchus mykiss ssp. | Not Listed | Species of Concern | | CA, NV, OR |
| Fishes | Warrior bridled darter | Percina sp. | Not Listed | Species of Concern | | AL |
| Fishes | Warrior darter | Etheostoma bellator | Not Listed | Status Undefined | | AL |
| Clams | Warrior pigtoe | Pleurobema rubellum | Not Listed | Status Undefined | | AL |
| Arachnids | Warton cave meshweaver | Cicurina wartoni | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Wart-stemmed ceanothus | Ceanothus verrucosus | Not Listed | Species of Concern | | CA |
| Clams | Wartyback | Cyclonaias nodulata | | Not Listed | | |
| Snails | Warty rocksnail | Lithasia lima | Not Listed | Species of Concern | | AL, TN |
| Flowering Plants | Wasatch Draba | Draba brachystylis | Not Listed | Resolved Taxon | | |
| Mammals | Wasatch pika | Ochotona princeps wasatchensis | Not Listed | Species of Concern | | UT |
| Clams | Washboard | Megalonaias nervosa | | Not Listed | | |
| Snails | Washington duskysnail | Amnicola sp | Not Listed | Resolved Taxon | | |
| Mammals | Washington ground squirrel | Urocitellus washingtoni | Not Listed | Resolved Taxon | | OR, WA |
| Flowering Plants | Washington monkey-flower | Mimulus washingtonensis washingtonensis | Not Listed | Species of Concern | | CA, NV, OR, WA |
| Flowering Plants | Watercelery | Vallisneria americana | | Not Listed | | |
| Fishes | Watercress darter | Etheostoma nuchale | Listed | Endangered | | AL |
| Flowering Plants | Waterfall's sedge | Carex latebracteata | Not Listed | Species of Concern | | AR, OK |
| Flowering Plants | Water howellia | Howellia aquatilis | Delisted | Recovery | | CA, ID, MT, OR, WA |
| Flowering Plants | Waterhyssop | Bacopa procumbens | | Not Listed | | |
| Flowering Plants | Water-loving checkermallow | Sidalcea oregana hydrophila | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Water Stargrass | Heteranthera dubia | | Not Listed | | |
| Flowering Plants | Water stitchwort | Stellaria fontinalis | | Not Listed | | KY, TN |
| Reptiles | Watling Island ground iguana | Cyclura rileyi rileyi | Listed | Endangered | | |
| Flowering Plants | Watson's Falseclapdaisy | Pseudoclappia watsonii | | Not Listed | | |
| Flowering Plants | Wavyleaf wild-quinine | Parthenium integrifolium | Not Listed | Species of Concern | | NC, SC |
| Clams | Wavyrayed Lampmussel | Lampsilis fasciola | | Not Listed | | |
| Ferns and Allies | Wawae`iole | Phlegmariurus mannii | Listed | Endangered | | HI |
| Ferns and Allies | Wawae`iole | Phlegmariurus nutans | Listed | Endangered | | HI |
| Insects | Wawona riffle beetle | Atractelmis wawona | Not Listed | Species of Concern | | CA |
| Snails | Wax Coil | Helicodiscus nummus | Not Listed | Resolved Taxon | | |
| Flowering Plants | Wayside aster | Eucephalus vialis | Not Listed | Species of Concern | | CA, NV, OR |
| Insects | Weak eopenthes click beetle | Eopenthes debilis | Not Listed | Species of Concern | | HI |
| Fishes | Weakfish | Cynoscion regalis | | Not Listed | | |
| Flowering Plants | Weak milk-vetch | Astragalus solitarius | Not Listed | Species of Concern | | CA, NV, OR |
| Flowering Plants | Webber's ivesia | Ivesia webberi | Listed | Threatened | | CA, NV |
| Flowering Plants | Webber's milk-vetch | Astragalus webberi | Not Listed | Species of Concern | | CA |
| Flowering Plants | Weber's catseye | Cryptantha weberi | Not Listed | Resolved Taxon | | CO |
| Flowering Plants | Weber's Whitlow grass | Draba weberi | Not Listed | Resolved Taxon | | |
| Amphibians | Web-footed coqui | Eleutherodactylus karlschmidti | Not Listed | Species of Concern | | PR, VI |
| Fishes | Webug sucker | Chasmistes fecundus | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Wedge-leaved horkelia | Horkelia cuneata sericea | Not Listed | Species of Concern | | CA |
| Flowering Plants | Wedge spurge | Chamaesyce deltoidea serpyllum | Listed | Endangered | | FL |
| Insects | Wedge-winged metromenus ground beetle | Metromenus cuneipennis | Not Listed | Species of Concern | | HI |
| Fishes | Weed Shiner | Notropis texanus | Not Listed | Status Undefined | | |
| Insects | Weist's sphinx moth | Euproserpinus wiesti | Not Listed | Resolved Taxon | | AZ, CO, MT, NM, TX |
| Insects | Wekiu bug | Nysius wekiuicola | Not Listed | Resolved Taxon | | HI |
| Snails | Wekiwa hydrobe | Aphaostracon monas | Not Listed | Status Undefined | | |
| Snails | Wekiwa siltsnail | Cincinnatia wekiwae | Not Listed | Status Undefined | | |
| Insects | Welch's rhyncogonus weevil | Rhyncogonus welchii | Not Listed | Species of Concern | | HI |
| Flowering Plants | Welder machearanthera | Psilactis heterocarpa | Not Listed | Species of Concern | | TX |
| Amphibians | Weller's salamander | Plethodon welleri | Not Listed | Resolved Taxon | | VA |
| Flowering Plants | Well's pixie-moss | Pyxidanthera barbulata brevifolia | Not Listed | Species of Concern | | NC, SC |
| Flowering Plants | Welsh phacelia | Phacelia welshii | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Welsh's cryptantha | Cryptantha welshii | Not Listed | Species of Concern | | NV |
| Flowering Plants | Welsh's milkweed | Asclepias welshii | Listed | Threatened | | AZ, UT |
| Flowering Plants | Wenatchee larkspur | Delphinium viridescens | Not Listed | Resolved Taxon | | WA |
| Flowering Plants | Wenatchee Mountains checkermallow | Sidalcea oregana var. calva | Listed | Endangered | | WA |
| Crustaceans | Wengerors' cave amphipod | Stygobromus wengerorum | Not Listed | Resolved Taxon | | CA |
| Mammals | West African manatee | Trichechus senegalensis | Listed | Threatened | | |
| Birds | West African ostrich | Struthio camelus spatzi | Listed | Endangered | | |
| Reptiles | Western Banded Gecko | Coleonyx variegatus | | Not Listed | | |
| Flowering Plants | Western benitoa | Benitoa occidentalis | Not Listed | Resolved Taxon | | CA |
| Birds | Western bluebird | sialia mexicana | Not Listed | Species of Concern | | |
| Flowering Plants | Western bog aster | Aster paludicola | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Western bog violet | Viola primulifolia occidentalis | Not Listed | Species of Concern | | CA, NV, OR |
| Amphibians | western (boreal) toad | Anaxyrus boreas | Not Listed | Status Undefined | | |
| Birds | Western bristlebird | Dasyornis longirostris (=brachypterus I.) | Listed | Endangered | | |
| Fishes | Western brook lamprey | Lampetra richardsoni | Not Listed | Resolved Taxon | | |
| Insects | Western Bumble bee | Bombus occidentalis | Petitioned for Listing, Under Review | Under Review | | AK, AZ, CA, CO, ID, MT, ND, NE, NM, NV, OR, SD, UT, WA, WY |
| Birds | Western Burrowing Owl | Athene cunicularia hypugaea | Not Listed | Species of Concern | | CO |
| Reptiles | Western Chicken turtle | Deirochelys reticularia ssp. miaria | Petitioned for Listing, Under Review | Under Review | | AR, MO, MS, TX |
| Flowering Plants | Western dichondra | Dichondra occidentalis | Not Listed | Resolved Taxon | | CA |
| Clams | Western fanshell | Cyprogenia aberti | Listed | Threatened | | AR, KS, MO, OK |
| Clams | Western Floater | Anodonta kennerlyi | | Not Listed | | |
| Mammals | Western giant eland | Taurotragus derbianus derbianus | Listed | Endangered | | |
| Insects | Western glacier stonefly | Zapada glacier | Listed | Threatened | | MT, WY |
| Mammals | Western gray kangaroo | Macropus fuliginosus | Delisted | Recovery | | |
| Birds | Western Grebe | aechmophorus occidentalis | Not Listed | Species of Concern | | |
| Mammals | Western grey squirrel | Sciurus griseus | Not Listed | Resolved Taxon | | CA, OR, WA |
| Birds | Western Gull | Larus occidentalis | Not Listed | Species of Concern | | |
| Mammals | Western hare wallaby | Lagorchestes hirsutus | Listed | Endangered | | |
| Flowering Plants | Western Joshua Tree | Yucca brevifolia | | Not Listed | | AZ, CA, NV, UT |
| Flowering Plants | Western lily | Lilium occidentale | Listed | Endangered | | CA, OR |
| Reptiles | Western long-nosed snake | rhinocheilus lecontei ssp. lecontei | Not Listed | Species of Concern | | |
| Birds | Western Meadowlark | Sturnella neglecta | Not Listed | Species of Concern | | |
| Fishes | Western Mosquitofish | Gambusia affinis | | Not Listed | | |
| Mammals | Western mouse | Pseudomys occidentalis | Listed | Endangered | | |
| Clams | Western Pearlshell | Margaritifera falcata | | Not Listed | | |
| Flowering Plants | Western prairie fringed Orchid | Platanthera praeclara | Listed | Threatened | | CO, IA, KS, MN, MO, ND, NE, SD, WY |
| Amphibians | western red-backed salamander | Plethodon vehiculum | Not Listed | Status Undefined | | |
| Amphibians | Western redback salamander | plethodon vehiculum | Not Listed | Species of Concern | | |
| Reptiles | Western red-tailed skink | eumeces gilberti ssp. rubricaudatus | Not Listed | Species of Concern | | |
| Algae | Western red-tailed skink | Plestiodon gilberti rubricaudatus | | Not Listed | | |
| Insects | Western regal fritillary | Argynnis idalia occidentalis | Proposed for Listing | Proposed Threatened | Proposed Listing | AR, CO, IA, IL, IN, KS, MN, MO, MT, ND, NE, OK, SD, WI, WY |
| Clams | western ridged mussel | Gonidea angulata | Petitioned for Listing, Under Review | Under Review | | |
| Birds | Western rufous bristlebird | Dasyornis broadbenti littoralis | Listed | Endangered | | |
| Fishes | Western Sand Darter | Ammocrypta clara | | Not Listed | | |
| Birds | Western Screech Owl | Megascops kennicottii | Not Listed | Status Undefined | | |
| Birds | Western Screech-Owl | Megascops kennicottii cardonensis | Not Listed | Species of Concern | | |
| Birds | Western Screech-Owl | Megascops kennicottii kennicottii | Not Listed | Species of Concern | | |
| Fishes | Western silvery minnow | Hybognathus argyritis | Not Listed | Species of Concern | | IA, IL, KS, MO, MT, ND, NE, SD, WY |
| Birds | Western Snowy Plover | Charadrius nivosus nivosus | Listed | Threatened | | CA, OR, WA |
| Amphibians | Western spadefoot | Spea hammondii | Proposed for Listing | Proposed Threatened | | |
| Amphibians | Western spadefoot | Spea hammondii | | Not Listed | | CA |
| Amphibians | Western spadefoot | Spea hammondii | Proposed for Listing | Proposed Threatened | | CA |
| Mammals | Western Spotted Skunk | Spilogale gracilis | | Not Listed | | |
| Amphibians | Western toad | Bufo boreas | Not Listed | Species of Concern | | |
| Birds | Western tragopan pheasant | Tragopan melanocephalus | Listed | Endangered | | |
| Birds | Western whipbird | Psophodes nigrogularis | Listed | Endangered | | |
| Insects | Westfall's clubtail | Gomphus westfalli | Petitioned for Listing, Under Review | Under Review | | AL, FL |
| Flowering Plants | West Florida cow-lily | Nuphar lutea ssp. ulvacea | Not Listed | Status Undefined | | |
| Mammals | West Indian Manatee | Trichechus manatus | Listed | Threatened | | AL, DE, FL, GA, LA, MD, MS, NC, NJ, PR, SC, TX, VA, VI |
| Flowering Plants | West Indian Walnut (=Nogal) | Juglans jamaicensis | Listed | Endangered | | PR |
| Birds | West Indian Whistling-Duck | Dendrocygna arborea | Not Listed | Species of Concern | | PR, VI |
| Flowering Plants | West's flax | Linum westii | Petitioned for Listing, Under Review | Under Review | | |
| Fishes | Westslope cutthroat trout | Oncorhynchus clarkii lewisi | Not Listed | Resolved Taxon | | CA, ID, MT, NV, OR, WA, WY |
| Insects | West Virginia burrowing mayfly | Ephemera triplex | Not Listed | Species of Concern | | WV |
| Amphibians | West Virginia spring salamander | Gyrinophilus subterraneus | Proposed for Listing | Proposed Endangered | Proposed Listing | WV |
| Insects | West Wills Valley cave beetle | Pseudanophthalmus assimilis | Not Listed | Species of Concern | | AL |
| Snails | Wet Canyon talussnail | Sonorella macrophallus | Not Listed | Status Undefined | | AZ |
| Flowering Plants | Wetherill milk-vetch | Astragalus wetherillii | Not Listed | Resolved Taxon | | CO, UT |
| Mammals | Wet Mountains yellow-bellied marmot | Marmota flaviventris notioros | Not Listed | Resolved Taxon | | CO |
| Snails | Wet-rock physa | Physella zionis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Wharton's dewberry | Rubus whartoniae | Not Listed | Species of Concern | | DE, KY, PA, TN |
| Flowering Plants | Wheeler's peperomia | Peperomia wheeleri | Listed | Endangered | | PR, VI |
| Flowering Plants | Wherry's pitcherplant | Sarracenia alabamensis ssp. wherryi | Petitioned for Listing, Under Review | Under Review | | |
| Flowering Plants | Wherry's Sweet pitcher-plant | Sarracenia rubra ssp. wherryi | Petitioned for Listing, Under Review | Under Review | | |
| Snails | Whetstone Holospira | Holospira whetstonensis | Not Listed | Resolved Taxon | | |
| Snails | Whetstone Talussnail | Sonorella insignis | Not Listed | Resolved Taxon | | |
| Birds | Whimbrel | Numenius phaeopus | Not Listed | Species of Concern | | |
| Birds | Whimbrel | Numenius phaeopus hudsonicus | Not Listed | Species of Concern | | |
| Flowering Plants | Whip `ena`ena | Gnaphalium sandwicensium flagellare | Not Listed | Resolved Taxon | | HI |
| Lichens | Whipple's claopodium moss | claopodium whippleanum | Not Listed | Species of Concern | | |
| Flowering Plants | Whipple's monkey-flower | Mimulus whipplei | Not Listed | Species of Concern | | CA |
| Birds | Whiskered Auklet | Aethia pygmaea | Not Listed | Species of Concern | | |
| Birds | Whiskered Screech-Owl | Megascops trichopsis | Not Listed | Species of Concern | | |
| Amphibians | Whistling Frog | Eleutherodactylus cochranae | Not Listed | Resolved Taxon | | PR, VI |
| Snails | White Abalone | Haliotis sorenseni | Listed | Endangered | | |
| Conifers and Cycads | Whitebark pine | Pinus albicaulis | Listed | Threatened | | CA, ID, MT, NV, OR, WA, WY |
| Fishes | White Bass | Morone chrysops | | Not Listed | | |
| Flowering Plants | White bear desert-poppy | Arctomecon merriamii | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | White birds-in-a-nest | Macbridea alba | Listed | Threatened | | FL |
| Flowering Plants | White bladderpod | Physaria pallida | Listed | Endangered | | TX |
| Flowering Plants | White blanketflower | Gaillardia aestivalis winkleri | Not Listed | Species of Concern | | TX |
| Flowering Plants | White Bluffs bladderpod | Physaria douglasii ssp. tuplashensis | Listed | Threatened | | WA |
| Flowering Plants | White-bracted, New England thoroughwort | Eupatorium leucolepis novae-angliae | Not Listed | Species of Concern | | MA, RI |
| Birds | White-breasted guineafowl | Agelastes meleagrides | Listed | Threatened | | |
| Birds | White-breasted Nuthatch | Sitta carolinensis aculeata | Not Listed | Species of Concern | | |
| Birds | White-breasted thrasher | Ramphocinclus brachyurus | Listed | Endangered | | |
| Birds | White-browed tit-spinetail | Leptasthenura xenothorax | Listed | Endangered | | |
| Fishes | White Catfish | Ameiurus catus | | Not Listed | | |
| Clams | White catspaw (pearlymussel) | Epioblasma perobliqua | Listed | Endangered | | IN, OH |
| Reptiles | White Cay ground iguana | Cyclura rileyi cristata | Listed | Threatened | | |
| Birds | White-cheeked pintail | Anas bahamensis | Not Listed | Status Undefined | | |
| Birds | White cockatoo | Cacatua alba | Listed | Threatened | | |
| Mammals | White-collared mangabey | Cercocebus torquatus | Listed | Endangered | | |
| Birds | White-collared Seedeater | Sporophila torqueola | Not Listed | Species of Concern | | |
| Flowering Plants | White column cory cactus | Escobaria albicolumnaria | Not Listed | Species of Concern | | TX |
| Fishes | White Crappie | Pomoxis annularis | | Not Listed | | |
| Birds | White-crowned Pigeon | Patagioenas leucocephala | Not Listed | Species of Concern | | |
| Snails | White desertsnail | Eremarionta immaculata | Not Listed | Species of Concern | | CA |
| Flowering Plants | Whited milk-vetch | Astragalus sinuatus | Not Listed | Species of Concern | | WA |
| Mammals | White-eared (=buffy tufted-ear) marmoset | Callithrix aurita (=jacchus a.) | Listed | Endangered | | |
| Birds | White eared pheasant | Crossoptilon crossoptilon | Listed | Endangered | | |
| Mammals | White-eared pocket mouse | Perognathus alticola alticola | Not Listed | Species of Concern | | CA |
| Birds | White-faced ibis | Plegadis chihi | Not Listed | Species of Concern | | CO |
| Flowering Plants | White fairypoppy | Meconella oregana | Not Listed | Species of Concern | | WA |
| Flowering Plants | White-felted paintbrush | Castilleja hololeuca | Not Listed | Resolved Taxon | | CA |
| Birds | white-flippered penguin | Eudyptula albosignata | Listed | Threatened | | |
| Flowering Plants | White-flowered Cinquefoil | Potentilla albiflora | Not Listed | Resolved Taxon | | |
| Flowering Plants | Whiteflower tansyaster | Dieteria canescens var. leucanthemifolia | Not Listed | Resolved Taxon | | CA, NV |
| Mammals | White-footed tamarin | Saguinus leucopus | Listed | Threatened | | |
| Mammals | White-footed vole | Arborimus albipes | Not Listed | Species of Concern | | CA, OR |
| Flowering Plants | White fringeless orchid | Platanthera integrilabia | Listed | Threatened | | AL, GA, KY, MS, SC, TN |
| Flowering Plants | White-haired goldenrod | Solidago albopilosa | Delisted | Recovery | | KY |
| Flowering Plants | White-haired leatherflower | Clematis albicoma | Not Listed | Resolved Taxon | | VA, WV |
| Birds | White-headed Woodpecker | Dryobates albolarvatus | Not Listed | Species of Concern | | |
| Birds | White-headed Woodpecker | Dryobates albolarvatus gravirostris | Not Listed | Species of Concern | | |
| Clams | White Heelsplitter | Lasmigona complanata | | Not Listed | | |
| Flowering Plants | White irisette | Sisyrinchium dichotomum | Listed | Endangered | | NC, SC |
| Fishes | Whiteline topminnow | Fundulus albolineatus | Not Listed | Resolved Taxon | | AL |
| Snails | White liptooth | Polygyra peregrina | Not Listed | Species of Concern | | AR |
| Flowering Plants | White-margined penstemon | Penstemon albomarginatus | Petitioned for Listing, Under Review | Under Review | | AZ, CA, NV |
| Flowering Plants | White meadowbeauty | Rhexia parviflora | Petitioned for Listing, Under Review | Under Review | | |
| Insects | White Mountains copper | Lycaena rubicus ssp. | Not Listed | Species of Concern | | CA, NV |
| Mammals | White Mountains ground squirrel | Spermophilus tridecemlineatus monticola | Not Listed | Resolved Taxon | | AZ |
| Insects | White Mountains icarioides blue | Plejebus icarioides ssp. | Not Listed | Species of Concern | | CA, NV |
| Flowering Plants | White Mountains paintbrush | Castilleja sulphurea | Not Listed | Species of Concern | | AZ |
| Insects | White Mountains saepiolus blue | Plejebus saepiolus ssp. | Not Listed | Species of Concern | | CA, NV |
| Insects | White Mountains sandhill skipper | Polites sabuleti albomontana | Not Listed | Species of Concern | | CA, NV |
| Insects | White Mountains skipper | Hesperia mirimae ssp. | Not Listed | Species of Concern | | CA, NV |
| Insects | White Mountains water penny | Psephenus montanus | Not Listed | Species of Concern | | AZ |
| Birds | White-naped Crane | Grus vipio | Listed | Endangered | | |
| Birds | White-necked crow | Corvus leucognaphalus | Listed | Endangered | | |
| Birds | White-necked rockfowl | Picathartes gymnocephalus | Listed | Endangered | | |
| Mammals | White-nosed saki | Chiropotes albinasus | Listed | Endangered | | |
| Fishes | White Perch | Morone americana | | Not Listed | | |
| Flowering Plants | White-rayed pentachaeta | Pentachaeta bellidiflora | Listed | Endangered | | CA |
| Flowering Plants | Whiterim scurf-pea | Pediomelum subacaule | Not Listed | Resolved Taxon | | AL, GA, TN |
| Flowering Plants | White River beardtongue | Penstemon scariosus albifluvis | Not Listed | Resolved Taxon | | CO, UT |
| Fishes | White River desert sucker | Catostomus clarki intermedius | Not Listed | Resolved Taxon | | NV |
| Fishes | White River speckled dace | Rhinichthys osculus ssp. | Not Listed | Resolved Taxon | | NV |
| Fishes | White River spinedace | Lepidomeda albivallis | Listed | Endangered | | NV |
| Fishes | White River springfish | Crenichthys baileyi baileyi | Listed | Endangered | | NV |
| Snails | White River Valley pyrg | Pyrgulopsis sathos | Not Listed | Resolved Taxon | | NV |
| Insects | White River Valley skipper | Hesperia uncas grandiosa | Not Listed | Resolved Taxon | | NV |
| Insects | White River wood nymph | Cercyonis pegala ssp. | Not Listed | Species of Concern | | NV |
| Insects | White sand bear scarab | Lichnanthe albopilosa | Not Listed | Species of Concern | | CA |
| Mammals | White Sands pocket gopher | Geomys arenarius brevirostris | Not Listed | Resolved Taxon | | NM |
| Fishes | White Sands pupfish | Cyprinodon tularosa | Petitioned for Listing, Under Review | Under Review | | NM |
| Mammals | White Sands woodrat | Neotoma micropus leucophaea | Not Listed | Species of Concern | | NM |
| Flowering Plants | White sedge | Carex albida | Listed | Endangered | | CA |
| Fishes | White Shiner | Luxilus albeolus | | Not Listed | | |
| Mammals | White-sided jackrabbit | Lepus callotis | Not Listed | Resolved Taxon | | NM |
| Flowering Plants | White-stemmed evening-star | Mentzelia albicaulis | Not Listed | Status Undefined | | |
| Fishes | White sturgeon | Acipenser transmontanus | Listed | Endangered | | ID, MT |
| Fishes | White sturgeon | Acipenser transmontanus | | Not Listed | | CA |
| Fishes | White Sucker | Catostomus commersonii | | Not Listed | | |
| Mammals | White-Tailed Deer | Odocoileus virginianus | | Not Listed | | |
| Birds | White-tailed Hawk | Buteo albicaudatus | Not Listed | Species of Concern | | |
| Birds | White-tailed Kite | Elanus leucurus | Not Listed | Species of Concern | | |
| Birds | White-tailed laurel Pigeon | Columba junoniae | Listed | Threatened | | |
| Mammals | White-tailed prairie dog | Cynomys leucurus | Not Listed | Resolved Taxon | | |
| Birds | White-tailed ptarmigan | Lagopus leucura | Not Listed | Status Undefined | | |
| Birds | White-tailed ptarmigan | Lagopus leucura | Not Listed | Status Undefined | | |
| Birds | White-tailed ptarmigan | Lagopus leucura | Not Listed | Status Undefined | | |
| Birds | White-tailed Tropicbird | Phaethon lepturus catesbyi | Not Listed | Species of Concern | | |
| Snails | Whitetail Woodlandsnail | Ashmunella lepiderma | Not Listed | Resolved Taxon | | |
| Birds | White-throated Ground Dove | Alopecoenas xanthonurus | Not Listed | Species of Concern | | |
| Clams | White wartyback (pearlymussel) | Plethobasus cicatricosus | Listed | Experimental Population, Non-Essential | | TN |
| Clams | White wartyback (pearlymussel) | Plethobasus cicatricosus | Listed | Endangered | | AL, TN |
| Crustaceans | Whitewater crayfish ostracod | Dactylocythere prinsi | Not Listed | Species of Concern | | NC |
| Snails | Whitewater Creek woodlandsnail | Ashmunella danielsi | Not Listed | Resolved Taxon | | |
| Flowering Plants | White-wicky | Kalmia cuneata | Not Listed | Species of Concern | | NC, SC |
| Birds | White-winged cotinga | Xipholena atropurpurea | Listed | Endangered | | |
| Birds | White-winged guan | Penelope albipennis | Listed | Endangered | | |
| Birds | White-winged Scoter | Melanitta fusca | Not Listed | Species of Concern | | |
| Birds | White-winged wood duck | Cairina scutulata | Listed | Endangered | | |
| Flowering Plants | Whiting's dalea | Psorothamnus thompsoniae var. whitingii | Not Listed | Species of Concern | | AZ, UT |
| Flowering Plants | Whitney sedge | Carex whitneyi | Not Listed | Resolved Taxon | | CA |
| Birds | Whooping crane | Grus americana | Listed | Experimental Population, Non-Essential | | LA, TX |
| Birds | Whooping crane | Grus americana | Listed | Experimental Population, Non-Essential | | |
| Birds | Whooping crane | Grus americana | Listed | Endangered | | KS, LA, MT, ND, NE, OK, SD, TX |
| Birds | Whooping crane | Grus americana | Listed | Experimental Population, Non-Essential | | AL, FL, GA, IA, IL, IN, KY, MI, MN, MS, NC, OH, TN, WI |
| Snails | Whorled mountainsnail | Oreohelix vortex | Not Listed | Species of Concern | | ID |
| Flowering Plants | Whorled Sunflower | Helianthus verticillatus | Listed | Endangered | | AL, GA, MS, TN |
| Snails | Wicker ancylid | Rhodacme filosa | Not Listed | Species of Concern | | AL |
| Flowering Plants | Wide-leaf warea | Warea amplexifolia | Listed | Endangered | | FL |
| Fishes | Widemouth blindcat | Satan eurystomus | Proposed for Listing | Proposed Endangered | | TX |
| Snails | Widemouth Holospira | Holospira mesolia | Not Listed | Resolved Taxon | | |
| Flowering Plants | Widstoe wild-buckwheat | Eriogonum aretioides | Not Listed | Species of Concern | | UT |
| Flowering Plants | Wiggins' cholla | Opuntia wigginsii | Not Listed | Resolved Taxon | | AZ, CA |
| Flowering Plants | Wiggin's croton | Croton wigginsii | Not Listed | Resolved Taxon | | AZ, CA |
| Flowering Plants | Wiggins' lily | Lilium pardalinum ssp. wigginsii | Not Listed | Resolved Taxon | | CA, NV, OR |
| Insects | Wilbur Springs minute moss beetle | Ochthebius reticulus | Not Listed | Species of Concern | | CA |
| Insects | Wilbur Springs shore bug | Saldula usingeri | Not Listed | Resolved Taxon | | CA |
| Insects | Wilbur Springs shore fly | Paracoenia calida | Not Listed | Species of Concern | | CA |
| Flowering Plants | Wild, Hill Country mercury | Argythamnia aphoroides | Not Listed | Species of Concern | | TX |
| Flowering Plants | Wild Rose Canyon buckwheat | Eriogonum eremicola | Not Listed | Species of Concern | | CA |
| Flowering Plants | Wild, silvery mercury | Argythamnia argyraea | Not Listed | Resolved Taxon | | TX |
| Flowering Plants | Wild spiderflower | Tarenaya spinosa | Not Listed | Resolved Taxon | | HI |
| Mammals | Wild yak | Bos mutus (=grunniens m.) | Listed | Endangered | | |
| Flowering Plants | Wilkin's harebell | Campanula wilkinsiana | Not Listed | Species of Concern | | CA |
| Flowering Plants | Wilkinson's whitlow-wort | Paronychia wilkinsonii | Not Listed | Species of Concern | | TX |
| Flowering Plants | Willamette daisy | Erigeron decumbens | Listed | Endangered | | OR |
| Insects | Willamette silverspot | Speyeria callippe extincta | Not Listed | Resolved Taxon | | CA, NV, OR |
| Flowering Plants | Willamette Valley larkspur | Delphinium nuttallii ssp. nuttallii | Not Listed | Species of Concern | | |
| Birds | Willet | Tringa semipalmata | Not Listed | Species of Concern | | |
| Snails | Williams' bronze shoulderband | Helminthoglypta arrosa williamsi | Not Listed | Species of Concern | | CA |
| Birds | Williamson's Sapsucker | Sphyrapicus thyroideus | Not Listed | Species of Concern | | |
| Birds | Williamson's Sapsucker | Sphyrapicus thyroideus nataliae | Not Listed | Species of Concern | | |
| Birds | Willow Flycatcher | Empidonax traillii | Not Listed | Species of Concern | | |
| Flowering Plants | Willow-leaved bidens | Bidens salicoides | Not Listed | Resolved Taxon | | HI |
| Flowering Plants | Willowy monardella | Monardella viminea | Listed | Endangered | | CA |
| Birds | Wilson's phalarope | Phalaropus tricolor | Not Listed | Status Undefined | | AK, AZ, CA, CO, ID, IL, IN, KS, MA, MN, MT, ND, NE, NM, NV, OH, OK, OR, SD, TX, UT, WY |
| Birds | Wilson's Plover | Charadrius wilsonia | Not Listed | Species of Concern | | |
| Birds | Wilson's Storm-Petrel | Oceanites oceanicus | Not Listed | Species of Concern | | |
| Birds | Wilson's warbler | wilsonia pusilla | Not Listed | Species of Concern | | |
| Insects | Wind's elfin butterfly | Incisalia mossi doudoroffi | Not Listed | Resolved Taxon | | CA |
| Clams | Winged Floater | Anodonta nuttalliana | | Not Listed | | |
| Clams | Winged Mapleleaf | Quadrula fragosa | Listed | Endangered | | AR, MN, MO, OK, TN, WI |
| Clams | Winged Mapleleaf | Quadrula fragosa | Listed | Experimental Population, Non-Essential | | AL |
| Clams | Winged spike | Elliptio nigella | Not Listed | Species of Concern | | AL, GA |
| Flowering Plants | winged water-starwort | Callitriche marginata | Not Listed | Species of Concern | | |
| Insects | Wing-shoulder minute moss beetle | Ochthebius crassalus | Not Listed | Species of Concern | | CA |
| Snails | Wing Snaggletooth | Gastrocopta procera | | Not Listed | | |
| Crustaceans | Wingtail crayfish | Procambarus latipleurum | Not Listed | Resolved Taxon | | |
| Flowering Plants | Winkler cactus | Pediocactus winkleri | Listed | Threatened | | UT |
| Fishes | Winter Flounder | Pseudopleuronectes americanus | | Not Listed | | |
| Ferns and Allies | Winter quillwort | Isoetes hyemalis | Not Listed | Status Undefined | | GA |
| Snails | Wintu sideband | Monadenia troglodytes ssp. wintu | Petitioned for Listing, Under Review | Under Review | | CA |
| Flowering Plants | Wiregrass gentian | Gentiana pennelliana | Not Listed | Species of Concern | | |
| Flowering Plants | Wireleaf dropseed | Sporobolus teretifolius | Petitioned for Listing, Under Review | Under Review | | GA, NC, SC |
| Flowering Plants | Wireweed | Polygonella basiramia | Listed | Endangered | | FL |
| Mammals | Wisconsin puma | Felis concolor schorgeri | Not Listed | Species of Concern | | IA, IL, KS, MN, MO, WI |
| Crustaceans | Wisconsin well amphipod | Stygobromus putealis | Not Listed | Species of Concern | | WI |
| Flowering Plants | Withered wooly milk-vetch | Astragalus mollissimus marcidus | Not Listed | Species of Concern | | TX |
| Flowering Plants | Wolf's evening-primrose | Oenothera wolfii | Not Listed | Species of Concern | | CA, NV, OR |
| Mammals | Wolverine | Gulo gulo | | Not Listed | | |
| Insects | wonder caddisfly | Neothremma prolata | | Not Listed | | OR |
| Flowering Plants | Wonderland Alice-flower | Aliciella caespitosa | Not Listed | Resolved Taxon | | UT |
| Snails | Wongs springsnail | Pyrgulopsis wongi | Not Listed | Species of Concern | | CA |
| Mammals | Wood Bison | Bison bison athabascae | Listed | Experimental Population, Non-Essential | | WY |
| Mammals | Wood Bison | Bison bison athabascae | Listed | Threatened | | AK |
| Birds | wood duck | Aix sponsa | Not Listed | Status Undefined | | |
| Amphibians | Wood Frog | Lithobates sylvaticus | Not Listed | Status Undefined | | |
| Birds | Woodhouse's Scrub-Jay | Aphelocoma woodhouseii | Not Listed | Species of Concern | | |
| Birds | Woodhouse's Scrub-Jay | Aphelocoma woodhouseii woodhouseii | Not Listed | Species of Concern | | |
| Flowering Plants | Woodland peperomia | Peperomia membranacea | Not Listed | Resolved Taxon | | HI |
| Mammals | Woodland vole | Microtus pinetorum | Not Listed | Status Undefined | | |
| Flowering Plants | woodland woollythreads | Monolopia gracilens | | Not Listed | | |
| Flowering Plants | Wood reedgrass | Calamagrostis perplexa | Not Listed | Species of Concern | | NY |
| Fishes | Wood River sculpin | Cottus leiopomus | Not Listed | Species of Concern | | ID |
| Insects | Woodruff's ataenius dung beetle | Ataenius woodruffi | Not Listed | Species of Concern | | |
| Birds | Wood stork | Mycteria americana | Listed | Threatened | Proposed Delisting | FL, GA, NC, SC |
| Birds | Wood Thrush | Hylocichla mustelina | Not Listed | Species of Concern | | |
| Reptiles | Wood turtle | Glyptemys insculpta | Petitioned for Listing, Under Review | Under Review | | CT, DC, DE, IA, MA, MD, ME, MI, MN, NH, NJ, NY, OH, PA, VA, VT, WI, WV |
| Crustaceans | Woodville Karst Cave crayfish | Procambarus orcinus | Not Listed | Resolved Taxon | | |
| Flowering Plants | woolly rosette grass | Dichanthelium scabriusculum | Not Listed | Resolved Taxon | | DC, NY, RI, VA |
| Flowering Plants | Woolly seablite | suaeda taxifolia | Not Listed | Species of Concern | | |
| Mammals | Woolly spider monkey | Brachyteles arachnoides | Listed | Endangered | | |
| Flowering Plants | Wooly berry | Vaccinium hirsutum | Not Listed | Species of Concern | | NC |
| Insects | Wooly Gulf dune scarab | Polylamina pubescens | Not Listed | Species of Concern | | |
| Insects | Wooly hydroporus diving beetle | Hydroporus hirsutus | Not Listed | Species of Concern | | CA |
| Birds | Worm eating Warbler | Helmitheros vermivorum | Not Listed | Species of Concern | | |
| Crustaceans | Worn Stygobromid | Stygobromus tritus | Not Listed | Resolved Taxon | | |
| Birds | Worthington's Marsh Wren | Cistothorus palustris griseus | Not Listed | Species of Concern | | |
| Lichens | Worthy Shield Lichen | Canoparmelia amabilis | Not Listed | Species of Concern | | |
| Fishes | wounded darter | Etheostoma vulneratum | Not Listed | Species of Concern | | NC |
| Fishes | Woundfin | Plagopterus argentissimus | Listed | Endangered | | AZ, NV, UT |
| Fishes | Woundfin | Plagopterus argentissimus | Listed | Experimental Population, Non-Essential | | AZ |
| Snails | Wreathed cactus snail | Xerarionta redimita | Not Listed | Resolved Taxon | | CA |
| Birds | Wrentit | Chamaea fasciata | Not Listed | Species of Concern | | |
| Flowering Plants | Wright fishhook cactus | Sclerocactus wrightiae | Listed | Endangered | | UT |
| Flowering Plants | Wright's Dogweed | Adenophyllum wrightii | Not Listed | Resolved Taxon | | |
| Flowering Plants | Wright's marsh thistle | Cirsium wrightii | Listed | Threatened | | AZ, NM |
| Flowering Plants | Wright's spiderwort | Tradescantia wrightii | Not Listed | Resolved Taxon | | NM, TX |
| Flowering Plants | Wright's trichocoronis | trichocoronis wrightii | Not Listed | Species of Concern | | |
| Flowering Plants | Wright's water-willow | Justicia wrightii | Not Listed | Species of Concern | | NM, TX |
| Flowering Plants | Wright's yellowshow | Amoreuxia wrightii | Not Listed | Resolved Taxon | | TX |
| Mammals | Wupatki Arizona pocket mouse | Perognathus amplus cineris | Not Listed | Species of Concern | | AZ |
| Flowering Plants | Wyoming Dodder | Cuscuta plattensis | Not Listed | Resolved Taxon | | |
| Mammals | Wyoming pocket gopher | Thomomys clusius | Not Listed | Resolved Taxon | | WY |
| Amphibians | Wyoming Toad | Anaxyrus baxteri | Listed | Endangered | | WY |
| Insects | Xerces blue | Glaucopsyche xerces | Not Listed | Resolved Taxon | | CA |
| Fishes | XL Spring tui chub | Gila bicolor oregonensis | Not Listed | Species of Concern | | CA, NV, OR |
| Reptiles | Yacare Caiman | Caiman yacare | Listed | Threatened | | |
| Flowering Plants | Yadkin River Goldenrod | Solidago plumosa | | Not Listed | | NC |
| Flowering Plants | Yadon's piperia | Piperia yadonii | Listed | Endangered | | CA |
| Crustaceans | Yalobusha Riverlet crayfish | Hobbseus yalobushensis | Petitioned for Listing, Under Review | Under Review | | MS |
| Flowering Plants | Yamaguchi phyllostegia | Phyllostegia yamaguchii | Not Listed | Resolved Taxon | | HI |
| Crustaceans | Yancey sideswimmer | Stygobromus carolinensis | Not Listed | Species of Concern | | NC |
| Fishes | Yangtze Sturgeon | Acipenser dabryanus | Listed | Endangered | | |
| Fishes | Yaqui catfish | Ictalurus pricei | Listed | Threatened | | AZ, NM |
| Fishes | Yaqui chub | Gila purpurea | Listed | Endangered | | AZ |
| Fishes | Yaqui sucker | catostomus bernardini | Not Listed | Species of Concern | | |
| Mammals | Yarkand deer | Cervus elaphus yarkandensis | Listed | Endangered | | |
| Snails | Yates' tight coin | Ammonitella yatesii | Not Listed | Species of Concern | | CA |
| Mammals | Yavapai Arizona cotton rat | Sigmodon arizonae jacksoni | Not Listed | Species of Concern | | AZ |
| Mammals | Yavapai Arizona pocket mouse | Perognathus amplus amplus | Not Listed | Species of Concern | | AZ |
| Snails | Yavapai mountainsnail | Oreohelix yavapai | Not Listed | Species of Concern | | AZ, UT |
| Crustaceans | Yazoo crayfish | Orconectes hartfieldi | Not Listed | Resolved Taxon | | MS |
| Fishes | Yazoo darter | Etheostoma raneyi | Not Listed | Resolved Taxon | | MS |
| Fishes | Yazoo Shiner | Notropis rafinesquei | | Not Listed | | |
| Flowering Plants | Yellow anisetree | Illicium parviflorum | Not Listed | Resolved Taxon | | GA |
| Insects | Yellow-banded andrenid bee | Perdita hirticeps luteocincta | Not Listed | Species of Concern | | CA |
| Insects | Yellow banded bumble bee | Bombus terricola | Not Listed | Resolved Taxon | | CT, IL, KY, MA, MD, ME, MI, MN, MT, NC, ND, NH, NY, OH, PA, RI, SD, TN, VA, VT, WI, WV |
| Birds | Yellow-bellied sapsucker | sphyrapicus varius | Not Listed | Species of Concern | | |
| Birds | Yellow-billed Cuckoo | Coccyzus americanus | Listed | Threatened | | AZ, CA, CO, ID, MT, NM, NV, OR, TX, UT, WA, WY |
| Birds | Yellow-billed Loon | Gavia adamsii | Not Listed | Resolved Taxon | | AK |
| Birds | Yellow-billed Magpie | Pica nuttalli | Not Listed | Species of Concern | | |
| Birds | Yellow-billed parrot | Amazona collaria | Listed | Threatened | | |
| Flowering Plants | Yellow blanketflower | Gaillardia flava | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Yellow bleedingheart | Dicentra ochroleuca | Not Listed | Resolved Taxon | | CA |
| Clams | Yellow blossom (pearlymussel) | Epioblasma florentina florentina | Delisted | Extinction | | TN |
| Clams | Yellow blossom (pearlymussel) | Epioblasma florentina florentina | Not Listed | Resolved Taxon | | AL |
| Amphibians | Yellow-blotched ensatina | Ensatina eschscholtzii croceator | Not Listed | Species of Concern | | CA |
| Reptiles | Yellow-blotched map turtle | Graptemys flavimaculata | Listed | Threatened | | MS |
| Insects | Yellow brachycercus mayfly | Brachycercus flavus | Not Listed | Species of Concern | | LA |
| Birds | Yellow-breasted chat | icteria virens | Not Listed | Species of Concern | | |
| Birds | Yellow-breasted Chat | Icteria virens virens | Not Listed | Species of Concern | | |
| Birds | Yellow-breasted Crake | Hapalocrex flaviventer hendersoni | Not Listed | Species of Concern | | |
| Birds | Yellow-browed toucanet | Aulacorhynchus huallagae | Candidate for Listing | Candidate | | |
| Fishes | Yellow Bullhead | Ameiurus natalis | | Not Listed | | |
| Flowering Plants | Yellow-bur navarretia | Navarretia prolifera lutea | Not Listed | Resolved Taxon | | CA |
| Conifers and Cycads | Yellow cedar | Callitropsis nootkatensis | | Not Listed | | AK, CA, NV, OR, WA |
| Fishes | Yellowcheek Darter | Etheostoma moorei | Listed | Endangered | | AR |
| Flowering Plants | Yellow coneflower | Rudbeckia nitida nitida | Not Listed | Species of Concern | | |
| Birds | Yellow-crested cockatoo | Cacatua sulphurea | Listed | Endangered | | |
| Birds | yellow-eyed penguin | Megadyptes antipodes | Listed | Threatened | | |
| Fishes | yelloweye rockfish | Sebastes ruberrimus | Listed | Threatened | | |
| Fishes | Yellowfin cutthroat trout | Oncorhynchus clarkii macdonaldi | Not Listed | Resolved Taxon | | CO |
| Fishes | Yellowfin madtom | Noturus flavipinnis | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Yellowfin madtom | Noturus flavipinnis | Listed | Experimental Population, Non-Essential | | VA |
| Fishes | Yellowfin madtom | Noturus flavipinnis | Listed | Experimental Population, Non-Essential | | TN |
| Fishes | Yellowfin madtom | Noturus flavipinnis | Listed | Threatened | | TN, VA |
| Birds | Yellow-footed Gull | Larus livens | Not Listed | Species of Concern | | |
| Mammals | Yellow-footed rock wallaby | Petrogale xanthopus | Listed | Endangered | | |
| Insects | Yellow-foot yellow-faced bee | Hylaeus flavipes | Not Listed | Species of Concern | | HI |
| Birds | Yellow-headed Blackbird | Xanthocephalus xanthocephalus | Not Listed | Species of Concern | | |
| Clams | Yellow lampmussel | Lampsilis cariosa | Not Listed | Species of Concern | | NC |
| Clams | Yellow lance | Elliptio lanceolata | Listed | Threatened | | DC, MD, NC, VA |
| Flowering Plants | Yellow larkspur | Delphinium luteum | Listed | Endangered | | CA |
| Reptiles | Yellow monitor | Varanus flavescens | Listed | Endangered | | |
| Reptiles | Yellow mud turtle | Kinosternon flavescens flavescens | Not Listed | Species of Concern | | IA, IL, MO, NE |
| Reptiles | Yellow Mud Turtle | Kinosternon flavescens | | Not Listed | | |
| Mammals | Yellow-nosed cotton rat | Sigmodon ochrognathus | Not Listed | Species of Concern | | AZ, NM, TX |
| Fishes | Yellow Perch | Perca flavescens | | Not Listed | | |
| Flowering Plants | Yellow Pond lily | Nuphar lutea ssp. sagittifolia | Not Listed | Status Undefined | | NC, SC, VA |
| Birds | Yellow Rail | Coturnicops noveboracensis | Not Listed | Species of Concern | | |
| Clams | Yellow Sandshell | Lampsilis teres | | Not Listed | | |
| Crustaceans | Yellow Shore Crab | Hemigrapsus oregonensis | Not Listed | Resolved Taxon | | |
| Birds | Yellow-shouldered blackbird | Agelaius xanthomus | Listed | Endangered | | PR |
| Insects | Yellow-sided clubtail | Stylurus potulentus | Petitioned for Listing, Under Review | Under Review | | FL |
| Amphibians | Yellow-spotted woodland salamander | Plethodon pauleyi | Petitioned for Listing, Under Review | Under Review | | KY, TN, VA, WV |
| Fishes | Yellowstone cutthroat trout | Oncorhynchus clarkii bouvieri | Not Listed | Resolved Taxon | | |
| Flowering Plants | Yellowstone Sand Verbena | Abronia ammophila | Not Listed | Resolved Taxon | | |
| Mammals | Yellow-tailed woolly monkey | Lagothrix flavicauda | Listed | Endangered | | |
| Flowering Plants | Yellow-tubered toothwort | Cardamine nuttallii | Not Listed | Species of Concern | | CA, NV, OR |
| Birds | Yellow warbler | dendroica petechia ssp. brewsteri | Not Listed | Species of Concern | | |
| Birds | Yellow Warbler | Dendroica petechia gundlachi | Not Listed | Species of Concern | | |
| Flowering Plants | Yellow-white catseye | Cryptantha ochroleuca | Not Listed | Resolved Taxon | | UT |
| Mammals | Yelm pocket gopher | Thomomys mazama yelmensis | Listed | Threatened | | WA |
| Flowering Plants | Yerba de zanja | Ruppia anomala | Not Listed | Resolved Taxon | | PR, VI |
| Fishes | Yoknapatawpha Darter | Etheostoma faulkneri | | Not Listed | | |
| Insects | Yontocket saytr | Coenonympha tullia yontockett | Not Listed | Resolved Taxon | | CA |
| Insects | Yorba Linda trigonoscuta weevil | Trigonoscuta yorbalindae | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Yosemite bitterroot | Lewisia disepala | Not Listed | Resolved Taxon | | CA |
| Snails | Yosemite mariposa sideband | Monadenia hillebrandi yosemitensis | Not Listed | Species of Concern | | CA |
| Flowering Plants | Yosemite onion | Allium yosemitense | Not Listed | Resolved Taxon | | CA |
| Amphibians | Yosemite toad | Anaxyrus canorus | Listed | Threatened | | CA |
| Flowering Plants | Yosemite wooly-sunflower | Eriophyllum nubigenum | Not Listed | Species of Concern | | CA |
| Flowering Plants | Young's snowbell | Styrax platanifolius ssp. youngiae | Not Listed | Species of Concern | | TX |
| Flowering Plants | Yreka phlox | Phlox hirsuta | Listed | Endangered | | CA |
| Flowering Plants | Yucaipa onion | allium haematochiton | Not Listed | Species of Concern | | |
| Flowering Plants | Yukon aster | Symphyotrichum yukonense | Not Listed | Species of Concern | | AK |
| Clams | Yukon Floater Mussel | Anodonta beringiana | | Not Listed | | |
| Birds | Yuma brown towhee | Pipilo fuscus relictus | Not Listed | Resolved Taxon | | AZ |
| Mammals | Yuma hispid cotton rat | Sigmodon hispidus eremicus | Not Listed | Species of Concern | | AZ, CA |
| Mammals | Yuma myotis | Myotis yumanensis | Not Listed | Species of Concern | | CO |
| Reptiles | Yuman desert fringe-toed lizard | Uma rufopunctata | Petitioned for Listing, Under Review | Under Review | | AZ |
| Mammals | Yuma puma | Felis concolor browni | Not Listed | Species of Concern | | AZ, CA |
| Birds | Yuma Ridgway's rail | Rallus obsoletus yumanensis | Listed | Endangered | | AZ, CA, NV |
| Birds | Yuma rufous-crowned sparrow | Aimophila ruficeps rupicola | Not Listed | Resolved Taxon | | AZ |
| Birds | Yunaska rock ptarmigan | Lagopus muta yunaskensis | Not Listed | Species of Concern | | AK |
| Mammals | Yunnan snub-nosed monkey | Rhinopithecus bieti | Listed | Endangered | | |
| Mammals | Zanzibar red colobus monkey | Procolobus (=Colobus) pennantii (=kirki) kirki | Listed | Endangered | | |
| Mammals | Zanzibar suni | Neotragus moschatus moschatus | Listed | Endangered | | |
| Flowering Plants | Zapata bladderpod | Physaria thamnophila | Listed | Endangered | | TX |
| Flowering Plants | Zarzarilla | Mimosa quadrivalvis var. urbaniana | Not Listed | Species of Concern | | PR, VI |
| Insects | Zayante band-winged grasshopper | Trimerotropis infantilis | Listed | Endangered | | CA |
| Flowering Plants | Ziegler's aster | Machaeranthera canescens ziegleri | Not Listed | Resolved Taxon | | CA |
| Flowering Plants | Ziegler's layia | Layia platyglossa | Not Listed | Species of Concern | | CA |
| Insects | Zigzag blackwater caddisfly | Agarodes ziczac | Not Listed | Species of Concern | | |
| Flowering Plants | Zion, coccineum wild-buckwheat | Eriogonum zionis coccineum | Not Listed | Resolved Taxon | | AZ |
| Flowering Plants | Zion tansy | Sphaeromeria ruthiae | Not Listed | Species of Concern | | UT |
| Flowering Plants | Zion whitlow-grass | Draba asprella zionensis | Not Listed | Resolved Taxon | | UT |
| Flowering Plants | Zion, zionis wild-buckwheat | Eriogonum zionis zionis | Not Listed | Resolved Taxon | | AZ, UT |
| Fishes | Zuni bluehead Sucker | Catostomus discobolus yarrowi | Listed | Endangered | | AZ, NM |
| Flowering Plants | Zuni fleabane | Erigeron rhizomatus | Listed | Threatened | | AZ, NM |