Mariana eight-spot butterfly (Hypolimnas octocula marianensis)
Taxonomy:
View taxonomy in ITISListing Status: Endangered
Where Listed: WHEREVER FOUND
General Information
The Mariana eight-spot butterfly (Hypolimnas octocula marianensis)(abbabang, libweibwogh), a butterfly in the Nymphalidae family, is known solely from the islands of Guam and Saipan, in the forest ecosystem. Like most nymphalid butterflies, orange and black are the two primary colors exhibited by this subspecies. The males are smaller than the females by at least a third or more in size. Males are predominantly black with an orange stripe running vertically on each wing. The stripe on the hindwings exhibits small black dots in a vertical row. Overall, the females appear more orange in color than the males, and black bands across the apical (top) margins of both pair of wings are exhibited. Along the inner margin of these black bands, large white spots are exhibited across the entire length of the wings (Schreiner and Nafus 1997, pp. 15, 2627). The caterpillar larva of this species is black in color with red spikes and a black head, differentiating it from similar- appearing caterpillars including Hypolimnas bolina and H. anomala (Schreiner and Nafus 1996, p. 10; Schreiner and Nafus 1997, p. 26). The larvae of this butterfly feed on two native plants, Procris pedunculata (no common name) and Elatostema calcareum (tapun ayuyu) (Schreiner and Nafus, 1996, p. 1). Both of these forest herbs (family Urticaceae) are found only on karst substrate within the forest ecosystem, draped over boulders and small cliffs (Schreiner and Nafus 1996, p. 1; Rubinoff 2013, in litt.).The species historical range included Guam, Northern Mariana Islands. See below for information about where the species is known or believed to occur.
» Range Information
Current Range
Current range maps are only shown within the jurisdictional boundaries of the United States of America. The species may also occur outside this region.
Wherever found
Listing status: Endangered
- States/US Territories in which this population is known to or is believed to occur: Guam, Northern Mariana Islands
- US Counties in which this population is known to or is believed to occur: View All
- USFWS Refuges in which this population is known to occur:
» Candidate Information
No Candidate information available for this species.
No Candidate Assessments available for this species.
No Uplisting Documents currently available for this species.
» Federal Register Documents
» Species Status Assessments (SSAs)
No Species Status Assessments (SSA's) are currently available for this species.
No Special Rule Publications currently available for this species.
» Recovery
- Species with Recovery Documents Data Explorer
- Recovery Priority Number: 6
No Delisting Documents currently available for this species.
» Critical Habitat
No Critical Habitat Documents currently available for this species.
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» Life History
Habitat Requirements
The majority of limestone forest habitat and known host plant populations of the butterfly occur in northern Guam on undeveloped, rugged karst terrain or the cliff-edges of limestone plateaus (Taborosi 2013, pp. 1416; Demeulenaere et al. 2018, p. 9). The larvae of this butterfly feed on two native plants, Procris pedunculata (no common name) and Elatostema calcareum (tapun ayuyu)(Schreiner and Nafus, 1996, p. 1). Both of these forest herbs (family Urticaceae) are found only on karst substrate within the forest ecosystem, draped over boulders and small cliffs (Schreiner and Nafus 1996, p. 1; Rubinoff 2013, in litt.). Based upon consistent observations of the species over time at a few survey sites containing larger aggregations of host plants, researchers have identified either the presence of pinnacle karst terrain or a relative absence of feral ungulates as a population need of the Mariana eight-spot butterfly (Rubinoff and Holland 2018, p. 224; and Demeulenaere et al. 2018, p. 21).
Food Habits
Adults use a long proboscis to feed on a variety of ephemeral food sources including primarily nectar of day blooming flowers, as well as rotting fruit, and occasionally dead animals The larvae of this butterfly feed on two native plants, Procris pedunculata (no common name) and Elatostema calcareum (tapun ayuyu) (Schreiner and Nafus, 1996, p. 1). Both of these forest herbs (family Urticaceae) are found only on karst substrate within the forest ecosystem, draped over boulders and small cliffs (Schreiner and Nafus 1996, p. 1; Rubinoff 2013, in litt.).
Movement / Home Range
The abbabang (libweibwogh, Mariana eight-spot butterfly, Hypolimnas octocula marianensis), a butterfly in the Nymphalidae family, is known solely from the islands of Guam and Saipan, in the forest ecosystem (Schreiner and Nafus 1996, p. 2; Schreiner and Nafus 1997, p. 26). It may be extirpated from Saipan (Schreiner and Nafus 1997, p. 26). In total, the Mariana eight-spot butterfly is recorded from approximately 14 locations on Guam. However, researchers estimate the species only consistently occurs at between 6 to 10 known locations that contain larger aggregations of the two host plant species.
Reproductive Strategy
The majority of life history and biological information available regarding the Mariana eight-spot butterfly comes from an unpublished report of rare butterfly surveys by Schreiner and Nafus (1996, entire), conducted in the early to mid-1990s in the Mariana Islands. As part of the endeavor, Schreiner and Nafus (1996, entire) also conducted a yearlong study of a population of the Mariana eight-spot butterfly located near the University of Guam. According to their surveys, Mariana eight-spot butterflies were most abundant between December and February. These months include the end of the wet season and the beginning of the dry season on Guam and correspond to expected growth of the host plant species. Conversely, population levels were very low in July and August, the beginning of the wet season. Adults use a long proboscis to feed on a variety of ephemeral food sources including primarily nectar of day blooming flowers, as well as rotting fruit, and occasionally dead animals. The number of eggs, larvae, and adult butterflies recorded at clusters of the hostplants varies according to the literature. However, consistently across the literature, researchers generally observe adult butterflies in proximity to its larval stage host plant species (Rubinoff and Kawahara 2011, in litt., p. 2; Rubinoff 2013, in litt., p. 1; Demeulenaere et al. 2018). Similarly, Schreiner and Nafus (1996, entire) noted an association in occurrence of the adult butterflies with the presence of host plants and with host plants occupied by the egg and caterpillar stages. While the length of time spent as a pupa and the adult butterflys longevity remain unknown (Moore 2013, p. 7), Schreiner and Nafus (1996, pp. 34), recorded developmental times for both the eggs and caterpillars they examined during their yearlong study of a population near the University of Guam in the mid-1990s. Caterpillars hatched after approximately 6 days and then required approximately 20 days to complete their development through 6 instars (an increment of the larval stage between molts) before pupating. Schreiner and Nafus (1996, p. 3) also noted that the number of pupae found within a given patch of host plants did not correspond to the prior number of large and conspicuous late-instar caterpillars within that same patch of host plants. They suggested that many of the caterpillars likely sought out a different and hidden location to begin the pupal stage (as opposed to predators consuming them). The larvae of this butterfly feed on two native plants, Procris pedunculata (no common name) and Elatostema calcareum (tapun ayuyu) (Schreiner and Nafus, 1996, p. 1). Like all butterfly species, the caterpillar life stage requires a sufficient amount of host plant material to feed upon to complete its development to the adult stage. During their study, Schreiner and Nafus (1996, pp. 34) noted that caterpillars would typically begin feeding on the same plant upon which they hatched and then migrate to a second, larger host plant after the fourth instar. However, no estimate was provided regarding the actual amount of plant consumed. As noted above, the Mariana eight-spot butterfly may also require a safe place to pupate (like most Lepidoptera), but the parameters for this requirement remain unknown. After the caterpillars successful pupation and metamorphosis into a butterfly, the individual requires abundant adult food resources including flower nectar and possibly rotting fruit and animals.
Other
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