The New Mexico Rare Arthropod Resource

Bicellonycha wickershamorum is found in montane desert habitats of the Madrean Sky Islands and the Arizona and New Mexico Mountains Ecoregions, at elevations ranging from 4,000-6,000 ft. (Cicero 1982, C. Mollohan pers. comm. 2020). This species typically occurs in marshy areas and other perennial wetland habitats along permanent streams and rivers (Cicero 1982, C. Mollohan pers. comm. 2020, A. Walker pers. obs.). Adults of both sexes are winged and capable of flight, as are all known species of its subfamily, Photurinae. The breeding season for the nominate subspecies lasts from early June to late July, typically before the monsoon season starts (J. Cicero pers. comm.). The Gila southwest spring firefly has been observed from late May through August, but the phenology of this subspecies is not well understood. Adults are not known to feed. Larvae have been observed preying on snails at night and are typically found in riparian areas next to gentle streams (J. Cicero pers. comm. 2020). Late-instar larvae pupate in soil chambers they have constructed.

The courtship flash pattern is a single, quick (about 0.14 seconds), greenish flash, emitted at intervals of about 0.8 seconds (Martin et al. 2023). Flashing displays begin at dusk and continue into the night, for up to two hours. Adults can often be found crawling up tall vegetation, in suitable habitats, before sunset (A. Walker pers. obs.). Adult males typically fly and flash along streams. At dusk males fly close to vegetation and often find females that have not produced response flashes. As the night goes on, males fly higher in the air and can only find females by their response flashes (J. Cicero pers. comm. 2020). Adults can sometimes be observed flying and flashing well away from streams (C. Mollohan pers. comm. 2020).

Bicellonycha wickershamorum is found in Arizona, New Mexico, and Sonora, Mexico. The nominate subspecies, B. w. wickershamorum Cicero, 1982 (Southwest Spring Firefly) is endemic to the Madrean Sky Island mountain ranges of southern Arizona and northern Sonora. In the US, it has been reported from the Huachuca and Galliuro Mountains (Cicero 1982), where populations have been observed in Bear Canyon, Scotia Canyon, the Canelo Hills, the Mule Shoe, and Empire Gulch, as well as sites near Sonoita (Cicero 1982, Walker 2024). In Sonora, it has been recorded only at Canjón Bonito (J. Cicero pers. comm. 2023). Prior to 2023, the other described subspecies, B. w. piceum Cicero, 1982 (Gila Southwest Spring Firefly), was known only from the type locality, near Morenci, Arizona. However, expanded survey efforts have documented it in Arizona’s Verde Valley and in the Gila Wilderness of New Mexico (Walker 2024).

Bicellonycha wickershamorum was assessed as Vulnerable on the IUCN Red List (Fallon and Cicero 2021a) and is one of five firefly species in the United States to be petitioned for protections under the Endangered Species Act (Fallon et al. 2023). In January of 2024, it received a positive 90 day finding, which means the US Fish and Wildlife Service agrees that there is sufficient information to suggest the species may be threatened (USFWS 2024). This triggers an in-depth review process before a listing decision can be made. The species is threatened with extinction due to its limited distribution, with few localities, and because of its reliance on wetland habitats in an increasingly arid landscape. Major threats to the species include increasing drought due to climate change, overuse of groundwater, riparian corridor fragmentation, habitat degradation and direct trampling due to cattle, intrusive recreation, light pollution, and hydrological modifications for farming, ranching, and copper mining. At the subspecies level, the nominate subspecies, B. w. wickershamorum, is listed as Vulnerable on the Red List (Fallon and Cicero 2021b) and Bicellonycha wickershamorum piceum is listed as Endangered (Fallon and Cicero 2021c). Bicellonycha w. piceum is not as well understood, and at the time the assessment was done, it was known from only the type locality. While it is now known from several localities across New Mexico and Arizona, most populations observed have very few individuals. This firefly is at high risk of habitat loss and more research is needed to better understand its conservation needs. For more information on the conservation status of this species, see the firefly species fact sheet on the Firefly Atlas (https://www.fireflyatlas.org/threatened-species-fact-sheets/) (Fallon and Walker 2024).

Because this species is nocturnal and associated with wetland and riparian habitats, it is threatened by drought, riparian corridor severance, habitat degradation and direct trampling due to cattle, intrusive recreation, light pollution, and hydrological modification for farming, ranching, and copper mining. The larval stage may be particularly sensitive to environmental change due to restricted dispersal capabilities and vulnerability to desiccation (Fallon et al. 2023)

Population size, trends, and abundance are not available for this species.

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