The Namdapha flying squirrel (Biswamoyopterus biswasi) is a flying squirrel endemic to Arunachal Pradesh in northeast India, where it is known from a single zoological specimen collected in Namdapha National Park in 1981.
The Namdapha flying squirrel has reddish, grizzled fur with white above and a pale grey crown; its patagium is orangish and its underparts are white. Its cheek teeth are simple, and its incisors are unpigmented. Septae are multiple in auditory bullae and sometimes honeycomb-shaped with 10 to 12 cells in it. It measures 40.5 cm (15.9 in) from head-to-vent and has a 60 cm (24 in) long tail. The hindfoot is 7.8 cm (3.1 in), and the ear is 4.6 cm (1.8 in) long.[3][4]
The Namdapha flying squirrel first described in 1981, based on a single zoological specimen collected in Namdapha National Park.[2] Its scientific name commemorates Biswamoy Biswas, director of the Zoological Survey of India.[3] It was the first member of the genus Biswamoyopterus; in 2013, the Laotian giant flying squirrel (Biswamoyopterus laoensis) was described.[5] In 2018, a new flying squirrel, the Mount Gaoligong flying squirrel (Biswamoyopterus gaoligongensis) was discovered in China.[6]
The Namdapha flying squirrel is endemic to Arunachal Pradesh in northeast India.[1] It inhabits tall Mesua ferrea jungles, often on hill slopes in the drainage basin area of Dihing River, particularly on the western slope of Patkai range in northeastern India.[3][4]
In April 2022, a putative Namdapha flying squirrel was recorded in Arunachal Pradesh.[7] To prove its validity, the researchers are planning to collect fecal samples for identification of DNA.[8]
The Namdapha flying squirrel is listed as critically endangered on the IUCN Red List. Its range may be restricted to a single valley, and it is threatened by poaching of animals for food within the park, and possibly by habitat destruction.[1] It is among the 25 "most wanted lost" species that are the focus of Re:wild's "Search for Lost Species" initiative.[9]