Eupetaurus nivamons, Jackson, Stephen M., Li, Quan, Wan, Tao, Li, Xue-You, Yu, Fa-Hong, Gao, Ge, He, Li-Kun, Helgen, Kristofer M. & Jiang, Xue-Long, 2022

Jackson, Stephen M., Li, Quan, Wan, Tao, Li, Xue-You, Yu, Fa-Hong, Gao, Ge, He, Li-Kun, Helgen, Kristofer M. & Jiang, Xue-Long, 2022, Across the great divide: revision of the genus Eupetaurus (Sciuridae: Pteromyini), the woolly flying squirrels of the Himalayan region, with the description of two new species, Zoological Journal of the Linnean Society 194, pp. 502-526 : 517-520

EUPETAURUS NIVAMONS Q. LI, JIANG, JACKSON & HELGEN SP. NOV.

Suggested common name: Yunnan woolly flying squirrel.

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: BE1BF61A-769A-42D6-8B11-56ECC0A871C8

Holotype: KIZ 034190 (field number BS1601 ), young adult female, skin, skull, and body preserved in ethanol, collected in January 2017. Sequences for 12S (rRNA) (GenBank no. MW 699658 ), 16S (GenBank no. MW 699662 ), Cytb (GenBank no. MW 699650 ) and IRBP (GenBank no. MW 699654 ) are deposited in GenBank.

Type locality: The holotype was collected on Biluo Snow Mountain , behind the village of Nageluo (Oi格洛) (27°53 ′ 23.54 ″ N, 98°45 ′ 43.90 ″ E), Bangdang Township (棒当乡), Gongshan County, Nujiang Prefecture, Yunnan Province, China .

Paratypes: Five specimens from the type locality: KIZ 034191 (field number BS1602 ), immature female, whole body preserved in ethanol ; KIZ 034192 (field number BS1603 ), immature female, cleaned skull with body preserved in ethanol ; KIZ 035088 (field number 20171101), adult female, skin, skull with body preserved in ethanol ; KIZ 035087 (field number 20171102), adult male, skin, skull with body preserved in ethanol; and KIZ 035086 (field number 20171103), adult male, whole body preserved in ethanol .

Referred specimens: KIZ 034189 (field number GS16078), immature female, skull, skin, and body preserved in ethanol, collected from Nanmowanshan Pass (Ữ山 -巴 坡 人 ¼¥DZ 丫 口), Mount Gaoligong, Gongshan, Yunnan. Two additional skins without skulls (KIZ 003299 and KIZ 003310), purchased at Lijiang or Gongshan, Yunnan in 1973 by Yingxiang Wang ( Yang & Wang, 1989) (the original label locality was written as Lijiang, which was later altered to Gongshan).

Diagnosis: Eupetaurus nivamons differs from E. cinereus in its more saturated brown dorsal pelage (clearer grey dorsal pelage in E. cinereus ) and closely resembles the external appearance of E. tibetensis , but its black tail tip is longer. The rostrum of E. nivamons is wider than in E. cinereus and E. tibetensis ; its temporal ridges are parallel rather than posteriorly convergent as in E. cinereus and E. tibetensis ( Table 3). Cheekteeth cusps and ridges are weakest among the taxa; the protocone and hypocone are not as developed as in the other two species, making the upper cheek teeth round in shape rather than heart shaped. Its lower molars are subrectangular, as in E. tibetensis , and less robust than the subsquare molars of E. cinereus . Eupetaurus nivamons has two short anterior fosettids in the lower molars (one long anterior fosettid in E. tibetensis ; one short anterior fosettid in E. cinereus ) ( Figs 7 , 8 ).

Descriptive notes: Eupetaurus nivamons is slightly smaller than E. cinereus (holotype head-body length 419 mm, tail length 440 mm, hind foot length 90 mm, ear length 44.5 mm and mass 1420 g). The dorsal pelage is grizzled greyish brown. The same colour extends to the forehead, turning pale grey along the cheeks to the throat. Ventral pelage is light ashy, with a median longitudinal line of coarse hairs. The margin of the patagium is black. The dorsal surfaces of the manus and pes are black, mixed with scattered straw-coloured hairs. The ears are pointed and hairy, externally black and internally white washed with khaki. The proximal half of the tail is similar in colour to the back but browner, and the distal half is black. A pale marking round the lower half of the otherwise brown body has been observed in one camera-trapped animal at Mount Gaoligong, Yunnan Province, China (Wang Jianhua, pers. obs.). The skull and dentition are as described above for the genus Eupetaurus and diagnosis of the species.

Etymology: The specific name is composed of the Latin nivalis, snowy, and mons, mountain. It is a noun in apposition.

Distribution: According to specimens, camera-trap images/videos and sightings by local people, E. nivamons is currently known from the alpine zone (3400–4450 m) on Mount Gaoligong [the watershed of the Ayeyarwady (= Irrawaddy) River and the Nu (= Salween) River] and Biluo Snow Mountain (the watershed of the Nu River and the Mekong River) ( Fig. 10 ). Given that the known distribution runs along the Chinese side of the border with Myanmar, the species is likely to occur in suitable habitats immediately across the border in north-eastern Myanmar (similar to the case of the recently described gibbon Hoolock tianxing Fan et al., 2017). It should also be sought in alpine areas of far south-eastern Tibet situated east of the Brahmaputra River ( Fig. 10 ).

Natural history: The specimen KIZ 034189 was collected from a cliff at an elevation of 3700 m a.s.l. near the spine of Mount Gaoligong. The surrounding natural vegetation is a mosaic of swamp meadows and dense shrubs ~ 0.5 m high. The main plants are currants (Ribes L.), barberries (Berberis L.), willows (Salix L.), roses (Rosa L.), rhododendron (Rhododendron L.) and juniper (Juniperus squamata Buch.-Ham. ex D.Don). The mean annual temperature is 3.9 °C, ranging from a low of −12.5 °C in January to a high of 19.6 °C in August. Mean annual humidity is 94.4%, ranging from a low of 70% in November to a high of 100% from April to September, except August [data from a nearby combined temperature and humidity meter (ibutton-MAXIM DS1923); Supporting Information, Supplementary Data SD8]. All cameratrap photographs and videos of E. nivamons were taken from similar cliff habitats at 3700–4450 m a.s.l. on Mount Gaoligong ( Fig. 11 ).

Large, round faecal pellets and partly eaten plant material were scattered under juniper scrub (Juniperus squamata) near the high-elevation cliff of Mount Gaoligong. Given that no other large rodents were documented in this habitat, we interpret this as evidence that juniper is an important food plant for E. nivamons in the area.

Potential predators of E. nivamons include the tawny owl (Strix aluco Linnaeus, 1758), leopard cat [Prionailurus bengalensis (Kerr, 1792)] and Siberian weasel (Mustela sibirica Pallas, 1773).

Camera-trap observations (N = 31) show that E. nivamons is active throughout the year, with a peak in October; and it is active from 19.30 to 06.00 h, with a peak from 19.30 to 00.00 h. Even in winter, fresh faecal pellets can be found on top of the snow under juniper shrubs, indicating that E. nivamons does not hibernate or migrate from the area during the coldest months of the year (Ge Gao, pers. obs.).

Conservation: We have documented this species at two principal localities, Mount Gaoligong and Biluo Snow Mountain. Mount Gaoligong is within a nationally protected nature reserve, whereas Biluo Snow Mountain has not been gazetted as a protected area. Owing to its high-elevation cliff habitat, far away from human settlements and covered by heavy snow for more than half of the year, E. nivamons is probably not heavily affected by human activities. The only known direct threat we documented is poaching for meat by herb collectors who visit the area from June to October. Given the apparent rarity of the animal and relatively small habitat area, we recommend an IUCN Red List classification of Near Threatened for this species. The loss of alpine habitats owing to ongoing climate change is a potential threat to the species in the near future.

Figures

Figure 7. Skulls of Eupetaurus, from left to right: E. cinereus (FLMNH 28583) from Pakistan; E. tibetensis NML 19524, holotype, from Tibet; and E. nivamons KIZ 034190, holotype, from Yunnan. Scale bars (under each skull series): 2 cm.

Figure 8. Cheek teeth of the nine known skulls of Eupetaurus species: A, Eupetaurus cinereus ZSI 9492, adult from Pakistan; B, E. cinereus BNHS 7108, adult (now reported lost) from Pakistan (McKenna 1962); C, E. cinereus FLMNH 28583, old adult, from Pakistan; D, Eupetaurus tibetensis NML 19524, holotype, young adult, from Tibet; E, Eupetaurus nivamons KIZ 034189, immature, from Yunnan; F, E. nivamons KIZ 034192, immature, from Yunnan; G, E. nivamons KIZ 034190, holotype, young adult, from Yunnan; H, E. nivamons KIZ 035087, adult, from Yunnan; and I, E. nivamons KIZ 035088, adult, from Yunnan. Left side is labial side.

Figure 10. Known localities of the three species of Eupetaurus.

Figure 11. General view of habitat of Eupetaurus nivamons: A, summer view; B, winter view; C, faecal pellets and partly eaten plants (yellow square) under Juniperus squamata; and D, E. nivamons.