Eupetaurus cinereus, THOMAS, 1888

Jackson, Stephen M., Li, Quan, Wan, Tao, Li, Xue-You, Yu, Fa-Hong, Gao, Ge, He, Li-Kun, Helgen, Kristofer M. & Jiang, Xue-Long, 2021, 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 (2), pp. 502-526 : 10-15

EUPETAURUS CINEREUS THOMAS, 1888

Suggested common name: Western woolly flying squirrel.

Lectotype: BMNH 88.9 .28.1, adult, skin, ‘ Astor District’ (= Astore, Pakistan).

Type locality: ‘Astor District, Kashmir’ (= Astore District, Pakistan).

Diagnosis: Eupetaurus cinereus differs from other Eupetaurus species in its overall more grizzled-grey pelage, with more pronounced grey frosting to the dorsal hairs (more saturated brown tones in the pelage of other species). Interspecific distinctions in the skull mainly concern the breadth of the rostrum and the shape of the frontal bones: the rostrum of E. cinereus is similar to that of E. tibetensis and narrower than that of E. nivamons ; the interorbital region of E. cinereus is broader than in the other two species, and its postorbital processes is larger; the temporal ridges of E. cinereus and E. tibetensis are convergent posteriorly rather than parallel in E. nivamons ( Table 3). The cusps and ridges of cheek teeth of E. cinereus are markedly more robust than in the other two species. The developed protocone and hypocone make the upper cheek teeth heart shaped, similar to E. tibetensis , and differ from the round ones in E. nivamons . Its lower molars are subsquare, also more robust than the subrectangular ones in the other two species. Eupetaurus cinereus preserves only one short anterior fosettid (one long anterior fosettid in E. tibetensis ; two short anterior fosettids in E. nivamons ) ( Figs 7 , 8 ).

Descriptive notes: Size large: head-body length 420–510 mm, tail length 430–545 mm, hind foot l e n g t h 8 3–9 3 m m a n d m a s s 2 5 0 0 g (Z a h l e r & Woods, 1997). The dorsal pelage is typically grizzled greyish, although a melanistic example was recorded by Chakraborty & Agrawal (1977) from Chitral, Pakistan. The pointed ears are hairy, with the outer fur black or brown and the fur of the inner ear greyish. The dorsal surface of the patagium is darker brown. The dorsal surfaces of the forefeet are black and those of the hindfeet are brown. The ventral pelage is pale brownish grey, with the hairs slate coloured basally and dirty white terminally. The tail is long, cylindrical and exceedingly bushy, with similar coloration to the body, often with the portion of the black tail tip short. The skull and dentition are as described above for the genus Eupetaurus and diagnosis of the species.

Distribution: Until recently, E. cinereus was known only by specimens and sightings from a few localities between 2400 and 3600 m a.s.l. in the western Himalayan region, concentrated around Gilgit in northern Pakistan, where its range appears to fall within a small area where the Himalayan, Karakoram and Hindu Kush Mountain Ranges meet ( Zahler, 1996; Zahler & Woods, 1997; Molur et al., 2005; Dinets, 2011; Qamar et al., 2012; Din et al., 2015).

More recently, Eupetaurus has been recorded by camera traps from the Upper Bhagirathi Basin, Uttarakhand, north-western India, at elevations of 2700 and 4800 m a.s.l. ( Pal et al., 2018, 2020). On the basis of the colour of the animals and their geographical location, we regard these records as representing E. cinereus . This indicates a wider geographical and elevational range of occurrence for this species along the western margins of the Himalayas. The increasing use of camera-trap survey techniques might demonstrate that the species occurs in areas intermediate between the widely separated known localities in the Gilgit region of Pakistan and the Bhagirathi Basin of India, perhaps even extending into western Nepal.

Natural history: This species resides on cliffs and rock faces at high elevations, and individuals are not normally tree dwellers except when feeding ( Roberts, 1997; Zahler & Woods, 1997). Within Pakistan, the habitat of E. cinereus is characterized by patchy forests, with herbs and shrubs of the genus Artemisia L., juniper ( Juniperus excelsa M.Bieb. ), Chilgoza pine ( Pinus gerardiana Wall. ex D.Don ), blue pine ( Pinus wallichiana A.B.Jacks. ), Morinda spruce [ Picea smithiana (Wall.) Boiss. ] and oaks ( Quercus L. spp.)> 2000 m a.s.l. ( Zahler & Woods, 1997; Zahler & Karim, 1999). In India, alpine vegetation associated with the 2700 m record includes Bistorta affinis (D.Don) Greene , Gentiana L. spp., Potentilla L. spp., Primula L. spp., Rhodiola L. spp. and Rhododendron anthopogon D.Don. The nearest forest was located 4 km downhill of this sighting and was dominated by Abies pindrow (Royle ex D.Don) Royle , Betula utilis D.Don and Rhododendron campanulatum D.Don. The 4800 m record was lacking any woody or arborescent vegetation, which contrasts with other records that typically associate the species with scattered conifers ( Pal et al., 2018).

In the original taxonomic description of the genus, Thomas (1888) speculated that it might feed on fungi, lichens, mosses and other rock-loving plants in its high-elevation environment. Roberts (1997) proposed that the buds and cones of the Morinda spruce ( Picea smithiana ) may be an important food source for E. cinereus , because buds occur in spring and cones in summer, which are shed in winter. Indeed, Zahler & Woods (1997) found that one captive specimen would eat the buds of Morinda spruce but refused all fruits, nuts and other food offered. More recently, faecal samples from four individuals were found to contain 92–100% pine needles ( Zahler & Khan, 2003). Other observations have found this species to consume the buds of blue pine, juniper, spruce, oaks, Chilgoza pine and deodar [ Cedrus deodara (Roxb. ex D.Don) G.Don ]. In August and September, they are also thought to visit walnut trees ( Juglans regia L.), although it is not clear what parts of the plants they eat ( Mirza & Rasool, 2005).

Known predators of E. cinereus include the red fox [ Vulpes vulpes (Linnaeus, 1758) ], snow leopard [ Panthera uncia (Schreber, 1775) ] and eagle owl [ Bubo bubo (Linnaeus, 1758) ] ( Zahler, 1996, 1998; Zahler & Dietemann, 1999; Qamar et al., 2012; Pal et al., 2020).

This species appears to be nocturnal, solitary and active all year round ( Zahler, 1996). A nest attributed to this species was reported from a shelf in a cave at 3230 m a.s.l. in Jutal Nala, northern Pakistan, which was made of bark and branches of juniper and grasses and looked like a flat bowl measuring 500 mm × 400 mm ( Oshida et al., 2005). A specimen has also been recorded in Sai Nullah (Gilgit, Pakistan) coming out of an old oak tree at ~ 2590 m a.s.l. Thus, there appears to be some flexibility in nesting locations if tree hollows are available ( Mirza & Rasool, 2005). An immature specimen at BMNH collected on 17 April suggests that breeding occurs early in spring and that two litters in a year could be produced ( Roberts, 1997). This is supported by observations of two or three young being produced per litter, with young observed in spring and in late summer ( Zahler & Woods, 1997).

Conservation: Eupetaurus cinereus is threatened by habitat loss owing to large-scale clear cutting of forests, particularly the destruction of highelevation pine woodlands ( Zahler & Woods, 1997; Zahler & Khan, 2003). It is also threatened to a lesser extent by expansion of agriculture, small-scale logging, infrastructure development and human settlements ( Molur et al., 2005). The total population size was estimated to be between 1000 and 3000 individuals within the known range in Pakistan in the mid-1990s ( Zahler & Woods, 1997). It is currently classified as Endangered by the International Union for Conservation of Nature (IUCN) ( Zahler, 2010), because it was considered likely to have suffered a recent reduction in population numbers from habitat loss ( Rao & Marwat, 2003; Hasan, 2008).

The recent discovery of the species in the state of Uttarakhand in north-western India ( Pal et al., 2018, 2020) demonstrates that it might have a considerably wider distribution than previously realized and indicates that protection and conservation in India is also fundamental for the long-term survival of E. cinereus . The species is included in Schedule II (Part II) of the Indian Wildlife (Protection) Act 1972 ( Molur et al., 2005; Pal et al., 2018).

Hunting is not thought to be a major threat to this species. The species might receive some traditional respect and de facto protection because it is considered be a source of a material called salajit (also spelt salaajeet or shilajit), which is thought to be a mixture of flying squirrel urine and faecal pellets and rock leachate ( Zahler, 1996; Zahler & Karim, 1998; Meena et al., 2010). Salajit is important in traditional medicine ( Hooper, 1903) and is collected from caves and sold in medicinal potions used to treat various diseases ( Zahler, 1996; Zahler & Karim, 1998; Meena et al., 2010). Historical references regarding the collection and use of salajit (e.g. Hooper, 1903) might provide clues concerning the historical distribution of E. cinereus or other Eupetaurus species in the Himalayan region, although other high-elevation species of flying squirrels, including the Kashmir flying squirrel [ Eoglaucomys fimbriatus (Gray, 1837) ], might also be sources of the substance ( Pyke, 2001).

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.