59.

Rohu’s Bat

Philetor brachypterus

French: Vespertilion brachyptere / German: Rohu-Fledermaus / Spanish: Vespertilionido de alas cortas

Other common names: Narrow-winged Brown Bat, Narrow-winged Pipistrelle, Short-winged Pipistrelle

Taxonomy. Vespertilio brachypterus Temminck, 1840,

“le district de Padang,” Sumatra, Indonesia.

A close relationship of Philetor to Tylonycteris was already suspected by some earlier authors; this was confirmed by the DNA-barcode study of C. M. Francis and colleagues in 2010, and in subsequent phylogenetic analyses. More recent phylogenetic studies by M. Ruedi and colleagues in 2017 and T. Gorfol and colleagues in 2018 and 2019 show Philetor to be closely related to Cassistrellus and Tylonycteris, the three forming a separate clade. The genus Philetorwas long considered to include only one named form, P. rohui, described by O. Thomas in 1902 from New Guinea. In 1966, J. E. Hill demonstrated that the Peninsular Malaysian form described by F. N. Chasen in 1940 as Eptesicus verecundus also belonged to Philetor, and he treated it as a race of P. hui. In 1971, Hill showed that Vespertilio brachypterus of Sumatra, at that time classified as a species of Pipustrellus, was also referable to Philetor, he treated it as a third race, and as it was the oldest name, it became the correct name for the species. Despite Hill's recognition of three subspecies, the actual pattern of variation has proved too complex to fit this taxonomy;it had been suggested that variations in the shape of the narial emargination (Uor V-shaped gap) justified the subspecies, but in 1983 K. F. Koopman regarded this feature as unreliable. In 2017, V. C. Lim and colleagues performed NJ analyses of the barcoding gene, and suggested cryptic species among Peninsular Malaysian and/or Bornean specimens. In a morphological study in 2017, U. Saikia and colleagues reidentified specimens supposedly of P. brachypterus from Nepal and Sikkim as Hypsugo joffrei; morphological data suggest that Philetor has a close evolutionary relationship with Tylonycteris and H. joffrei . The internal taxonomy ofthis species is in need of revision. Monotypic.

Distribution. Philippines (S Luzon, Catanduanes, Panay, Samar, Leyte, Negros, and Mindanao Is), Peninsular Malaysia, CW Sumatra, N & NW Borneo, Sulawesi, New Guinea and the Bismarck Archipelago (New Ireland and New Britain Is). A record from Java is erroneous, and a record from Bangka I does not appear to be authentic. Previous records from India (Sikkim) and C & E Nepal are misidentifications, now attributable to Joftre’s Pipistrelle ( Hypsugo joffrer).

Descriptive notes. Head-body 52-64 mm, tail 30-38 mm, ear 13-16 mm, hindfoot 8-10 mm, forearm 30-38 mm; weight 8-13 g. Males are larger than females in almost all dimensions. Fur is short and dense, the upperparts reddish to dark brown, with pale gray-brown bases and dark tips; underparts are paler, red brown to gray brown. Head is ratherflat, with no noticeable forehead. Sparsely haired muzzle is short and broad, and appears swollen. Nostrils are widely separated. Ears are short, triangular and of moderate size; posterior margin attaches to underside of throat; there is a small antitragal lobe at base of anterior margin; inner surface of ear sparsely haired; tragusis short, blunt, and fleshy. Eyes are minute, with no facial hairs. Wings are narrow, with fifth digit shortened, its tip reaching only to halfway along first phalanx of fourth finger; these are attached to the lower end of the tibiae. Males and females have unusually elaborate genitalia: elongated penis of male lacks a prepuce, and has a cushion-like, bristly pad at end of main shaft, followed by a narrow shaft supporting a broadened triangular structure; vulva of female is very small and is longitudinally oriented, rather than horizontally as in other bats, and there are five separate pads around the vulva; particularly striking is the deep dark brown color of part of the penis tip in Philetor, a feature not described before. Skull is short and somewhat spherical in appearance, with conspicuous peg-like projections over anterior edge of orbit. Skull slopes evenly in profile; rostrum is short, deep and broad. The indistinct supraorbital ridges terminate in very well-developed supraorbital processes; basioccipital pits are deep; braincase bulbous; sagittal crest and lambdoid ridges are slightly developed. Zygomata are extremely weak; interorbital region is broad. Dental formulais12/3,C1/1,P 1/2, M 3/3 (x2) = 32. I? is elongated and narrow basally with two cusps (bicuspidate), I” is smaller and conical, and separated from C'by a narrow diastema; C' has broad anterior face and well-defined secondary cusp posteriorly; P? is absent. There is a known case of an individual from Sulawesi (Bogani Nani Wartabone National Park) possessing a small P?; more material is needed to evaluate this unusual feature. P* is short,its length about half its width; crowded between C' and M'. Lower incisors are tricuspidate and separated from each other; lower molars are nyctalodont. Condylo-basal length 12-9-15 mm; maxillary tooth row 4-6-5 mm. Chromosomal complement has 2n = 26 and FN = 48 (Ulu Gombak, Peninsular Malaysia).

Habitat. Both pristine forest and disturbed areas. In the Philippines, the species occurs in primary and disturbed lowland forests from sea level to 1450 m. In Malaysia, it can be found in peat-swamp forest. Elsewhere in the region it has been recorded in degraded forest adjacent to good lowland and montane forest. On Mindanao (Mount Kitanglad) netted in disturbed lowland forest at 800 m, and in residual montane forest at 1450 m. In New Guinea found in primary and disturbed tropical moist forests. It can be found in coconut plantations adjacent to forest. It ranges from sea level up to elevations of 2100 m.

Food and Feeding. Rohu’s Bat appears to forage in relatively open areas and typically flies at high speed. It forages in the forest understory and subcanopy, and over grassland. Stomachs of three specimens contained insects including Coleoptera and Hymenoptera .

Breeding. Pregnant females with a single embryo were found from late May to mid-June in Borneo and March/April in Peninsular Malaysia. On Mindanao (Mount Kitanglad) an adult female netted in April was pregnant with a single near-term embryo.

Activity patterns. Rohu’s Bat leaves the day roost at dusk. It roosts in tree hollows and holes 1-5-4-5 m aboveground. Bats sometimes roost in coconut palms in New Guinea, but not in South Asia. In Papua New Guinea, one specimen was taken from a hollow tree that had previously been occupied by a Lesser Tree Mouse ( Chiruromys vates). On New Britain, most bats were found in hollow trees in rainforest. There appear to be no roosting records from caves. Echolocation call from Mount Makiling, Laguna Province, Luzon, had a mean frequency of 30-6 kHz. In New Guinea heard making an insect-like call from a hole in a coconut palm.

Movements, Home range and Social organization. Rohu’s Bats forage in relatively open areas and typically fly at high speed, having correspondingly narrow, stubby wings. Up to 55 individuals have been collected from a single tree. On New Britain, bats were found in mixed groups or segregated male and female groups.

Status and Conservation. Classified as Least Concern on The IUCN Red List in view of its wide distribution and expected large population. Rohu’s Bat occurs in a number of protected areas, and tolerates a degree of habitat modification. There appear to be no major threats. Surveys and research are needed overits entire range.

Bibliography. Amador et al. (2018), Bates & Harrison (1997), Boitani et al. (2006), Bonaccorso (1998), Brass (1964), Chasen (1940), Corbet & Hill (1992), Flannery (1995a, 1995b), Francis (2008a), Francis et al. (2010), Gor fol & Csorba (2018), Gorfol et al. (2019), Heaney, Balete, Alviola et al. (2012), Heaney, Balete, Dolar et al. (1998), Heaney, Balete & Rickart (2016), Heaney, Tabaranza et al. (2006), Heller & Volleth (1989), Hill (1966, 1971b), Hill & Harrison (1987), Hill & Rozendaal (1989), Kock (1981), Koopman (1982b, 1983), Lim, B.L. et al. (1972), Lim, V.C. et al. (2017), Medway (1983), Miller (1907), Payne et al. (1985), Phillipps & Phillipps (2016), Rosell-Ambal, Tabaranza, Bonaccorso et al. (2008), Ruedi, Eger et al. (2017), Saikia et al. (2017), Sediock (2001), Simmons (2005), Tate (1942b), Thomas (1902b), Volleth & Heller (1994a).