19.

Bornean Spotted-winged Fruit Bat

Balionycteris maculata

French: Cynoptére tacheté / German: Borneo-Fleckenkurznasenflughund / Spanish: Balionicterio maculado

Other common names: Spotted-winged Fruit Bat

Taxonomy. Cynopterus maculatus Thomas, 1893,

“ Sarawak,” western Borneo, Malaysia.

The two traditionally recognized subspecies, type maculata in Borneo (slightly larger and browner but otherwise very much alike) and sesmundi in Peninsular Malaysia, have 12% genetic divergence (using cytochrome-b sequences) that warrants species-level recognition. B. maculata is also distinguished morphometrically from B. setmundi. Monotypic.

Distribution. Borneo.

Descriptive notes. Head—body 50-74 mm (tailless), ear 7-11 mm, hindfoot 7-8 mm, forearm 38-43 mm; weight 11-14 g. Head of the Bornean Spotted-winged Fruit Bat is rounded, with short muzzle and sparse hair, and skin is brown; nostrils are shortly tubular and divergent; philtrum is divided into two separate lines from base of nostrils down to upper lip; and lower lip pads are large and fused. Lacrimal has white spot of bare skin. Eyes are large and bulging; iris is dark brown. Ears are short, rounded, and dark brown, with slightly swollen white spot at bases and small tubercles on dorsal surfaces. There is a line of swollen follicles of genal vibrissae. Head pelage is short, soft, and coffee-brown, and nape is sparsely haired; dorsum has longer, dark brown pelage. Uropatagium 1s narrow and hairy at center, and calcar is short. Males have throat gland. Chest and belly have gray hair bases, washed with yellowish brown tips; sides of neck have longer, yellowish hairs. Wing membranes attach to first toe and are dark grayish brown, flecked with white; all wing digit joints are white and slightly swollen. Skull lacks basicranial deflection. Laterally, rostrum is short, sloping into forehead; orbit is very large; zygomatic root is slightly above upper alveolar line; zygoma is thin and arched posteriorly; and braincase is round. Dorsally, rostrum is broad, postorbital foramen is absent; postorbital processes are very short and blunt; paranasal recesses are inflated and extended posteriorly; temporal lines are low and separate; there is almost no postorbital constriction; braincase is almost rounded; nuchal crest is barely marked; and zygomatic arches are moderately wide. Ventrally, palate is flat; tooth rows are lightly arched; post-dental palate is long and moderately converging, with straight caudal edge; palatine spine is inconspicuous and connected to sphenoid crest; and ectotympanic is small and wider anteriorly, internally edged by ribbon-like entotympanic. Mandible is thin, sloping into a low coronoid with rounded tip; condyle is small, level with lower alveolar line; and angle is distinct and round. Dental formula for all species of Balionycterisis12/1,C1/1,P 3/3, M 2/2 (x2) = 30. Upper dentition has two pairs of small incisors; C' is small and slightly decurved; P' is a spicule; next premolar (P?) is large and triangular; P* is low; molars are low, very small, and rectangular in occlusal outline; and M* is tiny and atavistic. Lower dentition has incisors that correspond to I, (I, absent), C,is very small, P,is peg-like, P, is large, posterior cheekteeth decrease in height and are rectangular, and M,is minute. Diploid numberis 2n = 24.

Habitat. Borneo lowland rainforest, including nutrient-poor heath and peat swamp forest and mangrove forests, and secondary forests up to elevations of ¢. 1000 m.

Food and Feeding. The Bornean Spotted-winged Fruit Bat is primarily an understory frugivore. It drinks from natural mineral lick pools when available.

Breeding. The Bornean Spotted-winged Fruit Bat is seasonally monoestrous and probably is polygynous (harem-forming). Births occur in October-December; postpartum estrus and subsequent mating occurs, overlapped with care of young. Successful mating results in a pregnancy with prolonged delay in embryonic development. Births occur during periods of greatest rainfall. Lactation lasts 2-4 months, after which young become progressively more independent. Both sexes attain sexual maturity within six months, around peak of flowering/fruiting centered in April. Males have significantly larger testes from early December to May. Sex ratio in adults is notsignificantly biased from 1:1.

Activity patterns. The Bornean Spotted-winged Fruit Bat presumably makes tents in which to roost.

Movements, Home range and Social organization. Feeding areas of Bornean Spottedwinged Fruit Bats occur within 1 km?* centered on the roost.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Bornean Spotted-winged Fruit Bat can adapt to disturbed habitats.

Bibliography. Bansa et al. (2018), Bates, Bumrungsri, Suyanto, Francis & Kingston (2008), Benda (2010a), Francis (1989), Giannini & Simmons (2007a), Khan et al. (2008), Kofron (2007a), Maryanto (2003), Mohd-Ridwan et al. (2018), Olson et al. (2001), Rahman et al. (2010), Suyanto & Struebig (2007).