Aethalops aequalis, G. M. Allen, 1938

Don E. Wilson & Russell A. Mittermeier, 2019, Pteropodidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 16-162 : 73-74

21.

Bornean Pygmy Fruit Bat

Aethalops aequalis

French: Cynoptere de Bornéo / German: Borneo-Zwergflughund / Spanish: Aethalops de Borneo

Other common names: Bornean Fruit Bat, Borneo Fruit Bat

Taxonomy. Aethalops aequalis G. M. Allen, 1938 ,

“Lumu Lumu, Mt. Kinabalu, British North Borneo,altitude 5500 feet [= 1676 m],” Sabah, Malaysia .

This species is monotypic.

Distribution. Endemic to the C Mts of Borneo.

Descriptive notes. Head-body 55- 70 mm (tailless), ear 9-12 mm, hindfoot 7-10- 5 mm, forearm 40-48 mm; weight 14-18 g. Head of the Bornean Pygmy Fruit Bat has moderately elongated muzzle and is almost naked, with blackish skin; nostrils are shortly tubular and divergent; philtrum is divided into two parallel grooves; and lower lip pads are triangular. Eyes are moderately large; iris is dark olive-brown to blackish brown. Ears are short and rounded, and pinna is black, with slightly paler medial rim. Head pelage is short, soft, and fuscous or blackish brown, continuing onto nape; dorsum has longer, darker, and woollier pelage, with browner dorsal flanks to bases of forearms. Uropatagium is reduced to a strip, uropatagium and tibia are thickly furred on both surfaces and dark cinnamon-brown, calcar is absent, and claws are whitish. Throat is thinly haired; chest and belly are mouse-gray, with soft brown-tipped hairs; and sides of neck are glandular and dark yellowish brown. Wing membranes are black from sides of body and attach between first and second toes. Skull lacks basicranial deflection, with rather pointed rostrum, gently sloping to forehead; orbit is large; zygomatic root is only slightly above alveolar line; zygoma is very thin and arched posteriorly; and braincase is globose. Dorsally, rostrum is moderately thin and pointed; paranasal recesses are inflated, passing blunt postorbital process; there is no postorbital foramina; postorbital constriction is barely noticeable; and skull is rounded, with almost no trace of temporal lines or nuchal crest. Ventrally, palate is flat; tooth rows are slightly arched; post-dental palate is long, ending straight with spine inconspicuous and joined to sphenoidal crest; and ectotympanic is small and wide anteriorly, edged internally by long entotympanic. Mandible is thin and straight; coronoid is long, low, and sloping; condyle is level with lower alveolar line; and angle is salient ventrally and slightly pointed posteriorly. Dental formula for all species of Aethalopsis12/1,C1/1, P3/3,M 1/2 (x2) = 28. Long upper incisors are of equal length; I' is thin and straight; I? is more robust, with longer roots and crowns bent medially; C' is small, weak, and slightly decurved; P' is minute; next premolar (P°) is large and almost triangular in lateral view; and last cheekteeth decrease in height and have rectangular outline. I is very small and distinctly bifid, with longer innerside; I, is absent; C, is very small and slightly decurved; P|is conspicuously pointed; P,is very large,laterally triangular, and as high as C; and posterior cheekteeth are low and small. Diploid number is 2n = 34, with ten metacentric and submetacentric pairs and seven acrocentric pairs of chromosomes.

Habitat. Bornean submontane and montane rainforests at elevations above 550 m but most frequently 1000-2700 m. The Bornean Pygmy Fruit Bat prefers forest understories.

Food and Feeding. The Bornean Pygmy Fruit Bat is primarily frugivorous, but it do use flowers such as banana flowers ( Musa sp. , Musaceae ).

Breeding. Female Bornean Pygmy Fruit Bats are pregnant in September—November. Adult-sized young with cartilaginous wingjoints are caught in April.

Activity patterns. No information.

Movements, Home range and Social organization. The Bornean Pygmy Fruit Bat is apparently solitary or lives in very small groups.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Overall population of the Bornean Pygmy Fruit Bat is not fragmented despite its montane habitat, and all Bornean subpopulations are genetically similar. It is locally common in montane forests.

Bibliography. Allen (1938a), Benda (2010a), Giannini & Simmons (2007a), Harada & Kobayashi (1980), Kitchener, Hisheh et al. (1993), Kumaran, Ketol et al. (2016), Kumaran, Struebig & Tingga (2016), Olson et al. (2001), Phillipps & Phillipps (2016), Tingga & Abdullah (2012a, 2012b).

Figures

15. Brooks's Dayak Fruit Bat (Dyacopterus brooksi), 16. Common Dayak Fruit Bat (Dyacopterus spadiceus), 17. Philippine Large-headed Fruit Bat (Dyacopterus rickarti), 18. Blanford’s Fruit Bat (Sphaerias blanfordi), 19. Bornean Spotted-winged Fruit Bat (Balionycteris maculata), 20. Malayan Spotted-winged Fruit Bat (Balionycteris seemundi), 21. Bornean Pygmy Fruit Bat (Aethalops aequalis), 22. Common Pygmy Fruit Bat (Aethalops alecto), 23. Common Swift Fruit Bat (Thoopterus nigrescens), 24. Suhaniah’s Swift Fruit Bat (Thoopterus suhaniahae), 25. Mindanao Pygmy Fruit Bat (Alionycteris paucidentata), 26. Fischer’s Pygmy Fruit Bat (Haplonycteris fischeri), 27. Luzon Pygmy Fruit Bat (Otopteropus cartilagonodus), 28. Salim Ali’s Fruit Bat (Latidens salimaliz), 29. Sundaic Black-capped Fruit Bat (Chironax melanocephalus), 30. Sulawesi Black-capped Fruit Bat (Chironax tumulus), 31. Lucas’s Short-nosed Fruit Bat (Penthetor lucasu)

Distribution. Endemic to the C Mts of Borneo.