15. Brooks's Dayak Fruit Bat Dyacopterus brooksi French: Cynoptere de Brooks / German: Brooks-Dayak-Flughund / Spanish: Dyacoptero de Brooks Other common names: Brooks's Fruit Bat Taxonomy. Dyacopterus brooksi Thomas, 1920, “Lebong Tandai, Upper Retaun River, about 100 miles [= 161 km] north of Bencoolen, Sumatra.” This species is monotypic. Distribution. Sumatra and SE Borneo. Descriptive notes. Head-body 116— 120 mm, til 17-20 mm, ear 19-21 mm, forearm 81-83 mm; weight 86-91 g. Muzzle is wide, almost hairless with brown skin; nostrils are shortly tubular and divergent, with thickened rims; marked philtrum is lined with small papillae, reaching upper lip; and lower lip has greatly enlarged, bulging warts. Eyes are large; iris is dark brown. Ears are short, grayish brown, and pointed. Head is very wide, with marked temporal muscles. Head pelage is very short and dark grayish brown, nape is sparsely haired, and dorsum is brown. Tail is long, surpassing wide uropatagium, and calcar is short. Throat and chest are sparsely haired and light brown that becomes darker on flanks; central belly is pale or creamy. Relatively broad tuft of yellowish hairs occurs on sides of neck. Wing membranes are dark gray from sides of body and attach into second toe, index claw is present, and all claws are unpigmented and whitish. Skull has no basicranial deflection and is robust and long. Laterally, rostrum is moderately short and deep; premaxillae are fused; narial opening is deeply concave; forehead is flat; orbit is large; infraorbital foramen unusually large, with zygomatic root above upper alveolar line; zygomais relatively thin and arched; and braincase is low and moderately long. Dorsally, rostrum is wide, paranasal recesses are inconspicuous, postorbital foramen is minute or obliterated, postorbital constriction is obvious, postorbital processes are short, temporal lines are joined in sharp sagittal crest, braincase is piriform, and nuchal crest flares. Ventrally, palate is flat; tooth rows are slightly diverging; post-dental is moderately short, converging, and without palatine spine; sphenoidal crest is inconspicuous; and ectotympanic is very wide, especially anteriorly. Mandible has sloping symphysis; ventral border is convex; coronoid is steeply sloping, with tip rounded; condyle is above lower alveolar line; and angle has moderately marked rim. There are 17-19 palatal ridges; posterior one-half is divided by median ridge. Dental formula for all species of Dyacopterusis 12/2, C1/1,P 2/3, M 1/2 (x2) = 28. Upper incisors are small and crowded, of similarsize, and slightly hooked; C! is strong and very long, moderately decurved, and proclivous, has vertical groove on its anteromedial surface, lingual cingulum, and posterior basal cusp; P' is absent; next premolar (P’) is massive, stout, high-crowned, very wide, and square in outline, with anteromedial cingular ledge; M' is smaller and low crowned. I,is slightly larger than I; C, is long, strong, and almost straight, with posterior cingulum; P is relatively large and wide, with triangular cusp; posterior cheekteeth are massive and very wide with squarish outline, changing from high- to low-crowned; and M, is peg-like. Habitat. Mature lowland primary rainforest. Food and Feeding. Brooks's Dayak Fruit Bat is primarily frugivorous and probably feeds heavily on figs (Ficus spp., Moraceae). Configuration of skull and dentition suggests it can consume hard fruit. Breeding. A lactating Brooks’s Dayak Fruit Bat was recorded in October. Activity patterns. No information. Movements, Home range and Social organization. No information. Status and Conservation. Classified as Vulnerable on The IUCN Red List. Brooks’s Dayak Fruit Bat is a rare and forest-dependent species, with population trend probably declining due to high rates of deforestation in Sumatra and Borneo. Population is fragmented at a large geographical scale between Sumatra and Borneo. It is present in some protected areas; e.g. Kayan Mentarang National Park (north-central Borneo). Bibliography. Helgen et al. (2007), Maharadatunkamsi et al. (2008), Thomas (1920c).

Published as part of Don E. Wilson & Russell A. Mittermeier, 2019, Pteropodidae, pp. 16-162 in Handbook of the Mammals of the World – Volume 9 Bats, Barcelona :Lynx Edicions on page 71, DOI: 10.5281/zenodo.6448815