7.

Common Thick-thumbed Bat

Glischropus tylopus

French: Pipistrelle de Dobson / German: Gewohnliche Dickdaumenfledermaus / Spanish: Pipistrela de Dobson

Taxonomy. Vesperugo tylopus Dobson, 1875,

“ North Borneo,” Malaysia.

This speciesis sister to G. aquilus, although it is morphologically most similar to G. javanus . The name batjanus from Bacan Island in the Moluccas has been regarded as a distinct species or a subspecies of G. tylopus, but is here regarded as synonym of G. tylopus . Monotypic.

Distribution. Malay Peninsula, N Sumatra, Borneo, Palawan I (Philippines), and Bacan I (Moluccas).

Descriptive notes. Head-body 39 mm (holotype), tail 32-39 mm, ear 8-11 mm, hindfoot 6-6 mm (holotype), forearm 27-30-9 mm; weight 3-5-5 g. All species of Glischropus have thick thumb and foot padsthat rely on friction for holding onto insides of bamboo stems, rocks, and large leaves. Pelage is reddish yellow without any banding both dorsally and ventrally. Ears are moderately sized for the genus, being rounded and dark brown. Face is also dark brown. Tragus is relatively narrow with a broadly rounded tip and is angled slightly forward. Skull is flatter than in the Indochinese Thick-thumbed Bat ( Glischropus bucephalus) and the Dark Thick-thumbed Bat ( G. aquilus); the species can be distinguished from the Javan Thick-thumbed Bat ( G. javanus) byits shorter forearm (generally less than 30 mm), and from the Dark Thick-thumbed Bat byits lighter and more reddish yellow pelage. I’ is much shorter than secondary cusp of I? and displaced outward; main cusp of I barely exceeds smaller cusplet of I; P! is small but in tooth row: lower molars are nyctalodont. Chromosomal complement has 2n = 30 (males) or 2n = 31 (females) and FN = 50; the species shows an X-autosome translocation in which a small acrocentric chromosome has been transferred to the X-chromosome.

Habitat. Throughoutits range, the Common Thick-thumbed Bat is generally found in forested regions with abundant bamboo, primarily at lower elevations, below 1000 m.

Food and Feeding. Common Thick-thumbed Bats are insectivorous.

Breeding. In the Malay Peninsula, a female gave birth to a single young in mid-April.

Activity patterns. Roosts have been found most commonly in dead or damaged bamboo stands as well as in rock crevices and banana leaves. Start frequency has been recorded at 95 kHz followed by a steep FM sweep ending in a QCF sweep at 49-45 kHz. Call durations were recorded at 2-7 milliseconds.

Movements, Home range and Social organization. Common Thick-thumbed Bats have been found in a group of twelve in bamboos in Brunei. They may share roosts with species of Tylonycteris, although this is unconfirmed.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Common Thick-thumbed Bat is relatively widespread but difficult to find throughoutits range. It can be found in regenerated forests after disturbance. Relatively little information is available on the species’ ecology, and further research is needed.

Bibliography. Csorba (2011), Csorba et al. (2015), Heaney et al. (1998), Heller (1989), Heller & Volleth (1989), Kofron (1994), Mohd-Hanif et al. (2015), Rosell-Ambal et al. (2008), Thewissen & Etnier (1995), Volleth & Yong (1987), Volleth et al. (2001).