Pipistrellus stenopterus Dobson 1875

41.

Narrow-winged Pipistrelle

Pipistrellus stenopterus

French: Pipistrelle a ailes étroites / German: Schmalfliigel-Zwergfledermaus / Spanish: Pipistrela de alas estrechas

Other common names: Malayan Noctule

Taxonomy. Vesperugo stenopterus Dobson, 1875,

“ Sarawak, Borneo,” Malaysia.

Pipistrellus stenopterus has been included in Nyctalus and Hypsugo by various authors but is best placed in Pipistrellus based on karyotypic and morphological data. Recent genetic data have placed it as sister to a clade including a few of the Eastern Pipustrellus species (P. coromandra, P. tenwis, P. javanicus, P. paterculus, and P. abramus), and it was placed in its own subgenus, Alionoctula, based on its unique morphology and genetic placement. Based on paraphyly of Pipistrellus as currently recognized, this subgenus eventually might be recognized as a distinct genus. Monotypic.

Distribution. Extreme S peninsular Thailand, Peninsular Malaysia, Singapore, Sumatra (including Galang I in the Riau Archipelago), N & W Borneo (including Labuan I), and a single specimen from SW Mindanao, Philippines.

Descriptive notes. Head-body 50-6 62-4 mam, tall 36-7-57 mm, car 11.5-16 mm, hindfoot 10-5-12-1 mm, forearm 37-42 mm; weight 13-22 g. The Narrowwinged Pipistrelle is considerably larger than all other species of or and is more Nyctaluslike. Muzzle is broad and thick, and wings are narrow. Pelage is short. Dorsum is dark reddish brown to dark chocolatebrown; venter is slightly paler and grayer. It might be sexually dimorphic, with females being reddish brown and smaller and males more brownish or grayish brown and larger. Ears are of moderate size and somewhat rounded (butstill subtriangular), with broadly rounded tips; tragus is broad, hatchetshaped, and strongly angled forward. Uropatagium extends from calcar to nearly tip oftail; only extreme tip is free. Fifth metacarpal is much shorter than fourth metacarpal, which gives its characteristic narrow wings that differentiate it from other species of Pipistrellus. Baculum is ¢.3-5 mm long (relatively short compared with Asiatic congeners) and more massive than in other Pipistrellus but gradually narrows from base to end; end is wider and bifurcated; tip points downward; and base has deep and narrow notch. Skull is large and broad, with short thick rostrum; braincase is rounded; there is no frontal depression; sagittal crestis well developed; supraorbital tubercles are well developed; zygomatic arches are moderately developed; post orbital processis slight; C! is large, with slight posterior cusp; I* is bicuspid, and I” is unicuspid or with very small secondary cusp; P? is large and within tooth row; and lower molars are nyctalodont. Chromosomal complement has 2n = 32 and FN = 50 (Malaysia).

Habitat. Lowland foothills, montane regions, plantations, and urban areas at elevations of 100-1200 m. In Lampung Province, southern Sumatra, the Narrow-winged Pipistrelle was recorded in a coffee plantation and coffee-rubber mixed plantation.

Food and Feeding. The Narrow-winged Pipistrelle is insectivorous. It forages over streams and open fields and around streetlights.

Breeding. No information.

Activity patterns. The Narrow-winged Pipistrelle is nocturnal and seems to be a highflying bat. It roosts in hollow trees in plantations and gardens and roofs of houses. Call shape is FM/QCEF, and search call has durations of 2—4 milliseconds and sweeps of 30-60 kHz. In the Krau Wildlife Reserve, central Peninsular Malaysia, two different feeding calls (low and high frequencies, respectively) were recorded with starting frequencies of 42.8 kHz and 56 kHz, terminal frequencies of 28 kHz and 32-9 kHz, peak frequencies of 31 kHz and 37 kHz, and durations of 13-8 milliseconds and 9-7 milliseconds.

Movements, Home range and Social organization. The Narrow-winged Pipistrelle is gregarious and will roost with the Lesser Asiatic Yellow Bat (Scotophilus kuhliz).

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Narrow-winged Pipistrelle is rarely caught, likely because it flies high and is hard to catch. It does not seem to face any major threats. In Singapore, it was not collected from 1986 to 2010 and was considered extinct from the island during that time.

Bibliography. Bumrungsri et al. (2006), Corbet & Hill (1992), Francis (2008a), Francis & Hill (1986), Heaney et al. (1998), Hill & Harrison (1987), Huang, J.C.C. et al. (2014), Kingston, Bumrungsri et al. (2008), Kingston, Jones et al. (2003), Kruskop, Solovyeva & Kaznadzey (2018), Lane et al. (2006), Leong et al. (2010), Lim, B.L. et al. (2003), Sum & Menne (1988), Volleth et al. (2001).