Rhinolophus acuminatus Peters 1871

62. Acuminate Horseshoe Bat

Rhinolophus acuminatus

French: Rhinolophe acuminò / German: Spitzsattel-Hufeisennase / Spanish: Herradura acuminado

Taxonomy. Rhinolophus acuminatus Peters, 1871,

“ Gadok.” Java, Indonesia.

Tentatively included in the megaphyllus species group but its placement there is uncertain; further genetic work is needed. The most recent genetic study placed the species as sister to R. malayanus, forming a clade sister to much of the megaphyllus, pusillus, philippinensis, and macrotis groups. Five subspecies recognized.

Subspecies and Distribution.

R. a. acuminatus Peters, 1871 - Krakatau I andJava.

R.a. audax K. Andersen, 1905 — Bali and Lombok Is.

. a. calypso K. Andersen, 1905 — Enggano I.

R. a. circe K. Andersen, 1906 — Nias I.

R. a. sumatranus K Andersen, 1905 - W Sumatra and N Borneo.

Subspecific identity of mainland populations in SE Asia, as well as the Philippines (Negros, Busuanga, Palawan, and Balabac Is) is uncertain, although mainland populations resemble individuals fromJava or Lombok.

Descriptive notes. Head—body 48—52 mm, tail 18- 9—31 mm, ear 16-7—21- 4 mm, hindfoot 9-10- 9 mm, forearm 44—53 mm; weight 9- 6-16 g. There are two color morphs: either grayish brown dorsally with hairs tipped light gray or silver, and grayish brown ventrally; or grayish brown tinged with russet dorsally, and pale reddish brown ventrally. Ears are small to medium-sized. Noseleaf has concave-sided lancet that becomes almost parallel-sided toward tip; connecting process is broad and triangular, with bluntly to sharply pointed tip; sella is variable between subspecies, being nearly parallel-sided to distinctly narrowed centrally, but with rounded tip consistently; horseshoe does not completely cover muzzle (7-8—10- 2 mm wide), has visible lateral leaflets, and has wide median emargination. Lower lip has three mental grooves. Baculum (based on specimens of subspecies calypso) has dorso-ventrally higher-than-wide basal cone; ventral notch on proximal margin of base is extremely deep, narrow, and divergent distally; shaft is slightly bent dorsally (although its ventral profile looks nearly straight in lateral view); there is slight constriction medially in dorsal view and also at very tip of bone. Skull is broad, with short rostrum (zygomatic width is significantly broader than mastoid width); anterior median swellings are considerably inflated while posterior swellings are less developed and shorter; sagittal crest is comparatively strong; frontal depression is shallow and very short; supraorbital crests are low with sharp ridges, combining at point in front of center of orbital cavity. P2 is moderately to well developed and generally within tooth row or slightly displaced, which separates C1 from P4; P3 is of medium size and displaced from tooth row, allowing P2 and P4 usually to touch, although not always. Chromosomal complement has 2n = 62 and FN = 60 (Thailand).

Habitat. Lowland dipterocarp forests, primary and secondary tropical forests, bamboo thickets, and some urban areas. Recorded at elevations of 60—250 m in the Philippines and at c. 1000—1700 m in Borneo.

Food and Feeding. Acuminate Horseshoe Bats are insectivorous. They are typically slow and maneuverable fliers that appear to forage in the subcanopy, several meters from the ground.

Breeding. A pregnant and a lactating female were captured in June on Palawan. Males with strong musky odor were collected in October in Vietnam, suggesting this was the mating seas © ®-

Activity patterns. The Acuminate Horseshoe Bat is nocturnal and roosts during the day, primarily in caves and hollow trees, but it has also been reported roosting in buildings and drainage manifolds- Call shape is FM/CF/FM with a peak F reported at 86-90 kHz (males) and 93—95 kHz (females) in Laos, 90 kHz in Vietnam, 80 kHz in Thailand, and 88—90 kHz in Sabah, Malaysia.

Movements, Home range and Social organization. The Acuminate Horseshoe Bat has been reported roosting in small to moderate-sized colonies. A roost in a monastery in Myanmar contained c.100 individuals.

Status and Conservation. Classified as Least Concern on T / ie IUCN Red List. The Acuminate Horseshoe Bat is apparently common throughout much of its wide range, and does not currently seem to be facing any major threats.

Bibliography. Bates, Thi Mar-Mar et al. (2004), Csorba et al. (2003), Esselstyn, Widmann & Heaney (2004), Francis (2008a), Harada, Minezawa et al. (1982), Heaney et al. (1998), Hood et al. (1988), Kruskop (2013a), Matveev (2005), Rosell-Ambal, McKinnon & Esselstyn (2008), Schedvin et al. (1994), Stoffberg et al. (2010), Zhang Lin et al. (2018).