(Temminck, 1840)
Rohu's bat
External characters (Table 106)
This is a small but robust Vespertilionid with a conspicuously short forearm, averaging 33.6 mm (31.7-35.7 mm) in extralimital specimens from New Guinea; according to Koopman, 1983 it is larger in Nepal with a forearm length of 38 mm. The wings are proportionally very small with the fifth metacarpal reduced in length in comparison to the fourth. The face is comparable to that of Nyctalus (Nno5) with a short, blunt, essentially naked snout. The nostrils are situated far apart and open obliquely outwards. The ears are short but broad; the anterior margin is slightly convex, the tip broadly rounded off and the posterior border with its base running forwards to finish behind and below the angle of the mouth. The tragus of each ear is fleshy and thickened; its inner margin is straight, its outer slightly convex with an inconspicuous basal lobule; it is broad and short, less than one third the height of the pinna. The legs are short and the wings are attached to the lower end of the tibiae. Pelage colour is unclear, since no fresh specimens have been examined. Thomas, 1902b suggests that the type series (taken from alcohol) were reddish brown and rather paler below. Others in The Natural History Museum, London appear a deeper chocolate brown. The penis is relatively very large and without a prepuce. Its glans is complex; its dorsal surface is a double, rough-surfaced cushion, from below the centre of which springs forward an upwardly curved projection, ending in a single pointed cushion with the opening of the urethra at its tip. The female genitalia are also complex, with two large, rounded cushions separated by a median groove. Thomas 1902b suggests that only the fine tip of the penis enters the tiny vagina during intercourse. The baculum is highly distinctive, with a short shaft, bilobate base and an upturned complex nobular globose tip (Fig. 232).
Cranial characters
The skull (Fig. 233) is short and somewhat spherical in appearance. Its condylo-canine length averages 13.1 mm (12.4-13.7 mm) in extralimital specimens; it is larger (14.5 mm) in the single extracted skull from Nepal (Koopman, 1983). The rostrum is short, deep and broad (Fig. 234). The indistinct supraorbital ridges terminate in very well developed supraorbital processes, which greatly exceed the width of the postorbital constriction. The narial emargination is greatly elongated posteriorly; the anterior palatal emargination is wide, its posterior margin with a median projection. The braincase is bulbous; the sagittal crest and lambdoid ridges are slightly developed. The zygomata are extremely fragile. The mandible is illustrated in (Fig. 234).
Dentition
- Upper toothrow length (C-M3) averages 4.6 mm (4.5-4.8 mm) in extralimital specimens and 5.0 in the specimen from Nepal (Koopman, 1983). The first upper incisor (I2) is bicuspidate, narrow and elongated, with well developed anterior and posterior cingular cusps. The second incisor (I3) is small and spicular, it has a narrow cingulum and a conical cusp; it is separated from the canine by a narrow diastema. The upper canine has a broad anterior face and a well defined secondary cusp posteriorly (Fig. 234). The small upper premolar (PM2) is absent. The large premolar (PM4) is short, its length about half its width; it is compressed between the canine and M1 (Fig. 235). M3, with a prominent parastyle, is about half the crown area of M2 which slightly exceeds M1 in size.
- The lower incisors are tricuspidate and separated from each other. The lower canine is short and has small anterior and posterior cingular cusps. The lower premolars are of equal height, the first (pm2) is not reduced, its length and width equal; the second (pm4) is much reduced, its length about half its width, its crown area about equal to that of pm2. m1 and m2 are about equal in crown area; m3 is slightly reduced.
Variation
Males exceed females in size (Kock, 1981). The subspecific status of specimens from Nepal is unclear. They are most similar to those from Malaysia, although their forearms are slightly longer; 38 mm for the two females from Nepal, 33-36 mm for the ten adult females from Malaysia (Koopman, 1983). Hill, 1972 referred specimens from Malaysia to P. brachypterus verecundus . Koopman, 1983 suggests that verecundus may prove to be a synonym of P. b. brachypterus .