(Vahl, 1797)
Short-nosed Fruit bat
External characters (Table 8)
This is a medium-sized fruit bat with an average forearm length of 70.2mm (64-79 mm). The wings arise from the flanks and therefore there is no narrowing of dorsal pelage (CS7); the membranes are dark brown throughout, but with pale fingers on the wing (CS3). The medial part of interfemoral membrane is hairy, above and below. The muzzle is short, broad and covered with hairs as far as the nostrils which project well forwards. The ears are simple and essentially naked; mocha brown in colour but with well defined pale anterior and posterior borders (CS4). The pelage is soft and silky in texture. In males, the chin, anterior part of the shoulders, sides of the chest, belly and thighs are characteristically orange tinted (RL5). The forehead and the nape of the neck are darker, a rich russet brown; posteriorly the back is grey-brown. In females, the collar is usually more tawny brown (CS7); the rump is grey brown and the belly a paler grey, with slightly lighter hair tips. The baculum is characterised by its well developed, low shoulders and simple unexpanded tip (Fig. 17).
Cranial characters
The skull has an average condylobasal length of 30.9 mm (28.4-33.3 mm). The rostrum is short and broad (RL12). The zygomata are robust, evenly rounded off anteriorly and comparatively long as compared to those of Rousettus and Eonycteris (ES4). The postorbital processes are well developed. The braincase is ovoid with a weak sagittal crest. In contrast to Pteropus , Rousettus and Eonycteris , the basicranial axis forms an essentially straight line with the palate. The supraoccipital is vertical. It projects equally posteriorly with the lambdoid crests. The tympanic bullae are little developed. The basioccipital region is broad. The horizontal ramus of each half mandible is short and robust. The coronoid process is broad; the angular process is rounded off below. The heavy build of the mandible is in sharp contrast to that of Eonycteris .
Dentition
- Upper toothrow length (C-M1) averages 11.1 mm (10.2-12.2 mm). The first (I2) and second (I3) upper incisors are small, peg-like and situated close to one another in a straight line (Fig. 22). The upper canine is relatively broad with its tip recurved when unworn (Fig. 20); it is without a groove on its inner anterior surface but has a secondary cusp on its inner side. The cingulum is well developed postero-laterally. The first upper premolar (PM2) is functionless; it is comparable in size to the incisors. The second premolar (PM3) is equal in crown area to third (PM4), it is relatively larger than that of Rousettus (Fig. 4) or Eonycteris (Fig. 31), its outer ridge is raised into an obtusely triangular cusp whilst the inner ridge forms a lower cusp. PM4 and M1 are similar in morphology to PM3.
- In the mandibular dentition (Fig. 22), the first incisor (i1) is subequal in size to the second (i2). The canine has a well developed secondary cusp on its inner aspect. The first lower premolar (pm2) is larger than the upper (pm2). The principal cusp of the second premolar (pm3) is subequal in height with the canine; it is triangular and sharply pointed (Fig. 20). The outer cusp of the third premolar (pm4) is lower than the second (pm3), it has a well developed inner ridge. m1 is subequal in size with pm4; its outer cusp is less developed. m2 is small, with a simple hollowed out crown.
Variation
Specimens from northern India tend to average larger than those from the south of the peninsula and Sri Lanka. Andersen, 1912 provisionally referred them to C. sphinx gangeticus but Agrawal, 1973 doubted the validity of this subspecies. Specimens from Bhutan are provisionally referred to C. sphinx angulatus which averages smaller than C. s. sphinx . The status of brachysoma from the Andaman Islands is unclear. Those referred to andamanensis and included by Andersen, 1912 in C. brachyotis appear more similar in size to C. sphinx . The status of scherzeri from the Nicobar Islands is also in doubt. Its pelage is very dark. It has a long forearm which is comparable in size to C. sphinx but very short ears and a relatively small skull with a robust rostrum. It appears to be a distinct taxon, possibly deserving specific status.