(Dobson, 1871)
Dawn bat
External characters (Table 13)
This is a medium-sized fruit bat with an average forearm length of 71.2 mm (66-78 mm). It superficially resembles a small Rousettus leschenaulti (RL7) but differs in the absence of a claw on the first finger (second digit) (RL14). The muzzle (ES1) is thinner; in consequence it appears longer. Unlike Cynopterus sphinx (CS1), the ears do not have pale outer margins but are dark brown throughout; they are narrowly rounded off. The wing membranes are a uniform dark brown, without the pale linear markings along the fingers seen in C. sphinx (CS3). The wings arise high up on the back and this leads to a narrowing of the dorsal pelage (ES5). The tail is short; its tip protrudes from the interfemoral membrane. The feet are moderately robust; the claws are chestnut brown. There is a large, kidney-shaped gland on either side of the anal opening. The pelage is short, velvety and closely flattened against the skin. It is dark brown above, relatively paler on the back of the head and shoulders. The underside is a mottled grey-brown (ES9). Males have a well marked ruff of slightly darker hairs on the chin and ventral aspect of the neck; in females this area is sparsely haired. The muzzle, from below the inner canthus of the eyes, is naked. The pelage scarcely extends on to the upper surface of the wings or interfemoral membrane; the tibiae are naked. The forearm is moderately hairy below.
Cranial characters
The skull (Fig. 32, ES7) with an average condylobasal length of 33.7 mm (31.7-36.3 mm) resembles that of Rousettus leschenaulti but is usually smaller (ES6). It is less robust than that of Cynopterus sphinx (RL12) with the rostrum longer and narrower and the postorbital processes less developed. The zygomata are short and delicate; their widest point is situated posteriorly. The braincase is not greatly inflated and in lateral profile the skull looks relatively flattened, especially anteriorly in comparison to Cynopterus . The occiput just forms the most posterior part of the skull. The exoccipital condyles are only a little deflected downwards, although slightly more so than those of Cynopterus and Rousettus . The palate is narrow, long and slightly tapered anteriorly (ES8). The tympanic bullae are of moderate size, similarly developed to those of Cynopterus . The mandible is delicate (Fig. 32), with the ramus of each half slender and elongated in comparison to C. sphinx (Fig. 20); the symphysis is protuberant. The coronoid process slopes backwards and the condyle and angular process are little developed.
Dentition
- Upper toothrow length (C-M2) averages 12.5 mm (11.9-13.4 mm). The first (I2) and second (I3) upper incisors are small, peg-like and widely spaced (Fig. 31). The upper canine is long, robust, sharply pointed and slightly recurved at the tip; there is a well marked longitudinal groove on the anterior surface. The first upper premolar (PM2) is small, scarcely exceeding the height of the cingulum of the canine. The cheekteeth are extremely narrow and small and unlike Cynopterus (Fig. 22), the second upper premolar (PM3) does not have an inner ridge raised as a low cusp. M2 is small.
- The lower dentition is delicate, apart from the canine which is well developed. m3 is very small and occasionally absent on at least one side of the mandible.
Variation
Specimens from the Indian subcontinent are provisionally referred to the nominate race E. s. spelaea . Males exceed females in size.