(Dobson, 1875)
Dormer's bat
External characters (Table 101)
This is a medium-sized pipistrelle with an average forearm length of 34.4 mm (32.7-36.3 mm). The tail is considerably shorter than the head and body. The pelage on the dorsal surface is grey-brown, with some of the hair tips almost silver in colour whilst the roots are dark brown/ black; overall there is a slight glossy sheen (Pdo1). The ventral surface is contrastingly paler, with all the hair tips white or pale buffy white and the roots very dark (Pdo2). The ears, naked areas of the face and membranes are a uniform mid-brown; in some specimens the veins in the interfemoral membrane are conspicuously marked in white. The wings and interfemoral membrane are essentially without hairs. The penis is large. The body weight of adult males ranges from 6.0-7.0 grams (Madhavan, 1978). The baculum has a long narrow, slightly sinuous shaft and a broadened, weakly bifid tip; the base is slightly broadened and bifid (Fig. 205).
Cranial characters
The skull (Fig. 217), with an average condylo-canine length of 13.3 mm (12.8-13.6 mm) is robust. The rostrum is broad and has abruptly incurving lateral margins, posterior to the lachrymal processes. There are slight linear depressions in the mid-line of the rostrum and laterally above the orbits. The zygomata are broad anteriorly; consequently they are essentially parallel sided rather than convergent anteriorly. The braincase is not greatly inflated; it is relatively small in comparison to the robust rostrum. The dorsal profile is almost straight from the nares to the lambda with only a very slight depression above the orbits. The lambda forms the most elevated part of the skull. The palate is concave and essentially parallel-sided. The basisphenoid pits are very shallow. The mandible is illustrated in (Fig. 217).
Dentition
- Upper toothrow length (C-M3) averages 5.4 mm (5.2-5.6 mm). The first upper incisor (I2) is usually without a secondary cusp but has a distinct posterior cingular cusp. The second upper incisor (I3) is absent or when present minute, barely attaining the cingulum of the first upper incisor (Fig. 218). I3 is situated closely adjacent to or sometimes in contact with, the upper canine. The upper canine is without a secondary cusp but has anterior and posterior cingular cusps. The first upper premolar (PM2) intruded from the toothrow, its crown area is two-thirds that of I2 (Fig. 219). The canine and the second premolar (PM4) are closely adjacent but not in contact.
- The first lower premolar (pm2) is slightly extruded from the toothrow; it is about two-thirds to three-quarters the crown area of the second lower premolar (pm4).
Variation
Thomas, 1915b recognised P. d. caurinus from Gujarat as distinct from P. d. dormeri from Karnataka on account of the colour of the fur (hoary grey versus brown), larger skull and longer toothrow. However, an analysis of measurements of this bat from throughout India shows that there is no significant regional difference in the length of the forearm, skull or toothrow. The pelage colour is individually variable (Agrawal, 1973). Therefore all specimens are here referred to the nominate race P. d. dormeri .