Horsfield, 1831
Asiatic Greater Yellow House bat
External characters (Table 78)
This is a robust bat with an average forearm length of 60.7 mm (55.4-65.8 mm) and a body weight ranging from 36 to 39 grams (Madhavan, 1980). The tail is long (She3), with only the terminal 2-3 mm projecting free from the interfemoral membrane. The muzzle is broad and blunt; it is swollen on the sides, dark in colour and mostly naked. The nostrils are simple in form, round and slightly outward facing. The ears are small in relation to the size of the head (She6); they are naked and have a number of transverse ridges. The antitragus of each ear is well formed and separated from the posterior margin of the pinna by a distinct notch. The tragus is half the height of the pinna and crescent shaped (Fig. 167). The pelage is fine and short; it is longer on the nape of the neck and throat. The head and back have pale buffy brown hair roots and darker olive-grey-brown tips; the nape of the neck is paler. The throat, chest and belly are pale yellow-buff throughout (She2). In some individuals the back is chestnut brown and the belly reddish or golden yellow. The interfemoral membrane and wings are uniformly dark brown and essentially naked, except for some hairs adjacent to the body and forearm on the ventral surface of each wing. In the wing, the third metacarpal slightly exceeds the fourth and fifth in length. The feet are about half the length of the tibiae. The baculum is small, bluntly triangular in shape and very narrow in lateral view (Fig. 168).
Cranial characters
The skull (Fig. 170) is robust with an average condylo-canine length of 20.2 mm (19.0-21.3 mm). The braincase is elongated and deep; the lambda is prominent and projects posteriorly above the supraoccipital. The lambdoid crests are well developed. The rostrum is short and broad, with prominent lachrymal processes above the orbits. The sagittal crest is variably developed, it is best defined posteriorly in old adult males; it bifurcates in the interorbital region and extends to the front of the orbits. The nasal aperture is very large; the dorsal surface of the rostrum is smooth. The zygomatic arches are moderately flared. The anterior emargination of the palate is broad and deep; it extends to the mid-point of the first upper premolar (pm4); the posterior extension of the palate is broad, with a median spine. The tympanic bullae are small, subequal in breadth to the basioccipital. The coronoid process of each half mandible is tall and triangular; the angular process is broad and a little outwardly deflected.
Dentition
- Upper toothrow length (C-M3) averages 7.7 mm (7.1-8.4 mm). The single upper incisor (I2) is powerful, unicuspid and with a well developed cingulum; it is in contact with the massive upper canine (Fig. 171). There is one upper premolar (PM4); it is large and attains two-thirds the height of the canine. M1 and M2 have their main cusps displaced outwards; the mesostyle is extremely reduced or even absent; the paracone and metacone are close together and the hypocone is absent. M3 is reduced, with only two commissures, of which the second is very short.
- The three lower incisors are tricuspidate and overlapping. The lower canine is tall and recurved. The first lower premolar (pm2) is very small, between one quarter and a third the crown area of the second (pm4); it is tightly compressed in the toothrow. pm4 is well developed and about two-thirds the height of the canine. m1 and m2 are about equal in size; the protoconid is the dominant cusp; the talonid of each tooth is distinctly smaller than the trigonid. The talonid of m3 is particularly reduced, with a crown area of about one quarter that of the trigonid.
Karyology
2N=36; 17 pairs of autosomes and one pair of sex chromosomes (Bhatnagar and Srivastava, 1974).
Variation
Specimens from throughout the subcontinent are here referred to the nominate subspecies S. h. heathii . However, there is considerable geographical variation in pelage colour. Those from the more arid regions, for example Pakistan (She4, She5) and Gujarat, are relatively pale, whilst those from humid areas, such as Bhutan Duars, Kerala and Sri Lanka are much darker, with some individuals a deep chocolate brown on the head and back.
Taxonomic remarks
There has been considerable confusion over the years as to the correct specific names for the large and small species of Scotophilus found in India. At various times, the name kuhlii has been assigned to the large species and temminckii and wroughtoni to the small. However, here following Hill and Thonglongya, 1972, all specimens of the larger species are referred to Scotophilus heathii.