(BrÜnnich, 1782)
Greater Mouse-tailed bat
External characters (Table 15)
This is the largest of the three species of Rhinopoma found in the Indian subcontinent with a forearm length of 68.0 mm (59.5-74.6 mm) (Rmi1). The tail is relatively short compared to that of R. hardwickii (Rha1); it does not usually exceed the length of the forearm. The face, ears and connecting membrane on the forehead are naked; the chin is also essentially without hairs. The dermal ridge on the muzzle is small. The ears are well developed, each with a bluntly sickle-shaped tragus. The feet are slender but average larger than those of R. hardwickii . The pelage is short and fine; it is grey brown on the dorsal surface and paler below. It is entirely restricted to the head and body with the membranes naked above and below; the lower back and the posterior lower abdomen are also naked (Rmi2). During the winter there may be considerable fat deposits stored in the region of the thighs, the lower portion of the abdomen and the upper part of the interfemoral membrane. The wings are short with a span of 210-285 mm (Sinha, 1980). The interfemoral membrane is rather small and inserted on each tibia distally at about three-quarters of its length. The baculum is very small; it has a bifid base, a simple tip and a deep groove on the ventral surface (Fig. 37).
Cranial characters
The skull (Rha7), with an average condylo-canine length of 18.9 mm (17.2-22.7 mm), exceeds in size that of the other two species of Rhinopoma known from region. The rostrum is relatively small and the nasals are not conspicuously inflated. The sagittal crest is prominent; commencing in the interorbital region it rises steeply over the frontals and is then sharply reflected backwards with an almost straight superior border. The lambdoid crests are weak and do not overhang the slightly protuberant supraoccipital. The premaxillae are horn-shaped; their expanded bases are not fused to each other in the mid-line nor are they fused to the maxillae. The supraorbital ridges are well developed; there is a well defined hollow, on each side, beneath the nasals, just posterior to the roots of the upper canines. The bony palate is broad and nearly flat; its surface is continuous with the medial expansions of the pterygoid plates, which partly overhang the V-shaped mesopterygoid space. There are no basioccipital pits. The inner margins of the tympanic bullae are flattened; they are relatively smaller than those of R. muscatellum . The general morphology of the mandible is similar to that of R. hardwickii (Fig. 40) but with the coronoid processes more robust. For a complete review of the cranial and post-cranial osteology of this species see Sinha, 1982.
Dentition
- Upper toothrow length (C-M3) averages 7.5 mm (7.0-8.0 mm). The upper incisor (I2) is minute, barely emerging from the gum and with the crown scarcely differentiated from shaft. The upper canine has anterior and posterior cutting edges, but lacks a distinct cingulum. There is one upper premolar (PM4). It is two-thirds the height of the canine; it possesses a low antero-medial protocone and a well developed antero-external cusp which lies over the postero-lateral part of the canine. M1 and M2 are about equal in size; the pattern of cusps and commissures is typical of the W-shaped insectivorous type; the metacone is the highest cusp and the protocone is well developed. M3 is reduced, with a protocone, paracone, parastyle and two commissures. The second commissure is short and recurved laterally; there is a small vestige of the third.
- The lower incisors (i1 and i2) are tricuspidate and set close together in an even curve. The lower canine has a small antero-medial cusp adjacent to I2. The first lower premolar (pm2) is oval-shaped; it has a small anterior and posterior cusp. The second premolar (pm4) is taller and broader than PM2. m1 and m2 are about equal in size, their cusps and commissures arranged in a simple W-pattern. m3 is reduced, with the talonid distinctly smaller than the trigonid.
Variation
Specimens from India are relatively large and are referred to R. m. kinneari ; according to Hill, 1977, forearm length ranges from 64.5-75.0 mm and condylo-basal length 19.5-21.2 mm. Specimens from Pakistan have been referred to R. m. microphyllum ; forearm length ranges from 62.9-71.5 mm and condylobasal length 17.6-19.2 mm. Van Cakenberghe and de Vree, 1994 suggested that further studies may reveal kinneari to be a synonym of R. m. sumatrae Thomas 1903 of Indonesia. According to Gaisler, 1970a, the males are significantly larger than the females.