(Linnaeus, 1758)
Lesser False Vampire
External characters (Table 25)
A smaller species than Megaderma lyra with an average forearm length of 56.9 mm (54.0-62.0 mm). The tibiae are relatively long (33 mm) and are about equal in size to those of M. lyra . The interfemoral membrane is also larger. The face differs in the shape of the vertical noseleaf which is shorter than that of M. lyra (Mly1), measuring some 6.5 mm in height; it has convex rather than straight sides and its longitudinal ridge has a characteristic heart-shaped base (Msp1). Generally, the horizontal base of noseleaf is larger than that of M. lyra ; its anterior margin is thickened and attached directly to the muzzle. The ears are joined medially much closer to the forehead, at about 10-15% of the height of inner margin (Msp2); in M. lyra the comparable figure is 30-50% (Rmi5). The posterior part of each tragus is narrower and taller. The pelage is a deep grey on the upper surface; it is paler grey on the belly. The baculum is small, with a distinctive base comprised of two prongs (Fig. 59).
Cranial characters
The skull, with average condylo-canine length of 22.7 mm (21.9-23.6 mm), is significantly smaller than that of M. lyra . The frontals and braincase are distinctly narrower. The basisphenoid pits are deeper and better developed and the basioccipital is narrower. Each half mandible has a short horizontal ramus. However, the coronoid process is taller than that of M. lyra (Fig. 56); it exceeds the canine in height and has a relatively steeper posterior margin sloping down to the well developed condyle.
Dentition
- The teeth, with an average Upper toothrow length (C-M3) of 9.8 mm (9.3-10.5 mm) are significantly smaller than those of M. lyra (Fig. 57). The morphology is generally similar except that the hypoconal flanges of the large second upper premolar (PM4), M1 and M2 are much less developed.
- In the lower dentition, the first premolar (pm2) is relatively larger than that of M. lyra ; it is about equal to the second (pm4) in crown area.
Karyology
2N=38, FN=64, based on specimens from Thailand; includes 14 pairs of metacentric-submetacentrics and four pairs of acrocentric chromosomes; the X chromosome is a medium-sized subtelocentric and the Y chromosome an acrocentric (Hood et al., 1988).
Variation
Specimens from India and Sri Lanka are referred to M. s. horsfieldi . Although Andersen, 1918 suggested that individuals from Sri Lanka average smaller than those from peninsular India and should be referred to a distinct subspecies M. s. ceylonense , there would appear to be a clear overlap in all measurements between the two taxa. Therefore, at present the form ceylonense is not considered taxonomically distinct.