Temminck, 1834
Least Horseshoe bat
External characters (Table 30)
This is a small species with an average forearm measurement of 37.0 mm (34.9-37.8 mm). This is significantly shorter than that of R. lepidus (39.8 mm; 37.0-41.8 mm). Unlike R. hipposideros , the third metacarpal is about equal to or exceeds the combined lengths of its respective phalanges (105%, 99-113%). The tibiae are relatively short. In lateral view, the connecting process of the sella is triangular in shape, comparable to but usually more acute in outline than that of R. lepidus (Rle2); in some specimens, it tends towards the more horn-like processes of R. subbadius and R. cognatus . When viewed from in front, the base of the sella, like that of R. lepidus has a broadly rounded outline (Rpu1). Unlike that of R. hipposideros , the inferior extremity of the sella does not project downwards (Fig. 73, Rpu2). Lancet shape and size varies from a short equilateral triangle to a more elongated structure. As in R. lepidus , the pelage is very fine and soft; the colour ranges from light buffy brown to dark teak brown on the dorsal surface, with paler hair bases; the ventral surface is paler.
Cranial characters
The skull is comparable in size and morphology to that of R. hipposideros . It differs from that of R. lepidus by its average smaller size, particularly noticeable in the condylo-canine length (13.6 mm; 13.0-14.0 mm); it also averages narrower across the zygomata and braincase. The rostral inflations are less well developed than those of R. lepidus and in consequence the rostral profile tends to be straighter, not curving upwards anteriorly. The rostrum and palate, as measured across the canines (C1-C1) and maxillary molars (M3-M3) are narrower.
Dentition
- Upper toothrow length (C-M3) averages 5.8 mm (5.4-6.0 mm). The upper and lower canines clearly exceed in size those of R. hipposideros . The small anterior premolar (PM2) is well developed and situated in the toothrow. Unlike R. hipposideros , the third upper molar (M3) is without a distinct fourth commissure and metastyle.
- The second lower premolar (pm3) is small and usually situated externally to the toothrow; the first (pm2) and third (pm4) lower premolars are sometimes in contact.
Variation
The single specimen from Malabar in southern India is provisionally considered as a discrete taxon R. p. gracilis . Specimens from northern India are referred to R. p. blythi which is characterised by its short tibiae (Sinha, 1973). However, according to Corbet and Hill, 1992 blythi is closely similar to gracilis .
Taxonomic remarks
Sinha, 1973 assigned all specimens currently referred to R. pusillus to R. cornutus . Hill and Yoshiyuki, 1980 noted that it was highly probable that cornutus and pusillus are conspecific but Corbet and Hill, 1992 maintained them as discrete species.