Horsfield, 1823
Intermediate Horseshoe bat
External characters (Table 27)
This is a smaller species than R. ferrumequinum with an average forearm length of 53.3 mm (50.0-55.0 mm). The ears are also significantly shorter (Raf1, Rfe1). The noseleaf is essentially similar in all characters to that of R. ferrumequinum although the horseshoe is relatively broader (BW15). In the wing, the third metacarpal averages 3.5% (0.4-6.6%) shorter than the fourth metacarpal and 6.2% (3.6-7.7%) shorter than the fifth. The first phalanx of the third metacarpal is short in comparison to that of R. ferrumequinum ; considerably less than half the length of the metacarpal. The second phalanx is long, about three-quarters the length of the metacarpal (73.1%, 66.3-80.4%). In R. rouxii from peninsular India and Sri Lanka, it is less than two-thirds the length (in R. r. sinicus from the Himalayas it is relatively longer, averaging 69.9%). The pelage is variable in colour ranging from buffy brown to a distinctive orange; females appear to average darker.
Cranial characters
The skull is smaller than that of R. ferrumequinum with an average condylo-canine length of 19.7 mm (18.7-20.5 mm). The zygomata are less flared posteriorly. The palate is exceedingly short, usually less than one quarter the length of the maxillary toothrow, in R. rouxii and R. ferrumequinum it is nearer one third; it is emarginated anteriorly to the level of the parastyle of m1 and posteriorly to the mesostyle of m2. The anterior border of the mesopterygoid space is significantly broader than that of R. ferrumequinum . The tympanic bullae are small; they cover about one third of the large cochleae. In each half mandible, the coronoid process is less developed than that of R. ferrumequinum , it only slightly exceeds the condyle in height; the angular process is more angulated outwards.
Dentition
- The upper toothrow (C-M3) averages 8.9 mm (8.5-9.5 mm) in length. It is shorter than that of R. ferrumequinum and the upper canine is less robust. The first upper premolar (PM2) is small but situated in the toothrow. The cingulum of the canine is not in contact with the second upper premolar (PM4). The maxillary premolars and molars are essentially similar in structure to those of R. ferrumequinum (Fig. 61b), although M3 is relatively larger with a crown area equal to two-thirds to three-quarters that of M2.
- In the mandibular dentition, the first (pm2) and third (pm4) premolars are in contact; the second (pm3) is usually very small and is situated externally to the toothrow.
Variation
Specimens from northern India are referred to R. a. himalayanus . This race averages larger than the nominate subspecies R. a. affinis but with the ears relatively smaller, the horseshoe narrower and the tail and tibiae comparatively short.