Yenbutra and Felten, 1983
Ratanaworabhan's Fruit bat
External characters (Table 10)
This is a small fruit bat, with an average forearm length of 58.2 mm (52-63 mm). It is similar to Cynopterus brachyotis (CB1) in general size and appearance, but with the external tail absent. The ears are simple (MN1), with broadly rounded tips and without the white margins seen in C. sphinx (CS1). The pelage is soft and fine, uniformly greyish brown on the back, slightly paler across the shoulders. The ventral surface is predominantly grey, with the flanks darker; the median belly has an olivaceous cast. The wing span measures 424 mm (Saha, 1984); the fourth metacarpal is slightly shorter than the third and fifth. The wings are a uniform brown. The interfemoral membrane is narrow; its medial part is hairy.
Cranial characters
The skull (Fig. 23) has an average condylobasal length of 26.2 mm (25.6-26.7 mm). It is similar in size and general form to that of C. brachyotis (Fig. 20) but differs in its shorter rostrum and narrow interorbital region. The rostrum has a squarish outline and in lateral profile is not elevated anteriorly. The basicranial axis, is virtually straight, with only the slightest downward deflection of the basioccipital region. The dorsal profile rises gradually to the midpoint of the braincase before declining steeply to the lambda. The interorbital region has a deep median groove and marked lateral swellings over the orbital margins. The zygomatic arches are flared outwards, especially posteriorly. The palate has a long postdental part. The mesopterygoid space is broad with an essentially straight anterior border. It is constricted behind with the median septum extending from the vomer for most of its length. The tympanic bullae are small. Each half of the mandible has a tall sloping coronoid process of which the anterior border is almost straight; the angular process is broad and rounded and the inferior margin of the horizontal ramus is straight.
Dentition
- Upper toothrow length (C-M1) averages 8.5 mm (8.4-8.6 mm). The dentition is Cynopterine, but with the second upper incisor (I3) reduced and with only one lower incisor (i2). There is only a very small gap between the first upper incisors. The canine (Fig. 23) is broad and robust and without an anterior groove. The premolars and molars are shorter and broader than those of Cynopterus (Fig. 22) The first upper premolar (PM2) is minute, it is located in the toothrow and is subequal in size with the upper incisor. The second premolar (PM3) is robust with a prominent antero-internal and distinct antero-external cusp. The morphology of the third premolar (PM4) and M1 is essentially similar but with PM4 distinctly larger.
- In the mandibular dentition, the single pair of incisors (i2) is situated close together between the canines. The first lower premolar (pm2) is larger than its upper counterpart. The posterior cheekteeth are broad, similar to their upper counterparts. m2 is small.
Variation
Specimens from India are provisionally referred to the nominate race M. n. niphanae . In Thailand, there was no significant difference in size between the sexes. Yenbutra and Felten, 1983 found a knob-like vestige of a tail in two individuals.