(MÜller, 1838)
Lesser Dog-faced Fruit bat
External characters (Table 9)
This species averages smaller than Cynopterus sphinx with a forearm length of 60.3 mm (57.3-63.3 mm). In general, it can be distinguished by its smaller ears which do not exceed 18 mm in length (CB1). In comparison to C. sphinx (CS1), the pale borders of the ears are narrow or absent (in material from the Indian subcontinent). The finger bones of the wing (CB2) tend to be darker as compared to the pale metacarpals and phalanges of C. sphinx (CS3). In all other external characters, the two species appear essentially similar. The baculum differs in the development of the shoulders, which are relatively higher in C. brachyotis (Fig. 19).
Cranial characters
The skull (Fig. 20) averages smaller than that of C. sphinx with a condylobasal length of 27.6 mm (26.0-28.8 mm). It is closely similar in morphology.
Dentition
Upper toothrow length (C-M1) averages 9.7 mm (8.9-10.7 mm). The dentition (Fig. 22) cannot be distinguished from that of C. sphinx except by its average smaller size.
Variation
Andersen, 1912 provisionally referred specimens from Sri Lanka to C. b. ceylonensis , although he suggested that the characters that distinguish this subspecies from C. b. brachyotis are trivial.
Taxonomic remarks
The relationship of the taxa sphinx and brachyotis in Sri Lanka and southern India is unclear. Phillips, 1934 included all specimens of Cynopterus from Sri Lanka in C. sphinx . He noted that individuals typical of C. s. sphinx are commonly distributed throughout the lowlands. However, in the hills, there is a distinct tendency among individuals towards a darkening of the pelage and a stunting of body size, which becomes more marked with increasing altitude. It is a gradual process, so much so that in almost any collection from a medium altitude of 2000 feet (615 metres) to 3000 feet (923 metres) both large and small individuals may be found (CB3), although the collection may consist of specimens taken from a single colony. In the highest mountains, at altitudes of 4000 feet (1231 metres) and over, very few, if any, individuals corresponding to the description of C. s. sphinx , will be found. The small dark form, ceylonensis alone is represented. "The highland and lowland form intergrade into one another so completely, at medium altitudes, that it is impossible to determine to which a given specimen is referable. ... they must be looked upon as merely well marked races of one and the same species." This view is contrary to Andersen, 1912 and was not followed by Hill and Thonglongya, 1972 and Kitchener and Maharadatunkamsi, 1991 who both refer ceylonensis to C. brachyotis . Yong et al., 1973 note that the karyology of C. sphinx and C. brachyotis suggest a close evolutionary relationship. A further study of this complex group is currently being undertaken in Sri Lanka.