Distinguishing between C. brachyotis and C. cf. brachyotis

The genus Cynopterus, known as the short-nosed fruit bats or dog-faced fruit bats, is widely distributed throughout the Indo-Malayan region of Southeast Asia.  Discriminating between species in this genus is rather difficult, and is further complicated by the fact that many species represent a complex of species with lacking information regarding status and distribution.  One such species is Cynopterus brachyotis which is represented by two forms: C. brachyotis and C. cf. brachyotis Forest.  Differentiation between these 2 forms has typically depended on measures of forearm length, but as Jayaraj et al. (2012) point out, many researchers choose different length values as the cut-off between forms.  Thus Jayaraj et al. developed a classification function based on detailed morphometric variation useful for discriminating between 2 forms of Cynopterus brachyotis.  Results indicate that C. brachyotis can be identified based on its brown fur that has a pronounced yellowish or reddish tinge and a forearm length greater than 60 mm.  Conversely, C. cf. brachyotis Forest has a smaller body size with duller coloration and a forearm length less than 60 mm.  Of the 28 morphometrics characters examined, 5 were considered useful for validating identification of museum specimens: forearm length (RL), 3rd molar tooth crown width and length (M3W, M3L), and 3rd digit metacarpal length and 2nd phalanx length (D3MCL, D3P1L).  Jayaraj et al. conclude that the 2 forms of C. brachyotis are morphologically distinct, which is congruent with previous results using molecular methods.

Jayarak, V.K, Laman, C.J. and M.T. Abdullah. 2012. A predictive model to differentiate the fruit bats Cynopterus brachyotis and C. cf. brachyotis Forest (Chiroptera: Pteorpididae) from Malaysia using multivariate analysis. Zoological Studies 51: 259-271. Jayaraj et al. 2012 Predictive model to differentiate C. brachyotis