Roos et al.(2008) recently reconstructed the evolutionary history of the Trachypithecus cristatus group and identified five populations that were ranked as species. The authors concluded that ‘‘further studies, including autosomal and Y chromosomal loci, are necessary to fully understand the evolutionary history of the silvered langur species group”. These data will be particularly important for the T. cristatus group given that males and females have very different dispersal patterns (Rosenblum et al., 1997). Here we would like to briefly alert to a little known case of hybridization between two species, discuss evidence from five nuclear loci, and investigate how many species would be supported under different species concepts (Laamanen et al., 2003). We conclude by urging all authors to be explicit about which species concept was used when proposing new species.