Systematic classification of Asian colobines

In order to study the differentiation of Asian colobines, fourteen variables were analysed in one way, on 123 skulls, including Rhinopithecus, Presbytis, Presbytiscus, Pygathrix, and Nasalis with both cluster and differentiated functions tests. Information on paleoenvironment changes in China and South-East Asia since late Tertiary have been used to examine the influences of migratory habits and the distribution range in Asian colobines. The cladogram among different Asian colobines genera was made from the results of various analysis. Some new points or revisions were suggested: 1. Following the second migratory way, ancient species of Asian colobines perhaps passed through Xizang along the northern bank of Tethis sea and Heng-Duan Shan regions, across Yunnan into Vietnam, since the ancient continent between Yunnan and Xizang was already located in on eastern bank of Tethis sea. Thus, during the evolution, Asian colobines must have had two original centres, i.e. "Sundaland" and Heng-Duan Shan Chinese regions; 2. Pygatrix possesses a lot of cranial features more similar to Presbytiscus than to Rhinopithecus. The small difference from the modification combines Pygatrix with other two genera as shown by Groves (1970), but it is better to put Pygatrix and Presbytiscus together as one genus; 3. Nasalis (2n=48) may be the most primitive genus within Asian colobines. Some features shared with Rhinopithecus, for example body size, terrestrial activities, limb proportion etc. ...seem to be considered as a common inheritance of symlesiomorphus characters; 4. Rhinopithecus, with reference to cranioface and cranium or to its origin, is a special genus of Asian colobine. It may represent the highest level of evolutionary position within various genera (Peng et al., 1985).