Zoogeography of Vietnamese primates

Based on geographic complementarity of congeneric taxa, the 22 species or well-defined subspecies of primates that inhabit Vietnam may be allocated to nine zoogeographic groups (lorises, two; macaques, three; langurs, three; gibbons, one). Analysis of group distributions reveals two major patterns: (1) four of the six non-macaque groups are essentially restricted to the eastern part of the Indochinese Peninsula, east of the Mekong River; and (2) species and subspecies in seven of the nine groups reach their northern or southern limits of distribution in central Vietnam, at 14-17 degrees N. The first pattern suggests that the Mekong River has been an important barrier to westward dispersal of nonmacaque primates in continental Southeast Asia. The second pattern suggests that a zoogeographic barrier formerly extended east and west across Vietnam at ca. 14-17 degrees N.