Molecular phylogenetic relationships among Sichuan snub-nosed monkeys (Rhinopithecus troxellanae) inferred from mitochondrial cytochrome-b gene sequences

The Sichuan snub-nosed monkey (Rhinopithecus roxellanae) is a species endem ic to China, and its distribution is the widest among all snub-nosed monkey s in China. To clarify whether there is subspecific differentiation within this species, we determined partial sequences of the cytochrome-b gene from four populations of R, roxellanae. First, 402bps of the partial sequences from R. roxellanae were compared with those from R. bieti and R. avunculus, and the phylogenetic tree was constructed by the neighbor-joining method. The genetic distance was only 0 - 0.02 among the four populations, and thei r sequences constituted a monophyletic group. Further, comparison of longer sequences (735bp) among the four populations revealed that there were only four substitutions and the genetic distance was only 0.001-0.005 among the m. Thus, we suggest that, at least on mtDNA phylogeny, the difference among the four populations does not reach the subspecies level, and that this sp ecies should be recognized as a monotypic species.