Molecular systematics of Indochinese primates

Abstract

Summary The systematics of primates distributed in the Indochinese bioregion is still controversial. Based on molecular data, we established a solid platform for the classification of all the Indochinese primate taxa. Accordingly, among strepsirrhines, two slow loris species (N. pygmaeus and N. bengalensis) occur in Indochina. The only cercopithecines distributed in Asia are members of the genus Macaca. Among them, five species occur in Indochina (M. arctoides, M. assamensis, M. fascicularis, M. mulatta and M. leonina). The distinct species status for all of them is confirmed and two subspecies are provisionally recognised for M. fascicularis. The colobines of Indochina are divided into the three genera Pygathrix, Rhinopithecus and Trachypithecus. The douc langurs (Pygathrix) are represented by the three monotypic species P. cinerea, P. nemaeus and P. nigripes. Within the snub-nosed monkeys (genus Rhinopithecus), the distinct species status for the four recognised species (R. avunculus, R. bieti, R. brelichi, R. roxellana) is confirmed, but further investigations are necessary to elucidate the taxonomic position of the three described R. roxellana subspecies. In Indochina, the genus Trachypithecus is represented by three species groups [T. obscurus], [T. cristatus] and [T. francoisi]. Based on the molecular data, the only Indochinese representative of the [T. obscurus] group, T. crepusculus, is mitochondrially more closely related to the [T. francoisi] group. However, in the Y-chromosomal data set, the taxon forms a clade together with the other [T. obscurus] group members, indicating that the species is the result of ancestral hybridisation between the two species groups. The [T. cristatus] group in Indochina is represented by the two species T. margarita and T. germaini, most likely separated from each other by the Mekong River. Within the [T. francoisi] group, the four taxa T. delacouri, T. francoisi, T. poliocephalus and T. laotum should be recognised as distinct species, with leucocephalus and hatinhensis being subspecies of T. poliocephalus and T. laotum, respectively. For the crested gibbons (genus Nomascus), we propose that N. hainanus, N. nasutus, N. concolor, N. leucogenys and N. gabriellae be recognized as distinct species. The subspecies of N. concolor are downgraded as synonyms of the nominate form, and N. siki is provisionally classified as subspecies of N. leucogenys, although further research is needed on this question.