DISCOVERY OF A CONTACT ZONE BETWEEN GOLDEN LANGURS (TRACHYPITHECUS GEEI) AND CAPPED LANGURS (TRACHYPITHECUS PILEATUS) IN BHUTAN. |
T. Wangchuk1; Y. Kawamoto2 and M. Aimi2
1Department of Biology, University of Maryland, 4614 Clemson Rd, College Park, MD, 20740, USA, 2Primate Research Institute, Kyoto University |
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| We report new information on the distribution of Golden
Langurs (Trachypithecus geei) and Capped Langurs (Trachypithecus pileatus) in Bhutan. The boundary is now confirmed as the Chamkhar / Mangde / Manas river complex, further west than previously thought. This reduces the distribution range of the endangered Golden Langur, previously estimated at about 2000 km2, to current estimates of 1,400 km2, a 30% reduction. The two species were also assumed to be completely allopatric, separated by natural barriers such as rivers and mountain ranges. However, recent field work found a contact zone where capped langurs have penetrated the river barrier into golden langur area due to the construction of a bridge in 1980. In this area, a single large group of 15 individuals with great variations in coat color patterns was observed. The group contained members with typical Golden Langur coat pattern as well as typical Capped Langur pattern with several that were gradations of intermediaries between the two. Preliminary mitochondrial DNA sequences of the cytochrome b marker show that hybridization may have occurred. Important questions about the taxonomic status of the species arise. Also, this provides a possible case study of the biological species concept with specific references to secondary contact zones and incomplete speciation.
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