The Tenasserim Lutung, Trachypithecus barbei (Blyth, 1847) is the least known of all of Asia’s primates. For instance, the only synthesis of colobine research (Davies and Oates, 1994) mentions T. barbei only once and does not provide any information on the species. Likewise, Corbet and Hill (1992)include the species as Semnopithecus incertae sedis, and Rowe (1996)does not mention it at all. The species is restricted to a tiny range around 14°00’-15°15’N, 98°00’-98°25’E on the Burma-Thailand border. It was described by Blyth (1847), but redescribed by him in 1863 in a way which has muddied the waters ever since.
On 21 March 2001, TG encountered a leaf monkey at the Bangkok Zoo which, to judge by facial characteristics, appeared to be a member of the T. obscurus group (sensu Groves, 2001, i.e. including T. obscurus and T. phayrei) but did not fit the description of either T. obscurus or T. phayrei. The mammal curator of the Bangkok Zoo, Dr. Yong Chai, suggested it might be a hybrid between the two species. The provenance of the animal is unknown; it was bought in an animal market. Because captive leaf monkeys have rarely bred in Asia (TG, pers. observation in numerous zoos), the study animal is unlikely to be captive bred. This leaf monkey will be referred to as simply “study animal” in the following text.
CPG examined the syntypes of Pr(esbytis) barbei Blyth in the Zoological Survey of India, Calcutta, in the early 1980s, and specimens of Thai and Burmese lutungs in the Natural History Museum, London, in the 1980s and 1990s and in October, 2003.