The Tenasserim lutung Trachypithecus barbei was previously known from museum specimens and field observations only. We discovered a zoo specimen and present the first confirmed evidence for the continued existence of the species since 1967. We describe the cranial pelage and coloration characteristics of this species which were previously unknown. We present first molecular evidence for recognizing T. barbei as a distinct species and for assessing its phylogenetic affinities relative to other members of the genus Trachypithecus. We document the taxonomic history of T. barbei and present a distribution map based on a compilation of all known locality records.