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Taxonomy of the Bornean Slow Loris, With New Species Nycticebus kayan (Primates, Lorisidae)


  • Contract grant sponsor: Systematics Research Fund of the Linnaean Society; Contract grant sponsor: Primate Conservation Inc.; Contract grant sponsor: International Animal Rescue Indonesia; Contract grant sponsor: Royal Society; Contract grant sponsor: Primate Society of Great Britain; Contract grant sponsor: Primate Conservation Inc.; Contract grant sponsor: Primate Action Fund; Contract grant sponsor: Margot Marsh Biodiversity Foundation; Contract grant sponsor: SYNTHESYS Project (European Community Research Infrastructure Action, FP6 “Structuring the European Research Area” Programme); Contract grant number: NL-TAF-3491.

Correspondence to: Rachel A. Munds, Department of Anthropology, 107 Swallow Hall, University of Missouri, Columbia, MO 65203, USA. E-mail:


More species of nocturnal primates are now recognized than in the past, because many are cryptic species. Subtle morphological disparities, such as pelage pattern and color variation, vocal cues, and genetics have aided in elucidating the number of diagnosable species in a genus. The slow lorises (genus Nycticebus) once included only two species, but recent taxonomic studies resulted in the description of three additional species; further incompletely explored variability characterizes each of the currently described species. The Bornean loris in particular is characterized by pelage and body size variation. In this study, we explored facemask variation in the Bornean loris (N. menagensis). Differing facemask patterns, particularly influenced by the amount of white on the face, significantly clustered together by geographic regions, separated by notable geographic boundaries. Our results support the recognition of four species of Bornean lorises: N. menagensis, N. bancanus, N. borneanus, and N. kayan. Genetic studies are required to support these findings and to refine further our understanding of the marked variability within the Bornean loris populations. Am. J. Primatol. 75:46-56, 2013. © 2012 Wiley Periodicals, Inc.