New Species of Bornean Slow Loris

15 December 2012

The sight of a Slow Loris (Nycticebus menagensis) staring down at you from the rainforest canopy, its eyes brightly illuminated by your headlamp, is always an exciting find. It was only three weeks ago, whilst I was on a nocturnal foray with a group of photographers in the jungles bordering Sarawak and Kalimantan, that I had my most recent encounter with a loris. Unfortunately, these nocturnal primates are nowhere abundant and sightings of them uncommon at best, due in part to patchy distributions and also sadly, capture for the pet trade.

A new paper in American Journal of Primatology presents a dramatic new view of the loris diversity in Borneo. Previously, three subspecies of loris were known from the island: N. m. bancanus, N. m. borneanus, and N. m. menagensis, which differed from each other in fur coloration and body size. However, taking into account other recent findings in loris diversity, the reseachers of the present paper undertook a thorough investigation on the variation of Bornean lorises, which had never been studied in great detail.

After critically examining a number of museum specimens and carefuly comparing their morphology and corresponding geographic locations, they concluded that there were not three, but four distinct loris types on Borneo, and went further to elevate each of these to its own species status. Thus the presently recognized species now include: N. bancanus, N. borneanus, N. menagensis, and the new N. kayan.

Several months ago I received an email from Dr. Anna Nekaris, who heads The Little Fireface Project, a non-profit organization dedicated to loris research and conservation. She pointed out that one of the animals which I had photographed in Sarawak several years ago represented the newly described Nycticebus kayan (pictured below). Specifically, the Kayan Loris can be distinguished from other Bornean lorises by a combination of features including its highly contrasting and distinctive face mask.

Nycticebus kayan

Like all lorises, the Kayan Loris is primarily nocturnal and feeds on a variety of insects and soft fruits. Lorises are also unique among primates in that they possess a venomous bite which is used in self-defense. The bite can cause fever, pain, and swelling, and in people who happen to be allergic the results may even be fatal. One Sarawakian who I met in Mulu National Park, had to be hospitalized for several days after being bitten when handling a wild loris.

Although more research, including genetic studies, remains to be done on Bornean lorises, the new discovery helps not only to shed light on the variations of these nocturnal primates, but also is a testament to the amazing diversity which is continuing to be revealed within Southeast Asian rainforests.


R. Munds, S. Ford, K.A.I. Nekaris. Taxonomy of the Bornean Slow Loris, with New Species Nycticbus kayan (Priamtes Lorisdae). American Journal of Primatology, December 2012; DOI: 10.

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