An international team of researchers has rediscovered the extremely rare primate Miller’s Grizzled Langur, a species which was believed to be extinct or on the verge of extinction.

Miller’s Grizzled Langur (Presbytis hosei canicrus) is part of the small primate genus Presbytis, found across Borneo, Sumatra, Java and the Thai-Malay Peninsula.

In the study, published in the American Journal of Primatology, the team confirms the continued existence of this monkey and reveals that it now lives in Wehea Forest, an area where it was previously not known to exist.

Wehea is a large 38,000 ha area of mostly undisturbed rainforest in East Kalimantan, Borneo, which contains at least nine known species of non-human primate, including the Bornean orangutan and gibbon.

“Discovery of Presbytis hosei canicrus was a surprise since Wehea Forest lies outside of this monkey’s known range. Future research will focus on estimating the population density for Presbytis hosei canicrus in Wehea and the surrounding forest,” said Brent Loken, an executive director of the conservation NGO Ethical Expeditions and Ph.D student at Simon Fraser University Canada. “Concern that the species may have gone extinct was first raised in 2004, and a search for the monkey during another expedition in 2008 supported the assertion that the situation was dire.”

“It was a challenge to confirm our finding as there are so few pictures of this monkey available for study,” said Loken. “The only description of Miller’s Grizzled Langur came from museum specimens. Our photographs from Wehea are some of the only pictures that we have of this monkey.”

The team found that Presbytis hosei canicrus continues to survive in areas west of its previously recorded geographic range.

“East Kalimantan can be a challenging place to conduct research, given the remoteness of many remaining forested areas, so it isn’t surprising that so little is known about this primate,” said Dr. Stephanie Spehar, a study co-author and assistant professor of anthropology at University of Wisconsin Oshkosh. “We are very grateful to our local partners. This discovery represents the hard work, dedication, and collaboration of Western and Indonesian scientists, students, NGOs, as well as local communities and government.”

“While our finding confirms the monkey still exists in East Kalimantan, there is a good chance that it remains one of the world’s most endangered primates. I believe it is a race against time to protect many species in Borneo. It is difficult to adopt conservation strategies to protect species when we don’t even know the extent of where they live. We need more scientists in the field working on understudied species such as Miller’s Grizzled Langur, clouded leopards and sun bears,” concluded Brent Loken.