The new macaque species has a distinctive yellow patch on its forehead.© M. D. Madhusudan

The surprise discovery of a new species of monkey in India bucks a trend. Named Macaca munzala or the Arunachal macaque (after the Arunachal Pradesh area in which it was sighted), it has been found at a time when many monkey species are in decline.

As a well populated country of over a billion people, India seems an unlikely place to discover a new primate species. The last time that researchers spotted a new macaque was in the Mentawai islands of Indonesia in 1903.

Careful labelling

The new species was found by scientists on a research expedition to unexplored high-altitude areas of northeastern India. They came across an unusual looking macaque with a distinctive crown of dark hairs surrounded by a prominent pale-yellow patch.

The animal's uncommon appearance hinted at its uniqueness. "It combined morphological traits of two species, and was therefore not a subspecies of an already known macaque species," says M. D. Madhusudan, an ecologist with the Nature Conservation Foundation in Mysore and a member of the expedition. He and his colleagues will report the discovery next year in the International Journal of Primatology.

After detailed investigation, he and his fellow researchers concluded that their new monkey was not a hybrid, because the two potential parent species did not occur together in the area. Also, it was not an isolated find. The expedition discovered a number of M. munzala troops over 1,200 square kilometres, all closely resembling one another.

New heights

The newly identified species has grabbed the attention of ecologists as it is one of the highest-dwelling primates in the world. "First and foremost, the discovery of a high-altitude macaque species has tremendous significance for our understanding of macaque biology," says coauthor Anindya Sinha of the Indian Institute of Science in Bangalore<fnr rid='f1'> *</fnr>, referring to the monkeys' ability to adapt to a wide range of habitats.

"It's significant that any large mammal species are being discovered now," says Neil Bemment, an expert on Old World monkeys and chairman of the British and Irish primate taxon advisory group, part of the international effort to name species.

He adds that it is not uncommon for scientists to pick out new monkey species, but that they usually only differ subtly from known species. "Sometimes people suddenly realize with genetic studies that one species is actually two," Bemment explains.

Finding a new species by direct observation, as the team in India did, remains far less common. "I would regard it as an important discovery," says Joseph Kemnitz, director of the National Primate Research Center at the University of Wisconsin, Madison. "We hear so much about primate species disappearing that it's fascinating to learn about the discovery of a new species." 

Indian Institute of Science in Bangalore