New monkey species revealed thanks to distinctive penis

Meet the world's newest monkey. The white-cheeked macaque, Macaca leucogenys, has been discovered in south-eastern Tibet, in biodiverse yet poorly studied forests in the politically volatile area.

It is distinguished from the other four macaque species in the region by its rounded glans penis and a dark, hairy scrotum. Other macaques there have a spear-shaped glans penis and white scrotums. It also has thick, long hair around its neck, unlike the other four species.

  The world's newest monkey, the White-cheeked Macaque, Macaca leucogenys, has been discovered in south-eastern Tibet.

It forages in a wide range of habitats, from tropical forests at an altitude of 1395 metres up to at 2700 metres in mixed forests of broad-leaves and conifers. The landscape of Tibetan state Modog, where it was found, encompasses low-lying grasslands, tropical and evergreen forests and alpine meadows, providing habitats for a great diversity of species.

"It is an area where there's been very little scientific exploration, partly because of political conflicts," says Paul Garber, executive editor of the American Journal of Primatology, where the discovery is reported.

"The forest in Modog is like a nature library, and we know very little about it," says Chao Zhao, a researcher at China's Dali University's Institute of Eastern-Himalaya Biodiversity Research, who worked on the study. "Discovery of the new macaque species suggests that there may be some species that still remain undiscovered in this area."

Caught on camera

His team set up camera traps in four Tibetan gorges capturing more than 700 photos of macaques. They then analysed the photos and compared them with photos of known species.

"Our photos clearly showed some morphological differences between the new species and other known species," says co-author Peng-Fei Fan, also at Dali University.

Given the isolation of this region, Michael A. Schillaci, an anthropologist at the University of Toronto, Scarborough, in Canada also thinks we would expect to see more new species there. But he says that pictures aren't enough to classify this as a new species yet. Only DNA can prove the monkey's distinction from other macaques, he says.

Regardless of its status, the macaque already faces threats from hunting by local tribes and planned construction in the region, the researchers say.

"Construction of hydropower stations would result in destroying and flooding extensive areas of forest along the rivers, the potential habitat for white cheeked macaques," they write. "The immigration of a large number of people into the area to construct the hydropower stations also will result in an increase in the bushmeat trade, deforestation, new roads, and the construction of housing for workers, all of which will have a negative impact on white-cheeked macaque conservation."

Journal reference: American Journal of Primatology, DOI: 10.1002/ajp.22394