It looks like we may have a new monkey species under our scientific radar, thanks to its stand out genitals. The newly discovered animal, the white-cheeked macaque (Macaca leucogenys), was recently identified as a previously unknown species due its distinctive penis and scrotal coloration that distinguish it from other macaques residing in the same area.

The monkey lives in southeastern Tibet, a biodiversity hotspot located at the junction between the Eastern Himalaya and Indo-Burma region. Although this area is known to be rich in wildlife and to possess a broad range of ecosystems, such as subtropical forests and alpine meadows, it remains a poorly studied area, partly because of political volatility.

Prior to this study, four different species of macaque had been described in the area, but some scientists had questioned these classifications. This was primarily due to the fact that one particular species seemed to display great variety in various visible characteristics, such as tail length, facial skin color and facial hair patterns.

With the goal of finding out more about macaque diversity in this region, scientists set up camera trips to survey the local populations residing in southeastern Tibet and then combined this data with direct field observations. Over a two year period, the scientists collected a total of 738 photos of macaques, which clearly demonstrated the presence of a macaque with different characteristics to those already described in the area.

For example, the distinctive species had a dark, hairy scrotum, unlike the other known species that possess white scrotums. Furthermore, the shape of the animal’s glans (the head of the penis) was also round, whilst the other macaques have arrow-shaped, or sagittate, glans’. Alongside their unique genitals, the white-cheeked macaque also had prominent white side- and chin-whiskers and a bushy neck, which further distinguished it from the other documented species. These findings have been published in the American Journal of Primatology and reported by New Scientist.

Although some scientists argue that a new species cannot be classified purely by photographs, the researchers decided not to obtain a voucher specimen, which is usually a cadaver, due to the ethical concerns surrounding killing wild primates. But if they could obtain some DNA samples, they would be able to back up their classification. Regardless, the researchers are hopeful that their discovery could be an indication that there are other previously unknown species waiting to be found in this area.

Unfortunately, even though we haven’t got to know this species yet, it is already threatened by man due to illegal hunting and habitat loss from the construction of hydropower stations. Since macaques raid crops in the area, the researchers report that half the local people interviewed would kill macaques to save their produce. The study therefore highlights the need for conservation and further biodiversity surveys in the area.