New frizzy-haired orangutan species discovered on Sumatra

A remote population of frizzy-haired orangutans on the island of Sumatra appears to be a new species of primate, scientists have revealed.

Numbers of the new species, Pongo tapanuliensis, are so small and their habitat is so fragmented that they are in danger of going extinct.

A study published on Thursday in the journal Current Biology says there are no more than 800 of the primates - making it the most endangered great ape species.

Researchers say the population is highly vulnerable and its habitat is under further pressure from development.

It is the first newly discovered great ape species in nearly 90 years.

Previously, science recognised six great ape species: Sumatran and Bornean orangutans; eastern and western gorillas; chimpanzees and bonobos.

Researchers analysed the skeleton of an adult male killed in a conflict with villagers.

They found the population's evolutionary split from other orangutans occurred about 3.4 million years ago.

The apes are confined to a range of about 425 sq miles in the Batang Toru forest, Tapanuli district, of northern Sumatra.

Historically, the population had low levels of interbreeding with Sumatran orangutans further north, but that completely ceased between 10,000 and 20,000 years ago, the study said.

Physical differences between the species include frizzier hair and a smaller head. They also differ in diet, restriction of habitat to upland areas and the males have a long call.

The Batang Toru population was discovered during a field survey by researcher Erik Meijaard in 1997 and a research station was set up in the area in 2006.

It was only until 2013 when the adult male skeleton became available that scientists realised how unique the population was.