The Australian National University (ANU) has played a leading role in the discovery of a new species of orangutan, which has been described for the first time in the latest edition of the Current Biology journal.
The Tapanuli orangutan is a population of just 800 apes located in a small patch of forest in the north of Indonesian island Sumatra, making it the most endangered of the now seven known species of great apes.
Anton Nurcahyo, a PhD scholar with the ANU School of Archaeology and Anthropology, undertook a morphology study of the only known specimen of the apes which, combined with a genomic analysis, confirmed the group as a new third species of orangutan.
Mr Nurcahyo said his research showed the new species had smaller measurements than the other two known species of orangutans - the Bornean and the Sumatran orangutans.
"It has a smaller skull, but larger canine teeth than other orangutan species," Mr Nurcahyo said.
Mr Nurcahyo said it was now crucial to protect the small population from extinction.
"We believe the population is no more than 800. They live in a very limited area of around 100,000 square hectares," he said.
"We need to protect the small amount of habitat these orangutans have left."
Professor Colin Groves, a renowned biological anthropologist who has discovered more than 50 species throughout his career, also contributed to the research.
"It's a very significant discovery," said Professor Groves, from the ANU School of Archaeology and Anthropology.
"The orangutan is one of our closest living relatives and we've now found there is more diversity within orangutans than we knew."
The research was conducted in collaboration with 34 institutions including the University of Zurich, the Sumatran Orangutan Conservation Programme, Bogor Agricultural Institute and Liverpool John Moores University.
The full paper - Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species - will be available here once embargo lifts: http://www.cell.com/current-biology/fulltext/S0960-9822(17)31245-9