A third species of orangutan has been recognised – but less than a thousand are still alive, warns new research.
Previously only two species of orangutans were identified – the Bornean and the Sumatran orangutan.
Now, researchers have described a new great ape species, the Tapanuli orangutan.
But with only around 800 remaining individuals in upland forest regions of North Sumatra, it is at great risk of extinction, according to the study.
A third species of orangutan has been recognised – but less than a thousand are still alive, warns new research. The new species has been called the Tapanuli orangutan (pictured)
Two species of Indonesian orangutans had previously been officially recognised – the Pongo abelii, living on the island of Sumatra, and the Pongo pygmeaeus, in Borneo.
In 1997, researchers from the Australian National University discovered an isolated population of orangutans in Batang Toru, a region within the three Tapanuli districts in North Sumatra.
A team led by experts at the University of Zurich (UZH) in Switzerland have now established that these orangutans are a distinct third species, Pongo tapanuliensis.
The study, from an international research team, forms part of the largest genomic study of wild orangutans to date.
They said the first indications of the uniqueness of the new species came from the skeletal material of an adult male orangutan killed in 2013.
When compared to other skulls it turned out that certain characteristics of the teeth and skull of the Tapanuli orangutan were unique.
Dr Matt Nowak, from the Sumatran Orangutan Conservation Programme (SOCP), said: ‘We were quite surprised that the skull was quite different in some characteristics from anything we had seen before.’
Study lead author Professor Michael Krützen, of UZH, said: ‘When we realised that the Tapanuli orangutans were morphologically different from all other orangutans, the pieces of the puzzle fell into place.’
Professor Krützen and his team have been researching the genetic lineage of all living orangutan populations for some time.
With only around 800 remaining individuals in upland forest regions of North Sumatra, the Tapanuli orangutan is at great risk of extinction, according to the study. When compared to other skulls certain characteristics of the teeth and skull were unique
The first indications of the uniqueness of the new species came from the skeletal material (pictured) of an adult male orangutan killed in 2013. When compared to other skulls it turned out that certain characteristics of the teeth and skull were unique
Previous study results combined with the new genome sequencing of 37 orangutans showed a picture that was consistent with the morphological findings.
Dr Maja Mattle-Greminger, also of UZH, said: ‘We identified three very old evolutionary lineages among all orangutans, despite only having two species currently described.’
Computer modelling aimed at reconstructing the history of the orangutan population enabled the researchers to verify their new findings.
Their calculations showed that the Tapanuli population was isolated from all other Sumatran populations of orangutans for 10,000 to 20,000 years.
Previous study results combined with the new genome sequencing of 37 orangutans showed a picture that was consistent with the morphological findings. Pictured is a member of the new species
Alexander Nater, from UZH, said: ‘The oldest evolutionary line in the genus Pongo is actually found in Tapanuli orangutans, which appear to be direct descendants of the first Sumatran population in the Sunda archipelago.’
Professor Krutzen said: ‘It is very exciting to discover a new great ape species in the 21st century.’
But he warned that the top priority now must be to protect the Tapanuli orangutan.
Professor Krutzen added: ‘All conservation efforts must focus on protecting the species’ environment.’
Computer modelling aimed at reconstructing the history of the orangutan population enabled the researchers to verify their new findings. Their calculations showed that the Tapanuli population was isolated from all other Sumatran populations of orangutans for 10,000 years
Two species of Indonesian orangutans had previously been officially recognised – the Pongo abelii (left), living on the island of Sumatra, and the Pongo pygmeaeus (right), in Borneo
He said more and more rainforest is being lost to agricultural use – virgin forests in the Batang Toru ecosystem are giving way to palm oil plantations.
And there are also plans to build a hydroelectric dam which would further intrude on the Tapanuli orangutans’ environment.
A recent survey carried out independently by Indonesian and international scientists indicated that no more than 800 Tapanuli orangutans remaining, making them the great ape species at greatest risk of extinction.
Dr Nowak, who supervises research into the Tapanuli orangutans at SOCP, said: ‘If steps are not taken quickly to reduce current and future threats and to conserve every last remaining bit of forest, a great ape species may become extinct within a few decades.’