With only a population of 800, the Tapanuli orangutans, which have thick curly hair, became the third species of the giant ape found in the country.
The Tapanuli orangutan or Pongo tapanuliensis has been named as a new species found in Sumatra, Indonesia, based on research from the Ministry of Environment and Forestry (KLHK), Lembaga Ilmu Pengetahuan Indonesia (LIPI), Institut Pertanian Bogor (IPB) and various other parties.
"It isn't an everyday event that we find a new species of great ape, so indeed the discovery is very exciting", said Michael Krutzen from the University of Zurich. The first hints suggesting the orangutans belonged to a distinct new species surfaced in 2013, when scientists examined the skull of an orangutan male killed in the area. Comparisons with skeletons of 33 Sumatran and Bornean male orangutans revealed a range of differences in the skull and teeth of the Tapanuli ape, including a distinctively narrow palate and a relatively short jaw joint.
They have smaller skulls and jawbones, when compared to the other two species - Borneo and Sumatran orangutans.
It's the first great ape species to be described by scientists in almost 90 years. Dubbed Pongo Tapanuliensis, the population was discovered 20 years ago, but it's only after comprehensive studies of the animals' genomes and skull morphology that scientists were able to confirm it as a distinct species.
"The Batang Toru orangutans appear to be direct descendants of the initial orangutans that had migrated from mainland Asia, and thus constitute the oldest evolutionary line within the genus Pongo", said Alexander Nater, researcher at the Unversity of Zurich.
There is no standardized worldwide system for recognition of new species, but to be taken seriously a discovery requires at least publication in a credible peer-reviewed scientific journal.
"It's very worrying", said Prof Wich, "to discover something new and then immediately also realise that we have to focus all of our efforts before we lose it".
There are only believed to be around 800 Tapanuli orangutans left. Orangutans typically do not live in high altitude areas.
"Great apes are among the best-studied species in the world", said Erik Meijaard, a researcher at the Australian National University. "Humans are conducting a vast global experiment, but we have near-zero understanding of what impacts this really has, and how it could ultimately undermine our own survival". That makes the Tapanuli population extremely vulnerable and the great ape species at the greatest risk of extinction.
Prior to the recognition of these orangutans living in Indonesia forest, there are seven living species of great ape that biologists recognize namely humans, chimpanzees, bonobos, eastern gorillas, western gorillas, Sumatran orangutans and Bornean orangutans.