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Tapanuli Orangutan, Pongo tapanuliensis, the Rarest Great Ape

A study published today (Nov. 2, 2017) in the journal Current Biology (“Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species“), lists the Tapanuli Orangutan  (Pongo tapanuliensis) as the rarest great ape on Earth, with population estimates lower than 800 individuals (for more info on the the rarest ape/primate species see Rarest Primates). The great apes are all found in the family Hominidae, and include: orangutans, gorillas, chimpanzees, and humans.

Credit: J. You (SCIENCE)
Credit: J. You (SCIENCE)

Found in the upland forest regions of the island of Sumatra, the Tapanuli orangutan was previously thought to be within the same species as the Sumatran orangutan. Scientists used genetic analysis to confirm the morphometric information ( = analysis of form [shape and size]) to distinguish the Tapanuli from the Sumatran orangutan. Morphologically identifying features included a generally smaller skull, teeth shape, and facial shapes. Interestingly the males long roar call (audio) has a longer duration and higher maximum frequency than the Sumatran or the Bornean orangutan. A bit more obvious to the casual observer, the Tapanuli orangutan has a body build more similar to the Sumatran (linear), but coloring more similar to the Bornean (but even more cinnamon-y). The Tapanuli is also frizzier than both other species, and the female is bearded.

 

Current (as of today) classification for the great apes, Hominidae (only currently extant [ = living] species included), and all but 3 are considered critically endangered and 2 of the remaining 3 are considered endangered:

  • Family Hominidae
  • Subfamily Ponginae
    • Tribe Pongini
      • Genus Pongo
        • Bornean orangutan, Pongo pygmaeus
        • Sumatran orangutan, Pongo abelii
        • Tapanuli orangutan, Pongo tapanuliensis
  • Subfamily Homininae
    • Tribe Gorillini
      • Genus Gorilla
        • Western gorilla, Gorilla gorilla
        • Eastern gorilla, Gorilla beringei
    • Tribe Hominini
      • Subtribe Panina
        • Genus Pan
          • Chimpanzee (common chimpanzee), Pan troglodytes
          • Bonobo (pygmy chimpanzee), Pan paniscus
      • Subtribe Hominina
        • Genus Homo
          • Human, Homo sapiens (modern human is designated Homo sapiens sapiens)