Bornean Orangutan - Taxonomy

Taxonomy

The Bornean orangutan and the Sumatran orangutan diverged about 400,000 years ago, with a continued low level of gene flow between them since then. The two orangutan species were considered merely subspecies until 1996; they were elevated to species following sequencing of their mitochondrial DNA.

The Bornean orangutan has three subspecies:

• Northwest Bornean orangutan P. p. pygmaeus – Sarawak (Malaysia) & northern West Kalimantan (Indonesia)
• Central Bornean orangutan P. p. wurmbii – Southern West Kalimantan & Central Kalimantan (Indonesia)
• Northeast Bornean orangutan P. p. morio – East Kalimantan (Indonesia) & Sabah (Malaysia)

There is some uncertainty about this, however. The population currently listed as P. p. wurmbii may be closer to the Sumatran orangutan (P. abelii) than to the Bornean orangutan. If this is confirmed, P. abelii would be a subspecies of P. wurmbii (Tiedeman, 1808). In addition, the type locality of P. pygmaeus has not been established beyond doubt; it may be from the population currently listed as P. wurmbii (in which case P. wurmbii would be a junior synonym of P. pygmaeus, while one of the names currently considered a junior synonym of P. pygmaeus would take precedence for the taxon in Sarawak and northern West Kalimantan). Bradon-Jones et al considered P. morio to be a synonym of P. pygmaeus, and the population found in East Kalimantan and Sabah to be a potentially unnamed separate taxon.