Sumatran Orangutan (Pongo abelii)
Until the 1990s, scientists thought there was only one species of orangutan, Pongo pygmaeus, with two subspecies, the Sumatran and Bornean orangutans. Well, DNA testing meant they could check to be sure, and what do you know? The Sumatran and Bornean orangutans turned out to be separate species. They’re pretty much indistinguishable unless you can inspect their genes, but I think the Sumatran ones have slightly longer hair.