Eastern black-handed tamarin

The eastern black-handed tamarin (Saguinus ursulus) is a species of tamarin, a small New World monkey, that is endemic to Brazil. It was described in 1807 by the German zoologist Johann Centurius Hoffmannsegg. It was later treated as a synonym, first of the golden-handed tamarin (Saguinus midas) and then of the black tamarin (Saguinus niger), the black-handed tamarin. In 2013 the species was revalidated on the basis of differences in coat color and in morphology, which molecular data corroborated. Mitochondrial DNA analysis split the black-handed tamarin into two species, the western black-handed tamarin (Saguinus niger) and the eastern black-handed tamarin (Saguinus ursulus). The Tocantins River, which divided the range, proved to be an effective barrier to gene flow, and together with minor differences in pelage color this led to the population east of the river being recognised as a separate species. The article lists it as Vulnerable on the IUCN Red List.