Saguinus nigricollis
The black-mantled tamarin, Saguinus nigricollis, is a species of tamarin from the northwestern Amazon in far western Brazil, southeastern Colombia and northeastern Peru. It has often included the Graells's tamarin as a subspecies (in which case the distribution extends into eastern Ecuador), but differs from that species in having reddish-orange rump and thighs. The two are often said to be sympatric in Colombia (a major argument for treating them as separate species), though the accuracy of...