The Widow monkey, Callicebus lugens
Humbold described in 1812 a new species of titi monkey, Simia lugens, supposed to come from “the forests on the banks of the Cassiquiare and the Rio Guaviaré, near San Fernando de Atabapo. The granite mountains on the right bank of the Orinoco, behind the Santa-Barbara mission”.
This is the darkest taxon of all members of the torquatus species group. Its hands are whitish or buffy orange. The tail is blackish; the under parts except throat blackish, reddish brown, or reddish; chest and belly brown or blackish; hairs surrounding ears uniformly blackish.
Its distribution ranges from eastern Colombia to southern Venezuela and parts of north-western Brazil.