Einar Lönnberg, the Swedish zoologist head of the Vertebrate Department of the Swedish Natural History Museum (Stockholm), described in 1939 Callicebus baptista based on specimens that he received from Lago do Baptista and Lago Tapajuna, East of the Río Tapajoz,Amazonas, Brazil. He described the species as having the same general colour pattern as C. moloch and C. hoffmannsi, but decidedly darker and more richly coloured. The whole crown of the head is clear grizzled grey. The back is rather dark brownish. The outside of the arms and legs is black, grizzled with white rings to a varying effect so that in some specimens the white is rather dominating on the upper arms. The hands and feet often are pure black more or less sprinkled with white. The sides of the head and neck, the whole lower side of the body, and the inside of the limbs are strongly rufous red. A few centimetres of the tail show the grizzled colour of the back, otherwise the visible parts of the tail is pure black with a narrow whitish tuft at the extreme end.
Its distribution is supposed to be in Central Amazonian Brazil, south of the Rio Amazonas and east of the Rio Madeira in the state of Amazonas east almost as far as the western limit of the state of Pará, and north of the Paraná do Canumã, Paraná do Urariá, and Paraná do Ramos.