Alouatta nigerrima occurs south of the Rio Amazonas in Brazil, west from the rios Tapajós and Juruena, to the Rios Madeira and Aripuanã, to about 9ºS. There are outlying populations north of the Rio Amazonas in the region of Oriximiná and Óbidos on the lower Rio Trombetas (Napier, 1976) and just south of the Rio Amazonas-Solimões, midway between the rios Maderia and Purus, at the Lago Janauacá (A. Rylands, pers. obs.; Langguth et al. 1987; Bonvincino et al. 1989; Gregorin 2006).