The Rio Purus titi monkey, Callicebus purinus
In 1927 Oldfield Thomas described the Rio Purus titi monkey, Callicebus torquatus purinus, based on specimens collected at Ayapua, Lower Purus River, South of Solimoes, Brazil.
This is a rufous taxon of the torquatus species group, with yellowish hands, a chestnut crown and a reddish-black tail.
It is now considered as a full species, with a distribution range in the state of Amazonas, Brazil, south of the Rio Solimões between the Rios Purús and Juruá. It extends south as far as the Rio Tapauá or possibly even the Rio Pauiní.