Callicebus is a genus of monkeys known as titi monkeys. Historically, titis were monogeneric, comprising only the genus Callicebus Thomas, 1903. Owing to the great diversity found across titi monkey species, a new genus-level taxonomy was recently proposed that recognises three genera within the subfamily Callicebinae; Cheracebus Byrne et al., 2016 for the species of the torquatus group (Widow titis); Plecturocebus Byrne et al., 2016 for the Amazonian and Chaco titis of the moloch and donacophilus groups; and Callicebus Thomas, 1903 sensu stricto, for species of the Atlantic Forest personatus group. In 2014, a previously unknown orange Callicebus was spotted in the Peruvian Amazon; it has not been determined whether this constitutes a color variant or a new species. Species There are 5 species in this genus: Barbara Brown's titi monkey, Callicebus barbarabrownae Coimbra Filho's titi monkey, Callicebus coimbrai Coastal black-handed titi monkey, Callicebus melanochir Black-fronted titi monkey, Callicebus nigrifrons Atlantic titi monkey, Callicebus personatus References Primate genera Taxa named by Oldfield Thomas Taxa described in 1903