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.