Some species have contrasting blackish or whitish foreheads, while all members of the genus Cheracebus have a white half-collar.

The diet of the titis consists mainly of fruits, although they also eat leaves, flowers, insects, bird eggs and small vertebrates.

Twins occur rarely, having been documented in only 1.4% of all births in captive groups of Plecturocebus moloch.

Fathers tend to engage in more grooming, food-sharing, inspecting, aggression and playing with infants than mothers.

[10] The number of known species of titis has doubled in recent years, with eight, P. stephennashi, P. bernhardi, P. caquetensis, P. aureipalatii, P. miltoni, P. urubambensis, P. grovesi, and P. parecis being described from the Amazon basin since 2000.

[11] While this typically is a highly unusual event in scientific classification, the possibility of naming a species of titi in exchange for a sizable donation to a nonprofit foundation was also presented a few years before, resulting in P. bernhardi being named after Prince Bernhard of the Netherlands.

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); Callicebus Thomas, 1903, for species of the Atlantic Forest personatus group; and Plecturocebus Byrne et al. (2016) for the Amazonian and Chaco titis of the moloch and donacophilus groups.