Head and body length is 240 - 610 mm, the tail is nonprehensile with lengths from 260-550 mm. Weights of adults range from 955 - 1400 g. among the three species with females generally larger than males. Coloration of the thick, soft fur ranges from reddish gray or yellowish to reddish brown on the upper parts and paler below. Callicebus have small rounded heads and flattened face. Some have a black band on the forehead while others have a white one.

All species of Callicebus are diurnal and monogamous, but each has different preferences when it comes to habitat. C. torquatus prefers high forest and lives in the canopy while C. moloch likes the understory and is often found foraging in bamboo thickets. The diet consists of leaves, vegetation, insects, small invertebrates, bird’s eggs, and small vertebrates with fruit being the favored food.

Social groups are usually only 2-7 individuals of the same family, including a strongly bonded couple with their offspring. All Callicebus are highly territorial and will aggressively defend their home ranges if threatened by other groups though physical fighting is rare. To establish their territory, adult male and female Callicebus will join in dawn duets, sometimes lasting as long as 15 minutes. Neighboring groups of Callicebus will answer with their own versions.

Breeding occurs at 2.5 - 3 years and then about every 12 months. One offspring is produced weighing about 70 g and attains adult weight at about 10 months. A week after the young is born it becomes the sole responsibility of the male Callicebus when it is not being nursed by its mother.

They are found in C Brazil, south of Amazon, between Rios Tapajos and Tocantins-Araguaia. The IUCN lists this species as vulnerable as a result of habitat loss and human activity.