These monkeys are highly sexually dimorphic in size and pelage characters. Adult males weigh around 21.5 kg and females around 9.4 kg. Male pelage is basically grayish-brown in color, with the ventrum colored like the back or darker. Hairs on the cheeks are lighter, forming "whiskers" which grade into a very pronounced, bushy, silver-colored mane. The long back hairs are wavey. Females are a plain olive-brown color. The skin may be very colorful in some animals. In both males and females, the skin surrounding the ischial callosities is pink or bright red. Males have skin of a similar color on their muzzle and face, whereas females possess a muted, grayish-brown face. The tail is long, and curved, with a graceful arch at the base. The natal pelage is black, although this is lost by approximately six months of age, when it is replaced by an olive-brown coat like that of the adult female.
The head and body length has been reported as 610 to 762 mm, with the tail adding an additional 382 to 610 mm.
Range mass: 9.2 to 21.5 kg.
Range length: 610 to 762 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful; ornamentation
Average basal metabolic rate: 21.095 W.