Diurnal monkey (family Cercopithecidae, usually genus Mandrillus) of equatorial African rainforests, known for its striking colouring. The stout-bodied, primarily terrestrial mandrill has a short tail, prominent brow ridges, and small, close-set, sunken eyes. The ribbed bare skin on the adult male's cheeks is bright blue, with scarlet on the nose; the buttock pads are pink to crimson, shading to bluish; and the beard and neck are yellow. The adult male is about 3 ft (90 cm) long and weighs about 45 lb (20 kg); the female is duller and smaller. Mandrills eat fruit, roots, insects, and small reptiles and amphibians.