This species wasn't described until 1988.
Head and body length: 47-68cm, Tail length: 48-80cm, Weight: Female: 3.5kg, Male: 6kg.
Sun-tailed guenons have long black limbs, a brown back and a grey and white tail with a bright orange tip. They have a grey crown, with white ear tufts, pale grey cheeks and an off-white bib. The males have a blue scrotum.
Sun-tailed guenons are found in Gabon.
They inhabit lowland dense tropical rainforest.
Little is known of the sun-tailed guenon's diet.
They live in groups of 5-15, typically with one male and numerous females. They are diurnal, arboreal and terrestrial.
Little is known about the sun-tailed guenon's reproductive biology.
The 2000 IUCN Red List classifies the sun-tailed guenon as Vulnerable.