The sun-tailed monkey lives only in the forests of central Gabon. It uses both the ground and trees and is associated with dense forest undergrowth.
Its body is gray-brown with a rusty-brown back, and its tail fades from white near the base to orange at the tip. Males have a more prominent white throat ruff.
In observations of a semi-free-ranging breeding colony, monkeys used both the ground and trees and fed mainly on the ground.
An extinction-risk assessment has not been added yet.