The sun-tailed monkey (Cercopithecus solatus), also known as the sun-tailed guenon, is a primate that lives semi-terrestrially in one hilly area of moist evergreen forest in Gabon. The sun-tailed monkey was only discovered in 1984, so not much is known about it. It is a frugivore. It weighs up to about 4 – 9 kg. Troops consist of one adult male and several females and young.