The doucs or douc langurs make up the genus Pygathrix, which consists of these 3 species:Red-shanked douc, Pygathrix nemaeus Black-shanked douc, Pygathrix nigripes Gray-shanked douc, Pygathrix cinerea
These colobine Old World monkeys, native to Southeast Asia, have an extremely striking appearance. The red-shanked douc characteristically has bright maroon legs and reddish patches around the eyes. In contrast, the grey-shanked douc is less vibrant, with speckled grey legs and orange markings on the face. Both have dappled grey bodies, black hands and feet and white cheeks, although the cheek hairs of the red-shanked douc are much longer. The black-shanked douc has black legs. Their long hind limbs and tail allow these monkeys to be very agile in their treetop habitat.
They live in small family groups headed by one adult male. A single group may have several adult females, and many children. Young males unaffiliated with a family group often make their own troops. Females usually bear a single offspring at a time, which is suckled for about a year.
Even though they are known as "douc langurs", they are in fact more closely related to the proboscis monkey and snub-nosed monkeys than to any of the langurs. They are part of the subfamily Colobinae of the family Cercopithecidae.