Pygathrix

The doucs or douc langurs make up the genus Pygathrix which are colobine Old World monkeys, native to Southeast Asia. 
They consist of these 3 species: red-shanked douc, black-shanked douc, and gray-shanked douc.

Cercopithecidae
Greek: kerkos tail;
Pithecia: From Ancient Greek πίθηκος (píthēkos, “monkey”) + -ia.
Pygathrix: the long rump hair
 Greek puge: rump.
 Greek thrix, trikhos: hair.
Douc (pronounced "duke") is a French Cochin-china name.