Black-shanked douc

The black-shanked douc (Pygathrix nigripes) is an endangered species of douc found mostly in the forests of Eastern Cambodia, with some smaller populations in Southern Vietnam. 

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.
"nigripes" refers to black shank color.