Delacour's langur or Delacour's lutung (Trachypithecus delacouri)

Delacour's langur (Trachypithecus delacouri) is a critically endangered species of Old World monkey endemic to northern Vietnam.

This langur is only found at Van Long Wetland Reserve and Kim Bang Forest nowadays.
The population at the Cuc Phuong National Park have not been seen again for several years.

Cercopithecidae
Greek: kerkos tail;
Pithecia: From Ancient Greek πίθηκος (píthēkos, “monkey”) + -ia.
Trachypithecus: from Greek τραχύς, trachýs meaning "rough" and πίθηκος, píthekos meaning "monkey".