Indochinese grey langur
Conservation status
Endangered  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Suborder:	Haplorhini
Infraorder:	Simiiformes
Family:	Cercopithecidae
Genus:	Trachypithecus
Species:	T. crepusculus
Binomial name
Trachypithecus crepusculus (Elliot, 1909)
Indochinese grey langur range in red
Synonyms
T. phayrei crepuscula

The Indochinese grey langur (Trachypithecus crepusculus) is a species of Old World monkey native to East and Southeast Asia.

It was formerly considered conspecific with Phayre's leaf monkey (T. phayrei), but a 2009 study found it to be a distinct species and the most basal member of the T. obscurus lineage, which contains several other species.^[2] Later studies have also found it to be a hybrid species originating from ancient hybridization between ancestral obscurus-group langurs and the Tenasserim lutung (T. barbei).^[3][4][5]

This species is found throughout Indochina, from northern Thailand east to Vietnam and west to eastern Myanmar, and ranges north to southern China south of the Salween River.^[4]

Unlike langurs that live in karst forests, which have a largely terrestrial lifestyle, the Indochinese grey langur inhabits old-growth evergreen forests and has a largely arboreal lifestyle.^[6]

This species' population is only thought to have about 2,400 to 2,500 mature individuals. It is threatened by habitat destruction and, especially in Vietnam and Laos, hunting, the latter of which is thought to have led to rapid declines in the species.^[4]