The Indochinese grey langur (''Trachypithecus crepusculus'') is a species of

Old World monkey Old World monkey is the common English name for a family of primates known taxonomically as the Cercopithecidae (). Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons ...

native to

East East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fa ...

and

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

Taxonomy

It was formerly considered conspecific with

Phayre's leaf monkey Phayre's leaf monkey (''Trachypithecus phayrei''), also known as Phayre's langur, is a species of lutung native to South and Southeast Asia, namely India, Bangladesh, and Myanmar. Populations from further east are now thought to belong to other s ...

(''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. Later studies have also found it to be a

hybrid species Hybrid speciation is a form of speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species. Previously, reproductive isolation between two species and their parents was tho ...

originating from ancient

hybridization Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...

between ancestral ''obscurus''-group langurs and the

Tenasserim lutung The Tenasserim lutung (''Trachypithecus barbei'') is a species of lutung. It is found in Myanmar and Thailand. It is named after the Tenasserim Hills The Tenasserim Hills or Tenasserim Range ( my, တနင်္သာရီ တေ� ...

(''T. barbei'').

Distribution

This species is found throughout

Indochina Mainland Southeast Asia, also known as the Indochinese Peninsula or Indochina, is the continental portion of Southeast Asia. It lies east of the Indian subcontinent and south of Mainland China and is bordered by the Indian Ocean to the west an ...

, from northern

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

east to

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

and west to eastern

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...

, and ranges north to southern

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

south of the

Salween River , ''Mae Nam Salawin'' ( , name_etymology = , image = Sweet_View_of_Salween_River_in_Tang_Yan_Township,_Shan_State,_Myanmar.jpg , image_size = , image_caption = Salween River in Shan State, Myanmar , map ...

Habitat and ecology

Unlike langurs that live in

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

forests, which have a largely terrestrial lifestyle, the Indochinese grey langur inhabits

old-growth An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological featur ...

evergreen forests An evergreen forest is a forest made up of evergreen trees. They occur across a wide range of climatic zones, and include trees such as conifers and holly in cold climates, eucalyptus, Live oak, acacias, magnolia, and banksia in more temperate zon ...

and has a largely

arboreal Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...

lifestyle.

Threats

This species' population is only thought to have about 2,400 to 2,500 mature individuals. It is threatened by

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and, especially in

and

Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...

, hunting, the latter of which is thought to have led to rapid declines in the species.

References

{{Taxonbar, from=Q20688544 Indochinese grey langur Primates of Southeast Asia Primates of East Asia Mammals of Myanmar Mammals of Laos Mammals of Thailand Mammals of Vietnam Mammals of China Endangered fauna of Asia Indochinese grey langur Taxa named by Daniel Giraud Elliot