The eastern black-crested gibbon (''Nomascus nasutus''), also known as the Cao-vit black crested gibbon or the Cao-vit crested gibbon, is a species of

gibbon Gibbons () are apes in the family Hylobatidae (). The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical rainforest from eastern Bangladesh to Northeast Indi ...

from southeast China and northern

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 it ...

. The term "Cao-vit" originated from the sounds of their calls or songs that villagers of Ngoc Khe, Phong Nam and Ngoc Con communes of Trung Khanh District, Cao Bang Province of Vietnam use to name for them. This name was officially used by gibbon experts since the rediscovery. From the 1960s until the 2000s there had been no confirmed sightings of the eastern black-crested gibbon and it was thought to be possibly extinct. In 2002 a small population was rediscovered by two FFI biologists in a karst forest of Trùng Khánh District, Cao Bằng Province, in northeast Vietnam. The species was endemic to Vietnam until 2006 when they were also found in a small forest in Guangxi Province of China, which is adjacent to Trung Khanh forests. In 2005 it was estimated that this population in Vietnam side was about 35-37 individuals.Vu Ngoc Thanh, Nguyen Xuan Dang, Nguyen Manh Ha, Luu Tuong Bach, Nguyen Thi Hien (2005). Survey and assessment of the Cao-vit gibbon population in Phong Nam – Ngoc Khe Proposed Species/habitat Conservation Area, Trung Khanh District, Cao Bang Province. Fauna & Flora International, Vietnam. The eastern black crested gibbon is one of the rarest and most critically endangered

primate Primates are a diverse order (biology), order of mammals. They are divided into the Strepsirrhini, strepsirrhines, which include the lemurs, galagos, and lorisids, and the Haplorhini, haplorhines, which include the Tarsiiformes, tarsiers and ...

s in the world. This status has resulted from

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then land conversion, converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban area, urban ...

of its habitat, encroachment, and

poaching Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set ag ...

Taxonomy

The eastern black crested gibbon is classified as separate from other crested gibbons based on molecular data, fur coloration, and differences in vocal communication. Previously it had been considered

conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organ ...

with the

Hainan black crested gibbon The Hainan black-crested gibbon or Hainan gibbon (''Nomascus hainanus''), is a Critically Endangered species of gibbon found only on Hainan Island, China. It was formerly considered a subspecies of the eastern black crested gibbon (''Nomascus ...

or as a subspecies of the

black crested gibbon The black crested gibbon (''Nomascus concolor'') is a Critically Endangered species of gibbon found in China, Laos, and northern Vietnam, with four subspecies. Taxonomy The taxonomy of the species is confused. Previously grouped in the ...

. Until the sequencing of the mitochondrial cytochrome ''b'' gene the Hainan black crested gibbon was thought to be ''Nomascus nasutus hainanus'', a subspecies of eastern black crested gibbon. The researchers proposed that the genetic separation showed it was a distinct species.

References

{{Taxonbar, from=Q1195996 eastern black crested gibbon Primates of East Asia Primates of Southeast Asia Mammals of China Mammals of Vietnam Critically endangered fauna of Asia eastern black crested gibbon Species endangered by deforestation Taxa named by Philippe Alexandre Jules Künckel d'Herculais it:Nomascus concolor#Sottospecie