The eastern black crested gibbon (Nomascus nasutus) is a species of gibbon

Gibbon

Gibbons are apes in the family Hylobatidae . The family is divided into four genera based on their diploid chromosome number: Hylobates , Hoolock , Nomascus , and Symphalangus . The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related...

 that was once widespread in China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 and Vietnam

Vietnam

Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

. There are two subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

.

It became extinct on the continent in the 1950s; and now roughly only 20 gibbons of the subspecies Nomascus nasutus hainanus (Hainan black crested gibbon) survive on Hainan Island and around 26 individuals of the subspecies Nomascus nasutus nasutus (Cao Vit black crested gibbon) were rediscovered in 2002 in Trùng Khánh District, Cao Bằng Province

Cao Bang Province

Cao Bằng is a province of northeastern Vietnam. The province has borders with Hà Giang, Tuyên Quang, Bắc Kạn, and Lạng Sơn provinces within Vietnam. It also has common international border with Guangxi province of the People's Republic of China...

, in northeast Vietnam, after last being seen in the 1960s.

The Eastern black crested gibbon is the rarest and most critically endangered

Critically endangered

Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...

 primate

Primate

A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

 in the world. This status has resulted from deforestation

Deforestation

Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

 of its habitat, encroachment, and poaching

Poaching

Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...

. It is considered to be one of "The World's 25 Most Endangered Primates

The World's 25 Most Endangered Primates

The World's 25 Most Endangered Primates is a list of highly endangered primate species selected and published by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group , the International Primatological Society , and Conservation International...

."