The Tonkin weasel or Vietnamese mountain weasel (''Mustela tonkinensis'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

weasel Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets, and European mink. Members of this genus are small, active predators, with long and slend ...

described by Björkegren in 1941. It is known only from a singular specimen collected from an undisclosed location in Northern

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

. Originally believed to be a form of either the

least weasel The least weasel (''Mustela nivalis''), little weasel, common weasel, or simply weasel is the smallest member of the genus ''Mustela,'' Family (biology), family Mustelidae and Order (biology), order Carnivora. It is native to Eurasia, North Ame ...

or the

yellow-bellied weasel The yellow-bellied weasel (''Mustela kathiah'') is a species of weasel Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets, and European mi ...

, the species was distinguished as a separate variety on the basis of skull differences by Groves in 2007.

Description

A standard-sized weasel, the Tonkin weasel measures between 20 and 25 centimetres in body length, with a tail length of between 10 and 11 centimetres. The upper section of the body is medium brown, while the throat, chest and stomach are white in colour. The colouring of the fur is regarded as 'vulgaris-type', which is characterised by an indented

demarcation line {{Refimprove, date=January 2008 A political demarcation line is a geopolitical border, often agreed upon as part of an armistice or ceasefire. Africa * Moroccan Wall, delimiting the Moroccan-controlled part of Western Sahara from the Sahraw ...

between the areas of brown and white colour in both the neck and trunk regions. The

is distinguished from other species by the size of the narrow skull.

Distribution and habitat

The recorded specimen is believed to have originated from a mountain range within the

Hoàng Liên National Park Hoang Lien National Park (, also known as ''Hoàng Liên Sơn, Dãy Hoàng Liên'') is a national park within Hoàng Liên Sơn, Hoang Lien Son Range, in the districts of Sa Pa (town), Sa Pa and Than Uyên District, Than Uyên of Lào Cai Provinc ...

in the Lào Cai Province. Although Björkegren initially recorded the location of the specimen as in close proximity

Sa Pa Sa Pa (, also written as Sapa) is a district-level town of Lào Cai Province in the Northwest region of Vietnam. The town has an area of and a population of 70,663 in 2022. The town capital lies at Sa Pa ward. It is one of the main market and t ...

, it has been concluded by Abramov that the point of origin was more likely to have been from Seo My Ty to the southwest of the town. Thereby, it is probable that the species, if extant, survives within temperate

fokienia ''Fokienia'' is a genus of conifer tree belonging to the cypress family. In its characteristics, ''Fokienia'' is intermediate between the genera of '' Chamaecyparis'' and '' Calocedrus''. Genetically ''Fokienia'' is much closer to ''Chamaecypari ...

forest of the sub-alpine highlands of Northern

Behaviour

In association with other endemic species, it is probable that the Tonkin weasel consumes a similar carnivorous diet. Therefore, it is likely that their diet may consist of birds, insects and other rodents, including

Père David's vole Père David's vole (''Eothenomys melanogaster'') is a species of rodent in the family Cricetidae. It is found in China, Myanmar, Taiwan, India, Vietnam, and Thailand. This species is a member of the ''melanogaster'' group, one of the two main grou ...

and the

Eurasian harvest mouse The harvest mouse (''Micromys minutus'') is a small rodent native to Europe and Asia. It is typically found in fields of cereal crops, such as wheat and oats, in reed beds and in other tall ground vegetation, such as long grass and hedgerows. I ...

. Despite adequate abilities in relation to climbing, it is unlikely that

arboreal Arboreal locomotion is the 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 (scansorial), but others are exclusively arboreal. The hab ...

and

scansorial Arboreal locomotion is the 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 (scansorial), but others are exclusively arboreal. The habi ...

animals would form a portion of their diet.

Population

The population of the species remains unknown, as it has only been recorded on a single occasion when caught in 1939. It remains possible that concentrations of the population still exist within the higher altitude areas of the

Indochina Mainland Southeast Asia (historically known as Indochina and the Indochinese Peninsula) 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 th ...

Peninsula, as there is no evidence that, despite extensive land clearing in the region, the weasel is in any way dependent on the temperate forest ecosystem. Despite surveys between 2005 and 2012 which involved numerous discussions with the local

Hmong Hmong may refer to: * Hmong people, an ethnic group living mainly in Southwest China, Vietnam, Laos, and Thailand * Hmong cuisine * Hmong customs and culture ** Hmong music ** Hmong textile art * Hmong language, a continuum of closely related ...

people and forest rangers, no supplementary sightings of the weasel have been reported to date.

Threats

The

is believed to be located within a region where

hunting Hunting is the Human activity, human practice of seeking, pursuing, capturing, and killing wildlife or feral animals. The most common reasons for humans to hunt are to obtain the animal's body for meat and useful animal products (fur/hide (sk ...

in all forms is relatively intense, and it is therefore tenable to suggest that the species may be in decline. The placement of traps to catch other

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

and

birds Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

in the highlands may also place the weasel in inadvertent danger. In addition, much of the suggested area of habitation has been prone to fragmentation for agricultural purposes.

References

Mammals of Asia Weasels Mammals described in 1941 {{carnivora-stub Species known from a single specimen