The northern chevrotain's taxonomic position is poorly known and continues to be debated. Originally described as a subspecies of lesser Malayan chevrotain (Tragulus kanchil), it has been proposed - on the basis of skull measurements - that the northern chevrotain is a separate species. However, only three museum specimens have been identified from two locations (northern Thailand and southern Yunnan province, China), and a lack of additional samples from the region prevents a definitive conclusion. It is unknown to what extent existing records of T. kanchil from northern southeast Asia actually represent T. williamsoni.

Head and body length: 52.5 cm, based on a single skin from an adult female

This diminutive ungulate has the typical wedge-shaped body form of chevrotains with the rump being the highest point. From the original description, published in 1916 based on a single specimen, the overall color is finely-speckled medium brown, with the back and rump tawny. The undersides are white, with a faint buff-colored line down the centre of the chest and abdomen. The front legs are more orange in color than the body, while the hind limbs are slightly darker. The tail is brown above and white on its underside. The sides of the neck are brighter than the body, while the nape of the neck has an indistinct stripe of slightly darker hair. The head (especially the forehead) is dark. On the throat, a white patch (continuous with the pale underjaw) is split into three sections by two narrow bands (6-8 mm wide) of brown fur.

Similar species

• Externally, the northern chevrotain is very similar to the lesser Malayan chevrotain (Tragulus kanchil), although it is significantly larger in overall size and is more tawny overall.

Nothing known. Presumably similar to other members of the genus Tragulus.

Very little is known about the habits of the northern chevrotain. The species is best known from Yunnan, China, but most published research focuses on distribution and habitat preferences (see below).

Family group: Solitary.

Diet: Suggested to be fruits and young leaves.

Main Predators: Unknown, but likely many medium-sized carnivores. Asian golden cat, leopard cat, dhole, and yellow-throated marten are all found in the same area as the northern chevrotain.

The presence of the northern chevrotain has only been confirmed in two localities: northern Thailand, where the first specimen was collected in 1916, and in China's southern Yunnan province (Xishuangbanna prefecture). Despite early supposition on range limits, this species is found on both sides of the Mekong River. In China, this species shows a preference for monsoon forest and evergreen broadleaf forest in river valleys at 7,00-1,000 m above sea level; key habitat components include proximity to water (rivers), canopy coverage, and dense ground-level shrubbery. The approximate range is depicted in the map below.

IUCN Red List: Data Deficient (2015).

CITES Listing: Not listed (2017).

Threats: Unmeasured; hunting pressure and habitat loss are likely.

The conservation status of this species is not understood, primarily due to taxonomic uncertainties and lack of distribution data. More research is needed for a proper assessment.