Tragulus williamsoni Kloss 1916

6.

Northern Chevrotain

Tragulus williamsoni

French: Chevrotain de Williamson / German: Thailand Kantschil / Spanish: Ciervo ratén de Tailandia

Taxonomy. Tragulus williamsoni Kloss, 1916,

Meh Lem, Thailand.

The recent reallocation of 1. williamsoni to species level was based on one specimen from northern Thailand, because the skull dimensions exceeded those of any other T. kanchitlike chevrotains from the Asian mainland. Recently, two additional specimens from Mengla, Yunnan, China have been identified that appear to support the species-level designation of this taxon. This, however, requires further careful study, because even though the two Chinese skulls are similar in size to the specimen from northern Thailand, verification of the measurements is still required. The taxonomic uncertainty of 71. williamsoni is compounded by the lack of available specimens of chevrotains from close to the type locality of T. williamson: with which to test for conspecificity with 7. kanchil and, if the taxon is validated, to determine whetherit is sympatric or parapatric with 7. kanchil. More material is needed for both 7. williamsoni and 1. kanchil, if it occurs there, from the northern parts of Thailand, adjacent southern China, and possibly northern Laos as well as northern Myanmar, to make an informed judgment. Monotypic.

Distribution. Thailand and southern China, mainly the Sanchahe part of the Mengman region and the Darongshu of the Longmen region, both in S. Yunnan, but possibly more widespread with potential presence in Laos, Vietnam, and Myanmar.

Descriptive notes. No measurements available. The type specimen of this species was described as larger than other 7. kanchil specimens from the Asian mainland, but with color patterns similar to 7. k. affinis. Photos of this type specimen show uniformly colored pale brown upperparts, with a barely visible darker nape streak; the species was described as being like 7. k. affinis but larger and with the upperparts deeper ochraceous and only moderately annulated with brown. Throat patterns are as in 7 k. affinis, with clearly defined white chin and neck stripes and a reddish-brown transverse throat band that separates the white neck and chin from the white chest (unlike in 7 versicolor, in which this dark band is discontinuous, and the white neck and chin and white chest thus connected). Dental formulais10/3; C1/1;P 3/3; M 3/3 (x2)= 34.

Habitat. A recent study in Yunnan showed that the species prefers valleys along banks of rivers or streams in low altitude, where they tend to use middle and lower slopes with the favorite fruit trees Ficus hirtal, Baccaurea samiflora, Alpinia kwangsiensis, and Phrynium capitatum. These plants occur along banks ofrivers or streams. Chevrotain habitat use was mostly affected by tall tree coverage, shrub coverage, and herb coverage, and distance to water.

Food and Feeding. Based on its habitat use and tree preferences in Yunnan, the diet of T. williamsoni appears to contain significant amounts offruit.

Breeding. Nothing known.

Activity patterns. Nothing known.

Movements, Home range and Social organization. Nothing known.

Status and Conservation. Classified as Data Deficient on The IUCN Red List, The species’ status cannot be assessed due to taxonomic uncertainty and a paucity of data on extent of occurrence, threats, habitat preferences and altitudinal range. Hunting is heavy in the species’ likely range and habitat perturbation is increasing there. The lack of understanding of the population-level effects on the species rule out inferential application of decline-based criteria. On the IUCN assessmentit is suggested that even modest additional information would allow categorization of the species, and thatit would likely warrant either Near Threatened or one of the threatened categories.

Bibliography. Aidong Luo et al. (1999), Cao Mingl et al. (2010), Kloss (1916, 1918), Meijaard & Groves (20044, 2004b), Shi Liming & Chen Yuze (1989), Timmins et al. (2008).