The distribution limits of this species are unknown, reflecting ambiguity over what the name refers to, and how to identify taxa within the M. rooseveltorum complex. For a description of the range of this species-complex see M. rooseveltorum. The syntypes of M. truongsonensis were collected from four houses in three locations in Hien District, west Quang Nam Province, Viet Nam. “The three locations are: Hien, the district capital, A Tin village, and A Plo village (15°56'59''N, 107°34'18''E)” (P.M. Giao et al. 1998). Two skulls which share the distinctive mtDNA sequences presented by P.M. Giao et al. (1998) for M. truongsonensis were collected in the adjacent area of Lao PDR, on the Dakchung Plateau (Amato et al. 1999b, 2000; R.J. Timmins pers. comm. 2008). Published range descriptions for M. truongsonensis (e.g. Groves and Schaller 2000; Grubb 2005) are hypothetical. Specimens and camera-trap photographs of animals of the M. rooseveltorum complex, but morphologically dissimilar to the M. rooseveltorum holotype (see taxonomic note) occur from the type locality of M. truongsonensis north to at least the northern highlands of Lao PDR and Viet Nam and probably into adjacent areas of China (R.J. Timmins pers. comm. 2008). M. truongsonensis may be found to occur throughout the range of the M. rooseveltorum species-complex (dark-pelaged animals appear to be widespread), but equally it could be much more localised.

Circumstantial evidence from Myanmar presents a possibility of more than one taxon in the M. rooseveltorum species complex in that region (see 2008 Red List account for M. putaoensis), with potentially similar pelage and skull character variation as shown in Indochina. Amato et al. (1999a, 1999b, 2000) placed M. putaoensis as the sister taxon to M. truongsonensis on the basis of mtDNA, and the holotype of the former species shares with specimens speculated to be M. truongsonensis long premaxillae that contact the nasals; in fact skulls of these two taxa may be (nearly) impossible to diagnose apart (R.J. Timmins pers. comm. 2008). Some uncertainty exists over the pelage characteristics of M. putaoensis, although the assumption is that they are reddish animals (see 2008 Red List account for M. putaoensis). Contrary to the statements of Rabinowitz et al. (1999) and others, which have not taken into account the patchiness of suitable surveying, the ‘small’ muntjacs comprising the M. rooseveltorum species-complex are not particularly restricted in range, but are rather widespread in montane areas of northern southeast Asia. The lack of evidence of the complex from many areas, giving an apparent disjunct distribution, is much more likely to reflect the paucity of suitable surveys than the genuine distribution pattern. Survey work in south-west and south-east China, much of Myanmar, the Himalayan region and northern and western Thailand have certainly been insufficient to conclude anything about the range of this species-complex in those regions.

Grubb (2005) suggested that various muntjac specimens recorded from China (in Sokolov 1957; Shou 1962) might be attributable to M. truongsonensis, without giving profound justification. It seems, on current knowledge, equally likely that they belong elsewhere in the M. rooseveltorum species-complex, or, as suggested by the original authors, that they refer to animals from the M. crinifrons species-complex (i.e. that species, M. feae and M. gongshanensis).

Muntiacus truongsonensis (Annamite Muntjac) is indigenous to the highland ranges of Indochina. It is named after the Annamite Mountain Range in Vietnam where it was discovered. Its presence has been confirmed in the Hoang Lien Son Range in the Lao Cai province of Vietnam and Southern Laos. Its range limits are unknown but are thought to closely resemble those of Muntiacus rooseveltorum, with the exception that M. truongsonensis extends into higher elevations.

Biogeographic Regions: oriental (Native )

Muntiacus truongsonensis is one of the smaller members of Muntiacus. The exact size of M. truongsonensis is unknown, but it has been described to be approximately 15 kg by local hunters. It has black fur on its legs and bright orange fur on its head. Dorsal pelage is brown and it has a broad flat tail with black dorsal fur and long white ventral fur which distinguishes it from its similar sized relative, Muntiacus rooseveltorum. It has white rings surrounding each hoof. Similar to other muntjac species, M. truongsonensis has ridges running from the top of the snout to the apex of the head, which give rise to short, simple, burred antlers that are hidden by tufts of long fur at the top of the head. Like those of many species of Muntiacus, the canines of M. truongsonensis are long and tusk-like. Muntiacus truongsonensis is the only muntjac species in which females and males have similarly sized canines.  No description has been given of juvenile M. truongsonensis. However, many related cervids, including species in Muntiacus, have young with spotted coats.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Habitat and Ecology

Systems

• Terrestrial

Muntiacus truongsonensis is a mountain dwelling cervid, found in dense, tropical, secondary, evergreen forests. Elevations where M. truongsonensis can be found extend up to and possibly exceed 1,000 m.

Range elevation: 1000 (high) m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: forest ; rainforest

Little is known about the diet of Muntiacus truongsonensis. While most munjacs are herbivorous, M. reevesi is known to be omnivorous, eating carrion and small animals. Other species of Muntiacus, such as Muntiacus vaginalis, are generalist herbivores eating a wide range of flora including fruit, twigs, seeds and foliage.

Little is known about the ecosystem roles of Muntiacus truongsonensis. However, close relatives have been described as important seed predators and dispersers and their barking has been suggested to act as a warning system to small mammals.

A range of large predators including tigers, leopards, and crocodiles commonly prey upon many muntjacs. Humans are the only confirmed predator of M. truongsonensis. Potential predatory defense mechanisms of M. truongsonensis are unknown.

Known Predators:

• humans (Homo sapiens)

Many species of Muntiacus are somewhat vocal, but it is not known if M. truongsonensis is included among them. Males "buzz" when approaching a female in estrus, and receptive females whine and lower their heads to males. Vocal species use barking as an alarm system to warn of potential dangers such as predators.

Communication Channels: acoustic ; chemical

Other Communication Modes: pheromones ; scent marks

Perception Channels: visual ; acoustic

No information was found on the longevity of M. truongsonensis in the wild or captivity.

The mating system of Muntiacus truongsonensis is unknown. Other species in the genus, including Muntiacus vaginalis and Muntiacus reevesi, mate year round. Male M. reevesi defend territories that overlap with those of females. Males compete for mates by locking antlers and pushing against each other. They use their tusks to scratch the faces and necks of rival males. Both sexes of M. reevesi are semi-vocal. Males "buzz" when approaching a female in estrus, and receptive females whine and lower their heads to males.

Members of Muntiacus living in similar habitats as Muntiacus truongsonensis, such as M. reevesi and M. vaginalis, are polygynous and aseasonal breeders. Gestation is variable in Muntiacus. For example, gestation in Muntiacus muntjak lasts for 180 days, while that of M. reevesi lasts for 210 days.

Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

There is no information available regarding parental investment in Muntiacus truongsonensis, but it is probably similar to that of close relatives. Muntiacus reevesi exhibits minimal parental care and weans offspring at 17 weeks. Like many small cervids in enclosed environments (e.g., forests), M. truongsonensis likely has young that exhibit hiding behavior in which young lie and hide for extended periods of time, while mothers wander off to graze and then return periodically to nurse.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)

Little is known of the potential conservation needs of Muntiacus truongsonensis, due in part to the difficulty of distinguishing it from closely related muntjacs species. As a result, this species is classified as "data defficient" on the IUCN's Red List of Threatened Species. Possible threats include hunting and habitat loss.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: data deficient

Population

Population Trend

Major Threats

Conservation Actions

There are no known adverse effects of Muntiacus truongsonensis on humans.

Muntiacus truongsonensis, like many other muntjacs, is hunted for their meat and their skins.

Positive Impacts: food ; body parts are source of valuable material