Trachypithecus obscurus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Primates Cercopithecidae

Scientific Name: Trachypithecus obscurus (Reid, 1837)
Infra-specific Taxa Assessed:
Common Name(s):
English Dusky Langur, Dusky Leaf Monkey, Spectacled Langur, Spectacled Leaf Monkey
French Semnopithèque Obscur
Spanish Langur Obscuro
Trachypithecus corax Pocock, 1934
Trachypithecus corvus (Miller, 1913)
Trachypithecus leucomystax (Müller & Schlegel, 1841)
Trachypithecus ruhei (Knottnerus-Meyer, 1933)
Trachypithecus smithii (Kloss, 1916)
Taxonomic Notes: It may be that the blackish insular subspecies (halonifer, carbo, styx, seimundi) represent a distinct taxon which has been entirely replaced on the mainland by the contrastingly toned T. obscurus.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Boonratana, R., Traeholt, C., Brockelmann, W. & Htun, S.
Reviewer(s): Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)
Considering the extensive habitat loss that has taken place within the range of the species, there is reason to believe that this species is in decline, probably at a rate of less than 30% over three generations (approximately 30 years), thus qualifying if for listing as Near Threatened. Almost qualifies as threatened under criterion A2cd.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species occurs in Malaysia (troughout the Malay Peninsula along with a few small adjacent islands), southern Myanmar (including the Mergui Archipelago), and southwestern Thailand (including adjacent islands). It is found north to 15°10'N in Myanmar and Thailand (Groves 2001).

T. o. obscurus
Found on Peninsular Malaysia, north to about Perlis (Groves 2001).

T. o. flavicauda
Found in northern Peninsular Malaysia, southern Myanmar (including James, Kisseraing, and King Islands in the Mergui Archipelago) and southwestern Thailand (including Koh Lak Island). On the mainland found from Perlis north to the northern border of the species' range (Groves 2001).

T. o. halonifer
Restricted to Penang Island, Malaysia (Groves 2001).

T. o. carbo
Found off the western coast of Malaysia and Thailand, specifically on Terutao and Dayang Bunting Islands, and on Langkawi Island (Malaysia) (Groves 2001).

T. o. styx
Occurs on East Perhentian Island and, possibly, adjacent eastern coastal Malaysia (Groves 2001).

T. o. seimundi
Occurs on Phangan Island (Pennan Island), Thailand; may possibly occur in adjacent eastern Thailand as well (Groves 2001).

T. o. sanctorum
Restricted to Zadetkyi Kyun (St. Matthew Island) in the Mergui Archipelago (Myanmar) (Groves 2001).
Countries occurrence:
Malaysia; Myanmar; Thailand
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:On the mainland, at five sites surveyed (Kuala Lompat, Pasoh, Sungai Kenyam, Ulu Sebol, and Lesong) the density was estimated 1.8-7.3 groups/km2, with an average group size of 14. A population at Khao Lommuak (11°49'N) numbered 80 individuals in an area of 0.5 km2. The population status of several of the insular forms (Penang, Langkawi, Dayang Bunting, Terutau, East Perhentian, Pennan) is unclear, but most are presumed to be stable.
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species prefers closed primary forests, but is also found in old-growth secondary and disturbed forests, urban areas, and parks. It is diurnal, primarily arboreal, and folivorous, although the diet is relatively varied and the animals will also consume fruit, flowers and other items. They are able to take advantage of unripe fruit, which have chemical defenses, by the same means that they break down toxins in plant leaves, using the bacteria found in their digestive system (MacKinnon and MacKinnon 1980).

Threats [top]

Major Threat(s): Hunting for food is a major threat, as is habitat loss and degradation due to expanding oil palm plantations, agriculture, and urbanization. In Peninsular Malaysia the animals are frequent victims of road-kill.

Conservation Actions [top]

Conservation Actions: This species is listed on CITES Appendix II. It is known to occur in a number of protected areas, including: Krau Wildlife Reserve, Taman Negara National Park (Malaysia); Kaeng Krachan National Park, Khao Sam Roi Yot National Park, Khao Sok National Park, Taratau National Park (Thailand). It is relatively common in captivity. There is a need for further survey work to determine the current population status of the insular forms.

Citation: Boonratana, R., Traeholt, C., Brockelmann, W. & Htun, S. 2008. Trachypithecus obscurus. The IUCN Red List of Threatened Species 2008: e.T22039A9349397. . Downloaded on 25 September 2018.
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