Trachypithecus laotum (Thomas, 1921)

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 550-755 : 752

158.

Laos Langur

Trachypithecus laotum

French: Langur du Laos / German: Laos-Langur / Spanish: Langur de Laos

Other common names: Lao/Laotian Langur, Laotian / White-browed Black Langur

Taxonomy. Pithecus laotum Thomas, 1921 ,

Ban Na Sao, SW French Laos, on the French side of the Mekong, in latitude about 17° 30° N.

There is an overlap with 7. ebenus in Thakek and Gnomalath districts, south Phou Hi Poun National Protected Area. 1. laotum is a member of the francois: species group, also known as the karst or limestone langurs. Monotypic.

Distribution. WC Laos, from S Bolikhamsal Province, probably with the Nam Kading River as the N barrier of the distribution, S to C Khammouane Province, at ¢.17° 40’ N; there are also reports from the corridor to Nakai-Nam-Theun National Protected Area, and from Khamkeut District, close to Lak Sao (18° 13’ N, 104° 47’ E).

Descriptive notes. Head—body 55-67 cm (males) and 46-54 cm (females), tail 85— 90 cm (males) and 81-85 cm (females); weight 7-8 kg (males) and 6-7 kg (females). Body coloration of the Laos Langur is black, with a chocolate brown tinge, as in the Hatinh Langur (7. hatinhensis ). Hairs on head, including cheeks and chin, are white except for crown, where black hairs form a crest. A stripe of black hairs runs from crest down to nape, sometimes connected with black pelage on back, sometimes interrupted with white hairs. Some black hairs form a scattered ring around face. Naked skin of face, ears, hands, and feet is jet-black. Females have a small irregular pubic patch, with depigmented skin and yellowish-white hairs.

Habitat. Steep limestone cliffs, with sparse vegetation. Patches of forest only remain on slopes and in valleys and canyons where the Laos Langur lives. About 50% ofits distribution is rocky scrub, 30% evergreen forest with shrubby vegetation, and ¢.10% mixed evergreen-deciduous forest.

Food and Feeding. There is no specific information available for this species, but Laos Langurs are known to be folivores.

Breeding. There is no information available for this species.

Activity patterns. Laos Langurs are diurnal, crepuscular, terrestrial, and arboreal. They are mainly terrestrial on limestone cliffs where theylive.

Movements, Home range and Social organization. There is no specific information available for this species, but Laos Langurs have been seen in groups of 5-10 individuals.

Status and Conservation. CITES Appendix II. Classified as Vulnerable on The [UCN Red List. Poaching of Laos Langursstill occurs despite being protected by Laotian law. Habitat loss is currently no threat because the extremely steep and dry habitat where they live does not support agriculture. The Laos Langur occurs in Nam Kading and Phou Hi Poun national protected areas in Laos.

Bibliography. Brandon-Jones (1995b), Duckworth, Boonratana et al. (2010), Duckworth, Salter & Khounbline (1999), Groves (2001), Nadler (1995, 2009b), Phiapalath (2010), Roos et al. (2007), Stevens et al. (2008), Walston & Vinton (1999).

Figures

149. Tenasserim Langur (Trachypithecus barber), 150. Dusky Langur (Trachypithecus obscurus), 151. Phayre’s Langur (Trachypithecus phayrei), 152. Indochinese Gray Langur (Trachypithecus crepusculus), 153. Cat Ba Langur (Trachypithecus poliocephalus), 154. White-headed Langur (Trachypithecus leucocephalus), 155. Delacour’s Langur (Trachypithecus delacouri), 156. Francois’s Langur (Trachypithecus francoisi), 157. Black Langur (Trachypithecus ebenus), 158. Laos Langur (Trachypithecus laotum), 159. Hatunh Langur (Trachypithecus hatinhensis)

Distribution. WC Laos, from S Bolikhamsal Province, probably with the Nam Kading River as the N barrier of the distribution, S to C Khammouane Province, at ¢.17° 40’ N; there are also reports from the corridor to Nakai-Nam-Theun National Protected Area, and from Khamkeut District, close to Lak Sao (18° 13’ N, 104° 47’ E).