Trachypithecus hatinhensis (Dao Van Tien, 1970)

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 : 752-755

159.

Hatunh Langur

Trachypithecus hatinhensis

French: Langur du Ha Tinh / German: Hatinh-Langur / Spanish: Langur de Hatinh

Other common names: Indochinese / Stripe-headed Black Langur

Taxonomy. Presbytis francoisi hatinhensis Dao Van Tien, 1970 ,

Xom Cuc (17° 56’ N, 105° 47° E) Ha Tinh Province (now in the Tuyen Hoa District, Quang Binh Province), Vietnam.

In the past, T. hatinhensis was placed as a subspecies of 1. francoisi or T. laotum . The taxonomic relationship to 7. ebenus and to another possibly distinct black langur in Laos is not fully clarified. 1. hatinhensis is a member of the francoisi species group, also known as the karst or limestone langurs. Monotypic.

Distribution. NC Vietnam (Quang Binh and Quang Tri province), and EC Laos (Khammouane Province). The records in other Vietnamese provinces (Nghe An, Thu Thien Hue, Gia Lai, Phu Yen) are errors.

Descriptive notes. Head-body 54-61 cm (males) and 55-58 cm (females), tail 83— 95 cm (males) and 78-92 cm (females); weight 6-9 kg (males) and 6.2-8.2 kg (females). Male and female Hatinh Langurs are similar in coloration, except for the pubic patch of females. Pelage is black, with a brown tinge. A narrow tract of white hairs runs from mouth along cheeks to ears, extending and broadening behind ears down to nape. Color and extension of this white stripe is highly variable, from a broad and clear white band to a smaller more grayish line. Compared with Francois’s Langur (1. francoisi ), whiskers of Hatinh Langurs do not have prolonged hairs on corners of mouth and a small white moustache connecting cheek stripes. Hairs on head form a crest that is bushier than in Francois’s Langur. As in other “limestone langur” species, female Hatinh Langurs have an irregular pubic patch, with depigmented skin and white or yellowish-white hair, extent of which is highly variable. Hatinh Langurs are born with a yellow-brown pelage but with individually variable patches of blackish shades on back, hips, and tail, which can be extensive in some individuals. Tail is already black at birth. Infants change to entirely black in less than six months. Facial skin is yellowish-brown and changes to black with pelage. Infant head color changes last. Occasionally, front part of head is yellowish-white until the age of two years,as is seen too in the Laos Langur (7. laotum ).

Habitat. [Limestone karst with its typical vegetation. Hatinh Langurs prefer areas with dense forest cover. Dense forest is present in ¢.90% ofits known distribution. The core population occurs in one of the largest karst blocks in Indochina in Phong Nha-Ke Bang National Park in north-central Vietnam and Nakai-Nam Theun National Protected Area in east-central Laos. Caves and cliffs are used as sleeping sites, normally for many years if there is no disturbance or poaching. The heights of the caves or crevices on the cliffs vary from ¢.20-60 m from their bases. Well-used sleeping sites are easily identified by the dark-yellow or brown stains on cliffs—marks of urine and feces.

Food and Feeding. Hatinh Langurs are highly folivorous. They eat leaves from 132 plant species, fruits from 26, roots from three, and bark from two. A group in a large semi-wild, 20ha enclosure of primary forest in their natural environment in Phong Nha-Ke Bang National Park feeds mostly on leaves (81:2%) but also fruits (8:7%), tips of vines and climbers (8:7%), and flowers (1:4%). Daily food consumption of an adult averages 880 g. Daily water consumption of an adult during hot weather can be up to 500 ml/day.

Breeding. Male Hatinh Langurs reach maturity at c¢.5 years old and females at c.4 years. The gestation period is 180-190 days. Females give birth to a single offspring. Births occur throughout the year but peak in January-March.

Activity patterns. Hatinh Langurs are diurnal, crepuscular, and terrestrial, but mainly arboreal. There are no studies of their activity patterns in the wild. Hatinh Langurs in a captive population at the Endangered Primate Rescue Center, Vietnam, spend an average of 72% of the day resting, 23% feeding, 3% engaged in social behavior, and 2% moving. Their time budget is very similar to closely related species occurring in the wild, except that individuals travel more in the wild. In Phong Nha-Ke Bang National Park, Hatinh Langurs return to the vicinity of their sleeping sites, on average 65 minutes before sunset. They forage and play until they enter their sleeping caves, c.14 minutes after sunset. They leave their caves and crevices before dawn at 05:00-05:30 h.

Movements, Home range and Social organization. Quadrupedalism is the most frequent form of locomotion. The Hatinh Langur appears to be more arboreal than the other “limestone langur” species. Differing from Francois’s Langur, They hold their tails in a concave-upward inflection when walking and especially when running. In a large semi-wild, 20ha area with natural vegetation, Hatinh Langurs spent 66-3% of their time in trees, 17-7% in scrub, 12:4% on fallen dead tree trunks, and 3:6% on rocks. There is no information about their home ranges in the wild. From 1995 to 1996, average group sizes of Hatinh Langurs in Phong Nha-Ke Bang National Park were 7-8 individuals. In 2007, average group size was 5-1 individuals (n = 23). Poaching may be the reason for the decrease. Groups normally have one male, three to four females, and their immature offspring. A group with 30 individuals has been seen.

Status and Conservation. CITES Appendix II. Classified as Endangered on The IUCN Red List. The Hatinh Langur is protected by law in Vietnam and Laos. They occur in only two protected areas in Vietnam, Phong Nha-Ke Bang National Park in Quang Binh Province and Bac Huong Hoa Nature Reserve in Quang Tri Province. In Laos, they most probably occur only in Nakai-Nam Theun National Protected Area. Poaching is the main threat, mostly for traditional medicine. The main hunting method is to trap individuals inside their sleeping caves by covering the entrance with a net. Hunting with rifles has apparently diminished in Vietnam because of gun legislation controls and the confiscation of guns by local authorities. The largest population of Hatinh Langurs is most probably that in Phong Nha-Ke Bang National Park, with an estimated 1754 individuals. The population density is estimated at 0-5 groups/km? and 1-7 ind/km?. A captive breeding program was established at the Endangered Primate Rescue Center, Cuc Phuong National Park, Vietnam, and there have been successful births of Hatinh Langurs since 1996.

Bibliography. Brandon-Jones (1995b), Duckworth, Boonratana et al. (2010), Duckworth, Salter & Khounbline (1999), Fooden (1996), Groves (2001), Haus (2008), Haus, Vogt & Forster (2009), Haus, Vogt, Forster, Vu Ngoc Thanh & Ziegler (2009), Klein (1999), Le Xuan Canh (1992/1993), Nadler (1994, 1996b, 1996¢c, 1997, 2010a, 2010b), Nadler & Streicher (2004), Nadler, Momberg et al. (2003), Nadler, Vu Ngoc Thanh et al. (2007), Nguyen Manh Ha (2006), O'Brien (2006), O'Brien et al. (2006), Pham Nhat (2002), Pham Nhat et al. (1996/1997), Roos (2003b, 2004), Stevens et al. (2008), Ulibarri (2006), Vogt et al. (2008).

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. NC Vietnam (Quang Binh and Quang Tri province), and EC Laos (Khammouane Province). The records in other Vietnamese provinces (Nghe An, Thu Thien Hue, Gia Lai, Phu Yen) are errors.