Presbytis suamensis
Creators: name: Russell A. Mittermeier
name: Anthony B. Rylands
name: Don E. Wilson
Publisher: name: Lynx Edicions
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Primates
Cercopithecidae
Presbytis
Presbytis suamensis

description: 119.
Pale-thighed Langur
Presbytis stamensus
French: Langur a cuisses pales / German: Weil 3schenkellangur / Spanish: Langur de muslos blancos
Other common names: White-thighed Langur, White-thighed Surili; Bintan Island/Bintan Pale-thighed Langur (rhionis), Chasen’s/Mantled Pale-thighed Langur (paenulata), Lyon's/Riau Pale-thighed Langur (cana), Malayan Pale-thighed Langur (siamensis)
Taxonomy. Semnopithecus siamensis S. Miiller & Schlegel, 1841,
Malaya, Malacca.
In addition to the subspecies below, an extremely pale form, described as white with a little gray on its back and a blackish crest, has been reported from near Jambi in eastern Sumatra. The subspecies are rather poorly defined. Four subspecies recognized.
Subspecies and Distribution.
P.s.siamensisS.Muller&Schlegel,1841 —MalayPeninsula,inSThailand(populationisolatereportedat6°22"N,101°08E,wellwithinthedistributionofP.femoralisrobinsoni)andmostofPeninsularMalaysia(itisabsentintheNWtotheNtothePiahValleyinPerakState,andintheS).
P.s.canaG.S.Miller,1906—CESumatra(betweentheSiakandIndragiririvers)andtheRiauArchipelago(PulauKundurI).
P.s.paenulataChasen,1940—CESumatra(confinedtoasmallwedgeofcoastalforest,withapopulationisolatereportedfromnearLakeToba);itisseparatedfromP.femoralispercurabytheRokanRiver.
P.s. rhionis G. S. Miller, 1903 — Riau Archipelago (for certain only from Bintan but may occur also on Batam and Galang Is).
Descriptive notes. Head-body 34-39 cm, tail 67-89 cm; weight 4.3-8.2 kg. The Palethighed Langur is similar to the Banded Langur (P. femoralis), but much paler grayishbrown in color and with a blackish brow, hands, and feet. Underside is whitish, continuous with a grayish-whitish zone on outsides of thighs. In general,it is pale brown-gray to buff above with a whitish underside (extending to inner surfaces of limbs and reaching down to wrists and ankles, and forward to throat and cheeks). Hands and feet are raven-black, asis tail, except for some white underits base. There is some slight clinal variation running north to south. The “Bintan Pale-thighed Langur” (FP. s. rhionis) 1s yellow-brown, with a gray fringe above and a white underside, the latter color reaching ankles but not under tail. Its head and lower limbs are blacker. There is usually a single whorl on forehead. Its buccal depigmentation extends up to the nose. The “Riau Pale-thighed Langur” (P. s. cana) is similar to the Bintan Pale-thighed Langur, but it has a rather darker tail and limbs. Its fur is yellowish-gray above, with a darker head. Its white underside extends to chin, cheeks, wrists, and ankles, and backs of thighs have a wide gray area.Its tail is lighter below but not white. Its face is gray, with bluish eye-rings and a pinkish muzzle, and number of forehead whorls varies from two, one, or none. In the “Mantled Pale-thighed Langur” (P. s. paenulata), dorsal side is dark reddish-brown, while underside and inner surfaces of limbs are whitish to pale grayish-brown. Its outer limbs are brown, except for gray-white on backs of thighs and arms. Its hands and feet are black. Its tail is like its back above but paler below. Its face is black, with complete white eye-rings and pinkish lips, and its crest is small and black with a pale patch in front.
Habitat. Primary and secondary rainforest, swamp, mangrove forest, and rubber tree plantations. Only a little information on habitat and ecology is available for the Palethighed Langur, but it is most likely similar to closely related species. The Bintan Palethighed Langur occurs in lowland wet forest, swamp forests, secondary regrowth, and “rubber gardens” (fallow secondary forest in slash-and-burn agriculture that is planted with rubber trees).
Food and Feeding. The Pale-thighed Langur eats mainly young leaves and fruits, along with seeds and flowers.
Breeding. There is no set breeding season for the Pale-thighed Langur. The female usually gives birth to a single young, although twins have been reported. The gestation period is c.168 days. Infants are whitish-gray, with a distinctive dark cross pattern along their backs and shoulders.
Activity patterns. The Pale-thighed Langur is diurnal and arboreal.
Movements, Home range and Social organization. The Pale-thighed Langur has not been studied in the wild. Social groups have up to 18 individuals, with a single adult male, up to eight females, and their offspring.
Status and Conservation. CITES Appendix II. Classified as Near Threatened on The IUCN Red Lust, including the subspecies siamensis, cana and paenulata, but the subspecies rhionis is classified as Data Deficient. Deforestation and conversion of habitat most likely are major threats to the Pale-thighed Langur, and hunting to a lesser extent. Oil palm plantations are fast replacing lowland forests whereit lives. The “Malayan Palethighed Langur” (Ps. siamensis) occurs in Taman Negara National Park in the states of Pahang, Kelantan, and Terengganu, and Krau Wildlife Reserve in Pahang, Malaysia. It is not clear if the other subspecies occur in any protected area. Their taxonomy is disputed and distributional boundaries are unknown, so that an assessment ofits protected status is difficult. Further research on the Pale-thighed Langur is urgently needed to clarify conservation needs of the subspecies.
Bibliography. Aimi & Bakar (1992, 1996), Brandon-Jones (1984), Brandon-Jones & Nijman (2011), Brandon-Jones et al. (2004), Groves (2001), Nijman, Geissman & Meijaard (2008b), Yanuar (1993/1994).
description: Published as part of Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, pp. 550-755 in Handbook of the Mammals of the World – Volume 3 Primates, Barcelona :Lynx Edicions on pages 722-723, DOI: 10.5281/zenodo.6867065