Order : PRIMATES
Family : Cercopithecidae
Species : Presbytis siamensis siamensis

Head-body length : approx. 50 cm
Tail length : approx. 70 cm
Weight : maximum approx. 6.5 kg

Play alarm call of P. s. siamensis ►

Presbytis siamensis (White-thighed Surili) is taxonomically divided into 4 subspecies, each of which occurs in separate geographical areas of southernmost Thailand, Peninsular Malaysia and Indonesia (eastern Sumatra and the Riau Archipelago) (Ang & Traeholt, 2020). 

Presbytis siamensis siamensis (Malayan Pale-thighed Langur) is fairly common in the lowland and lower montane forests of much of Peninsular Malaysia. The range of this subspecies also extends into southernmost Thailand.

The closely related subspecies Presbytis siamensis rhionis (Bintan Island Pale-thighed Langur) occurs much further south, in the Riau Islands of Indonesia.

Presbytis siamensis siamensis is slender in build, with greyish or brownish-grey fur which becomes light grey to whitish on the underside and around the cheeks. Juveniles have distinctive spiked fur on top of the head. The eyes are framed by light fur/skin beneath and a line of pale fur at the side. The tail is dark.

Social groups of the species comprise an adult male, several females, juveniles and young. They feed on young leaf shoots, seeds and forest fruits.

Fig 1 : Female P. s. siamensis with infant in lowland mixed primary/secondary forest at Kledang Saiong, Ipoh, Perak, Peninsular Malaysia.

Fig 2 : P. s. siamensis in lower montane forest at Fraser's Hill, Peninsular Malaysia.

Fig 3 : Adult from Ulu Chepor, Perak, Peninsular Malaysia feeding on a fruit of Artocarpus elasticus.

Fig 3 : Adult from Ulu Chepor, Perak, Peninsular Malaysia feeding on a small, unidentified, forest fruit.


References :

Francis, C.M. 2019. A Field Guide to the Mammals of South-east Asia. Second Edition. New Holland. 416 pp.