© Andie Ang
Taxonomy & Occurrence
Presbytis percura is a monotypic species (no subspecies). It is only found in the Riau Province of Sumatra, Indonesia . Its distribution appears to be bounded by the Rokan River in the north while the southern limit is at least until Kampar River .
Up until 2019, three subspecies of banded langurs were recognised: East Sumatran Banded Langur (P. femoralis percura) from Sumatra, Raffles' Banded Langur (P. f. femoralis) from Singapore and Malaysia, and Robinson's Banded Langur (P. f. robinsoni) from Malaysia, Thailand, and Myanmar. Genetic data suggested that at least P. f. femoralis and P. f. robinsoni were different species  which was also in agreement with their morphological characters. However, resolving all subspecies-level boundaries within banded langurs required data for P. f. percura, which was the least studied among them . Most recently, DNA mitochondrial genomes were obtained for P. f. percura, and based on multiple species delimitation algorithms applied to a dataset covering 40 species and 43 subspecies of Asian colobines, all three subspecies of banded langurs were resurrected to species .
IUCN Conservation Status
Little is known about the East Sumatran Banded Langur as there were limited studies on the species. However, what is clear is that the species faces a high risk of extinction. Compared to other provinces in Sumatra, Riau experienced the highest rate of deforestation, and similarly produced more palm oil and paper pulp . These land use changes have resulted in highly fragmented forest remnants and degraded habitats that are surrounded by oil palm, rubber, and timber plantations (e.g., Acacia and Eucalyptus) within the range of the East Sumatran Banded Langur. Additionally, forest fires due to hot weather conditions and open burning for agricultural purposes destroy millions of hectares of land in Indonesia on an annual basis, and Riau is often one of the worst impacted areas, owing in part to its high concentration of peatland .
Seeing this Species
In Riau, the East Sumatran Banded Langurs are mainly found within the fragmented landscape of rubber and paper pulp plantations.
Access to this reserve requires permit from the authorities.
Probability of success: ◆ ◆ ◇ ◇ ◇
Overlapping species: It is believed that 10 primate taxa, including the East Sumatran Banded Langur, occur in Riau Province [6,7]
Agile Gibbon (Hylobates agilis)
Southern Pig-tailed Macaque (Macaca nemestrina)
Sumatran Slow Loris (Nycticebus hilleri)
Black-and-white Langur (Presbytis bicolor)
Riau Pale-thighed Langur (Presbytis siamensis cana)
Silvered Langur (Trachypithecus cristatus cristatus)
The Black-crested Sumatran Langur (P. melalophos) may possibly be found in Riau Province, but its taxonomy remains unclear and the different colour variants of the species make it difficult to determine the boundaries of its ranges .
Local contacts: Andie Ang (firstname.lastname@example.org)
The Riau Pale-thighed Langur can also be found in Riau Province
© Andie Ang
An East Sumatran Banded Langur holding a rubber fruit with its mouth
© Andie Ang
 Ang A., Roesma D.I., Nijman V., Meier R., Srivathsan A. & Rizaldi, 2019. Faecal DNA to the rescue: Shotgun sequencing of non-invasive samples reveals two subspecies of Southeast Asian primates to be Critically Endangered species. Scientific Reports 10, 9396.
 Rizaldi, Ilham K., Prasetio I., Lee Z., Jabbar S. & Ang A., 2019. Preliminary study on the distribution and conservation status of the East Sumatran banded langur Presbytis femoralis percura in Riau Province, Sumatra, Indonesia. Asian Primates Journal 8: 25-36.
 Ang A., D'Rozario V. Jayasri S.L., Lees C.M., Li T.J. & Luz S., 2016. Species Action Plan for the conservation of Raffles' banded langur (Presbytis femoralis femoralis) in Malaysia and Singapore. IUCN SSC Conservation Breeding Specialist Group, Apple Valley, MN, USA.
 Uryu Y., Purastuti E., Laumonier Y., Sunarto S.B.Y.S.A., Hadian O., Kosasih D.A. & Stüwe M., 2010. Sumatra’s forests, their wildlife and the climate, windows in time: 1985, 1990, 2000, and 2009. WWF-Indonesia Technical Report, Jakarta, Indonesia.
 World Bank, 2016. The cost of fire: An economic analysis of Indonesia’s 2015 fire crisis. Indonesia Sustainable Landscapes Knowledge Note 1, Washington, DC, USA.
 Nekaris K.A.I. & Jaffe S. 2007. Unexpected diversity of slow lorises (Nycticebus spp.) within the Javan pet trade: implications for slow loris taxonomy. Contributions to Zoology 76(3), 187-196.
 Mittermeier, R.A., Rylands, A.B. & Wilson, D.E. 2013. Handbook of the mammals of the world, Vol. 3, Primates. Lynx Edicions, Barcelona, Spain.
 Groves C.P. & Roos C., 2013. Black-crested Sumatran langur. In: Handbook of the mammals of the world, Vol. 3, primates, R.A. Mittermeier, A.B. Rylands and D.E. Wilson (eds.), p.718. Lynx Edicions, Barcelona, Spain.
Page Last Updated: 3 July 2022