Surili

The surilis are a group of Old World monkeys and make up the entirety of the genus Presbytis. They live in the Thai-Malay Peninsula, on Sumatra, Borneo, Java and smaller nearby islands.[1] Besides surili, the common names for the monkeys in the genus also sometimes use the terms "langur" or "leaf monkey."

Surili[1]
Javan surili
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Cercopithecidae
Subfamily: Colobinae
Genus: Presbytis
Eschscholtz, 1821
Type species
Presbytis mitrata
Eschsholtz, 1821
(Simia melalophos Raffles, 1821)
Species

11, see text

Description

Surilis are rather small, slimly built primates. Their fur at the top is brown, grey, black, or orange, and at the lower surface whitish or greyish, sometimes also orange, with some species having fur designs at the head or at the hips.[2][3] Their German name of Mützenlanguren ("capped langurs") comes from the hair on their head, which forms a tuft. They differ from the other langurs by characteristics in the shape of their head (particularly the poorly developed or absent brow ridges, and the prominent nasal bones),[2] in the teeth, and by the size of their small thumbs. Surilis range in adult length from 40 to 60 cm (with a 50- to 85-cm-long tail) and a weight of 5 to 8 kg.[2]

Behaviour

Diurnal forest dwellers, they spend nearly their entire lives in the trees. They live in groups of up to 21 animals (typically 10 or fewer animals in most species) consisting of a male, several females, and their young.[3] A few species have been observed in monogamous pairings (particularly the Mentawai langur),[3] although this might be a reaction to the decrease of their habitat. Lone males and all-male groups have also been reported.[2] The groups are hierarchically developed, with intergroup communication that is both vocal and postural.

Diet

The surilis' diet consists of leaves, fruits, and seeds.[3]

Breeding

Gestation time is 5–6 months, and births are typically of single young. Newborn animals are white colored and have a black strip at the back, although some have a cross-shaped mark. By one year old, the young are weaned and at an age of 4–5 years, they are fully mature. The typical life expectancy in the wild remains poorly known for most species, but captive Sumatran surilis have lived more than 18 years.[2]

Conservation

Several species in this genus are restricted to regions with extensive habitat destruction, and are also threatened by hunting. Consequently, eight of the 11 species are rated as vulnerable or worse by IUCN,[4] and the Sarawak surili has been referred to as "one of the rarest primates in the world."[5] Recently, a subspecies of Hose's langur called Miller's grizzled langur, thought to be extinct, was rediscovered in the Wehea Forest on the eastern tip of Borneo island,[6] though it remains one of the world's most endangered primates.[7]

Taxonomy

Two other genera, Trachypithecus and Semnopithecus, were formerly considered subgenera of Presbytis.[1] The species-level taxonomy of Presbytis is complex, and significant changes have been proposed for several in recent years.[1][8][9][10]

References
  1. Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 170–172. ISBN 0-801-88221-4. OCLC 62265494.
  2. Novak, R. M. (1999). Walker's Mammals of the World. 6th edition. Johns Hopkins University Press, Baltimore. ISBN 0-8018-5789-9
  3. Rowe, N. (1996). The Pictorial Guide to the Living Primates. Pogonias Press, Rhode Island. ISBN 0-9648825-0-7
  4. IUCN (2008). 2008 IUCN Red List of Threatened Species. Retrieved on 2008-12-15.
  5. Nijman, V.; Hon, J. & Richardson, M. (2008). "Presbytis chrysomelas". IUCN Red List of Threatened Species. 2008: e.T39803A10268236. doi:10.2305/IUCN.UK.2008.RLTS.T39803A10268236.en.
  6. The Guardian, guardian.co.uk, Friday 20 January 2012: 'Extinct' monkey rediscovered in Indonesia jungle.
  7. "'Extinct' monkey still lives in Borneo". CBC News.
  8. Meyer, Dirk; Rinaldi, Ir. Dones; Ramlee, Hatta; Perwitasari-Farajallah, Dyah; Hodges, Keith; Roos, Christian (2011). "Mitochondrial phylogeny of leaf monkeys (genus Presbytis, Eschscholtz, 1821) with implications for taxonomy and conservation". Molecular Phylogenetics and Evolution. 59 (2): 311–319. doi:10.1016/j.ympev.2011.02.015. PMID 21333742. Retrieved 2020-04-08.
  9. Ang, A.; Roesma, D.I.; Nijman, V.; Meier, R.; Srivathsan, A. & Rizaldi (2020). "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.
  10. Abdul-Latiff MAB; Baharuddin H; Abdul-Patah P; Md-Zain BM (2019). "Is Malaysia's banded langur, Presbytis femoralis femoralis, actually Presbytis neglectus neglectus? Taxonomic revision with new insights on the radiation history of the Presbytis species group in Southeast Asia" (PDF). Primates. 60 (1): 63–79. doi:10.1007/s10329-018-0699-y. PMID 30471014.
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