Trachypithecus is a genus of Old World monkeys containing species known as lutungs, langurs, or leaf monkeys. Their range is much of Southeast Asia (northeast India, Vietnam, southern China, Borneo, Thailand, Java, and Bali).

The name "lutung" comes from the Sundanese language meaning "blackness", ultimately from Proto-Austronesian *luCuŋ (which originally referred to the Formosan rock macaque); it is preferred in one paper because the authors wanted the name langurs to only refer to monkeys in the genus Semnopithecus, The scientific name of the genus comes from the Ancient Greek τραχύς (trakhús), meaning "rough", and πίθηκος (píthēkos), meaning "monkey".

Evolution

thumb|Trachypithecus cristatus robustus skull

Genetic analysis indicates that the ancestors of the modern species of lutung first differentiated from one another a little over 3 million years ago, during the late Pliocene. The various species alive today then diverged during the Pleistocene, presumably driven by habitat changes during the Ice Ages. The oldest fossils clearly identified as belonging to the genus date from the middle Pleistocene of Vietnam and Laos; later fossils are also known from Thailand, Java, and Sumatra. The closest living relatives of the lutungs are probably either the gray langurs or the surilis, although the exact relationships remain unclear, possibly due to hybridisation between these genera during the course of their recent evolutionary history.

Taxonomy

thumb|[[Nilgiri langur, formerly classified within the genus Trachypithecus but since moved to the genus Semnopithecus ]]

As of 2005, the authors of Mammal Species of the World recognized the following Trachypithecus species:

  • Genus Semnopithecus
  • formerly T. vetulus group - moved into genus Semnopithecus in most recent classifications
  • Purple-faced langur, Semnopithecus vetulus
  • Nilgiri langur, Semnopithecus johnii
  • Genus Trachypithecus
  • T. cristatus group
  • Javan lutung, Trachypithecus auratus
  • Silvery lutung, silvery langur or silvered leaf monkey, Trachypithecus cristatus, but also used for T. germaini
  • Indochinese lutung or Germain's langur, Trachypithecus germaini
  • Tenasserim lutung, Trachypithecus barbei
  • T. obscurus group
  • Dusky leaf monkey, Trachypithecus obscurus
  • Phayre's leaf monkey, Trachypithecus phayrei
  • T. pileatus group
  • Capped langur, Trachypithecus pileatus
  • Shortridge's langur, Trachypithecus shortridgei
  • Gee's golden langur, Trachypithecus geei
  • T. francoisi group
  • Francois' langur, Trachypithecus francoisi
  • Hatinh langur, Trachypithecus hatinhensis
  • White-headed langur, Trachypithecus poliocephalus
  • Laotian langur, Trachypithecus laotum
  • Delacour's langur, Trachypithecus delacouri
  • Indochinese black langur, Trachypithecus ebenus

Since then, the T. vetulus group (the purple-faced langur and the Nilgiri langur) have been moved the genus Semnopithecus based on DNA and other evidence.

In 2008, Roos et al. described the Malay Peninsula form of the silvery lutung as a separate subspecies and subsequently it has been elevated to a separate species within the T. cristatus group as the Selangor silvered langur, T. selangorensis. Roos et al. also elevated the West Javan Langur, Trachypithecus mauritius, and Annamese Langur, Trachypithecus margarita, to species status (formerly subspecies of T. auratus and T. germaini, respectively). Lastly, the White-headed langur (T. leucocephalus), previously thought to be a subspecies of the Francois langur (T. Francois) or Cat Ba langur (T. poliocephalus), is currently recognized as a distinct species by IUCN Red List assessors and the American Society of Mammalogists, based on a 2007 paper by Groves.

This leaves the current understanding of the genus Trachypithecus to be: