Simias concolor, Pig-tailed Langur The Pig-tailed Langur (Simias concolor, monotypic in genus Simias) is a large, rather heavily built Old World monkey, which is adapted to climbing with its long arms. Its fur is black-brown, and its hairless face is also black. It is the only monkey in the subfamily Colobinae to have a relatively short tail; the tail is only slightly furred and is only 15 cm long. The short nose is pointed upward. The Pig-tailed Langur reaches a full grown length of approximately 50 cm and a weight of 7 kg. Traditionally, it has been placed in the genus Nasalis together with the Proboscis Monkey – a treatment still preferred by some.
This primate lives only on the Mentawai Islands, where it is known as Simakobou in Siberut and Simasepsep on the southern islands of Sipura, North Pagai, and South Pagai. Two of these islands, North- and South-Pagai, are its main range. It is a diurnal and arboreal rain forest dweller, rarely coming to the ground. It lives in small groups (3 to 8 animals), which consist of a male, one or more females, and their offspring. Its diet consists mainly of leaves and, to a lesser extent, fruits and berries. Nothing of its reproduction is known.