First Report on the White Morph Western Purple-Faced Leaf Langur (Trachypithecus vetulus nestor) in Sri Lanka

Abstract

The endemic Purple- faced leaf langur in Sri Lanka is represented by four sub species. Of the four sub species, the western purple faced leaf langur [Trachypithecus vetulus nestor- Bennet, 1835) has grayish black pelage colour and faint white rump patch and is mainly found in low tropical rain forests up to I000m in the Western and Sabaragamuwa provinces. While morph of the western purple- faced leaf langur was first discovered during a survey in 2010 in the Galigamuwa Divisional Secretariat Division, Kegalle District, Sabaragamuwa Province. The habitats of these langurs are mainly rubber plantations and private home gardens. Initially all the black langur troops with while colour morph individuals were identified in the Aruggammana, Hathnapitiya and Kurunegoda GN divisions. Out of sixteen purple faced langur troops surveyed, white morphs were recorded in 12 troops. Twenty eight white morph purple faced langurs were recorded, which was comprised of eight adult males, 6 adult females and 14 sub adults/infants of unidentified sex. The white morph purple-faced langurs are always associated with normal black colour langurs. In completely white individuals the face, crown hair, hair on the back of the head, ears and the eyes are black or reddish as in normal individuals. However their pelage colour, limbs and tails are completely white. The mixed coloured individuals have brownish ash patches on the under arms and on the back. Albinism can be ruled out as their faces and other areas of exposed skin are black and they do not have red eyes. Western Purple-faced leaf langurs are endemic and critically endangered due to habitat loss. The discovery of white morph of these sub species makes it more important to conserve these animals in terms of preserving their biodiversity.