The purple-faced langur (Semnopithecus vetulus), endemic to Sri Lanka, is an arboreal primate characterised by its dark brown fur, dark face with whitish sideburns, and a relatively long tail. Four subspecies have been identified, differing slightly in colouration and size. These monkeys inhabit closed-canopy forests and rarely descend to the forest floor. While their diet primarily consists of leaves, they also consume fruits, seeds, and flowers. These langurs use a variety of vocalisations to communicate, including harsh barking calls to warn their troop of danger.