The southern plains gray langur (Semnopithecus dussumieri) is a species of old world monkey native to the Indian subcontinent. These monkeys live in groups in forests and other rural habitats, with some groups being habituated to human contact and feeding. They are herbivorous, feeding by day mainly on foliage, fruits and flowers, and sleeping at night high in a tree.
The taxonomy of the gray langur is in a state of flux. At first, all gray langurs were included in a single species, Semnopithecus entellus, with several subspecies, but more recently some authorities have elevated these to species status. The southern plains gray langur was the common name ascribed to Semnopithecus dussumieri by Mammal Species of the World (3rd edition) in 2005. Along with several other Semnopithecus, it had been previously considered a subspecies of the northern plains gray langur, Semnopithecus entellus, i.e., Semnopithecus entellus dussumieri. Subsequent genetic research has revealed that Semnopithecus dussumieri is an invalid taxon. As a result, the populations of gray langurs that had been considered to be southern plains gray langur are by some considered to be populations of northern plains gray langurs S. entellus. However Semnopithecus dussumieri is accepted as a species by other authorities.