Integrative taxonomy confirms the species status of the Himalayan langurs, Semnopithecus schistaceus Hodgson, 1840

Abstract

Taxonomy is replete with groups where the species identity and classification remain unresolved. One such group is the widely distributed Hanuman langur (Colobinae: Semnopithecus). For most part of the last century, the Hanuman langur was considered to be a single species with multiple subspecies. Nevertheless, recent studies using an integrative taxonomy approach suggested that this taxon is a complex, with at least three species. However, these studies did not include the Himalayan population of the Hanuman langur whose taxonomic status remains unresolved. The Himalayan population of Hanuman langurs has been classified as a distinct species with multiple subspecies or been subsumed into other species. These classification schemes are wholly based on morphological characters which are sometimes insufficient to delimit different species. Here, we have integrated data from multiple sources viz. morphology, DNA, and ecology to resolve the taxonomy of the Himalayan langur and to understand its distribution limit. Our results with three lines of evidence corresponding to three different species concepts show that Himalayan langur is a species distinct from Semnopithecus entellus of the plains. Additionally, these results did not show any support for splitting of the Himalayan langur into multiple subspecies. Our study supports the classification proposed by Hill (Ceylon Journal of Science, XXI, 1939) and we recommend Semnopithecus schistaceus Hodgson, 1840 as species name for the Himalayan langur and subsume all the known subspecies into it.

Geography vs. past climate: the drivers of population genetic structure of the Himalayan langur

“…Himalayan langur, (Primate: Colobinae) is a widely distributed alloprimate found in most parts of the Himalayas. It is distributed in Nepal and parts of India, Pakistan and Bhutan [ 52 ], the Black mountain range and the Sunkosh river in Bhutan forms the easternmost distribution limit for this species [ 53 ]. Until recently, there was much ambiguity in the taxonomy of these langurs owing to presence of multiple classification schemes, however IUCN recognised three species— Semnopithecus ajax , Semnopithecus schistaceus and Semnopithecus hector , as per the classification scheme proposed by Groves [ 54 ].…”

“…In this context, a recent systematic study resolved the taxonomy of these langurs using an integrative approach based on three lines of evidence from molecular, morphological and ecological data. The authors have now subsumed the three recognised species into a single widespread species Semnopithecus schistaceus Hodgson, 1840 [ 52 ].…”

Mitochondrial Genetic Diversity and Structure of the Langur Population in a Complex Landscape of the Nepal Himalaya

“…The taxonomy of langurs in the Himalaya has remained inconclusive despite a recent phylogenetic study, based on a single mitochondrial gene sequence, that has classified all Himalayan populations into a single species [25]. The IUCN currently recognizes two species under the genus Semnopithecus in Nepal, viz.…”

“…The phylogeny of colobine monkeys corresponds to a complex evolutionary history, evolving multiple discrete radiations and inhabiting a wide range of habitats in tropical Africa and in southern and south-eastern Asia [24]. The Himalayan langurs inhabiting the temperate forests of India and Nepal have been described to be distinct both morphologically and behaviorally from conspecifics in other ecological niches [10,25]. A recent phylogenetic study based on a single mitochondrial gene (CYTB, 775 bp) described the population of langurs across Himalaya under a single species and argued the Nepal population belonging to two distinct (eastern and western) lineages [25].…”

“…The Himalayan langurs inhabiting the temperate forests of India and Nepal have been described to be distinct both morphologically and behaviorally from conspecifics in other ecological niches [10,25]. A recent phylogenetic study based on a single mitochondrial gene (CYTB, 775 bp) described the population of langurs across Himalaya under a single species and argued the Nepal population belonging to two distinct (eastern and western) lineages [25]. Population genetic analysis of the Nepal Himalayan langurs has revealed a strong genetic structuring by the riverine barriers [6].…”