The langur can seem deceptively common. Its geographical range, after all, extends across most of South Asia, and the adaptable primate is equally at ease in Himalayan highlands, in the rainforests of the Western Ghats and in Rajasthan's desert fringes.
But in a finding that could have major conservation implications for the langur, scientists have established that it is in fact not a single species, Semnopithecus entellus , as earlier assumed, but consist of at least four distinct species.
Scientists at the Centre for Ecological Sciences (CES), Indian Institute of Science (IISc) have, through an analysis of the langur’s physical traits and genetic profile, found three genetically different species: Semnopithecus entellus (found across north India) S. priam (drier parts of peninsular India) and S. hypoleucos (mostly in the Western Ghats).
Besides the three species, the status of a fourth one — Himalayan langur S. schistaceus — needs to be resolved says the paper published in a recent edition of the journal Conservation Genetics . Hypotheses have for long abounded about the taxonomy of langurs, and about whether they consist of over a dozen subspecies or a few species.
Subtle morphological differences set langur populations apart: langurs carry their tails differently, their colouration varies, and while some have a tuft of fur on their head, others do not, said co-author K. Praveen Karanth, of CES.
To crack the puzzle, the research group studied DNA from 72 scat samples, and confirmed that langurs are not in fact a single species as earlier believed. The Semnopithecus entellus found across north India is most widely distributed, while S. priam and S. hypoleucos have much smaller ranges in peninsular India, says Dr. Karanth adding there is now a need to assess the status of each population and devise conservation plans.
Langurs possibly split into different species three to five million years ago. He said. “India is a vast country with very different climatic and ecological conditions, which langur populations have clearly adapted to.”
Langurs were once considered a single species, and therefore assumed to have no imminent threat. “However if Hanuman langurs constitute a species complex then some of these species might have restricted distributions and their populations might be threatened,” says the paper.
