Until fairly recently all the Grey Langurs of the south-Asian genus Semnopithecus were lumped as one species, S. entellus. Now they have been split into about seven or eight species. They are distinguished not only by their genetics but also visibly by colouration (especially of the limbs) and by tail carriage (i.e. whether the tail is carried looped forwards or backwards).
I have recently seen four of the species in India (priam, dussumieri, hypoleucos and ajax) so am uploading photos of all four for comparitive purposes.
This pictured species is the Black-footed Grey Langur S. hypoleucos which has a restricted range in southwest India. This photo was taken at the Tholpetty Wildlife Sanctuary in Kerala, and unfortunately is the best I managed to get. I also saw them much more easily and much better at the Someshwara Wildlife Sanctuary at Agumbe in Karnataka, but didn't get any photos which were worth showing*. Vivek Menon in his field guide to Indian mammals gives this species a large range because he doesn't recognise S. dussumieri, instead combining that species' southerly populations with S. hypoleucos.
