Taxonomic Composition of the Oligodon arnensis (Shaw 1802) Species Complex (Squamata: Colubridae) with the Description of a New Species from India

We review the taxonomic status of Oligodon arnensis (Shaw 1802) after examining all the name-bearing types of its synonyms, and evaluating morphological and biogeographic evidence. Oligodon arnensis sensu lato is widely distributed throughout Peninsular India, Sri Lanka, Pakistan, Nepal, Bhutan, and Bangladesh. We demonstrate that southern, eastern, and western populations in India represent three distinct species. Oligodon arnensis sensu stricto described from Arnee (now Arani), Tamil Nadu, southern India, is distributed in southern India up to 1500 m above sea level. Oligodon albiventer Günther 1864 and Simotes russellii var. ceylonensis Müller 1887 described from Sri Lanka closely match O. arnensis sensu stricto, and hence we treat them as junior synonyms. We resurrect Coluber russelius Daudin 1803 from the synonymy of O. arnensis, designate a lectotype, and restrict its type locality to Vizagapatam (now Visakhapatnam), Andhra Pradesh, eastern Peninsular India. Based on morphological differences we describe a new species from Kurduvadi, in the Deccan plateau of western India representing the western Indian population of O. arnensis sensu lato. We provide redescriptions for O. arnensis sensu stricto and O. russelius comb. nov. based on museum specimens, as both were named based on illustrations (iconotypes). Based on our update of the currently confirmed localities for O. arnensis, O. russelius comb. nov. and the new species, we discuss their biogeography and conservation status.