Revealing two centuries of confusion: new insights on nomenclature and systematic position of Argyrogena fasciolata (Shaw, 1802) (auctt.), with description of a new species from India (Reptilia: Squamata: Colubridae)

Abstract

Coluber fasciolatus Shaw, 1802 (today Argyrogena fasciolata auctt.) is the name used for a widespread terrestrial colubrid snake species inhabiting subtropical and tropical dry deciduous/thorn forests of South Asia from Pakistan to India, with unconfirmed records of distribution in Nepal, Bangladesh and Myanmar and a single doubtful record from the northern tip of Sri Lanka. During the past 200 years, A. fasciolata (common name Banded racer) has been placed in different genera, i.e. Tyria Fitzinger, 1826, Zamenis Wagler, 1830, Coryphodon Duméril, Bibron and Duméril, 1854, and Coluber Linnaeus, 1758 where it primarly remained until the mid 1960s and exceptionally until the year 2011. Three subsequently introduced names, viz. Coluber hebe Daudin, 1803, Coluber curvirostris Cantor, 1839, and Argyrogena rostrata Werner, 1924 were synonymized with C. fasciolatus shortly after its description. Based on a combination of characters including body pattern, external morphology and osteological differences Wilson (1967) reviewed the taxon fasciolatus Shaw and considered it as generically distinguishable, removed it from the then heterogeneous and undefined collective genus Coluber and assigned it to the resurrected genus Argyrogena Werner, 1924. Shaw’s (1802) description of C. fasciolatus was based exclusively on the information of Russell’s “Nooni Paragoodoo” published in 1796 in his “Account of Indian Serpents, collected on the coast of Coromandel; […]”. Our analysis of the original data and the depicted type specimen in Russell (1796) revealed that the name fasciolata was initially established for a species distinct from that currently known as the “Banded racer”, and that Russell’s data have been used simultaneously but unwittingly, for more than 150 years, as original source for two valid species from two different genera. Specimens of Banded racer found in the southeastern part of peninsular India are morphologically and genetically distinct from populations of the rest of the distribution area. These populations from central and southern Tamil Nadu state represent a different species, consequently described as a new species herein. Furthermore, examination of specimens of the Banded racer from different populations across its entire range, including the type specimen of the genus Argyrogena (A. rostrata Werner), reveals a similarity in morphology with the genus Platyceps Blyth, 1860. This was further supported by molecular data which demonstrates that the genus Argyrogena is nested within Platyceps.