The delusion of stripes: A century-old mystery of five-lined sun skinks (Reptilia: Scincidae: Eutropis) of Peninsular India elucidated

We re-evaluate the taxonomic identities of five-lined skinks of the genus Eutropis (E. trivittata, E. beddomei, E. nagarjunensis, and E. bibronii) inhabiting the Indian subcontinent. Previously it has been considered that E. trivittata is distributed in the western India and E. dissimilis in the northern India (from north-eastern India up to Pakistan). Based on our analysis, we revealed that the illustration (iconotype) of the untraceable type specimen of E. trivittata depicted by Hardwicke in Gray (1834) from “Dumdum” near Kolkata, West Bengal matches the typical E. dissimilis, also described from “Bengal”. The senior synonym, E. trivittata is a morphologically unique species, which is also supported by divergence in the mitochondrial 12S and 16S regions. E. trivittata is clearly separated with divergences of 5–7% from E. beddomei, E. vertebralis and E. nagarjunensis for 16S rRNA. After placing E. dissimilis with the synonymy of E. trivittata, the taxonomic status of the western Indian ‘E. trivittata’ required to be clarified. Therefore, we resurrect Mabuia vertebralis Boulenger, 1887, a junior synonym of western Indian E. trivittata, and redescribe its holotype collected from “Belgaum”, Karnataka. Although, morphologically closest to E. beddomei, Eutropis vertebralis comb. nov. is a sister taxon to E. nagarjunensis with divergence of 4% in the same mitochondrial regions. Based on our update of the currently confirmed localities for E. vertebralis comb. nov. and E. trivittata, we conducted a Species Distribution Modelling (SDM) using the Maximum Entropy algorithm to predict their distribution range, and we discuss their conservation status.