Taxonomic reassessment of Eirenis thospitis and Eirenis hakkariensis based on morphological and genetic evidence

The taxonomic status of Eirenis thospitis and Eirenis hakkariensis has long been debated due to their close morphological similarity and overlapping geographic distributions. In this study, we investigated their relationship using morphological characters together with mitochondrial (cyt b, 16S rRNA) and nuclear (C-mos) DNA markers. Morphological examination revealed highly similar external features in both taxa, including a slender body, indistinct head, smooth dorsal scales, and comparable head scalation patterns. The sole meristic difference was the number of dorsal scale rows at mid-body (E. thospitis: 15; E. hakkariensis: 17), while all other morphometric and pholidotic characters showed considerable overlap. Phylogenetic analyses based on combined mitochondrial and nuclear datasets showed that E. thospitis and E. hakkariensis form a single well-supported monophyletic clade. Divergence time estimations suggested that diversification within the sampled species began in the Middle Miocene (∼14.67 Mya), whereas the node involving E. thospitis and E. hakkariensis was estimated at 0.10 Mya. Considering the morphological, molecular, and biogeographical evidence collectively, E. hakkariensis is more appropriately interpreted as conspecific with E. thospitis rather than as an independent species or subspecies. Accordingly, E. hakkariensis Schmidtler & Eiselt, 1991 is herein proposed as a junior synonym of E. thospitis Schmidtler & Lanza, 1990.