Hidden Diversity in a Narrow Valley: Description of New Endemic Palearctic Rock Lizard Darevskia (Squamata: Lacertidae) Species from Northeastern Turkey

Darevskia is a particularly species-rich radiation of Palearctic rock lizards from the Caucasus region. Thanks to intense systematic and taxonomic research, the knowledge of species-level diversity within this genus has increased over the last quarter century. Here, we described a new species, Darevskia salihae sp. nov. from northeastern Turkey. The new taxon is differentiated from other nearby taxon by the low number of dorsal scales in the middle of the body, the shorter body length, and the absence of blue dots both on the lateral region above the forelimbs and on the margin of the ventral plates. In addition to their morphological differences, the new taxon is phylogenetically different from close groups. It is located in a separate subclade from the rudis-valentini-portschinskii subclade. This distinction is supported by both a high bootstrap value (100) and a high posterior probability value (1.00). These two subclades are separated from each other by a genetic distance of almost 4%. This separation is supported not only genetically and morphologically, but also geographically. Since the habitat of the new taxon is limited to a high mountain and a narrow valley, it does not provide an opportunity for a different Darevskia species to shelter because it creates geographical isolation. However, Darevskia parvula that live closest to the habitat of the new taxon live only at the habitat boundaries and do not enter areas where the new taxon is found. Therefore, it might be possible that while it was separated from the rudis-valentini-portschinskii group during the evolutionary transformation, it remained as a refuge and relict in a narrow area as a result of the collapse of the valleys and the partial uplift of the Kaçkar Mountains.