Biodiversity of the endangered coastal beetle Scarites laevigatus: is the northern Adriatic population a geographical subspecies or a case of introgressive hybridisation? (Coleoptera: Carabidae)

The ground beetle Scarites laevigatus Fabricius, 1792 is a specialized predator occurring in the Mediterranean sandy shores, currently threatened with disappearance due to the widespread modification of beach ecosystems. The present study purposes a morphological analysis of the northern Adriatic form, described by Puel in 1938 as a subspecies with the name venetianus, in comparison with the typical form of this taxon and S. terricola. The examination of pronotum, elytra, body shape, male genitalia and wing development, suggests that the studied population is different from the nominotypical form and might originate from the introgressive hybridisation of S. terricola with the north Adriatic populations of S. laevigatus. This hypothesis is discussed in the light of current knowledge of the systematics and ecology of the putative parent species.