Variations in body shape of mountain habitat specialist Carabus croaticus and its sister species Carabus caelatus (Coleoptera: Carabidae) populations across Dinaric Alps

Abstract

There are abundant phenotypic variations of Carabus croaticus Dejean 1826, an endemic species of the Dinaric Alps, and its sister species Carabus caelatus Fabricius 1801, resulting in taxonomic inflation at intraspecific level, synonymy and inconsistency between relevant catalogues and checklists. The main aims of this research were to explore population structure based on morphology and geographic patterns of phenotypic variability, and compare the results with taxa described by nonmetric visual comparisons of morphological traits. Our study included 224 specimens of C. croaticus and 192 specimens of C. caelatus, covering most of their distributional range. Shapes of the pronotum and head were analysed using geometric morphometrics (GMM). Principal component and canonical variate analyses were used to characterize the main features of shape variation between populations and mountain ranges. GMM delimitated interspecific morphological variations but at the intraspecific level it showed many overlaps within populations for both species. Conducting the morphological analyses for the first time on most of the described phenotypic variants of studied species, we wanted to provide a new evidence for the possible solution of the taxonomic relations within these two endemic species by measuring body shape variability, and thus to enable a better understanding of the evolutionary processes in the Dinaric Mountains.