The Cochlostoma (Holcopoma) westerlundi group in Italy (Caenogastropoda: Cochlostomatidae)

Currently, the Cochlostoma (Holcopoma) westerlundi (Paulucci, 1879) group includes three subspecies inhabiting southern Italy up to southeastern Sicily. C. w. westerlundi (Paulucci, 1879) is limited to southern Calabria, C. w. yapigium (Westerlund, 1885) is widespread across the Salento (the southeastern extremity of the Apulia region) and C. w. dionysii (Paulucci, 1879) is endemic to the environs of Siracusa (SE Sicily). There is also a fourth taxon, C. paganum (Westerlund, 1885) described for Otranto (LE, Apulia), considered a synonym of C. w. yapigium. Up to now, the molecular genetics of C. westerlundi s.l. have been unknown and the morphological data of several populations are still lacking. Hence, the systematic classification of the group is tentative. Aiming at filling this gap, mtDNA (16S rDNA and COI) partial sequences were investigated and, in addition, the reproductive apparatus of C. w. westerlundi was described for the first time. Molecular sequences and anatomical data were used to test the taxonomic and phylogenetic status of the examined populations. Maximum Likelihood and Bayesian analysis revealed three clusters, strongly supported, corresponding to the three taxa. For the first time, synonymy between paganum and yapigium was confirmed by molecular evidence. Genetic distances between groups (DxyJC) ranged from 2.6% to 5% (16S rDNA) and from 6.3% to 8.3% (COI). Molecular and morphological data led us to suggest elevating the three subspecies to the species rank.