Morphology and taxonomic assessment of eight genetic clades of Mercuria Boeters, 1971 (Caenogastropoda, Hydrobiidae), with the description of five new species

The freshwater snail genus Mercuria is widely distributed in lowland waters across Western Europe, Northern Africa and the Mediterranean islands. Approximately two-thirds of currently recognised species are described based on their shell morphology, which may vary within due to biotic abiotic factors. Recent molecular phylogenies that included numerous previously documented populations recovered 14 clades, nine correspond nominal five, undescribed taxa. Here, we formally describe five taxa as new provide morphological descriptions other anatomical structures for three inferred clades M. maceana elucidate taxonomic status assess utility characters delimitation Mercuria. Taken together, evidence suggest identifications synonymies, having implications known geographic range studied species, including type similis. Anatomical measurements geometric morphometric analysis shape revealed no clear differentiation among analysed, predicting importance data elucidating diversity genus.