No abstract

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

The genus Pyramidula presents a Palearctic geographical distribution, being described in Spain four species not distinguishable from an anatomical point of view. In the present study, we compare our samples along with the previously recognized species P. rupestris, P. saxatilis, P. pusilla, P. cephalonica; P. jaenensis, and P. chorismenostoma by means of molecular studies. Also, we compared P. jaenensis from the studied locality with P. rupestris according to the shell shape by means of geometric morphometric methods. The analysis of the Thin-Plate Spline graph showed that P. jaenensis presented an expansion on the growth to the first whorls and the apex, whereas the height of the body whorl was moderately contracted, while in P. rupestris the opposite was found. We found significant differences between both species based on shell shape. We also provide new information about morphological features that could be used in future studies of this genus attempting to stablish a baseline to test whether the Spanish species are cryptic species or not. The present study also extends the distribution of Pyramidula to Madrid, Spain, establishing for the first time the presence of P.