Recurrent founder-event speciation across the Mediterranean likely shaped the species diversity and geographic distribution of the freshwater snail genus Mercuria Boeters, 1971 (Caenogastropoda: Hydrobiidae)

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

“…The recovered species exhibited low levels of intraspecific COI divergence (0%-1.3%), except M. midarensis Boulaassafer, Ghamizi & Delicado, 2018 (0%-3.4%), and a generally high degree of morphological variation within species (Boulaassafer et al 2018). Recently, species delimitation methods conducted on a DNA-sequence dataset with dense geographic sampling detected 14 groups in Mercuria, of which five may represent new species (Miller et al 2022). The proposed species classification for some of the populations, which was based on mitochondrial and nuclear sequences, contrasts with previous identifications made by other taxonomists using mostly shell characters.…”

“…The Western Palaearctic freshwater snail genus Mercuria Boeters, 1971 comprises 30 currently recognised species (25 extant and 5 extinct; MolluscaBase 2022) that are primarily distributed in lowland localities in Mediterranean and Atlantic coastal regions (Glöer et al 2015). Within the Mediterranean, this genus has been found in the Iberian and Italian peninsulas, southern France, some western Mediterranean islands and north-western Africa (Glöer et al 2010(Glöer et al , 2015Boeters & Falkner 2017;Holyoak et al 2017;Boulaassafer et al 2018;Miller et al 2022). On the Atlantic coast, confirmed records include the southern British Islands, northern continental Europe and Macaronesia (Kerney 1992(Kerney , 1999.…”

“…The morphological characters of most of the populations studied and species proposed by Miller et al (2022), and their degree of intraspecific variability, remain unknown. In fact, whether the species clades of Mercuria inferred in that study can even be distinguished based on morphological characters remains to be determined.…”

“…In fact, whether the species clades of Mercuria inferred in that study can even be distinguished based on morphological characters remains to be determined. In this study, our main goal is to fill this data gap by (i) describing the morphology of eight of the 14 putative species proposed by Miller et al (2022), formally describing five of them here as new species, and the species M. maceana (Paladilhe, 1869), for which the shell and radula of a few museum specimens have also been examined, (ii) assessing their taxonomy and geographic distribution and (iii) quantifying shell shape variation among some of the species. The only putative species proposed by Miller et al (2022) not included in the present study is M. rolani Glöer, Boeters & Walther, 2015, due to the lack of material.…”

“…In this study, our main goal is to fill this data gap by (i) describing the morphology of eight of the 14 putative species proposed by Miller et al (2022), formally describing five of them here as new species, and the species M. maceana (Paladilhe, 1869), for which the shell and radula of a few museum specimens have also been examined, (ii) assessing their taxonomy and geographic distribution and (iii) quantifying shell shape variation among some of the species. The only putative species proposed by Miller et al (2022) not included in the present study is M. rolani Glöer, Boeters & Walther, 2015, due to the lack of material. As a result of this study, we have a more accurate taxonomic assessment of the component populations of nine species of Mercuria, which will help clarify the overall geographic distribution of these taxa and their conservation status.…”