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).

Dispersal is known to play an important role in shaping the diversity and geographic range of freshwater gastropods. Here, we used phylogenetic methods to test for the influence of dispersal and other biogeographic processes (such as vicariance) on the speciation and distribution patterns of Mercuria Boeters, 1971, a snail genus widely distributed in the western Palaearctic. The 25 extant species traditionally thought to comprise the genus, which were described mainly on the basis of morphology, have been recorded from lowland waters in both the Mediterranean and Atlantic river basins of Europe and North Africa. Using molecular phylogenies based on three gene fragments (COI, 16S rRNA and 28S rRNA) from 209 individuals, four molecular species delimitation methods and a shell characterization, we identified 14 putative species in our dataset, nine of which correspond to species classified by traditional taxonomy. Furthermore, biogeographical modelling favoured a scenario in which recurrent founder-event speciation since the late Miocene is the most probable process explaining the species diversity and distribution of the Mediterranean clades, whereas episodes of postglacial northward colonization from Iberian refugia by the species M.tachoensis may explain the current presence of the genus in Atlantic lowlands. The dispersal events inferred for Mercuria, probably promoted by multiple factors such as the changing connectivity of drainage basins driven by climate change or better access for avian dispersal vectors in lowlands, may explain the rare case among hydrobiids of a species-rich genus containing individual species with a large distribution area.

Living on the mountains: patterns and causes of diversification in the springsnail subgenus Pseudamnicola (Corrosella) (Mollusca: Caenogastropoda: Hydrobiidae).

Hydrobiidae is one of the largest families of freshwater gastropods comprised of approximately 400 genera and 1000 species. Despite this high level of diversity, most hydrobiid species inhabit fragile ecosystems in restricted distribution areas. In this work, we analyze modes of speciation and causes of diversification in the hydrobiid springsnail subgenus Pseudamnicola (Corrosella). Species of this group typically live in nutrient poor springs and streams and are restricted to mountainous regions of the Iberian Peninsula (Spain) and Southern France. Previous morphological and molecular (based only on the cytochrome c oxidase subunit I (COI) gene) studies revealed 11 nominal Corrosella species. In this study, we enhance published molecular results by generating new data from mitochondrial (16S rRNA and COI) and nuclear ribosomal regions (18S and 28S rRNA) from 50 Corrosella populations. As a result of this study we have identified one new species, making a total of twelve recognized species in the subgenus Corrosella. Our phylogenetic results also reveal the existence of three lineages within the subgenus, and the estimation of time divergence indicates the occurrence of three main speciation events during the upper Miocene to Pleistocene. We test the influence of several geographical and ecological variables and observe that diversification patterns are related to habitat fragmentation rather than environmental conditions. This result suggests that the high level of diversity observed within the subgenus may have resulted from a non-adaptive radiation. The formation of the Iberian Peninsula mountain ranges (the Pyrenees in the north and the Betic Cordillera in the south) and the configuration of the Iberian current hydrographic system played important roles in Corrosella speciation. Additionally, during the Miocene the Iberian Peninsula experienced a gradient of increasing temperature and dryness from north to south, which together with a high level of tectonic activity, may have caused the majority of the diversity found in the southern Iberian Peninsula.

Morphological and molecular evidence for cryptic species of springsnails [genus Pseudamnicola ( Corrosella) (Mollusca, Caenogastropoda, Hydrobiidae)].

Several Pseudamnicola (Corrosella) populations of the central and eastern Iberian Peninsula have been ascribed to Pseudamnicola (Corrosella) astieri (Dupuy, 1851), though recent evidence demonstrates the species could be endemic to the departments of Var and Alpes-Maritimes in France. Through the identification of cryptic species using a combined morphological and phylogenetic approach, this paper provides a detailed morphological description of Pseudamnicola (Corrosella) astieri, clarifying its taxonomic boundaries and confirming it as a French endemic. In parallel, by comparing Pseudamnicola (Corrosella) populations from the provinces of Castellón and Valencia in Eastern Spain, it was observed that rather than Pseudamnicola (Corrosella) astieri they represented a new species here described as Pseudamnicola (Corrosella) hauffeisp. n. Among other characters, the two species show marked differences in shell shape, male and female genital systems, radular formula and concentration of the nervous system. Pseudamnicola (Corrosella) hauffeisp. n. was also compared morphologically to another two Pseudamnicola (Corrosella) species living in nearby areas [Pseudamnicola (Corrosella) hinzi Boeters, 1986 and Pseudamnicola (Corrosella) navasiana (Fagot, 1907)], molecularly to Pseudamnicola (Corrosella) falkneri (Boeters, 1970), the type species of the subgenus, and to the rest of the Pseudamnicola (Corrosella) species described so far. Morphological differentiation between the species is supported by a genetic divergence of 7.4% inferred from a partial sequence (658 bp) of the mitochondrial gene cytochrome c oxidase subunit I (COI). On the basis of an average 8% (5.39 to 11.15%) divergence estimated for the COI gene in other Pseudamnicola (Corrosella) species reported in GenBank, the existence of two specific entities is here proposed, which will have impact on conservation policies both in France and in Spain.