Local endemic and threatened freshwater hydrobiids of Western Greece: elucidation of anatomy and new records

Shell features are key factors for systematics and evolutionary biology studies of freshwater gastropods. Based mostly on shell morphology, 19 species of the springsnail genus Radomaniola (family Hydrobiidae) have been described. Although the scarce differentiation of various shell dimensions suggests morphological stasis, the evolutionary dynamics of shell and other anatomical structures have not yet been explored fully. By inferring a phylogeny and a time-calibrated species tree from mitochondrial (COI and 16S) and nuclear (28S) sequences of 15 recognized species, we initially examine the species diversity of the Radomaniola dataset and then, through phylogenetic comparative methods, assess the evolutionary correlation, pace and mode of 40 continuous shell and anatomical characters. By synthesizing the results of four species delimitation methods and through morphological examinations, we recognize 21 groups, for which taxonomy is discussed here. Seven new species are described. We reveal a high degree of correlated evolution between characters of the shell, which are constrained by a single morphological optimum, consistent with the morphological stasis model. Anatomical traits diverged rapidly in an unconstrained manner or toward multiple optima. These findings indicate that in order to understand the morphological evolution of springsnails, it is essential to examine different organs in detail.

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Multilocus phylogeny, species delimitation and biogeography of Iberian valvatiform springsnails (Caenogastropoda: Hydrobiidae), with the description of a new genus

Delicado

Arconada

Aguado

et al. 2019

Zoological Journal of the Linnean Society

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Valvatiform gastropods of the family Hydrobiidae are frequently found in European spring-fed systems. Their simplified and sometimes convergent morphological structures and restricted geographical ranges make the description and identification of valvatiform species challenging. In the Iberian Peninsula, to date, 20 valvatiform species have been described morphologically. To test morphological species delimitations and to evaluate the role of physical geography on their evolutionary history, we analysed two mitochondrial (COI and 16S rRNA) and two nuclear (28S rRNA and 18S rRNA) gene fragments of 16 valvatiform species from the Iberian Peninsula. Molecular species delimitation methods consistently inferred 11 of the nominal species. Our phylogenetic analyses recovered the species Islamia azarum as an independent lineage, distantly related to other genera, which we place in the new genus Deganta. Furthermore, Iberian valvatiform hydrobiids do not form a monophyletic subunit, but they are included in two distinct clades of Hydrobiidae. Divergence times indicate that speciation in these clades is likely to have coincided with the formation of major Iberian mountain ranges and river basins. Similarities of geographical subdivision and divergent times between this assemblage and the non-valvatiform genus Corrosella provide strong evidence for the role of the Iberian geographical barriers in shaping the biogeography of these springsnails.

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Local endemic and threatened freshwater hydrobiids of Western Greece: elucidation of anatomy and new records

Cited by 6 publications

References 25 publications

The Biogeographic Characteristics of the River Basins of Greece

The Biogeographic Characteristics of the River Basins of Greece

Shell features and anatomy of the springsnail genus Radomaniola (Caenogastropoda: Hydrobiidae) show a different pace and mode of evolution over five million years

Multilocus phylogeny, species delimitation and biogeography of Iberian valvatiform springsnails (Caenogastropoda: Hydrobiidae), with the description of a new genus

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