Who lives where? Molecular and morphometric analyses clarify which Unio species (Unionida, Mollusca) inhabit the southwestern Palearctic

Abstract

Many doubts still exist about which freshwater mussel Unio species inhabit Northwest Africa. While some authors refer to the presence of Unio delphinus in the Atlantic North African basins of Morocco, a recent International Union for Conservation of Nature (IUCN) assessment performed on Moroccan Unio species, recognised the existence of a distinct species, Unio foucauldianus, with a critically endangered conservation status. The present study delivered new genetic, morphological, and geographical distribution data on two Unio species (i.e. U. delphinus and U. foucauldianus) greatly increasing the almost non-existent data on these taxa. Bayesian phylogenetic analysis revealed two highly supported geographically concordant clades, which diverged by 3.2 ± 0.6 % (uncorrected p distance): the first distributed across Iberia and corresponding to U. delphinus, and the second distributed across Morocco, corresponding to U. foucauldianus. These results were corroborated by the analysis of ten newly developed microsatellite loci as well as shell morphometry. We suggest that the IUCN critically endangered conservation status of U. foucauldianus should be revised and probably down-listed since its actual distribution is much wider than previously described. Phylogenetic relationships with the other Unio species were resolved, showing that U. delphinus and U. foucauldianus fall inside the pictorum lineage. The estimated molecular rate reported herein (0.265 ± 0.06 % per million years) represents the first for the Unionida and could be used as a reference in future studies.Electronic supplementary material The online version of this article

Lifting the curtain on the freshwater mussel diversity of the Italian Peninsula and Croatian Adriatic coast

“…Although the majority of published studies on freshwater mussels have evaluated genetic diversity based mainly on partial distributions (e.g. Nagel et al 1996;Machordom et al 2003;Araujo et al 2005Araujo et al , 2009Geist et al 2010;Prié and Puillandre 2014), recent ones have included detailed phylogeographic data covering entire species ranges (Froufe et al , 2016a. These studies highlighted Iberia, North Africa and the Balkans as primary refugia, in accordance with what has been described for the majority of other taxa (e.g.…”

“…Recent molecular works have updated the phylogeny of this genus, which currently encompasses four main lineages: pictorum, crassus, tumidus and gibbus (Froufe et al 2016a;Lopes-Lima et al 2017b). Many doubts still exist about which Unio species inhabit the Italian Peninsula.…”

Conservation of freshwater bivalves at the global scale: diversity, threats and research needs

“…More powerful genetics and morphometric tools are also increasingly available, for instance, new statistical tools for species delimitation using molecular and/or other types of data such as morphometry and anatomical traits (e.g. Froufe et al, 2016b;Pfeiffer et al, 2016). These tools are particularly important owing to the fact that many species present hidden cryptic diversity (Froufe et al, 2016b;Pfeiffer et al, 2016).…”

“…Froufe et al, 2016b;Pfeiffer et al, 2016). These tools are particularly important owing to the fact that many species present hidden cryptic diversity (Froufe et al, 2016b;Pfeiffer et al, 2016). Additionally, nextgeneration sequencing is now allowing for quicker and less expensive robust phylogenies using methods like whole-transcriptome and whole-mitogenome analyses with a wide range of markers (Guerra et al, 2017;Lopes-Lima et al, 2017c).…”

The female and male mitochondrial genomes of Unio delphinus and the phylogeny of freshwater mussels (Bivalvia: Unionida)

“…However, the recently redescribed Unio delphinus (Froufe et al 2016a;Lopes-Lima et al 2016) is restricted to the main Atlantic basins of the Iberian Peninsula (Froufe et al 2016a). This species was considered as 'Near Threatened' in the last IUCN Red List assessment, making its genetic characterization a priority for conservation (Cuttelod et al 2011;Lopes-Lima et al 2014).…”