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The genus Coralliogalathea of the family Galatheidae is easily differentiated from other genera in the family by its small size, the presence of three to four small lateral teeth on the rostrum and the lack of the first pair of gonopods in males. The genus currently consists of only a single species, Coralliogalathea humilis, which lives in close association with corals in the Indian and Pacific Oceans. Using material collected across its distribution, we analysed both morphological characters and molecular markers (COI, 16S, 28S and 18S) to investigate cryptic species diversity, phylogenetic relationships within the genus, and the phylogenetic position of Coralliogalathea within the family Galatheidae. Our results support the validity of the two species previously synonymized with C. humilis and three new sympatric species found in Espiritu Santo, Vanuatu. Although these species are distinguishable only by subtle morphological characters, they are highly dissimilar genetically and constitute relatively deep divergent lineages. Furthermore, phylogenetic analyses of Galatheoidea resolved Coralliogalathea as an ancient genus within the superfamily that most probably diversified during the Eocene. [ABSTRACT FROM AUTHOR]

Delimiting species boundaries is a fundamental yet challenging task that has been especially problematic in morphologically conserved lineages. The use of genetic markers and phylogenetic approaches has proven of paramount importance to resolve these cases. Using the genus Unio as a case study, we have analysed two mitochondrial markers, cytochrome c oxidase subunit I (COI) and 16S rRNA (16S), phylogenetically and phylogeographically to explore species limits and evolutionary lineages within the group. We followed two different approaches to define species boundaries: the generalized mixed Yule coalescence model in a Bayesian framework and the Poisson tree process model. Phylogenetic relationships among species and divergence times were also assessed using relaxed molecular clock analyses. Taken together, we provide a sound systematic framework for Western Palaearctic Unio species, addressing phylogenetic relationships, and the taxonomy, biogeographic patterns and evolutionary history of this group in this region. The Unio clade from the studied area had a clear phylogenetic structure with four robust lineages that include the following species: (1) Unio durieui + Unio gibbus; (2) Unio tumidus; (3) Unio pictorum, Unio delphinus + Unio foucauldianus, Unio elongatulus, Unio mancus, Unio ravoisieri, Unio tigridis; and (4) Unio tumidiformis + (Unio bruguierianus + (Unio crassus + Unio ionicus)). Deeper analyses, including filling gaps in distributions, should be conducted to disentangle the U. crassus, U. pictorum and U. tigridis species complexes. [ABSTRACT FROM AUTHOR]

The distribution of circum-Mediterranean fauna was dramatically affected by palaeogeographical events during the Cenozoic. The biogeographical history of freshwater mussels is related to the development of the continental watershed during the Tertiary and Pleistocene glacial cycles. Our study model is Potomida littoralis (Cuvier, 1798), a Palaearctic freshwater mussel with a patchy circum-Mediterranean distribution encompassing areas of North Africa, south-western Europe, Greece and the Levant. Our phylogenetic reconstructions, network analyses and coalescence estimations indicate that the clade Potomida has a clear geographical structure with four robust lineages from Turkey, Greece, North Africa and Iberian Peninsula plus France. This structure is only disrupted in two cases: specimens from the Ziz River (Morocco) clustered with Tunisian lineages, and samples from the north-eastern Iberian Peninsula were found to have been recently introduced from Morocco. We considered two different calibration strategies of a molecular clock to evaluate divergence times between lineages. The first, based on palaeogeographical events, resulted in substitution rates up to three times lower than the average for molluscs. When such mean values were considered for calibrating the molecular clock, the group's origin and diversification events were incongruent with the fossil record and the likelihood of gene flow between lineages. Rather than a pattern of recent speciation, our results suggest low levels of substitution and a pattern of 'slow evolution', probably linked to its long generation time and longevity. From a taxonomic viewpoint, the genus Potomida is currently considered monospecific. Reflecting the data presented herein, we propose the existence of an eastern species, named P. acarnanica (Kobelt, 1879) in Greece and Turkey, and another named P. littoralis (Cuvier, 1798), with a wide distribution ranging from France to Tunisia. [ABSTRACT FROM AUTHOR]

Two symbiotic polychaetes living in brachyuran crabs in the western Mediterranean and the nearby eastern Atlantic, Iphitime cuenoti and Ophryotrocha mediterranea, were analysed to determine their phylogeographical patterns and the possible effects of known oceanographic barriers in the study area. The analysed species live in hosts inhabiting well-differentiated depths, a factor that may be crucial for understanding the different patterns observed in each species. Iphitime cuenoti was found in four different host crabs between 100 and 600 m depth and showed some level of genetic homogeneity, reflected in a star-like haplotype network. Furthermore, barrier effects were not observed. By contrast, O. mediterranea was exclusively found in a single host crab species living between 600 and 1200 m depth. Phylogeographical analyses showed two lineages that pre-date the existence of current barriers. The geological history of the study area, including the most recent glaciation events, probably led to a secondary contact between the lineages, thus forming a single metapopulation. The phylogeographical pattern found in each species may be explained by differences in dispersal ability, habitat, and host crab specificity that have led them to be differentially affected by historical events. This study is the first to use a phylogeographical approach on symbiotic polychaetes. [ABSTRACT FROM AUTHOR]

The genus Pseudamnicola comprises a group of tiny springsnails inhabiting several continental and insular regions of the Mediterranean basin. Given the limited dispersal capabilities of these animals, it is difficult to explain the wide distribution range of the genus and, more specifically, its presence in isolated habitats, such as on islands. Thus, to investigate the process(es) that may explain these distribution patterns, we morphologically re-described and genetically analysed the six Pseudamnicola ( Pseudamnicola) species occurring in the Iberian Peninsula and the nearby Balearic Islands. Genetic relationships were explored by sequencing two mitochondrial ( cytochrome c oxidase subunit I and 16S rRNA) and one nuclear ( 28S rRNA) gene in 19 populations. Our morphological study confirmed the presence of previously described species, whereas our phylogenetic results revealed three lineages within the subgenus: one clade grouping the species from Minorca Island with an Iberian Peninsula species, a second clade grouping the three species from Majorca Island, and a third clade that consists of a single species, which occurs in both the Iberian Peninsula and Ibiza Island. Calculated speciation times show that the cladogenetic events involving the insular species seem to have occurred after the current conformation of the Balearic Islands ( c. 20 Mya). Therefore, the speciation process may have been related to subsequent transmarine colonizations, probably during the Messinian Salinity Crisis, and the Pleistocene glaciations when landmass corridors connected the islands with the continent. © 2014 The Linnean Society of London [ABSTRACT FROM AUTHOR]