Species delimitation and multi-locus species tree solve an old taxonomic problem for European squat lobsters of the genus Munida Leach, 1820

The taxonomy of Munida Leach, 1820 from the north-eastern Atlantic and Mediterranean Sea was studied using a comparative analysis of morphological characters and molecular markers (mitochondrial and nuclear). Generalized Mixed Yule Coalescence and the Poisson tree process models were used to delimit two groups of closely related species associated with uncertain nomenclature and taxonomic status: (1) Munida intermedia A. Milne Edwards & Bouvier, 1899, M. rugosa (Fabricius, 1775), M. sarsi Huus, 1935 and M. tenuimana Sars, 1872 and (2) M. rutllanti Zariquiey-Álvarez, 1952 and M. speciosa von Martens, 1878. We found that M. tenuimana is restricted to northern Atlantic waters (north of approx. 48° N), while Mediterranean and Bay of Biscay specimens previously assigned to this taxon actually belong to a different species, indicating that the name Munida perarmata A. Milne Edwards & Bouvier, 1894 should be resurrected. Furthermore, M. rutllanti is shown to be a junior synonym of M. speciosa, a species that has thus far only been reported along western Africa. In addition, three species are re-described and a key to European Munida is provided. The validity of the morphological characters used to distinguish the different species is discussed. Phylogenetic analyses revealed three independent lineages with unsolved relationships among them, including high genetic distances for some species. These findings indicate highly divergent lineages of the European Munida and several events of colonization along the eastern Atlantic.