Recent Changes in the Distribution of Autochthonous Marine Molluscs in the Mediterranean Sea

The changes in the distribution of two autochthonous molluscs in the Mediterranean Sea are described from the early nineteenth century to date. Echinolittorina punctata (Gastropoda: Littorinidae) had until the end of the twentieth century a distribution limited to the western Mediterranean (southern Spain and from Morocco to northern Tunisia, a few localities in southern Sicilia) and to the eastern Mediterranean (from Egypt to Syria). At the end of the twentieth century the range started to expand to all along the coast of Sicilia and northward along the Italian peninsula. Today, the species is found north of Roma. Eastonia rugosa (Bivalvia: Mactridae) used to have a distribution limited to the western Mediterranean, not exceeding the Siculo-Tunisian sill. During the end of the twentieth century and in the 2000s, the species was recorded from the Gulf of Gabes and from progressively northern localities in Italy. Today the species is found north of Livorno, in Toscana. The distributional changes of a few more Mediterranean molluscs is described in less detail, but wishes to highlight potential further descriptors of change of the biodiversity of the Mediterranean Sea.