Further two alien species for the Sicilian waters: Aplus assimilis (Reeve,1846) and Mitrella psilla (Duclos, 1846) (Gastropoda Neogastropoda)

The finding of two further non indigenous species for the Eastern Sicilian rocky coast is here reported. The neo-gastropods Aplus assimilis (Reeve, 1846) and Mitrella psilla (Duclos, 1846) were found living inside the arbor of Catania. Specimens regularly collected during these last five years demonstrate the stability of the populations of both the species inside the harbor, while no other materials emerged from the exam of samples collected around the finding lo-cality. The presence of both the species along Italian coasts was previously ascertained in few scattered localities, while the current represents the first report for Sicily. A human-mediated diffusion is here supposed as for other species found in the island. This last finding brings back to the top the problem of the numerous alien species arrivals during these latest years in Sicily and, more generally, in the Mediterranean Sea.