First record of Aporodoris millegrana (Alder et Hancock, 1854) (Gastropoda Heterobranchia Nudibranchia) in the Ionian Sea, central Mediterranean Sea

The first record of Aporodoris millegrana (Alder et Hancock, 1854) (Gastropoda Heterobranchia Nudibranchia) in the Ionian Sea (central Mediterranean Sea) is here presented. This species was originally described for the British Isles and then, under different synonyms, was reported for the Atlantic coasts of France, Canary Islands, Madeira and the Strait of Gibraltar. In the Mediterranean Sea, this species has been only reported for different localities along the Catalan coast. This record is based on the finding of a A. millegrana specimen in a station along the central-eastern coast of Sicily (Italy). The individual was found under a stone at a depth of 6.4 m on a rocky seabed. In the last years, some Atlantic Nudiplera, which were never reported before, have been increasingly found in the Ionian Sea. In view of the rising water temperature in the Mediterranean Sea, the Atlantic termophilic species could settle in new areas of the Mediterranean. Nevertheless, it is not excluded that maybe A. millegrana, since is rare and with a sciaphilous behaviour, could be underestimated until now in the Mediterranean Sea.