Thirteen macromollusca species are reported in Gizzeria harbour (Catanzaro, Italy). Among them two alien species, Cerithium scabridum and Musculista senhousia, deserve attention. The probable causes for their arrival and possible survival in the area are discussed, as is their impact on local fauna. In absence of recent reviews, a map regarding the known Italian sites of the latter is given. In the light of this last finding it is possible to speculate that its distribution could be strongly underestimated.
