The non-indigenous ascidian Distaplia bermudensis in the Mediterranean: comparison with the native species Distaplia magnilarva and Distaplia lucillae sp. nov.

Three species of Distaplia from the Mediterranean are described: D. bermudensis is a species introduced from the western Atlantic Ocean, which principally differs from the native D. magnilarva in having hermaphroditic zooids. The new species D. lucillae differs from the preceding ones in the structure of its stomach wall which is regularly plicated both externally and internally. Distaplia lucillae has colonies with hermaphroditic, but only male ripe, zooids and exclusively female colonies; this is a condition closely related to D. magnilarva though different. A key to European Distaplia is provided.