Range extension and conservation status of Cymbula nigra (Gastropoda: Patellidae) in the Tunisian shores

Cymbula nigra is the largest limpet in the Mediterranean. It has been listed since 1993, as an ‘endangered species’. Its historical range in the Mediterranean includes the southern Spanish, the Moroccan and the Algerian coasts. Recent observations have confirmed its proliferation in southern Spain and its progression along the European and North African Mediterranean coasts. Field surveys carried out along the Tunisian coasts during winter 2011 revealed the presence of this species in the Gulf of Tunis and the Cap Bon. The finding of C. nigra represents a range extension possibly enhanced by the current global warming, as it is a ‘warm‐water species’. The absence of records in previous surveys to the same sampling sites (2006–2007), together with the small sizes recorded in 2011, confirms the recent installation of the species. The limpet was recorded in areas spared of pollution, characterized by a predominant influence of the Atlantic current, and also showed a preference for steep cliffs exposed to strong waves. This is the first population study of this endangered gastropod outside of its original range of distribution. The determination of the ecological characteristics of newly colonized habitats might serve as a starting point for the establishment of appropriate recommendations for its conservation.