The end of the run? New evidence of the complete colonization of the Mediterranean Sea by the Atlantic invader crab Percnon gibbesi (Crustacea: Decapoda: Percnidae)

After the finding of several specimens of Percnon gibbesi in Elba Island (Tuscan Archipelago), a preliminary census of the populations inhabiting the island coasts was run. Elba Island coasts were investigated by means of underwater linear transects to estimate the crab population density and distribution. The non-native crab population is found in the south and west coast with high density in the southern part of the Island. Crabs share the same habitat of other herbivorous species, such as the crustaceans Pachygrapsus marmoratus or Palaemon elegans, and the Paracentrotus lividus or Arbacia lixula sea urchins, but no interactions were observed.