First occurrence of the needle-spined urchin Diadema setosum (Leske, 1778) (Echinodermata, Diadematidae) in the southern Mediterranean Sea

The first occurrence of Diadema setosum in the southern Mediterranean waters is recorded from the shores of Libya and Egypt, through the input by citizens’ science. The expansion of this invasive sea urchin in the Mediterranean basin is briefly discussed.