About Carcinus aestuarii Nardo, 1847
Carcinus aestuarii (Nardo, 1847), commonly called the Mediterranean green crab, is a littoral crab native to the Mediterranean Sea. This species shares many similarities with Carcinus maenas, and was historically sometimes classified as a subspecies of C. maenas rather than a distinct standalone species. However, a molecular biological study using the COI gene found substantial genetic differences between the two taxa, confirming that they are separate species. The two species can be visually distinguished by the shape of the front of the carapace between the eyes: this region is short and toothed in C. aestuarii, while it is longer and smoother in C. maenas. The gonopods of the two species also differ: C. aestuarii has straight, parallel gonopods, while C. maenas has curved gonopods. This species is distributed in the Atlantic Ocean around the Canary Islands, along all Mediterranean coasts, in the Black Sea and the Azov Sea, and within the Suez Canal.
