Résumé
The American blue crab, Callinectes sapidus Rathbun, 1896 is native to the western Atlantic. The present work reviews the spread of C. sapidus in the European Atlantic, the Mediterranean, Black Sea and Sea of Azov, and identifies its first occurrence in the Merja Zerga and Khnifiss lagoons on the Moroccan Atlantic coast. These first and southernmost records on the African Atlantic widen the current biogeographic distribution of the species worldwide. Genetic analysis of specimens from both the Mediterranean (Marchica lagoon) and Atlantic (Merja Zerga and Khnifiss lagoons) coasts of Morocco, based on COI (Cytochrome c oxidase subunit I), confirmed the species sequences as being those of Callinectes sapidus. Moroccan populations have low haplotypic diversity with only two haplotypes (haplotype 1 and haplotype 7). These two haplotypes correspond to the two different haplotypes already found in the Mediterranean. Haplotype 1 from Merja Zerga, Marchica and Khnifiss lagoons was 100% identical to the sequences ON248058 in GenBank, while haplotype 7 from the Marchica and Merja Zerga lagoons was 100% identical to the sequences ON248059. Very likely, the origin and pathway of colonisation of the populations established in the three Moroccan lagoons is the result of the expansion of the species along the Mediterranean Sea and now the Atlantic coast of Africa.