Volume 2 Article informations Genetic diversity and population structure of the banded Murex, Hexaplex trunculus (Linnaeus, 1758) across the Siculo-Tunisian Strait Zined Marzouka,*, Anne Chenuilb, Didier Aurelleb, Khaled Saida Abstract Population structure of Hexaplex trunculus sampled along four Tunisian coasts was studied. We have scored the genetic variation of the mitochondrial Cytochrome c oxidase subunit I gene (COI) among a total of 45 specimens. Our analyses revealed 14 different haplotypes and two groups of haplotypes, separated by the Siculo-Tunisian Strait. Haplotype diversity showed an increasing north to south gradient which may be explained by the hydrographical patterns in the study area. The overall estimate of genetic divergence (FST) revealed significant genetic differentiation between all population pairs. Finally, populations seem to be deviated from mutation/drift equilibrium suggesting a recent demographic expansion or natural selection. These results may have management implications since H. trunculus is a harvested species with a high commercial value. Key word: Hexaplex trunculus, Genetic diversity, COI, Tunisian coasts.