Characterization of Coolia spp. (Gonyaucales, Dinophyceae) from Southern Tunisia: first record of Coolia malayensis in the Mediterranean Sea.

This study provides the first report of the presence of Coolia malayensis in the Mediterranean Sea, co-occurring with C. monotis. Isolated strains from the Gulf of Gabes, Tunisia (South-eastern Mediterranean) were identified by morpho-logical characterization and phylogenetic analysis. Examination by light and scanning electron microscopy revealed no significant morphological differences between the Tunisian isolates and other geographically distant strains of C. monotis and C. malayensis. Phylogenetic trees based on ITS1-5.8S-ITS2 and D1-D3/28S rDNA sequences showed that C. monotis strains clustered with others from the Mediterranean and Atlantic whereas the C. malayensis isolate branched with isolates from the Pacific and the Atlantic, therefore revealing no geographical trend among C. monotis and C. ma-layensis populations. Ultrastructural analyses by transmission electron microscopy revealed the presence of numerous vesicles containing spirally coiled fibers in both C. malayensis and C. monotis cells, which we speculate to be involved in mucus production.