The genotypic diversity of seventy-one Vibrio strains isolated from the culture of oysters and clams was analyzed by using ribotyping and sequencing of 16S rRNA gene. The combination of both techniques led to clustering, the separation of V. splendidus-related species and the identification of 91.5% of studied strains. New genotypic, phenotypic and biotypic information on V. tasmaniensis, V. kanaloae, V. pomeroyi, and V. neptunius was provided. Vibrio splendidus biotype 1 and Vibrio mediterranei were also identified. Different riboclusters of V. splendidus, V. tasmaniensis, and V. neptunius were obtained showing genotypic diversity of these species. A unique ribocluster in V. kanaloae, V. pomeroyi, and V. mediterranei was obtained. Venerupis rhomboides (P.) was susceptible to experimental infections with strains of V. kanaloae, V. neptunius, V. pomeroyi, and V. splendidus biotype 1. Mortalities of challenged clams and the isolation of strains from internal organs confirmed the presence of virulent strains among the isolates and pointed to the risk of molluscan culture outbreaks.