Facultatively anaerobic marine bacteria isolated from cultured clams, Ruditapes decussatus and Ruditapes philippinarum, were previously investigated using amplified fragment length polymorphism (AFLP) and 16S rRNA gene sequence analyses. The isolates formed two AFLP clusters and belonged to the genus Vibrio, more precisely to the Splendidus clade. In this study, phylogenetic analyses based on sequences of the housekeeping genes rpoA, rpoD, pyrH, atpA and recA supported their inclusion in that clade forming two well differentiated groups with respect to the rest of the species within the clade, and confirmed that they formed two groups, separated from the rest of the species of the clade. DNA-DNA hybridization demonstrated that the isolates constitute two novel species of the genus Vibrio, which can be phenotypically differentiated from their closest relatives. The names Vibrio atlanticus sp. nov. and Vibrio artabrorum sp. nov. are proposed, with Vb 11.11(T) ( = CECT 7223(T) = LMG 24300(T)) and Vb 11.8(T) ( = CECT 7226(T) = LMG 23865(T)) as the type strains, respectively.