Four novel isolates (R-40508T, R-40507, R-40903 and R-21419) were obtained from different cnidarian species (Phyllogorgia dilatata, Merulina ampliata and Palythoa caribaeorum) from different places in Brazil and Australia. The novel isolates formed a tight phylogenetic group based on 16S rRNA, recA, topA, ftsZ, mreB and rpoA gene sequences. Their closest phylogenetic neighbours were the type strains of Photobacterium leiognathi, P. rosenbergii and P. halotolerans, sharing 97.1–97.5% 16S rRNA gene sequence similarity. DNA–DNA hybridization between a representative strain (R-40508T) and the type strains of these Photobacterium species revealed less than 20% relatedness, showing that the new isolates belong to a novel species. Several phenotypic features allow the differentiation of the novel species from its closest phylogenetic neighbours. It has gelatinase and lipase activity and can utilize melibiose, but it cannot grow on 6% NaCl. In addition, the novel species has the fatty acid iso-C16 : 0, but lacks the fatty acids C17 : 0, C17 : 0 cyclo, iso-C17 : 0, C17 : 1v8c and iso-C17 : 1v9c. The name Photobacterium jeanii sp. nov. is proposed for this species, with the type strain R-40508T (5LMG 25436T 5CAIM 1817T). The G+C content of the type strain is 45.5 mol%.