A novel, strictly aerobic, heterotrophic, gliding, Gram-negative, oxidase-, catalase-, beta-galactosidase- and alkaline phosphatase-positive marine bacterium, designated strain KMM 6220(T), was isolated from seawater and studied by using a polyphasic taxonomic approach. The DNA G+C content of strain KMM 6220(T) was 59.9 mol%. The predominant fatty acids were iso-C(15 : 1), iso-C(15 : 0), iso-C(15 : 0) 3-OH, iso-C(17 : 0) 3-OH and C(16 : 1)omega7/iso-C(15 : 0) 2-OH. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that strain KMM 6220(T) formed a cluster with the misclassified strains [Flexibacter] aggregans NBRC 15974 and [Flexibacter] tractuosus NBRC 16035 and with the type strains of Reichenbachiella agariperforans and Roseivirga ehrenbergii with levels of similarity of 95.9, 94.4, 92.0 and 91.8 %, respectively. On the basis of its phenotypic, chemotaxonomic, genotypic and phylogenetic characteristics, strain KMM 6220(T) is considered to represent a novel species of a new genus in the phylum Bacteroidetes, for which the name Fulvivirga kasyanovii gen. nov., sp. nov. is proposed. The type strain of the type species is KMM 6220(T) (=CCTCC AB 206119(T)=KCTC 12832(T)).