<jats:p>Five heterotrophic, aerobic, halotolerant and pigmented bacterial strains with gliding motility were isolated from Antarctic sea water; one other isolate was collected from the sea urchin <jats:italic>Strongylocentrotus intermedius</jats:italic> in the Gulf of Peter the Great in the Sea of Japan. 16S rRNA gene sequence analysis indicated that the strains are members of the family <jats:italic>Flavobacteriaceae</jats:italic>, the nearest neighbour (with 97·1 % sequence similarity) being the misclassified species [<jats:italic>Cytophaga</jats:italic>] <jats:italic>marinoflava</jats:italic>. DNA–DNA hybridization experiments and chemotaxonomic and phenotypic analyses demonstrated that the six novel isolates represent a single species distinct from [<jats:italic>C.</jats:italic>] <jats:italic>marinoflava</jats:italic>. On the basis of its separate phylogenetic lineage (the nearest neighbours show 92 % sequence similarity), [<jats:italic>C.</jats:italic>] <jats:italic>marinoflava</jats:italic> is reclassified as <jats:italic>Leeuwenhoekiella marinoflava</jats:italic> gen. nov., comb. nov. A second species of this new genus, <jats:italic>Leeuwenhoekiella aequorea</jats:italic> sp. nov., is proposed for the six novel isolates, with strain LMG 22550<jats:sup>T</jats:sup> (=CCUG 50091<jats:sup>T</jats:sup>) as the type strain.</jats:p>