A Gram-negative, non-motile and rod-, oval- or coccoid-shaped bacterial strain, DSW-25(T), which is phylogenetically closely related to the genera Staleya and Sulfitobacter, was isolated from seawater of the East Sea, Korea, and subjected to a polyphasic taxonomic study. Strain DSW-25(T) grew optimally at pH 7.0-8.0 and at 25 degrees C. It contained Q-10 as the predominant ubiquinone and C(18 : 1) omega 7c as the major fatty acid. Major polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid. The DNA G+C content was 56.9 mol%. Strain DSW-25(T) exhibited 16S rRNA gene sequence similarity values of 98.4 % to the type strain of Staleya guttiformis and of 96.6-97.6 % to Sulfitobacter species. There were no distinct phenotypic, particularly chemotaxonomic, properties to differentiate Staleya guttiformis and strain DSW-25(T) from the genus Sulfitobacter. DNA-DNA relatedness data and differential phenotypic properties, together with the phylogenetic distinctiveness, demonstrated that strain DSW-25(T) differs from recognized Sulfitobacter species and Staleya guttiformis. On the basis of phenotypic, chemotaxonomic, phylogenetic and genetic data, strain DSW-25(T) was classified in the genus Sulfitobacter as a member of a novel species, for which the name Sulfitobacter donghicola sp. nov. is proposed. The type strain is strain DSW-25(T) (=KCTC 12864(T) =JCM 14565(T)). It is also proposed that Staleya guttiformis be transferred to the genus Sulfitobacter as Sulfitobacter guttiformis comb. nov.