Three Gram-negative, non-motile, non-spore-forming, slightly halophilic rods (strains SW-110(T), SW-116 and SW-140) were isolated from sea water of a tidal flat of the Yellow Sea in Korea and subjected to a polyphasic taxonomic study. The three isolates did not produce bacteriochlorophyll a and were characterized chemotaxonomically by having ubiquinone-10 as the predominant respiratory lipoquinone and C(18 : 1)omega7c and C(17 : 1)omega6c as the major fatty acids. The DNA G+C content of the three isolates was between 62.2 and 62.9 mol%. Strains SW-110(T), SW-116 and SW-140 showed no difference in their 16S rRNA gene sequences, and their mean level of DNA-DNA relatedness was 94.8 %. Phylogenetic analyses based on 16S rRNA gene sequences showed that the three strains form a distinct phylogenetic lineage within the cluster comprising Erythrobacter species. Similarities between the 16S rRNA gene sequences of strains SW-110(T), SW-116 and SW-140 and the type strains of Erythrobacter species ranged from 98.4 % (with Erythrobacter longus) to 97.7 % (with Erythrobacter flavus). Levels of DNA-DNA relatedness between strains SW-110(T), SW-116 and SW-140 and the type strains of all recognized Erythrobacter species were in the range 5.3-12.7 %. On the basis of polyphasic taxonomic data, strains SW-110(T), SW-116 and SW-140 were classified as a novel Erythrobacter species, for which the name Erythrobacter aquimaris sp. nov. is proposed. The type strain is SW-110(T) (=KCCM 41818(T)=JCM 12189(T)).