A Gram-negative, aerobic, halophilic bacterium, designated strain JC2041(T), was isolated from a sediment sample of getbol, the Korean tidal flat. Results of 16S rDNA sequence analyses indicated a moderate relationship to Thalassomonas viridans within the gamma-Proteobacteria (94.9 % similarity). Depending on the tree-making algorithm used, the isolate either formed a monophyletic clade with T. viridans or was recovered as a sister group of a class containing the genera Thalassomonas and Colwellia. Phenotypic features of the getbol isolate were similar to those of T. viridans, but several physiological and chemotaxonomic properties, including nitrate reduction, amylase, lecithinase, Tweenase and utilization of 13 carbon sources, distinguished strain JC2041(T) from T. viridans. The polyphasic data presented in this study indicate that the isolate should be classified as a novel species in the genus Thalassomonas. The name Thalassomonas ganghwensis sp. nov. is therefore proposed for the getbol isolate; the type strain is JC2041(T) (=IMSNU 14005(T)=KCTC 12041(T)=DSM 15355(T)).