A polyphasic taxonomic study was performed to characterize a new bacterial isolate, designated KMM 3654(T), from a marine bottom sand sample. The strain was Gram-negative, encapsulated, aerobic, moderately halophilic and grew between 0.5 and 10 % NaCl and at 4-42 degrees C. Its DNA G+C content was 56.4 mol%. Isolate KMM 3654(T) was phylogenetically closely related to members of the genus Oceanimonas, showing 96.7 and 95.6 % 16S rRNA gene sequence similarity to Oceanimonas doudoroffii DSM 7028(T) and Oceanimonas baumannii ATCC 700832(T), respectively. Strain KMM 3654(T) shared some physiological and chemotaxonomic properties with these two Oceanimonas species, but differed from them in morphology, growth at 4 degrees C, urease activity, weak phenol degradation and utilization of phenylacetate. On the basis of phenotypic and phylogenetic evidence, Oceanisphaera litoralis gen. nov., sp. nov. is proposed, with the type strain KMM 3654(T) (=DSM 15406(T)).