Strain S33(T) was isolated from oil-contaminated sediment of Tae-an coastal region of South Korea. Cells are aerobic, motile, Gram staining-negative, and coccoid shaped. Strain S33(T) grew optimally at the temperature of 25 degrees C ( range of 4-40 degrees C), pH 6.0 ( range of pH 6.0-10.0), and in the presence of 1 % ( w/v) NaCl ( range of 0-10 %). Ubiquinone-8 was the predominant respiratory quinone. C-16:0, summed feature 3 ( comprising C(16: 1)x7c/C-16: 1 omega 6c) and C-18:1 omega 7c were the major fatty acids. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. Strain S33(T) showed the ability to degrade benzene, toluene, and ethylbenzene after 3 days incubation. 16S rRNA gene sequence analysis showed that the strain S33(T) was most closely related to Oceanisphaera sediminis TW92(T) ( 97.3 %), Oceanisphaera profunda SM1222(T) ( 97.2 %), and Oceanisphaera ostreae T-w6(T) ( 97.1 %) and <97 % with other members of the genus Oceanisphaera. The genomic DNA G+C mol% content of strain S33(T) was 51.0 mol%. Based on distinct phenotypic, genotypic, and phylogenetic analysis, strain S33(T) was proposed to represent a novel species in the genus Oceanisphaera as Oceanisphaera aquimarina sp. nov. (= KEMB 1002-058(T) = JCM 30 794(T)).