A Gram-negative, non-motile, rod-shaped bacterium, strain SS011B1-20(T), was isolated from sediments of the South China Sea. Growth occurred at NaCl concentrations between 0 and 10 % and at temperatures between 10 and 37 degrees C. Strain SS011B1-20(T) contained Q-10 as the major respiratory quinone and C(18 : 1)omega7c (81.2 %), C(16 : 0) (7.0 %) and C(18 : 1) methyl (4.3 %) as the predominant fatty acids. The G+C content of the genomic DNA was 64.7 mol%. A phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain SS011B1-20(T) belonged to a clade within the genus Oceanicola in the Alphaproteobacteria, the highest sequence similarities being found with respect to Oceanicola batsensis (96.3 %) and with Oceanicola granulosus (94.9 %). Strain SS011B1-20(T) could be clearly distinguished from other Oceanicola species on the basis of the genotypic, phenotypic and phylogenetic data. Thus, it is proposed that strain SS011B1-20(T) represents a novel species of the genus Oceanicola, with the name Oceanicola nanhaiensis sp. nov. The type strain is SS011B1-20(T) (=LMG 23508(T)=CGMCC 1.6293(T)).