An aerobic and heterotrophic, Gram-negative bacterial isolate, strain HY34(T), was isolated from sediment of an oilfield in the South China Sea, China. The taxonomy of strain HY34(T) was studied by phenotypic and phylogenetic methods. Strain HY34(T) formed faint-pink colonies on marine agar 2216. Cells of strain HY34(T) were non-motile, ovoid or short rods. Strain HY34(T) was positive for catalase and oxidase, and nitrate was reduced to nitrite. The nearly complete 16S rRNA gene sequence of strain HY34(T) was obtained and sequence analysis showed that it, together with the genus Rubellimicrobium, formed a distinct clade close to some members of the Roseobacter clade in the family Rhodobacteraceae, and it showed highest sequence similarities to Oceanicola granulosus HTCC2516(T) (93.8 %), Silicibacter lacuscaerulensis ITI-1157(T) (93.3 %), Dinoroseobacter shibae DFL 12(T) (93.3 %) and Rubellimicrobium thermophilum C-lvk-R2A-2(T) (92.2 %). Bacteriochlorophyll a was not detected. The ubiquinone system was Q-10. The major polar lipids were phosphatidylglycerol, phosphatidylcholine and an unidentified glycolipid. The major fatty acids (>10 %) were C(18 : 1) omega 7c and C(16 : 0). The DNA G+C content of this strain was 69.4 mol%. A polyphasic analysis supported the conclusion that this strain represents a novel genus and species, which we designated Wenxinia marina gen. nov., sp. nov. The type strain of Wenxinia marina is HY34(T) (=CGMCC 1.6105(T) =JCM 14017(T)).