A novel bacterium, strain JL1095(T), was isolated from the surface water of the Yangtze Estuary, China (31A degrees N, 122A degrees E). Cells were Gram negative, aerobic, oval-shaped with one peak end and motile by gliding. Cells divided by binary fission. Growth occurred at 15-50 A degrees C (optimum at 35 A degrees C), 2-10 % (w/v) NaCl (optimum at similar to 3 %) and pH 6.0-9.0 (optimum at pH similar to 7.6). Strain JL1095(T) was able to utilize various sole-carbon-source, such as Tween 40, Tween 80, acetic acid, l-arabinose, d,l-lactic acid, urocanic acid, methyl-pyruvate, alpha-hydroxy butyric acid, beta-hydroxy butyric acid, and gamma-hydroxy butyric acid. The major cellular fatty acids were C-16:0, C-18:0, C-19:0 omega 8c cyclo, C-20:1 omega 7c, and Summed Feature 8. The whole respiratory ubiquinone was Q-10. The genomic DNA G+C content of strain JL1095(T) was 51.5 %. According to the phylogenetic analysis, strain JL1095(T) formed a monophyletic branch at the periphery of the evolutionary radiation occupied by the genera Labrenzia, Pannonibacter, Stappia, Wenxnia, and Amaricoccus. The sequence similarity was 92.8 % with the most closely relating strain Stappia indica B106(T), and 92.6 % with the type species Stappia stellulatum IAM 12621(T). Based on the biochemical characteristics, chemotaxonomy and phylogenetic analysis, strain JL1095(T) is considered to be a novel genus which belongs to the family Rhodobacteraceae. The novel strain is named Acuticoccus yangtzensis gen. nov., sp. nov. The type strain of Acuticoccus yangtzensis is JL1095(T) (=CGMCC 1.12795 = DSM 28604).