A polyphasic study was carried out to clarify the taxonomic position of a novel strain R-30(T) isolated from the surficial layer of sediment from Taihu Lake of China. The strain formed pink colored colonies comprising coccodial cells on R2A agar. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain R-30(T) clustered with the strains of genus Roseococcus and strain Rubritepida flocculans, with Roseococcus suduntuyensis SHET(T) as the closest relative, sharing 95.6% similarity. The major fatty acids (＞5%) were 18：1ω7c (66.7%), 16： 1ω7c/16：1ω6c (10.2%) and 16：0 (8.0%). The major polar lipids were diphosphatidyl glycerol (DPG), phosphatidyl methylethanolamine (PME), phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC). The genomic DNA G+C content was 73.9 mol%. On the basis of the phylogenetic analysis and physiological and biochemical characteristics, we conclude that strain R-30(T) represents a novel genus and species of the family Acetobacteraceae, for which we propose the name Sediminicoccus rosea gen nov. sp. nov. with R-30(T) (= CGMCC 1.12302(T) = NBRC 109675(T)) as the type species and type strain.