A facultatively anaerobic, mesophilic, chemoorganoheterotrophic bacterium, designated YP2 T , was isolated from oil sludge enrichment in China. Cells of the strain were Gram-stain-negative, non-motile, rod-shaped or slightly curved with 0.8-3.0 µm in length and 0.4-0.6 µm in diameter. Spore formation was not observed. The strain YP2 T grew optimally at 25 o C (range from 15 to 30 o C) and pH 7.1 (range from pH 7.1 to 8.3) without NaCl. The major cellular fatty acids were C 16:0 , sum in feature 3 (C 16:1 ω7c and/or C 16:1 ω6c), sum in feature 8 (C 18:1 ω7c and/or C 18:1 ω6c), and the main polar lipids were aminolipid, phosphatidylethanolamine, phosphatidylglycerol, phospholipid and unidenti ed lipids. The respiratory quinone was Q-10. The DNA G + C content was 66.0%. Strain YP2 T shared 90.2% 16S rRNA gene sequence similarity with the most related Oceanibaculum nanhaiense L54-1-50 T belonging to the order Rhodospirillales of the class Alphaproteobacteria. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain YP2 T formed a distinct evolutionary lineage within the order Rhodospirillales. On the basis of phenotypic, phylogenetic and phylogenomic data, we propose that strain YP2 T represents a novel species in a novel genus, for which Shumkonia mesophila gen. nov., sp. nov., within a new family Shumkoniaceae fam. nov.. The type strain is YP2 T (= CCAM 826 T = JCM 34766 T ).