A Gram-staining-negative, catalase-positive, carbaryl-degrading, non-spore-forming, non-motile, rod-shaped bacterium, designated strain X23(T), was isolated from a wastewater treatment system. Phylogenetic analysis based on 16S rRNA gene sequence indicated that the strain belongs to the genus Sphingobium. The highest 16S rRNA gene sequence similarity observed for the isolate was 96.6 % with the type strain of Sphingobium amiense. Chemotaxonomic data [major ubiquinone: Q-10; major polar lipids: diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, sphingoglycolipid, phosphatidylethanolamine and unknown aminolipids and phospholipids; major fatty acids: summed feature 7 (C(18 : 1)ω7c, C(18 : 1)ω9t and/or C(18 : 1)ω12t), C(16 : 1)ω5c, C(14 : 0) 2-OH and C(16 : 0) 2-OH] as well as the inability to reduce nitrate and the presence of spermidine as the major polyamine supported the affiliation of the strain to the genus Sphingobium. Based on the phylogenetic analysis, whole-cell fatty acid composition and biochemical characteristics, the strain could be separated from all recognized species of the genus Sphingobium. Strain X23(T) should be classified as a novel species of the genus Sphingobium, for which the name Sphingobium qiguonii sp. nov. is proposed, with strain X23(T) (=CCTCC AB 208221(T) =DSM 21541(T)) as the type strain.