A Gram-negative, motile and rod-shaped Sphingomonas-like bacterial strain, DS-28(T), was isolated from the soil of Dokdo, Korea, and was subjected to a polyphasic taxonomic study. It grew optimally at around pH 6.5 and 25 degrees C in the presence of 0-0.5% NaCl. It contained Q-10 as the predominant ubiquinone and C(18:1)omega7c, C(14:0) 2-OH and C(16:0) as the major fatty acids. Major polar lipids were sphingoglycolipid, phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content was 67.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain DS-28(T) belonged to the genus Sphingomonas. Levels of 16S rRNA gene sequence similarity between strain DS-28(T) and the type strains of Sphingomonas species were in the range 93.3-98.3%. DNA-DNA relatedness data and differential phenotypic properties, together with the phylogenetic distinctiveness, demonstrated that strain DS-28(T) is distinguishable from recognized Sphingomonas species. On the basis of phenotypic, phylogenetic and genetic data, strain DS-28(T) represents a novel species of the genus Sphingomonas, for which the name Sphingomonas insulae sp. nov. is proposed. The type strain is DS-28(T) (=KCTC 12872(T)=JCM 14603(T)).