A Gram-negative, motile and rod-shaped bacterial strain, BIO-TAS2-2(T), of the class Alphaproteobacteria, was isolated from a soil in Korea and studied using a polyphasic taxonomic approach. Strain BIO-TAS2-2(T) grew optimally at pH 7.5-8.5 and 30 degrees C and in the presence of 0-1.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences showed that strain BIO-TAS2-2(T) fell within the clade comprising species of the genus Brevundimonas, forming a coherent cluster with Brevundimonas terrae KSL-145(T) and Brevundimonas diminuta LMG 2089(T). It exhibited 16S rRNA gene sequence similarity values of 96.0-98.7 % to members of the genus Brevundimonas and Mycoplana bullata IAM 13153(T). Strain BIO-TAS2-2(T) contained Q-10 as the predominant ubiquinone and cyclo-C(18 : 1)omega7c and C(16 : 0) as the major fatty acids. The DNA G+C content was 67.0 mol%. Strain BIO-TAS2-2(T) exhibited DNA-DNA relatedness levels of 12-19 % with the type strains of phylogenetically related Brevundimonas species and M. bullata. The novel strain could be differentiated from Brevundimonas species and M. bullata by differences in phenotypic characteristics. On the basis of phenotypic, phylogenetic and genetic data, strain BIO-TAS2-2(T) is considered to represent a novel species of the genus Brevundimonas, for which the name Brevundimonas naejangsanensis sp. nov. is proposed. The type strain is BIO-TAS2-2(T) (=KCTC 22631(T)=CCUG 57609(T)). In this study, it is also proposed that Mycoplana bullata be transferred to the genus Brevundimonas as Brevundimonas bullata comb. nov. (type strain TK0051(T)=ATCC 4278(T)=DSM 7126(T)=JCM 20846(T)=LMG 17157(T)).