Two bacterial strains, 5420S-12(T) and 5420S-16(T), isolated from air samples, were characterized using a polyphasic approach. 16S rRNA gene sequence analysis showed that strain 5420S-12(T) was related phylogenetically to Microvirga subterranea FaiI4(T) (97.4 % sequence similarity) and Microvirga guangxiensis 25B(T) (97.1 %) and that strain 5420S-16(T) was closely related to Balneimonas flocculans TFB(T) (98.0 %) and Microvirga guangxiensis 25B(T) (97.2 %). The G+C content of the genomic DNA was 62.2 mol% for strain 5420S-12(T) and 61.5 mol% for strain 5420S-16(T). The major fatty acid was C(18 : 1)ω7c. The results of DNA-DNA hybridization and the phenotypic data showed that strains 5420S-12(T) and 5420S-16(T) could be distinguished from phylogenetically related species and represent two novel species within the genus Microvirga, for which the names Microvirga aerophila sp. nov. (type strain 5420S-12(T) =KACC 12743(T) =NBRC 106136(T)) and Microvirga aerilata sp. nov. (type strain 5420S-16(T) =KACC 12744(T) =NBRC 106137(T)) are proposed. Furthermore, the reclassification of Balneimonas flocculans as Microvirga flocculans comb. nov. (type strain TFB(T) =JCM 11936(T) =KCTC 12101(T) =IAM 15034(T) =ATCC BAA-817(T)) is proposed and an emended description of the genus Microvirga is provided.