The taxonomic status of five actinomycete strains, 3-28(8)^T, 4-20(13), 3D-70(20), 5-81(36) and 3D-72(35)^T, isolated from sandy soil was studied using the polyphasic approach. All isolates produced branching substrate mycelia and developed spherical spore vesicles on aerial hyphae containing non-motile spores. They contained meso-diaminopimelic acid and the N-acetyl type of peptidoglycan. The predominant menaquinones were MK-9(H₄) and MK-9(H₆). Madurose, mannose, ribose, galactose and glucose were detected in the whole-cell hydrolysate. The diagnostic phospholipids were phosphatidylethanolamine and ninhydrin-positive phosphoglycolipids, and iso-C_16:0 and 10 methyl C_17:0 were detected as the major cellular fatty acids. These morphological and chemotaxonomic data were related to those of the genus Streptosporangium in the family Streptosporangiaceae. Phylogenetic analysis based on 16S rDNA sequence data suggested that the strains belong to the family Streptosporangiaceae, but not to any known genus, and form a monophyletic clade with Streptosporangium viridialbum and “Streptosporangium cinnabarinum”. The signature nucleotides of the members of this clade are different from those of any known genera of the family Streptosporangiaceae. On the basis of phylogenetic analysis and the characteristic patterns of signature nucleotides as well as the morphological and chemotaxonomic data, the genus Sphaerosporangium gen. nov. is proposed for our five isolates and the type strains of Streptosporangium viridialbum and “Streptosporangium cinnabarinum”. DNA–DNA hybridization and phenotypic characterization indicate that the new genus comprises four species, Sphaerosporangium melleum sp. nov. with the type strain 3-28(8)^T (=JCM 13064^T =DSM 44954^T), Sphaerosporangium rubeum sp. nov. with the type strain 3D-72(35)^T (=JCM 13067^T =DSM 44936^T), Sphaerosporangium cinnabarinum sp. nov. (=JCM 3291 =DSM 44094) and Sphaerosporangium viridialbum comb. nov. (=JCM 3027^T =DSM 43801^T).