A Gram-positive, aerobic, non-motile, mesophilic strain, designated YIM 45721T, was isolated from a rhizosphere soil sample in Yunnan Province, China. On the basis of 16S rRNA gene sequence similarity analysis, strain YIM 45721T was assigned to the genus Microlunatus and was most closely related to the type strain of Microlunatus phosphovorus (98.2 % 16S rRNA gene sequence similarity). Chemotaxonomic data, including cell-wall peptidoglycan structure, menaquinones and fatty acid profile, supported affiliation of strain YIM 45721T to the genus Microlunatus. Results of DNA-DNA hybridization and physiological and biochemical tests enabled strain YIM 45721T to be differentiated genotypically and phenotypically from M. phosphovorus. Therefore, strain YIM 45721T represents a novel species of the genus Microlunatus, for which the name Microlunatus aurantiacus sp. nov. is proposed. The type strain is YIM 45721T (=CCTCC AB 206067T=DSM 18424T).