A novel actinomycete, designated strain NEAU-ycm2(T), was isolated from edible Chinese black ants (Polyrhachis vicina Roger) and characterized using a polyphasic approach. The organism was found to have morphological and chemotaxonomic characteristics typical of the genus Micromonospora. The 16S rRNA gene sequence of strain NEAU-ycm2(T) showed highest similarity to those of Micromonospora sonneratiae 274745(T) (99.12%), Micromonospora pattaloongensis TJ2-2(T) (98.85%), Micromonospora pisi GUI 15(T) (98.76%), Polymorphospora rubra TT 97-42(T) (98.42%) and Micromonospora eburnea LK2-10(T) (98.21%). Phylogenetic analysis based on the 16S rRNA gene and gyrB gene demonstrated that strain NEAU-ycm2(T) is a member of the genus Micromonospora and supported the close phylogenetic relationship to M. sonneratiae 274745(T), M. pattaloongensis JCM 12833(T) and M. pisi GUI 15(T). Furthermore, a combination of DNA-DNA hybridization and some physiological and biochemical properties indicated that the novel strain could be readily distinguished from its closest phylogenetic relatives. Therefore, it is proposed that NEAU-ycm2(T) represents a novel species of the genus of Micromonospora, for which the name Micromonospora polyrhachis sp. nov. is proposed. The type strain is NEAU-ycm2(T) ( = CGMCC 4.7100(T) = DSM 45886(T)).