A novel actinomycete, designated strain YIM 46034(T), was isolated from an evergreen broadleaved forest at Menghai, in southern Yunnan Province, China. Phenotypic characterization and 16S rRNA gene sequence analysis indicated that the strain belonged to the family Micromonosporaceae. Strain YIM 46,034(T) showed more than 3 % 16S rRNA gene sequence divergence from recognized species of genera in the family Micromonosporaceae. Characteristic features of strain YIM 46,034(T) were the production of two types of spores, namely motile spores, which were formed in sporangia produced on substrate mycelia, and single globose spores, which were observed on short sporophores of the substrate mycelia. The cell wall contained meso-diaminopimelic acid, glycine, arabinose and xylose, which are characteristic components of cell-wall chemotype II of actinomycetes. Phosphatidylethanolamine was the major phospholipid (phospholipid type II). Based on morphological, chemotaxonomic, phenotypic and genetic characteristics, strain YIM 46,034(T) is considered to represent a novel species of a new genus in the family Micromonosporaceae, for which the name Planosporangium flavigriseum gen. nov., sp. nov. is proposed. The type strain of Planosporangium flavigriseum is YIM 46,034(T) (=CCTCC AA 205,013(T) =DSM 44,991(T)).