Abstract
The phylogenetic structure of the genus Actinoplanes was determined by comparative 16S rDNA sequence analysis of the type strains of all validly described Actinoplanes species and other strains of Actinoplanes. Actinoplanes minutisporangius IFO 15962(T) and 'Actinoplanes aurantiacus' IFO 13967 were placed outside the family Micromonosporaceae and appeared to be closely related to the genus Cryptosporangium. On the basis of their morphological and chemotaxonomic characteristics and phylogenetic analysis, these strains were reclassified into the genus Cryptosporangium. DNA--DNA hybridization revealed that these strains differed from the species previously described in this genus. Therefore, the transfer is proposed of Actinoplanes minutisporangius Ruan et al. 1986 and 'Actinoplanes aurantiacus' IFO 13967 to the genus Cryptosporangium as Cryptosporangium minutisporangium comb. nov. and Cryptosporangium aurantiacum sp. nov.