In order to establish the molecular taxonomy of the genus Rhizopus, all described species of the genus were collected and the nucleotide sequences of the internal transcribed spacer of the rRNA gene (rDNA ITS), actin, and translation elongation factor 1alpha (EF-1alpha) were determined. Quantitative real-time PCR revealed that R. americanus had a R. stolonifer-type ITS sequence as the dominant sequence type, although it had three different types of ITS sequences in a single genome. Phylogenetic analysis and gene genealogy concordance phylogenetic species recognition (GCPSR) identified eight species in the genus, whereas recent morphological taxonomy includes 10 species. R. niveus is proposed to be re-classified as R. delemar, and R. sexualis and R. americanus are re-classified as R. stolonifer.