I need to identify a three strains of Rhizopus, the strains don´t have a lot differents, i made the molecular identification with ITS but i need complement with the taxonomy key.
You could perform a comparative sequence analysis and design a phylogenetic tree.
The phylogenetic tree would be based on the nucleotide sequence multialignment of the ITS region of different Rhizopus species. You can obtain the sequences from genbank and use the program clustal omega for the multiple alignment.
This would let you know if there is a difference between the ITS regions at a species level.
I recommend you to read the following article:
"Sequence Analysis of the Internal Transcribed Spacer of Ribosomal DNA in the Genus Rhizopus"