Just checking the web under "cyanobacteria nomenclature" this abstract comes up:
https://www.ncbi.nlm.nih.gov/pubmed/28243951
Seems this is a can of worms. I'm sure there are authorities for things like Nostoc commune dating back to when they were considered plants, so I suppose you could find and use those.
Older books on algal taxonomy will have them. For example, my "How to know the Freshwater Algae" has Nostoc commune Vauch.