Procaryotic Genera
   Domain "Bacteria" Woese et al. 1990
     Phylum Cyanobacteria (ex Stanier 1974) Cavalier-Smith 2002 [monotypic] - cyanobacteria
       Class "Cyanobacteria" Cavalier-Smith, 2002
         Subsection IV
           Family I see Family Family 4.1 nom. inval.
             Form genus Nostoc Vaucher ex Bornet & Flahault (1888)