Domain Bacteria Woese et al. 1990
   Phylum Cyanobacteria (ex Stanier 1974) Cavalier-Smith 2002 - cyanobacteria
     Class "Cyanobacteria" Cavalier-Smith, 2002
       Subsection IV
         Subgroup II see Family II
           Form genus Calothrix C.Agardh ex É. Bornet & C. Flahault 1886 [ICBN]