Phylum Cyanobacteria Garcia-Pichel et al. (2020) see Phylum Cyanobacteriota Oren et al. 2022
   Class Cyanophyceae Hauck (1885) see Class Chroococcophyceae Hollerbach et al. 1953
     Order Nostocales Borzì (1914) see Order Nostocales corrig. Borzì 1914
       Family Geitleriaceae C. Kilgore & J.R.Johans. (2018), incertae sedis [monotypic] see Family Hapalosiphonaceae Elenkin 1917
         1 Genus Geitleria Friedmann (1955) see Genus Geitleria Friedmann 1955