Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Domain Bacteria Woese et al. 1990 [paraphyletic?]
             Superphylum Terrabacteria Battistuzzi et al. 2004
               Phylum Cyanobacteria (ex Stanier 1974) Cavalier-Smith 2002 - cyanobacteria
                 Class "Cyanobacteria" Cavalier-Smith, 2002
                   Subclass Nostocophycideae
                     Order Nostocalesᵀ Borzì (1914)
                       Family Hapalosiphonaceae Elenkin (1917), nom. cons.
                         Genus Hapalosiphonᵀ C. Nägeli in F.T. Kützing ex Bornet & Flahault 1886-1888[1887]
                           Hapalosiphon fontinalis (C.A. Agardh) ex Bornet 1889
                           Hapalosiphon hibernicus W. and G.S. West 1896
                           Hapalosiphon intricatus W. and G.S. West 1894