plantenrijk Haeckel (1866) - plants
   [Division] Protophyta Sachs (1874) - primitive plants
     Class Schizomycetes Nägeli 1857 nom. inval. - bacteria and related forms see Class Schizomycetes Nägeli 1857 (Approved Lists 1980) nom. illeg., nom. rej.
       Order Eubacteriales Buchanan 1917 nom. inval. see Order Eubacteriales Buchanan 1917 (Approved Lists 1980)
         Family Lactobacteriaceae Orla-Jensen 1921 nom. inval.
           Genus Methanococcus Kluyver and van Niel 1936 nom. inval. see Genus Methanococcus Kluyver and van Niel 1936 (Approved Lists 1980)