eukaryotes see Domain Eukaryota Chatton, 1925
   Kingdom Protozoa Goldfuss, 1818 [paraphyletic] - protozoa
     Subkingdom Natozoa Cavalier-Smith, 2021 [paraphyletic]
       Infrakingdom Archezoa Cavalier-Smith, 1983 [monotypic] see Phylum Metamonada Grassé, 1952
         Phylum Metamonada Grassé, 1952
           Subphylum Trichozoa Cavalier-Smith, 1997
             Infraphylum Fornicata Simpson, 2003
               Class Eopharyngea Cavalier-Smith, 1993
                 Order Retortomonadida orth. inval. [monotypic] see Order Retortamonadida Grassé, 1952
                   Genus Retortamonas Grassi, 1879