Kingdom Protozoa Goldfuss, 1818 - protozoa
   Subkingdom Corticata Lankester, 1878 see Subkingdom Biciliata
     Infrakingdom Excavata T. Cavalier-Smith, 2002 see Supergroup Excavata Cavalier-Smith, 2002
       Superphylum Discicristata Cavalier-Smith, 1998
         Phylum Euglenozoa Cavalier-Smith, 1981
           Subphylum Plicostoma Patterson, 1988 ex T. Cavalier-Smith, 1998 see Phylum Euglenozoa Cavalier-Smith, 1981
             Class Diplonemea Cavalier-Smith, 1993
               Order Diplonemida Cavalier-Smith, 1993
                 Genus Rhynchopus Skuja, 1948