living organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Eukaryotae see Domain Eukaryota Chatton, 1925
     Kingdom Animalia Linnaeus, 1758 - animals
       Subkingdom Eumetazoa Butschli, 1910 see [unranked] Eumetazoa Bütschli, 1910
         Phylum Platyhelminthes Gegenbaur, 1859 - flatworms
           Class Cestoda - tapeworms see Infraclass Cestoda
             Subclass Eucestoda - eucestodes see [unranked] Eucestoda
               Order Trypanorhyncha Diesing, 1863
                 Suborder Cystidea see Suborder Trypanoselachoida Olson, Caira, Jensen, Overstreet, Palm & Beveridge, 2010
                   Family Eutetrarhynchidae Guiart, 1927
                     1 Genus Christienella
                     2 Genus Prochristienella nom. null. see Genus Prochristianella Dollfus, 1946
                     3 Genus Parachristienella nom. null. see Genus Parachristianella Dollfus, 1946
                     4 Genus Eutetrarhynchus Pintner, 1913