Kingdom Protozoa Goldfuss, 1818 - protozoa
   Subkingdom Gymnomyxa (Lankester, 1878) Cavalier-Smith, 2002 see Kingdom Protozoa Goldfuss, 1818
     Infrakingdom Sarcomastigota Cavalier-Smith, 1983 see Subkingdom Sarcomastigota Cavalier-Smith, 1983
       Phylum Choanozoa Cavalier-Smith, 1981
         Class Cristidiscoidea Page, 1987 see Kingdom Nucleariae Tedersoo, Sánchez-Ramírez, Kõljalg, Bahram, Döring, Schigel, May, Ryberg & Abarenkov, 2018