[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Eukaryota Chatton, 1925 - eukaryotes see Domain Eukaryota Chatton, 1925
     Class Dinophyceae Pascher (1914)
       Subclass Peridiniphycidae Fensome, F.J.R. Taylor, G. Norris, Sarjeant, Wharton & G.L. Williams (1993)
         Order Gonyaulacales F.J.R. Taylor (1980)
           Suborder Ceratiineae Fensome, F.J.R. Taylor, G. Norris, Sarjeant, Wharton & G.L. Williams (1993)
             Family Ceratiaceae Kof. (1907)
               Genus Ceratium Schrank (1793)
                 Ceratium contortum (Gourret) Cleve
                   1 Ceratium contortum var. contortum (Gourret, 1883) Cleve
                   2 Ceratium contortum var. karstenii (Pavillard) Sournia
                   3 Ceratium contortum var. robustum (Karsten) Sournia