[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 hexacanthum Gourret (1883)
                   1 Ceratium hexacanthum var. contortum Lemmermann
                   2 Ceratium hexacanthum var. hexacanthum Gourret, 1883
                   3 Ceratium hexacanthum f. pavillardii (Rampi) Sournia
                   4 Ceratium hexacanthum f. spirale (Kofoid) Schiller