[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 Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics
       Subclass Biddulphiophycidaea (Round & Crawford, in Round et al., 1990) see Subclass Biddulphiophycidae Round & R.M. Crawford (1990)
         Order Biddulphiales Willi Krieg. (1954)
           Family Biddulphiaceae Kütz. (1844)
             Genus Biddulphia Gray (1821)
               1 Biddulphia alternans (J.W. Bailey) Van Heurck (1883)
               2 Biddulphia pelagica Schröder
               3 Biddulphia pulchella Gray (1821) see Biddulphia biddulphiana (Sm.) Boyer (1901)
               4 Biddulphia tridens (Ehrenberg) Ehrenberg