Kingdom Chlorobiota C.Jeffrey ex Doweld (2001) - plants see Subkingdom Viridiplantae Caval.-Sm. (1981)
   Subkingdom Pteridobiotina Britton & A. Br. (1896)
     Superdivision Cycadophytanae Doweld (2001) see Superphylum Cycadophytanae Doweld (2001)
       Division †Pteridospermatophyta Meyen
         Class †Moresnetiopsida Doweld (2001)
           Order †Moresnetiales Doweld (2001)
             Family †Eurystomataceae A.G. Long (1975)
               Genus †Tantallosperma P.D.W.Barnard & A.G. Long (1973)