Phylum Radiolaria Müller, 1858 see Subphylum Radiozoa Cavalier-Smith, 1987
   Superclass Polycystina Ehrenberg, 1838 see Superclass Polycystinia Ehrenberg, 1838
     Class Stauraxonaria Afanasieva & Amon, 2005
       Order Lobatiradiata Afanasieva & Amon, 2005
         Family Myelastridae Riedel, 1971
           Genus Pentaphiastrum Afanasieva & Amon, 2005, nom. null. see Genus Pentophiastrum Haeckel, 1887