[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Appendiculata {Lankester}
         Branch Gnathopoda Straus-Durkheim, 1829
           Grade Condylopoda
             Class Arachnida Lamarck, 1801
               Metarachnæ
                 Order Pycnogonida Latreille, 1810 see Class Pycnogonida Latreille, 1810
                   1 Genus Pycnogonum Brünnich, 1764
                   2 Genus Phoxochilidium Agassiz, 1846 see Genus Phoxichilidium Milne-Edwards, 1840