[Phylum] [Arthropoda] Siebold, 1848 - arthropods
   Chelicerata Heymons, 1901
     Euchelicerata Weygoldt & Paulus, 1979
       [Order] Pseudoscorpiones De Geer, 1778
         1 [Suborder] †Palaeosphyronida Harvey, 2019 [monotypic]
         2 [Suborder] Heterosyphronida Dunlop, Penney & Jekel, 2020, orth. inval. see Suborder Heterosphyronida Chamberlin, 1929
         3 Homosyphronida Dunlop, Penney & Jekel, 2020, orth. inval. see Group Homosphyronida Chamberlin, 1929