Chelicerata Heymons, 1901 see Superclass Chelicerata Heymons, 1901
   Euchelicerata Weygoldt & Paulus, 1979
     [Class] Arachnida Lamarck, 1801
       1 [Order] Scorpiones Koch, 1837 - scorpions
       2 [Order] Opiliones Sundevall, 1833 - harvestmen
       3 [Order] †Phalangiotarbida Haase, 1890
       4 [Order] Pseudoscorpiones De Geer, 1778
       5 [Order] Solifugae Sundevall, 1833
       6 [Order] Palpigradi Thorell, 1888 - palpigrades
       7 [Subclass] Acari Leach, 1817 - mites and ticks
       8 [Order] Ricinulei Thorell, 1876 - ricinuleids
       9 Pantetrapulmonata Shultz, 2007