Arthropoda Siebold, 1848 - arthropods Euarthropoda Subphylum Chelicerata Heymons, 1901 Pycnogonida Latreille, 1810 - pycnogonids 1 Genus †Palaeoisopus Broili, 1928 2.1 Genus Pycnogonum Brünnich, 1764 2.2 Genus †Haliestes Siveter, Suton, Briggs & Siveter, 2004