Hydrachnidia Krantz, 1978 - water mites
   Superfamily Hydryphantoidea Piersig, 1896 - water mites
     Family Hydryphantidae Piersig, 1896
       Subfamily Euthyadinae Viets, 1931
         01 Genus Albertathyas Smith & Cook, 1998
         02 Genus Almuerzothyas Goldschmidt & Gerecke, 2003
         03 Genus Amerothyasella Smith & Cook, 1999
         04 Genus Austrotrombella Southcott, 1991
         05 Genus Columbiathyas Smith & Cook, 1998
         06 Genus Dacothyas Motas, 1959
         07 Genus Deuterothyas Lundblad, 1941
         08 Genus Euthyas Piersig, 1898
         09 Genus Heterothyas Lundblad, 1941
         10 Genus Ignacarus Gerecke, 1999
         11 Genus Iranothyas Bader, 1984
         12 Genus Japonothyas Imamura & Mitchell, 1967
         13 Genus Javathyas Viets, 1929
         14 Genus Kazakhithyas Smit, 2016
         15 Genus Notopanisus Besch, 1964
         16 Genus Panisellus Viets, 1925
         17 Genus Panisopsis Viets, 1926
         18 Genus Panisus Koenike, 1896
         19 Genus Parathyas Lundblad, 1926
         20 Genus Parathyasella Viets, 1949
         21 Genus Placothyas Lundblad, 1926
         22 Genus Siskiyouthyas Smith & Cook, 1998
         23 Genus Tadjikothyas Sokolow, 1948
         24 Genus Thyasella Viets, 1926
         25 Genus Thyasides Lundblad, 1926
         26 Genus Thyopsella Cook, 1955
         27 Genus Thyopsis Piersig, 1899
         28 Genus Thyopsoides Smith & Cook, 1999
         29 Genus Trichothyas Viets, 1926
         30 Genus Vietsia Lundblad, 1926
         31 Genus Zschokkea Koenike, 1892