Hydrachnidia Krantz, 1978 - water mites
   Superfamily Hygrobatoidea Koch, 1842
     Family Pionidae Thor, 1900
       Subfamily Tiphyinae Oudemans, 1941
         1 Genus Acercella Lundblad, 1941
         2 Genus Acercopsis Viets, 1926
         3 Genus Australotiphys Cook, 1986
         4 Genus Neotiphys Habeeb, 1957
         5 Genus Pionides Thor, 1900
         6 Genus Pionopsis Piersig, 1894
         7 Genus Tiphys Koch, 1836