Hydrachnidia Krantz, 1978 - water mites Superfamily Arrenuroidea Thor, 1900 Family Athienemanniidae Viets, 1922 1 Subfamily Africasiinae Cook, 1974 [monotypic] 2 Subfamily Athienemanniinae Viets, 1922 3 Subfamily Notomundamellinae Cook, 1986 4 Subfamily Stygameracarinae Smith, 1990 [monotypic]