Hydrachnidia Krantz, 1978 - water mites Superfamily Arrenuroidea Thor, 1900 Family Chappuisididae Motaş & Tanasachi, 1946 1 Subfamily Chappuisidinae Motaş & Tanasachi, 1946 [monotypic] 2 Subfamily Morimotacarinae Imamura, 1962 3 Subfamily Tsushimacarinae Cook, 1974 [monotypic] 4 Subfamily Uchidastygacarinae Imamura, 1956 [monotypic]