Hydrachnidia Krantz, 1978 - water mites Superfamily Arrenuroidea Thor, 1900 Family Mideopsidae Koenike, 1910 Subfamily Mideopsinae Koenike, 1910 Genus Xystonotus Wolcott, 1900 1 Subgenus Xystonotus (Xystonotus) Wolcott, 1900 2 Subgenus Xystonotus (Mixomideopsis) Cook, 2001