Hydrachnidia Krantz, 1978 - water mites Superfamily Arrenuroidea Thor, 1900 Family Acalyptonotidae Walter, 1911 [monotypic] Genus Acalyptonotus Walter, 1912 1 Subgenus Acalyptonotus (Acalyptonotus) Walter, 1912 2 Subgenus Acalyptonotus (Paenecalyptonotus) Smith, 1976