Water mites (Acari:Hydrachnidiae and Stygothrombiae) parasitic on aquatic animals in Japan

Water mites are known to live in aquatic habitats and larval or post-larval stages are temporarily or habitually parasitic on the body surface of aquatic animals in their life cycle. Associations on the species level have been documented for 25 species, 14 genera, and 11 families in Hydrachnidiae with 44 species, 36 genera, 24 families, and six orders in Arthropoda and seven species, four genera, two families, and two orders in Mollusca. Host-parasite correspondences between mite and host taxa were observed. A large number of water-mite genera containing Hydrodroma, Hydryphantes, Protzia, Thyas, Lebertia, Sperchon, Hygrobates, Atractides, Piona, Pionopsis, Neumania, Arrenurus, and Stygomomonia were parasitic on dipteran insects. Protzia and Stygomomonia were also parasitic on trichopteran hosts, and Hydryphantes, Eylais, and Hydrachna were parasitic on coleopteran hosts. Aquatic hemipterans were infested with Hydrachna and Lebertia. Lebertia, Piona, and Arrenurus also lived on odonates. On the other hand, plecopterans were exclusively infested with Wandesia, Partnunia, and Stygothrombium. Unionicola was uniquely parasitic on freshwater gastropods and bivalves.