For the first time in limnofaunistic bibliography, the present taxonomic knowledge about the different clades of chelicerata having adapted to an aquatic or amphibious lifestyle along various evolutionary pathways is brought together in an overview for the Central-European fauna. A total number of 746 taxa is covered, over 99 % of these at species level. In Volume 7/2-1 altogether 211 species are treated - 70 species of spiders, 7 species of Astigmata (3 of which to be identified only at family, genus, resp. species group level), 17 species of Oribatida, 27 species and one subspecies of Halacaridae, 45 species of terrestrial Parasitengona (4 of which to be identified only at genus level) and 45 species of Hydrachnidia (4 Stygothrombioidea, 3 Hydrovolzioidea, 16 Hydrachnoidea and 22 Eylaoidea). Volume 7/2-2 deals with 179 species of Hydrachnidia (58 Hydryphantoidea and 121 Lebertioidea). This third volume (Volume 7/2-3) includes taxonomic keys and ecological information for 355 species of the two highly diverse Hydrachnidia superfamilies Hygrobatoidea (241 species and one subspecies) and Arrenuroidea (113 species). The chelicerata volumes of this series are a basic tool for all limnologists interested in diversity and ecology – in particular for biologists investigating the ecotones between ground and surface water, between bottom substrata and open water, and between water and land.

Chelicerata are a basically terrestrial group of invertebrates, including many clades whose representatives have never found an evolutionary way to aquatic live. An exception is made by some spiders and the highly diverse aquatic mites which in inland water habitats are represented by members of numerous different clades having evolved an aquatic or amphibious lifestyle along various evolutionary pathways. For the first time in limnofaunistic bibliography, the present taxonomic knowledge about these different groups of invertebrates is brought together in an overview for the Central-European fauna. This second volume includes taxonomic keys and ecological information for the two species-rich superfamilies Hydryphantoidea and Lebertioidea of the freshwater mites (Hydrachnidia). A further volume in preparation will include the remaining two superfamilies, Hygrobatoidea and Arrenuroidea. The chelicerata volumes of this series are a basic tool for all limnologists interested in diversity and ecology - in particular for biologists investigating the ecotones between ground- and surface water, between benthos and plankton, and between water and land.

Chelicerata are a basically terrestrial group of invertebrates, including many clades whose representatives have never found an evolutionary way to aquatic live. An exception is made by the spiders, which include a considerable number of hygrophilous species, and by the highly diverse aquatic mites which in inland water habitats are represented by members of numerous different clades having evolved an aquatic or amphibious lifestyle. For the first time the present taxonomic knowledge about these different groups of invertebrates is brought together in an overview for the Central-European fauna. This volume includes taxonomic keys and ecological information concerning hygrophilous and aquatic spiders, a general introduction to mites, and the treatment of three mite groups generally known from terrestrial habitats. Also, the freshwater-dwelling representatives of the originally marine Halacaridae are treated, and the species-rich true freshwater mites (Hydrachnidia) are represented in a general overview.