The subphylum Clitellata of the phylum Annelida contains several classes of organisms dwelling in freshwater systems. The systematic concepts of these groups are still a matter of discussion at all taxonomic levels involved. It is hoped that the interrelationships of systematic entities within and above the species level will be better understood as additional and more precise data on morphology, anatomy, and genetics become available. The aim of this volume is to present a compilation of valid tax described from the western Palaearctic area, including the fauna of the Egyptian Nile, in order to serve as a fundament for future work. This contribution covers three classes of leeches: the Branchiobdellida, which live as epizoons on freshwater decapods, the small class Acanthobdellea, comprising highly specialised parasites living on freshwater fishes, and finally the class Hirudinea, which contains species commonly known as the "classical" leeches. Standardised descriptions of the morphology of all species are given. Whenever possible, these are amended by data on anatomical details to allow correct identifications. Most of the species are illustrated, many of them for the first time. The keys cover all taxa known from the geographical range under consideration. They are especially constructed to be used by biologists in the field, thus enabling fast access to an unknown species without dissection. Whenever possible, information on biology, ecology and distribution is supplied, although many of these data have to be used very carefully to avoid the hitherto known frequent misinterpretations.

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.

A chapter on Staphylinidae in a 1976 book on marine insects was the last general work on coastal rove beetles worldwide. Since then, phylogenetic studies on rove beetles have yielded a different perspective on that family, now with well over 50,000 species. Almost 400 species of them are now believed to be restricted to sea coasts. The detailed distribution and current classification of the coastal species are here documented in a review of the world literature accompanied by discussion and numerous color photographs of habitus and habitat.

Winner of the 2022 Marsh Book of the Year Award A long-awaited volume in the New Naturalist series examining the trees of Britain.

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