The book "Chelicerata" provides a comprehensive overview of the terrestrial group of Chelicerata, which includes a variety of invertebrates. This group has hardly adapted evolutionarily to aquatic habitats, with the exception of some spiders and the diverse aquatic mites found in inland waters. For the first time, this specialized book consolidates taxonomic knowledge about these various invertebrates, specifically for the fauna of Central Europe. The second volume contains taxonomic keys and ecological information on the species-rich superfamilies Hydryphantoidea and Lebertioidea of freshwater mites. Another volume is in preparation and will address the remaining superfamilies Hygrobatoidea and Arrenuroidea. The Chelicerata volumes in this series are an essential tool for limnologists interested in the diversity and ecology of these organisms, particularly for biologists studying the transitional areas between benthic and surface water as well as between benthos and plankton.