The collections of the Section Mesofauna concentrate on the soil-dwelling taxa of the paraphyletic mite group Actinidida, which consists of the Prostigmata and the equally paraphyletic Endeostigmata. Concerning species and individual richness, this mite group represents one of the major and often dominant microarthropod groups in the soil. Nonetheless, it remains taxonomically and ecologically relatively unknown; for instance, hardly any determination keys exist at a species level even for the central European fauna. Research within the collections thus mainly concerns the identification of typical species assemblages of various habitat types as well as developing a reference collection of central European species. Taxonomic emphasis is on Eupodina and Endeostigmata.