The sixth volume of this series "Acarorum Catalogus" is devoted to the families Rhinonyssidae and Spinturnicidae of the superfamily Dermanyssoidea. About 555 species are listed therein, with synonymies and citations in various papers. The book also contains a list of by-country distributions, type localities and lists of authors who published on any known species of Rhinonyssidae and Spinturnicidae. There are also lists including hosts of these mites. The bibliographies consist of 475 titles (Rhinonyssidae) and 430 titles (Spinturnicidae).