Beetle fauna in Osaka city and its transition.
Through examination of the museum collection, literature citation, and field surveys conducted by citizen scientists, 867 species of beetles were recorded in Osaka City. Of them, 195 species are considered to be candidates for Red List, and many disappeared in the 1950s and the 1980s. The number of beetle species is currently highest in the area along two major rivers: some species only occurred there originally, however, some species were previously found in urban areas but nowadays restricted to the area. There are also newly distributed species including introduced species. Overview of such long-term changes can be made, only by the collection of a large number of specimens, including not only rare species but also common species.