European and Caucasian species of Megasternum Mulsant, 1844 (Coleoptera: Hydrophilidae)

Revised data on the distribution of European and Caucasian species of Megasternum Mulsant, 1844 are given: M. concinnum Marsham, 1802, M. immaculatum Stephens, 1829, M. caucasicum Kuwert, 1890 stat. rev. and M. prometheus Shatrovskiy, 1990. For M. caucasicum, the status of valid species has been restored. Redescriptions of the species are given. Lectotypes of M. concinnum, M. immaculatum and M. caucasicum are designated here: Diagnostic characters of all species are illustrated by photographs. The ecological features and distribution of species are presented. New finds for regional faunas are recorded: M. immaculatum (for Belarus, Italy, and European part of Russia), M. caucasicum (for Russia), M. concinnum (for Morocco and Nepal).