Checklist of the Water beetles of Switzerland. Part 2: Gyrinidae, Haliplidae, Paelobiidae, Sphaeriusidae. — An updated checklist of Gyrinidae, Haliplidae, Paelobiidae (= Hygrobiidae) and Sphaeriusidae (= Microsporidae) of Switzerland is given and briefly annotated. But for a few exceptions, the work is based on the identification of specimens by the author. Paelobiidae and Sphaeriusidae are each represented by a single species. After exclusion of misidentifications and highly unlikely or insufficiently documented data, 8 species of Gyrinidae and 16 species of Haliplidae are listed. Peltodytes rotundatus (Haliplidae) is new to the Swiss fauna. Eleven modifications are to be made in the current catalogues and a complete revision of the red list of threatened species of Swiss Hydradephaga is recommended