New records of Cecidomyiidae, Dixidae and Mycetophilidae (Diptera) from the Czech and Slovak Republics

New records of Cecidomyiidae, Dixidae and Mycetophilidae (Diptera) are presented from various localities in the Czech Republic and Slovakia. Three species of Cecidomyiidae, four species of Dixidae and two species of Mycetophilidae are new to the Czech Republic. One species of Cecidomyiidae, two species of Dixidae and two species of Mycetophilidae are new to Slovakia. Problems with the interpretation of the species Dixella nigra (Staeger, 1840) and Dixella bankowskae (Vaillant, 1969) are also commented on.