A morphological and molecular study of 17 Cylindrotomidae species revealed that the two subspecies of Cylindrotoma distinctissima, the Nearctic C. americana Osten Sacken, 1865, stat. reval. and the Palearctic C. distinctissima (Meigen, 1818), represent separated lineages and consequently are raised to species level. Cylindrotoma japonica Alexander, 1919, syn. nov. and C. distinctissima alpestris Peus, 1952, syn. nov. are now known to be junior synonyms of C. distinctissima. Triogma kuwanai limbinervis Alexander, 1953, syn. nov. and T. nimbipennis Alexander, 1941, syn. nov. are now placed into synonymy under Triogma kuwanai (Alexander, 1913). The Japanese Cylindrotomidae are all redescribed and all available literature and distribution data are summarised. Supplementary descriptions and illustrations for male and female terminalia of Cylindrotoma nigriventris Loew, 1849, Diogma dmitrii Paramonov, 2005, Liogma nodicornis (Osten Sacken, 1865), Phalacrocera replicata (Linnaeus, 1758), P. tipulina Osten Sacken, 1865, and Triogma trisulcata (Schummel, 1829) are provided. The following new distribution records are outlined; Diogma caudata Takahashi, 1960 from Arkhangelsk Oblast, Russia; D. glabrata (Meigen, 1818) from Belarus, Latvia, and Altai Republic, Amur Oblast, Novgorod Oblast, Magadan Oblast, Samara Oblast, and Kuril Islands (Shikotan I and Paramushir I) in Russia; Liogma serraticornis Alexander, 1919 from Khabarovsk Krai, Russia; Phalacrocera replicata from Khabarovsk Krai, Russia; and the presence of Cylindrotoma nigriventris in Altai Republic, Russia is confirmed.