Species of the subgenus Symplecta Meigen with Arctic, or at least partly Arctic, distributions are revised. Five species are redescribed: S. (S.) novaezemblae (Alexander), S. (S.) scotica (Edwards), S. (S.) mabelana (Alexander), S. (S.) sheldoni (Alexander), and S. (S.) horrida (Lackschewitz). Two new species are described: S. (S.) edlundae sp. nov. (Northwest Territories and Yukon, Canada) and S. (S.) echinata sp. nov. (eastern Siberia, Russia). Five new synonyms are proposed: Erioptera (S.) sunwapta Alexander and Helobia intermedia Lackschewitz = S. (S.) scotica; Erioptera (S.) platymera Alexander = S. (S.) mabelana; S. (S.) rotundiloba Podenas and Gelhaus = S. (S.) sheldoni; and Erioptera (Psiloconopa) chaetophora Alexander = S. (S.) horrida. Symplecta (Symplecta) scotica and S. (S.) mabelana are restored as full species from subspecies rank. Symplecta (Symplecta) horrida, previously placed in Erioptera (Mesocyphona) Osten Sacken, is transferred to Symplecta s.s. The distinctions between S. (S.) cana (Walker) and S. (S.) hybrida (Meigen) are clarified and the sympatric and syntopic occurrences of these species are documented. A key to the species treated, and illustrations of both male and female terminalia, are provided and the distribution of each species is outlined.