Ephydra lacustris Meigen, 1830: 118. Lectotype, female (designated by Zatwarnicki & Irwin, 2018: 96). Germany (MNHN). Scatella tenuicosta Collin, 1930: 136. Great Britain (Essex: Pitsea & Walton-on-the-Naze; Dorset: Arne).
Scatella thermarum Collin, 1930: 138. Iceland.
Distribution: AF: Cape Verde Is. NE: Greenland, USA. PA: Austria, Azores, Bulgaria, Canary Is., China, Cyprus, Czechia, Denmark, Egypt, Finland, France, Germany, Great Britain, Greece, Hungary, Iceland, Ireland, Italy, Jordan, Madeira Is., Norway, Poland, Russia (European Territory), Spain, Sweden, Switzerland, Tunisia, Turkey, former Yugoslavia.
Egyptian localities: Eastern Desert: Safaga. Sinai: St. Catherin (Wadi Arbaein).
Dates of collection: July & August.