(Fig. 7 A, B)
Material examined. CANADA: Manitoba, Lake Winnipeg, Pine Dock, 2 males, 10.vii. 1969; 20 Mile Creek, 1 male, 6.viii. 1969; Calder's Dock, 1 male, 27.vii. 1971; Beaver Creek, emergence trap, 1 male, 28.vi. 1971. All the Lake Winnipeg specimens were caught in the Narrows.
Distribution and ecology. The species is known from Fennoscandia, Central Europe, Russian Far East, Ontario, and Northwest Territories, Manitoba and Ontario south to Alabama and Florida (Fittkau 1962: 261; Roback 1971: 261; Bilyj 1988; Oliver et al. 1990: 11; Epler 2003, 2010; Caldwell 2009; Saether & Spies 2004; Ashe & O’Connor 2009: 158). The species is most common in all kinds of smaller waters, but occurs also in the littoral zone of lakes. It appears to be most characteristic in bog waters (Fittkau 1962: 261) although Brundin (1949: 680) regards the species as eurytrophic shallow water form.