(Fig. 3 A–D)
Material examined. CANADA: Manitoba, Lake Winnipeg, emergence trap, Beaver Creek, 1 male, 21.vii. 1971.
The specimen from Lake Winnipeg has somewhat more smoky wings and slightly darker spots (Fig. 3 C) than that illustrated by Roback (1971 fig. 123). The gonostylus (Fig. 3 D) also has a slightly stronger heel than illustrated by Roback (1971 fig. 124). In other details, however, the Lake Winnipeg specimen fits the description by Roback (1971: 69) and the identification has been confirmed by Dr. S. S. Roback.
Distribution and ecology. This species is a summer form known from all over Europe, from Siberia, Turkey and Java, and from Manitoba, Michigan, Pennsylvania and Wisconsin (Oliver et al. 1990: 16, Saether & Spies 2004, Ashe & O’Connor 2009: 232). The larva lives in lakes, ponds and running waters. T. vilipennis is very rare in Lake Winnipeg.