1. Antenna with proximal and medial articles transparent, colorless, contrasting with dark brown
distal article. Hypostome with intermediate teeth between primary teeth; paralateral teeth
absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Prosimulium sp.Antenna with proximal, medial, or both articles lightly to darkly pigmented. Hyposoma without intermediate teeth; paralateral teeth present. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 2
2. Hypostoma with lateral and sublateral teeth not clustered on prominent, common lobes (medium and lateral teeth can be extended beyord sublateral teeth, but not prominent lobes;
heavily sclerotized anterior portion of hypostoma occupying at most 1/6 total length of
hypostome. Antenna longer than stalk of labral fan by about 1/2 length of distal article.
Hypostoma with outer margin of lateral cluster of teeth typically sloped inwardly. . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stegopterna sp.Hypostoma with 1 or more sublateral teeth and 1 or more paralateral teeth clustered on
prodominant, common lobes, giving hyopstoma trilobed appearance (consisting of
median tooth and 2 lateral lobes); heavily sclerotized anterior portion of hypostoma
occupying 1/3 or more total length of hypostoma. . . . . . . . . . . . . . . . . Simulium sp.
Key to Genera of Simuliidae Nymphs