Key to imagos of North American Neoephemera species

(modified from Bae & McCafferty, 1998)

1 Forewing longitudinal veins purplish black. Body length> 13 mm ...................................... N. purpurea

- Forewing longitudinal veins pale. Body length 7–10.5 mm ..................................................... 2

2(1) Caudal filaments annulated on alternating segments.......................................................... 3

- Caudal filaments not annulated...........................................................................4

3(2) Male dorsal maculations as in Fig. 18; male foretibia at least 2× as long as mid- and hind- tibia and all female leg lengths sub- equal (Figs 23–25); legs white with apical banding on femora faint or absent; obovate anteronotal protuberance on the meso- thorax (Fig. 29)................................................................................. N. eatoni

- Male dorsal maculations as in Fig. 19; male fore tibia <2× the length of mid and hind tibia (Figs 26–28); females with hind legs longer than mid legs; legs smoky with distinct purplish black apical banding on femora; anteronotal protuberance a curvilinear triangle (Fig. 30).......................................................................... N. youngi

4(2) Forefemora colored with purplish grey markings. Tarsi annulated...................................... N. compressa

- Forefemora pale. Tarsal annulation absent............................................................ N. bicolor