1. Abdominal gills 2-7 consist of clusters of slender filaments; uncommon; eastern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Habrophlebia vibrans
Abdominal gills 2-7 forked or bilamellate, not as above . . . . . . . . . . . . . . . . . . . . . . . 2
2. Abdominal gill 1 of single linear lamella or asymmetrically forked; gills 2-7 broadly lamellate with apex three lobed . . . . . . . . . . . . . . . . . . . . . . . . . . Choroterpes basalis
Abdominal gill 1 forked or bilamellate, either similar to or different from those on succeeding segments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Gills on abdominal segment 1 much narrower and shaped differently than those of segments 2-7; each lamella of gills on segments 2-7 termianted in single slender filament that may or may not be flanked by one or two blunt lobes . . . . . . . . . . . .Leptophlebia
Gills on abdominal segment 1 not conspicuously narrower or shaped differently than those on segments 2-7; gills on 2-7 forked or bilamellate . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Gills on middle abdominal segments evenly forked or bilamellate with fork about 1/3 from base; i.e., not deeply forked; lateral tracheal brances conspicuous. . . . . . . . . . . . . . . . . 5
Gills on middle abdominal segments forked or bilamellate, but either broader, narrower, more deeply forked, or with lateral tracheal branches less conspicuous than above . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paraleptophlebia (in part)
5. Labrum with moderately deep V-shaped median emargination; row of distinctive spinules present on posterior margins of abdominal terga 6-10 or 7-10 only; uncomon; Midwest or East . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Habrophlebiodes americana
Labrum with shallow, variably shaped median emargination; row of small to minute spinules present on posterior margins of abdominal terga 1-10; widespread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Paraleptophlebia and Neoleptophlebia (in part)
Key to Ohio Leptophlebiidae Nymph Genera