Key to Aeshnidae Nymph Genera
Posterolateral margins of head decidedly angulate. . . . . . . . . . . . . . . . . . . . . . . . 2
Posterolateral margins of head rounded (sometimes bluntly angular in Aeshna). . . 8
Dorsum of abdomen broadly rounded. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 3
Dorsum of abdomen with a low median ridge. . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Palpal lobes of labium squarely truncated at distal ends; paraprocts about as long as abdominal segments 9 + 10; epiproct tapering to apex that may be pointed or cleft; usually with conspicuous pale spot on dorsum of abdominal segment 8. . . Boyeria
Palpal lobes of labium tapering to a point; paraprocts longer than abdominal segments 9 + 10; epiproct parallel-sided in distal half, ending in a cleft tip; no conspicuous pale spot on dorsum of abdominial segment 8. . Basiaeschna janata
Median ridge of abdomen with blunt dorsal hooks on segments 7-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nasiaeschna pentacantha
Median ridge of abdomen without dorsal hooks. . . . . . . . . . . . Epiaeschna heros
Compound eyes as long as their greatest width; lateral spines only on abdominal segments 7-9; paraprocts about as long as abdominal segments 8 + 9. . . . . Anax
Compound eyes much shorter than their greatest width; lateral spines usually on abdominal segments 6-9 (rarely on 5-9 or 7-9 only); paraprocts shorter than abdominal segments 8 and 9 (usually equal to 9 + 10). . . . . . . . . . . . . . . Aeshna