Key to Dragonfly Nymph Families
Modified from Tennessen, 2008
1. Prementum and palpal lobes of labium flat or nearly so, without dorsal premental setae and usually without palpal setae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Prementum and palpal lobe of labium forming a spoon-shaped structure, usually with dorsal premental and always with palpal setae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Antennae 4-segmented; fore and middle tarsi 2-segmented; ligula without a median cleft. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gomphidae
Antennae 6- and 7-segmented; fore and middle tarsi 3-segmented; ligula with a median cleft. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aeshnidae
3. Distal margin of each palpal lobe cut into large and irregular dentations (toothed projections) without associated setae; ligula represented by a toothlike process cleft in the middle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cordulegastridae, Cordulegaster
Distal margin of each palpal lobe smooth or with smaller and more regular dentations, each crenation (rounded projections) bearing 1 or more setae; ligula not as above. . . . . . . . . . . . 4
4. Head with a prominent frontal horn between bases of antennae; legs very long, the hind femur extending to or beyond the hind margin of abdominal segment 8; metasternum with a broad postero-mesal tubercle; abdomen strongly depressed, almost circular in dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Macromiidae
Head without a prominent frontal horn between bases of antennae (exception: Neurocordulia molesta); legs shorter, the hind femur usually not extending to the hind margin of absomenal segment 8; metasernum without a postero-mesal tubercle; abdomen less depressed, more elongate in dorsal view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Ventral surface of prementum with a medial groove extending from basal hinge to at least halfway to ligula; crenulations (rounded projections) on distal margin of palpal lobe separated by deep notches, crenulaton usually one-forth to one-half as high as long; cerci usually more than half as long as paraprocts. . . . . . . . . . . . . . . . . . . . . Corduliidae
Ventral surface of prementum without a basal medial groove (some Perithemis have a vestigial line that appears to be a meial groove); crenulations on distal margin of palpal lobe usually separated by shallow notches, crenulations usually one-tenth to one-sixth as high as long; cerci usually less than half as long as paraprocts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Libellulidae
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Key to Dragonfly Nymph Families