1a |
a. Tibial spurs twice the length of the intervening spaces, at least proximally |
2 |
1b |
a. Tibial spurs at most barely longer than the intervening spaces |
3 |
|
2a(1a) |
a. Vein M1A extending at least the length of 8 cells |
Argia |
b. M2 arising near the 6th or 7th postnodal crossvein in the forewing, near the 5th or 6th crossvein in the hindwing |
c. Wings petiolated only to level of the 1st antenodal crossvein |
2b |
a. Vein M1A extending at most the length of 5 cells |
Nehalennia (in part) |
b. M2 arising near the 5th postnodal crossvein in the forewing, near the 4th crossvein in the hindwing |
c. Wings petiolated to level beyond the 1st antenodal crossvein |
|
3a(1b) |
a. Intersternum with a prominent, moundlike tubercle bearing numerous long, stiff setae |
Amphiagrion saucium (Burmeister) |
b. Wings long, nearly equal in length to the abdomen |
c. Stocky, red to reddish brown and black |
3b |
a. No prominent intersternal tubercle present |
4 |
b. Wings shorter, at most 0.75x length to the abdomen |
c. Usually not stocky, usually colored differently |
|
4a(3b) |
a. Dorsum of thorax and abdomen mostly metallic green |
Nehalennia (in part) |
b. Abdominal length 19-25mm |
c. Prothoracic femora with 2 distinct external black stripes, 1 at base of spines |
4b |
a. Dorsum of thorax and abdomen usually not metallic green |
5 |
b. Abdominal length variable |
c. Prothoracic femora without a black stripe, or with one black stripe that may cover the entire external surface |
|
5a(3b) |
a. Postocular area dark, without pale spots, although crest crest of occiput may be pale |
Chromagrion conditum (Hagen, in Selys) |
5b |
a. Postocular area entirely pale or with pale spots ranging from narrow linear areas to large round spots, sometimes confluent with each other or with pale crest of occiput |
6 |
|
6a(5b) |
a. Vein M2 arising proximal to or near the 4th postnodal crossvein in fore wing, and proximal to or near 3rd postnodal in hind wing |
7 |
6b |
a. Vein M2 arising near 5th postnodal crossvein or beyond in fore wing, near 4th or beyond in hind wing |
8 |
|
7a(6a) |
a. Black humeral stripe divided along its entire length by a narrow, pale stripe |
Enallagma (in part) |
b. Prothorax with a pale dorsomedial spot |
7b |
a. Black humeral stripe entire along its length or lacking |
Ischnura (in part) |
b. Prothorax without a pale, dorsomedial spot or entirely pale |
|
8a(6b) |
a. Anal crossing links Cu to the posterior border in the fore and hind wings |
Enallagma (in part) |
8b |
a. Anal crossing links Cu to A in fore and usually the hind wings, and does not reach the posterior border |
9 |
|
9a(8b) |
a. Ab2-3 sterna modified with secondary genitalia, markedly different in shape from remaining segments |
Males, 10 |
b. End of abdomen without ovipositor, relatively undifferentiated |
9b |
a. Ab2-3 unmodified and not markedly different from other abdominal segments |
Females, 12 |
b. Prominent ovipositor under the last abdominal segment |
|
10a(9a) |
a. Pterostigma of fore wing different in shape, color, or size from pterostigma of hind wing |
Ischnura |
b. Ab10 with a posterodorsally projecting bifid process at least one-half as long as the segment |
10b |
a. Pterostigma of fore and hind wings similar in color, shape, and size |
11 |
b. Ab10 with at most a very low, widely bifid prominence one-fourth as long as the segment |
|
11a(10b) |
a. Paraprocts distinctly bifid in lateral view, with a broader inferior lobe and a more slender superior lobe or spine |
Coenagrion |
b. Cerci with well-developed ventromedial lobes that either extend anteroventrally or posteroventrally, in the latter case extending well beyond the distal end of the dorsolateral lobe and broadly expanded apically |
11b |
a. Paraprocts not bifid in lateral view, usually subtriangular with posterodorsally directed apex, at most with an obtuse, posteroventral angulation |
Enallagma (in part) |
b. Cerci without such lobes, if with ventral or posteroventral lobes, these extend little, if any, beyond the dorsal lobes and are not expanded apically |
|
12a(9b) |
a. Humeral suture usually pale, but, if a black stripe present, then no apical spine on venter of Ab8 |
Ischnura |
12b |
a. Humeral suture usually with a black stripe, but, if pale, then an apical spine is present on venter of Ab8 |
12 |
|
13a(12b) |
a. Ab8 without a ventroapical spine |
Coenagrion |
13b |
a. Ab8 with a ventroapical spine |
Enallagma (in part) |
|