1a |
a. Forewing triangle with anterior side angulate |
Nannothemis bella (Uhler) |
b. Anal loop insdistinct, open to rearward |
c. Very small dragonflies, wings hyaline and <16mm in length |
1b |
a. Forewing triangle with anterior side straight |
2 |
b. Anal loop distinct, closed at toe |
c. Larger dragonflies, wings >16mm, if short, then either deep yellow or strongly patterned with brown |
|
2a(1b) |
a. Pterostigmata trapezoidal, each with proximal and distal margins widely divergent anteriorly, the proximal margin nearly perpendicular to the costa and vein R1 |
3 |
b. Hindwings each with nodus positioned closer to wing base than the pterostigma |
c. Hindwings usually very widely expanded basally, usually with at least 5 cell rows between wein A2 and anal angle of wing, with several unusually elongated cells near wing margin anterior to anal angle |
d. Vein Appl usually well-developed |
2b |
a. Pterostigmata usually not trapezoidal, each with proximal and distal margins approximately parallel to each other and both oblique to costa and vein R1 |
4 |
b. If pterostigmata somewhat trapezoidal, then hindwings each with nodus closer to the base of the pterostigma than to the wing base |
c. Hindwings not usually expanded basally, usually with no more than 4 cell rows between wein A2 and anal angle of wing, without unusually elongated cells near wing margin anterior to anal angle |
d. Vein Appl absent or poorly developed |
|
3a(2a) |
a. Hindwings with two cubito-anal crossveins |
Pantala |
b. Veins M2 and Rs strongly undulate |
|
a. Hindwings with one cubito-anal crossveins |
Tramea |
b. Veins M2 and Rs not strongly undulate |
|
4a(2b) |
a. Midvein of anal loop angulated < 30° at ankle |
5 |
4b |
a. Midvein of anal loop angulated distinctly more than 30° at ankle |
6 |
|
5a(4a) |
a. Forewing triangles with anterior side nearly as long as the proximal side |
Perithemis tenera (Say) |
b. Sexually dimorphic, wings of male deep amber yellow with little or no brown, wings of female usually with extensive brown markings but mostly hyaline in the distal 1/4-1/3 |
c. Hindwings usually shorter than 22mm |
5b |
a. Forewing triangles with anterior side only about 1/2 as long as the proximal side |
Celithemis |
b. Usually not strongly sexually dimorphic, wings often with extensive brown markings but never amber without brown markings |
c. Hindwings 22mm or longer, usually longer than 25 mm |
|
6a(4b) |
a. Wings each with a very long cell just posterior to pterostigma, 3x or 4x the length of cells immediately proximal to it, thus with no crossveins immediately behind pterostigma or a single crossvein almost at its distal end |
Pachydiplax longipennis (Burmeister) |
6b |
a. Wings each with cells posterior to pterostigma no more than 2x length of adjacent cells, thus with 1 or more crossveins immediately behind pterostigma |
7 |
|
7a(6b) |
a. Vein M2 distinctly undulate or, if undulation slight, male with spines on outer angle of metafemur very short, stout, hooked proximally |
8 |
b. Posterior margin of pronotum smoothly convex, without median notch |
7b |
a. Vein M2 not undulate; male with spines on outer angle of metafemur slender, not hooked proximally |
11 |
b. Posterior margin of pronotum variable but often with distinct median notch |
|
8a(7a) |
a. Vein Cu1 in hindwing arising at posterior angle of triangle |
9 |
8b |
a. Vein Cu1 in hindwing arising from outer side of the triangle, clearly anterodistal to the posterior angle |
11 |
|
9a(8a) |
a. Forewings with one cell row between veins M4 and Mp1, or at most with single doubled cell |
Ladona julia (Uhler) |
b. Triangle almost always 2-celled |
9b |
a. Forewings with 2 or 3 cell rows between veins M4 and Mpl for distance of at least two cells |
10 |
b. Triangle usually at least 3-celled |
|
10a(9b) |
a. Sternum of Ab1 of male with paired ventral processes |
Plathemis lydia (Drury) |
b. Female with lateral margins of middle abdominal segments parallel and with lateral carinae of Ab9 well-developed |
c. Wings with wide, brown band at nodus |
10b |
a. Sternum of Ab1 of male without paired, ventral processes |
Libellula |
b. Female with lateral margins of middle abdominal segments tapering gradually posteriorly and with lateral carinae of Ab9 absent or very weakly developed |
c. Wings variably patterned |
|
11a(7b,8b) |
a. Forewing triangle with proximal side <2x long as anterior side |
Leucorrhinia |
b. Pterostigmata each short and thick, about twice as long as wide, at least in male |
c. Tergum of Ab4 without distinct lateral carinae |
d. Forewings each with veins M4 and Cu1 divergent to wing margin |
e. Face white |
11b |
a. Forewing triangle with proximal side more than twice as long as anterior side |
12 |
b. Pterostigmata each about 3x or more as long as wide |
c. Tergum of Ab4 with distinct lateral carinae |
d. Forewings each with veins M4 and Cu1 variable |
e. Face not white in most species |
|
12a(11b) |
a. Forewings each with 6-7 paranal cells before subtriangle |
Erythemis simplicicollis (Say) |
b. Meso- and metafemora each with distal 3-4 spines much longer than more proximal spines |
12b |
a. Forewings each with 5 paranal cells before subtriangle |
13 |
b. Meso- and metafemora each with spines subequal or gradually increasing in length distally |
|
13a(12b) |
a. Wings each with one crossvein immediately behind pterostigma |
Sympetrum |
b. Posteror margin of pronotum directed dorsally, with median notch deep and V-shaped |
c. Tergum of Ab3 with lateral carinae distinctly more weakly developed than that of Ab4 |
13b |
a. Wings each usually with two or more crossveins behind pterostigma |
Erythrodiplax umbrata(Linnaeus) |
b. Posterior margin of pronotum directed posterodorsally, with median notch shallow and V-shaped or absent |
c. Tergum of Ab3 with lateral carinae usually about as well developed as that of Ab4 |
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