142 



Smith and Pritchard: Odonata 



Family CO ENAG R IONIDAE (= AGRiONIDAE auct.) 



These are small, mostly brightly colored damselflies 

 with clear wings. The colors run to black and blue, 

 but red, orange, green, brown, and yellow also occur. 

 The females are often dichromatic, the homeochrc- 

 matic form being like the male in color and often also 

 in markings, whereas the heterochromatic form differs 

 from the male not only in color but often also in the 

 pattern. The naiads are green or brown and are usually 

 climbing forms in still water. 



Key to Nearctic Genera 

 Adults 



1. Vein Cu, only 3 cells long; Cu 2 rudimentary 



Neoneura 



— Veins Cu, and Cu, both well developed (fig. 4:74) 



2 



2. Tibiae with spines much longer than intervals between 

 them 3 



— Tibiae with spines about as long as intervals between 

 them 5 



3. Wing with 2 distinct rows of cells behind Cu, 



Hyponevra 



— Wing with 1 row of cells behind Cu 2 (sometimes a few 

 scattered double cells) (fig. 4:61c) 4 



4. Vein Cu, 4 or 5 cells long Argiallagma 



— Vein Cu 2 10 or more cells long (figs. 4:61c; 4:71) 



Argia 



5. Occiput almost entirely pale or with pale postocular 

 spots or markings 6 



— Occiput dark without pale postocular spots or markings 



12 



6. Male with stigma of fore and hind wings similar (fig. 

 4:67a,6) 7 



— Male with stigma of fore and hind wings different as to 

 size or shape (fig. 4:67c, d) 11 



7. Wings stalked to the anal crossing Teleallagma 



— Wings not stalked as far as anal crossing (fig. 4:67) 



8 



8. Stigma with costal margin shorter than "radial" margin 



Hesperagrion 



— Stigma with costal margin not shorter than "radial" 

 margin (figs. 4:67; 4:78) 9 



9. Male with a bifurcate process dorsally on eighth 

 abdominal segment; female with large ventral spine 

 on 8 (California) (fig. 4:77) Zoniagrion 



— Male without a bifurcate process on eighth abdominal 

 segment (figs. 4:80; 4:84) 10 



10. Female without a ventral spine on eighth abdominal 

 segment; penis with long membranous processes dis- 

 tally or subdistally (fig. 4:80) Coenagrion 



— Female with a spine on eight abdominal segment; 

 penis without long distal or subdistal processes (figs. 

 4:84; 4:85) Enallagma 



11. Male with stigma of fore wing removed from costa; 

 female with hind tibia entirely pale (fig. 4:67d) .... 



Anomalagrion 



— Male with stigma of fore wing adjacent to costa; female 

 hind tibia with outer face black (figs. 4:67c; 4:88) 



Ischnura 



12. Hind wing with costal side of stigma shorter than 

 radial side Hesperagrion 



— Hind wing with costal side of stigma as long as or 

 longer than radial side (fig. 4:66) 13 



13. Body black or tan and red 14 



— Body black and blue or green 15 



14. Male with dorsal appendages bifid; female with ventral 

 spine on abdominal segment 8; body short and thick set 



__ Amphiagrion 



— Male with dorsal appendages entire (fig. 4:76a); female 

 without ventral spine on eighth abdominal segment; 

 body slender Telebasis 



15. Body metallic green; frons angular in profile 



Nehalennia 



— Body blue and black; frons rounded in profile 



Chromagrion 



Naiads 10 



1. Gills not more than twice as long as broad (fig. 4:72); 

 no mental setae 2 



— Gills usually 4 or more times as long as broad, rarely 

 only 2 ! /2 times as long as broad; mental setae present 

 (figs. 4:79; 4:82) 3 



2. One to 4 lateral setae Argia 



— Lateral setae absent, or occasionally 1 weak seta 

 just before base of hook Hyponeura 



3. Posterolateral margins of head angulate 4 



— Posterolateral margins of head rounded (figs. 4:79; 

 4:81; 4:93) 5 



4. Gills ovate-lanceolate, widest near middle, one-third 

 as broad as long, with little or no pigmentation (fig. 

 4:82) Amphiagrion 



— Gills oblanceolate, widest toward the distal end, 1/6 as 

 broad as long, darkly pigmented except on apical 

 margin Chromagrion 



5. Labium with 1 or 2 mental setae 6 



— Labium with 3 or more mental setae, usually 5 or 6 

 (fig. 4:79/,c) 8 



6. Mental setae 2 7 



— Mental setae 1 and a small rudiment; lateral setae 5-6; 

 main gill tracheae proximally sparse, distally close 

 together (fig. 4:82) Nehalennia 



7. Lateral setae 6-7 (southern California to Texas); dark 

 colored Telebasis 



— Lateral setae usually 4-5, sometimes 6, generally pale 



a few Enallagma 



8. Tips of median gill broadly rounded or, if acute, at 

 most angulate or slightly pointed (fig. 4:81; 4:83) .. 9 



— Tips of median gill ending in slender, tapering taillike 

 tips?— tips much longer than wide (figs. 4:79; 4:93) . 13 



9. Mental setae 5-6, or if less, then lateral setae 6-7 

 (fig. 4:81) 10 



— Mental setae 3-4; lateral setae 4-5; marginal setae of 

 mentum 3-9 many Enallagma 



10. Gills broadly rounded at tip; median gill 2\ 2 times as 

 long as greatest width; Arizona Hesperagrion 



— Gills acutely tipped; median gill 3-5 times as long as 

 greatest width (fig. 4:81) 11 



11. Third antennal segment 3 times as long as first seg- 

 ment; gills with pigment in tracheae only; mental setae 

 3; length 18 mm. (Atlantic Coast) Teleallagma 



— Third antennal segment usually not more than 2}' 2 times 

 as long as first segment; if longer, then gills have 

 more than tracheal pigment 12 



12. Antennae 6-segmented; mental setae 0-5, often 3 



many Enallagma 



— Antennae 7-segmented; mental setae 4-5 . . . Coenagrion 



13. Gills with 5 or 6 black crossbars; lateral keels of 

 abdomen edged with a row of spicules and numerous 

 long hairs; lateral setae 5 (California) (fig. 4:79) 



Zoniagrion 



— Gills with one to three crossbars or none; lateral keels 

 of abdomen with at most slight indication of setae; 

 lateral setae 5 or 6 (figs. 4:82; 4:93) 14 



14. Gills without pigment except in tracheae (fig. 4:82); 

 small, body length 9.5 mm. when mature, gills 4.5 mm.; 

 lateral setae 5; mental setae 4 (eastern U.S.) 



Anomalagrion 



— Gills usually with cuticular pigment (fig. 4:82; 4:93); 

 larger, body length 10 mm. or more when mature, gills 

 5 mm. or more; lateral setae 5-6 Ischnura 



"Naiads of Neoneura and Argiallagma are unknown. 



