145 



Smith and Pritchard: Odonato 





m — r 



I - 1 .. T .,«*«l^ 



C.i 



Fig. 4:74. Wings of Argia illustrating venation of the Zygoptera. 

 A, anal vein; Ac, anal crossing; anx, antenodal cross veins; 

 ar, arculus; C, costal vein; Cu, cubital vein; M. median vein; 

 n, nodus; pnx, postnodal cross veins; pt, pterostigma; q, quad- 

 rangle; R, radial vein; Rs, radial sector; Sc, subcostal vein 

 ((Walker, 1953). 



Fema les 



1. Mesothorax with a pair of conspicuous, black pits on 



S either side of the anterior fork of the mediodorsal 

 carina (fig. 4:70c-e) 2 



— Mesothorax without more than a tiny, transverse de- 

 ■ pression on either side of the anterior fork of the 

 v mediodorsal carina (fig. 4:70a, b) 5 



2. Mesothoracic pits large, circular and open (fig. 4:70a") 



emma 



— Mesothoracic pits partly covered by mesostigmal 

 laminae (fig. 4:70c, e) 3 



3. Mesostigmal lamina with flange on either side con- 

 stricted, no broader than long (fig. 4:70e) 4 



— Mesostigmal lamina with flange on either side broadly 

 angulate, obviously wider than long (fig. 4:70c) .... 



vivida 



1 4. Wing with stigma surmounting more than one cell (fig. 

 ii 4:71) moesta 



— Wing with stigma surmounting one cell or less . . . hinei 

 ' 5. Mesothorax with a mere black line along mediodorsal 



carina sedula 



I — Mesothorax with mediodorsal stripe well developed . 6 



j 6. Abdominal segments 4 to 6 mostly black dorsally; with 



a slight median depression between anterior fork of 



mediodorsal lamina (fig. 4:706) alberta 



— Abdominal segments 4 to 6 mostly pale dorsally; with 

 a deep depression between anterior fork of mediodorsal 

 lamina (fig. 4:70a) nahuana 



Naiads 11 



1. Gills with a marginal fringe of stiff bristles mixed with 

 fine long hairs toward apex 2 



— Gills without stiff marginal setae, or with only a few 

 near the base, uniformally dark except along apical 

 margin which is paler; labium with 1 lateral seta 



moesta 



2. Gills broadest at or before the middle, rounded at base 

 (fig. 4:72) 3 



— Gills broadest beyond the middle, narrowed toward the 

 base; labium with 3 lateral setae; gills with coarse 

 dark blotches on a pale background and a dark cross- 

 band immediately beyond middle sedula 



3. Antennae shorter than head; labium with 4 lateral 

 setae; gills acute at apex vivida 



— Antennae slightly longer than head; labium with 1 

 lateral seta; gills with round-angulate apices and a 

 fine filament at tip (fig. 4:72) emma 



"The naiads of alberta, hinei, and nahuana are not described. 



Fig. 4:75. Amphi'ogron. a, male of abrevi'ofum," b, female of 

 abreviatum; c, naiad of saucium (Walker, 1953). 



Genus Amphiagrion Selys, 1876 



These are small, stout-bodied damselflies, the males 

 of which are red and black in color and the females 

 of which are nearly tan (fig. 4:75). 



The genus is widespread in North America, Amphia- 

 grion saucium (Burmeister) 1839 being the eastern 

 representative and A. abbreviatum (Selys) 1876 being 

 the species found from Oklahoma and Kansas to 

 British Columbia and California. 



The naiad is thickset with prominent hind angles 

 of the head. It breeds in shallow seepage pools, 

 the spring-fed water of swales, and the small shallow 

 beds of rivulets, all of which are densely filled with 

 aquatic vegetation such as sedges and reeds. 



Genus Telebasis Selys, 1865 



The genus Telebasis is comprised of dainty, slender, 

 red damselflies that are mostly tropical American in 

 distribution. The one known species in our fauna, 

 T. salva (Hagen) 1861 (fig. 4:76), occurs throughout 

 the southwestern United States, from Oklahoma to 

 California and south to Panama. One of the closely 

 related species known from Mexico, T. incolumis 

 Williamson 1930, occurs from Baja California south- 

 ward to Guatemala. 



Telebasis salva is found in shallow waters contain- 

 ing palustral vegetation. They fly low in and about 

 the grasses. Females oviposit in algal mats or under 

 floating sticks. The naiad has the peculiar habit of 

 flapping the lateral gills against the middle gill about 

 once a second. 



Genus Zoniagrion Kennedy, 1917 



The genus Zoniagrion is based on a single, slender, 

 blue and black damselfly that is closely allied to the 

 genus Enallagma. 



Zoniagrion exclamationis (Selys) 1876 (figs. 4:77; 



