British Insects: the Odonata
Adults. Adults about 32–35–38 mm long. Average wingspan 43 mm (male), or 46 mm (female).
The eyes lateral and widely separated; red (in the male), or brown to red (in the female).
Legs black and yellow, or black and brown (the undersides of femora and coxae yellowish brown). Thoracic antehumeral stripes present (these short and anterior, in the female), or absent (the thorax entirely black, in the male); red to brown (reddish brownish). The wings held vertically in repose; similar in shape and venation; petiolate; unpatterned and clear. The inner wing venation blackish. Discoidal cell a simple quadrilateral, not longitudinally divided (trapezoid, without transverse veinlets). The wings exhibiting 4–5 postquadrilateral cells between the quadrilateral cell and the subnodus. Antenodal veins in the forewings 2. Pterostigma present; elongated but only about about twice as long as wide; light brown. The hindwings with two rows of cells distal to the pterostigma between the costa and the radial vein.
Abdomen linear from a conspicuously swollen base; 25–30 mm long; predominantly dull black (and pruinosed blueish grey, in the male), or green to bronze, or black (greenish bronzy-black in the female); predominantly transversely banded (segments 1, 9 and 10 blue in the male only, the female with thin blue bands between segments 8 and 9, and 9 and 10; and both sexes with thin yellow bands between the other segments); without mid-dorsal spots. The male abdomen without auricles on segment 2; with paired inferior anal appendages. Abdominal segment 8 of the female without a ventral apical spine.
Nymphs. The nymphs elongate and slender-bodied, gradually tapering posteriorly; when mature, 29–32 mm long.
The antennae with the scape considerably shorter than the other segments taken together; with the first flagellar segment longer than the pedicel. The mask narrowed gradually to the hinge; without a median cleft. The prementum bearing 6–8 major setae (3+3, 4+4, to 3+5). The body of the labial palps bearing 6–7 major setae. The outer margins of the labial palps without spines. Distal margins of the labial palps crenate and coarsely toothed. The moveable hooks of the labial palps without setae. The apical combs of the tibiae mainly of trifurcated setae.
The abdomen terminating in three conspicuous caudal gills. The three caudal appendages all lamellar. The caudal lamellae blunt; with transverse dark bands (three, postnodally); hairy on both margins to beyond the middle; nodate, with the marginal hairs coarser proximally to the node and finer beyond it; with much-branched primary tracheal branches leaving the main trunk at an upward angle. The gizzard with 8–16 radially symmetrical folds.
Distribution. Northern England, English Midlands, East Anglia, Wales, southeast England, southwest England, and central southern England (locally common, mainly in the Midlands and southeastern England and the Welsh border). Adults on the wing early May to early October (generally in best mature condition late May to early August).
Classification. Zygoptera; family Coenagriidae.
Illustrations. • Erythromma najas (from Lucas). • Erythromma najas: nymph, with dissections (Lucas).
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: Dragonglies and Damselflies (Odonata). Version: 1st January 2012. http://delta-intkey.com’.