British Insects: the Odonata
Adults. Adults about 30–33–36 mm long. Average wingspan 42 mm; hindwings 16–20 mm long.
The eyes lateral and widely separated; brown (-ish, in the female), or blue (-ish, in the male). The front of the head immediately interior to the eyes not pale whitish blue (mostly black).
The prothorax deeply two-cleft posteriorly, resulting in a distinctly 3-lobed posterior margin. Legs black and blue (-ish, below). Hind tibia without a featherlike expansion. Thoracic antehumeral stripes present (the humeral stripes also conspicuous); blue (in the male), or greyish (in the female). 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 3 postquadrilateral cells between the quadrilateral cell and the subnodus. Antenodal veins in the forewings 2. Pterostigma more or less isodiametric; pale with a dark centre (black-centred, surrounded by a pale ring). The hindwings with only one row of cells distal to the pterostigma between the costa and the radial vein.
Abdomen linear from base to tip (very slender); 25–30 mm long; predominantly blue and bronze, or blue and black (blue and bronzy-black in both sexes); mostly predominantly transversely banded (similar in both sexes. Segments 1 and 2 are complexly patterned dorsally with black, while segments 3 to 7 are anteriorly blue and posteriorly black banded; segment 8 is blue in the male, and almost entirely black in the female); without mid-dorsal spots. Abdominal segment 2 of the male blue, with a black U-shaped dorsal mark which is joined to the black circlet behind it (usually), or blue, with a black U-shaped dorsal mark which is separated from the black circlet behind it (rarely). 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.
The head with prominent spots; in dorsal view markedly narrowing from immediately behind the eyes. The postocular lobes curving sharply to the back of the head from some distance behind the eyes. The antennae 7 segmented; 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 8(–10) major setae (usually 4+4). The body of the labial palps bearing (5–)6 major setae. The outer margins of the labial palps without spines. 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 oval; blunt; hyaline without coloured markings; 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 Ireland (rare in the north of England). Adults on the wing early May to early August (generally in best mature condition early June to late July).
Classification. Zygoptera; family Coenagriidae.
General comments. Usually but not always distinguishable from C. puella by the fact that the dorsal black U-shaped mark on segment 2 is joined to the black band posterior to it.
Illustrations. • Coenagrion pulchellum (from 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’.