British Insects: the Odonata
C. aenea (Linnaeus, 1758), partim.
Downy Emerald Dragonfly.
Adults. Adults about 44–48–52 mm long (the sexes of similar length). Average wingspan 68 mm; hindwings 31–34 mm long.
The eyes dorsally narrowly apposed; green (in both sexes).
Legs long, black. Thoracic antehumeral stripes absent. The wings spread more or less horizontally in repose; dissimilar in shape and venation; sessile; suffused with colour at their bases only (close to the body only). The tinting light brown. The inner wing venation blackish. Discoidal cell divided longitudinally into a conspicuous triangle and supra-triangle. Antenodal veins in the forewings about 7–10 (fewer in the hindwings); without distinct primaries, and those in the costal and subcostal spaces more or less aligned. Pterostigma well over twice but no more than five times as long as wide; black.
Abdomen swollen both basally and distally and markedly constricted in between; 34–38 mm long; predominantly green to bronze (or coppery); metallic; plain; without mid-dorsal spots. The male abdomen auriculate on segment 2; with a single inferior anal appendage.
Nymphs. The nymphs stout, the body expanded in the middle; when mature, 22.5–25 mm long.
The head in dorsal view markedly narrowing from immediately behind the eyes. The mask narrowed gradually to the hinge; without a median cleft. The prementum bearing 24–30 major setae (12+12 to 15+15). The body of the labial palps bearing 8–9 major setae. Distal margins of the labial palps strongly crenate. Legs longer than the abdomen.
The abdomen terminating in five short spine-like appendages. The cerci more than half the length of the paraprocts. The abdomen with mid-dorsal spines. The mid-dorsal abdominal spines prominent on segments 4 to 9 (these recurved). The gizzard with 4–8 folds.
Distribution. Northern Scotland, northern England, East Anglia, Wales, southeast England, southwest England, Isle of Wight, and central southern England (mostly encountered in the southeast of England). Adults on the wing late may to early August (generally in best mature condition late May to mid-July).
Classification. Anisoptera; family Corduliidae.
Illustrations. • Cordulia linaenea (from Lucas). • Cordulia linaenea: nymph (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’.