British Insects: the Odonata
S. danae Sulzer (1776).
Black Darter Dragonfly.
Adults. Adults (27–)32(–35) mm long (the female somewhat shorter than the male). Average wingspan 46 mm; hindwings 22–26 mm long.
The eyes dorsally narrowly apposed to dorsally broadly contiguous; brown.
Legs black. Thoracic antehumeral stripes absent. The wings spread more or less horizontally in repose; dissimilar in shape and venation; sessile; unpatterned and clear (in the male), or suffused with colour at their bases only (in the female). The tinting amber (or saffron). The inner wing venation blackish. Discoidal cell divided longitudinally into a conspicuous triangle and supra-triangle. Antenodal veins in the forewings 6–8 (fewer in the hindwings). Pterostigma elongated but only about about twice as long as wide to well over twice but no more than five times as long as wide (in the male), or well over twice but no more than five times as long as wide (in the female); black (in both sexes).
Abdomen rather stoutly linear from base to tip to linear from a conspicuously swollen base (in the female), or swollen both basally and distally and markedly constricted in between (conspicuously constricted forward of the middle, in the male); 20–24 mm long; predominantly yellow to brown (or orange-brown, in the female), or black (in the male); plain (apart from a dark olive lateral suffusion on segments 2 and 3 of the male; and a black band on segment 1, and median black dashes on the yellowish segments 8 and 9 of the female); without mid-dorsal spots. The male abdomen without auricles on segment 2; with a single inferior anal appendage.
Nymphs. The nymphs stout, the body expanded in the middle; when mature, 14–16 mm long.
The head in dorsal view markedly narrowing from immediately behind the eyes. The postocular lobes curving smoothly to the back of the head from immediately behind the eyes. The antennae 7 segmented. The mask having the prementum hollowed dorsally; without a median cleft. The prementum bearing (20–)26–28(–30) major setae (10+10 to 15+15, usually 13+13 to 14+14). The body of the labial palps bearing (10–)11(–12) major setae. Legs longer than the abdomen.
The abdomen terminating in five short spine-like appendages. The cerci no more than hald the length of the paraprocts. The abdomen with mid-dorsal spines. The mid-dorsal abdominal spines prominent on segments 5 to 7 only, but sometimes a vestigial one on segment 8. The gizzard with 4–8 folds.
Distribution. Northern Scotland, southern Scotland, northern England, English Midlands, East Anglia, Wales, southeast England, southwest England, Isle of Wight, Ireland, and central southern England (very local in the east Midlands and East Anglia). Adults on the wing early July to late October (generally in best mature condition mid-July to mid-September).
Classification. Anisoptera; family Libellulidae.
General comments. The female exhibiting a characteristic black triangle on the thorax.
Illustrations. • Sympetrum sanguineum and S. scoticum (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’.