British Insects: the Odonata
White-faced Darter Dragonfly.
Adults. Adults about 34–37–40 mm long (the male 35.5–39 mm, the female 34–36 mm). Average wingspan 53 mm; hindwings 23–27 mm long.
The eyes dorsally narrowly apposed; brown.
Thoracic antehumeral stripes present (these broad); yellow (in the female), or red (in the male). The wings spread more or less horizontally in repose; dissimilar in shape and venation; sessile; unpatterned and clear (the forewings of both sexes), or with a sharply defined, dark brown basal fascia (the hindwings of the male), or suffused with colour at their bases only and with a sharply defined, dark brown basal fascia (the hindwings of the female). The tinting in the female hindwings, additional to the dark patch, amber. The inner wing venation blackish. Discoidal cell divided longitudinally into a conspicuous triangle and supra-triangle. Antenodal veins in the forewings 7–9 (fewer in the hindwings). Pterostigma more or less isodiametric to elongated but only about about twice as long as wide (nearly square, in the male), or elongated but only about about twice as long as wide (in the female); dark brown.
Abdomen linear from a conspicuously swollen base to swollen both basally and distally and markedly constricted in between (only rather gently constricted in the female); 22–24 mm long (female), or 24–27 mm long (male); predominantly black (with red markings in the male, yellow in the female); complexly patterned (with broad transverse bands, lateral spots and large cruciate or diamond-shaped marks on segments 2 and 3, median spots or longitudinal lines on other segments, and narrow transverse bands on the posterior segments, the markings red in the male and golden yellow in 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, 18–20 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 24–30 major setae (12+12 to 15+15). The body of the labial palps bearing 10–11 major setae. Distal margins of the labial palps weakly crenate. 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 4 to 6 (and sometimes with a vestige on segment 7). The ventral surface of the abdomen with distictive dark longitudinal bands. The gizzard with 4–8 folds.
Distribution. Northern Scotland, northern England, English Midlands, Wales, and southeast England. Adults on the wing late may to early August (generally in best mature condition early June to mid-July).
Classification. Anisoptera; family Libellulidae.
Illustrations. • Leucorrhinia dubia (from Lucas). • Leucorrhinia dubia: B. Ent. 712. • Leucorrhinia dubia: B. Ent. 712, legend+text. • Leucorrhinia dubia: B. Ent. 712, text cont..
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’.