British Insects: the Odonata


L. Watson and M. J. Dallwitz

Platycnemis pennipes (Pallas, 1771)

White-legged Damselfly.

Adults. Adults about 33–36–39 mm long. Average wingspan 45 mm.

The eyes lateral and widely separated; brown (in the female), or blue (in the male).

Legs whitish blue, dark-lined along the upper surface. Hind tibia with a conspicuous featherlike expansion. Thoracic antehumeral stripes present (humeral stripes also conspicuous); blue, or green, or green to yellow (blue or greenish in the mature male, yellowish-greenish 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 but almost rectangular, without crossing veinlets). The wings exhibiting 2 postquadrilateral cells between the quadrilateral cell and the subnodus. Antenodal veins in the forewings 2. Pterostigma present; dark brown to reddish brown (in the male), or yellow (in the female).

Abdomen linear from base to tip, or linear from base to tip to linear from a conspicuously swollen base; 27–31 mm long; predominantly grey ((-ish), in some females), or blue (with black markings, in males), or green (with black markings, in typical females); predominantly longitudinally lined to complexly patterned (with a median black line, crossed by a thin black band towards the posterior of segments 2–6; the line broadened and conspicuously medianly split on segments 8 and 9); without mid-dorsal spots. The male abdomen without auricles on segment 2; with paired inferior anal appendages.

Nymphs. The nymphs elongate and slender-bodied, gradually tapering posteriorly; when mature, 18.5–22 mm long.

The antennae with the scape considerably shorter than the other segments taken together; with the first flagellar segment shorter than the pedicel. The mask narrowed gradually to the hinge; without a median cleft. The outer margins of the labial palps armed with small spines. Distal margins of the labial palps rather irregularly finely toothed to coarsely toothed (with one large tooth). 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 narrowly oblanceolate; (apiculate-) pointed (the apiculum longer than in Coenagriidae); hairy on both margins to beyond the middle; without nodes, and with no clear demarcation between proximal and distal series of marginal hairs; with much-branched primary tracheal branches leaving the main trunk at an upward angle. The gizzard with 8–16 radially symmetrical folds.

Distribution. English Midlands, East Anglia, Wales, southeast England, and southwest England. Adults on the wing early May to late August (generally in best mature condition mid-June to late July).

Classification. Zygoptera; family Platycnemididae.

General comments. Both sexes exhibit the featherlike expansion of the hind tibia which immediately distinguishes this species.

Illustrations. • Platycnemis pennipes (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.’.