miércoles, 10 de enero de 2007
Sympetrum Vulgatum (Vagrant Darter Dragonfly)
Vagrant Darter Dragonfly.
Adults. Adult body about 33–36–39 mm long. Average wingspan 60 mm; hindwings 26–28 mm long.
The eyes dorsally narrowly apposed to dorsally broadly contiguous; brown, or red (or reddish brown). The narrow black band at the base of the frons conspicuously continued for some distance down the inner sides of the eyes.
Thoracic antehumeral stripes present to absent (if detectable, less conspicuous than in some other dragonflies); brown (somewhat paler against the brown thorax). The wings spread more or less horizontally in repose; dissimilar in shape and venation; sessile; very briefly suffused with colour at their bases only. The tinting amber (or saffron). The inner wing venation (reddish-) brown. Discoidal cell divided longitudinally into a conspicuous triangle and supra-triangle. Antenodal veins in the forewings 6–8 (fewer in the hindwings). Pterostigma reddish brown, or red (ruddy, and black edged).
Abdomen linear from a conspicuously swollen base, or swollen both basally and distally and markedly constricted in between; 24–28 mm long; predominantly crimson red (in the male), or green, or yellow (olive-yellow, in the female); plain, or predominantly transversely banded, or complexly patterned (apart from median black dashes on segments 8 and 9 of both sexes, which are characteristic of the genus, males have lateral yellow spots on segments 2 and 3, and narrow yellow bands between the segments); 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, 17–18 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. The prementum bearing 28–30 major setae (14+14 to 15+15). 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 (?); gizzard with 4–8 folds.
Adults on the wing early July to early September.
Classification. Anisoptera; family Libellulidae.
General comments. A very rare species, readily distinguishable from S. striolatum by the narrow black band at the base of the frons being continued down the inner sides of the eyes.