Black-tailed skimmer
| Black-tailed skimmer | |
|---|---|
_male_Estonia.jpg) |
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| Male, Tallinn Estonia | |
_mature_female.jpg) |
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| Female, Norfolk, England | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Odonata |
| Suborder: | Anisoptera |
| Family: | Libellulidae |
| Genus: | Orthetrum |
| Species: | O. cancellatum |
| Binomial name | |
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Orthetrum cancellatum (Linnaeus, 1758) |
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The black-tailed skimmer, Orthetrum cancellatum, is a dragonfly of Europe and Asia. It occurs nearly all of Europe except northern UK and Scandinavia; to the east, the range extends to Kashmir and Mongolia.
The adult male has a blue abdomen with a black tip and transparent wings, and the female has a yellow (later: brown) body with black bands along the abdomen and transparent wings. Even the immature males look that way.
This species has expanded its range, assisted by the creation of gravel pits which give it the extensive open unvegetated areas it prefers. It was first recorded in Great Britain in Essex in 1934. It is decreasing rapidly in the Maltese Islands.
The black-tailed skimmer is a fairly large dragonfly (the length of 44–50 mm, 29–35 mm abdomen, rear wing 35–41 mm.) with relatively broad, flattened abdomen, but not as broad as to chaser species. With age, adult males develop extensive blue pruinescence on their abdomen, offset by yellow lateral patches. The middle lobe of the pronotum is large and notched in the middle. The chest is yellow or yellowish-brown. The abdomen is more or less flattened. The base of the hind wings without a dark opaque spots. The pterostigma is dark brown or black. On the front wings pterostigma 2–3 mm long. Anal appendages black. The females and immature males are a deep yellow color, with wavy black lines dorsally on their abdomen. Males and females have the costal vein (the leading edge of the wing) yellow or black.
The species is similar to its much more localized congener the White-Tailed Skimmer, but readily identifiable in the field. The males develop a blue pruinescence on the abdomen darkening to the rear with S8-10 becoming black. Its eyes are very dark green. They fly swift and low, skimming the water surface. Females retain their color and markings though they become quite grayish brown with age. This species could be confused with Keeled skimmer or Scarce chaser.
young male
adult male
Young female
Female
Female
Adults about 47–53 mm long. Average wingspan is about 77 mm; hindwings 35–40 mm long.The eyes dorsally narrowly apposed to dorsally broadly contiguous; brown (in the female), or blue (in the male).Legs black and brown (the femoral bases brown). Thoracic antehumeral stripes absent. The wings spread more or less horizontally in repose; dissimilar in shape and venation; sessile; unpatterned and clear. The inner wing venation blackish. Discoidal cell divided longitudinally into a conspicuous triangle and supra-triangle. Antenodal veins in the forewings 10–13 (fewer in the hindwings).Pterostigma well over twice but no more than five times as long as wide.Abdomen lanceolate 30–35 mm long; predominantly blue (in the male), or brown (in the female), or grey (sometimes, in old females); rather plain (in the male, but often with orange lateral markings, and darkened over the terminal segments), or predominantly longitudinally lined (the female with a dark medio-lateral band on either side along each segment); without mid-dorsal spots. The male abdomen without auricles on segment 2; with a single inferior anal appendage. ♂: Adults have a bluish or blue-gray patina on the body, gradually darkening with age. The young have a grid pattern on a yellow-brownish abdomen. ♀: Yellow-brownish abdomen with a lattice pattern (wide longitudinal dark brown stripes and bright crescent-shaped spots). 10 tergite of abdomen black.
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Wikipedia