Eastern Blacktail. Swartstertskepper
Nesciothemis farinosa (Förster, 1898)
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Eastern Blacktail, Nesciothemis farinose, Genus Nesciothemis, Family Libellulidae, fairly large sized with a black head, black eyes, very pale powdery bluish-grey thorax and abdomen. Last section of the abdomen is black with yellow stripes.
Key identification features:
- Face light brown below, dark brown above. Labrum dark brown with deep yellow margin. Anteclypeus, postclypeus and lower frons mottled light grey to dark brown. Frons shiny black and dimpled on top. Head dull black above, dimpled with minute peaks.
- Eyes deep brownish black above, dark grey below.
- Thorax blue/grey pruinose with age, When young yellow with brown stripes Dorsal thorax pruinose from brown before lateral thorax. When young distinctive cream line runs all the way along neck and over thorax between wing bases to base of abdomen but will pruinose to grey with age leaving, the grey strip between the wings visible Thorax covered with dense, pale bluish grey pruinescence.
- Wings clear to slightly smoky becoming smokier with age.Older males have dark wing tips similar to younger females. Veins near the basal end of wing pruinose to grey Pterostigmas deep yellowish brown, 4.2–4.5 mm long.
- Abdomen straight narrowing from s 6 to a point at the claspers. Segments 1 - 5, like thorax, with pale bluish grey pruinescence. S 6 - 10 black with yellow markings above.The yellow marking become faint or disappear with age. Abdominal s 9-10 never become pruinose and s 7-8 rarely so.Dark claspers.
- Thorax light brown on sides, dark brown above. Distinctive cream line runs all the way along neck and over thorax between wing bases to base of abdomen.
- Wings clear, but brown at tips, becoming clear, and finally smoky with age.
- Abdomen light yellowish brown with a dark brown line running either side of length of abdomen. Distinct yellowish foliations on s 8, with dark brown margins.
Similarities with other species:
- Habits and appearance similar to Orthetrum.
- Mature Orthetrum (Skimmers) have bluish eyes. In the Easter Blacktail, N. farinosa, the eyes become dark brown dorsally.
- Mature Orthetrum species appear whitish to light bluish , Eastern Blacktail, N. farinosa, contrast with their densely pale pruinose thorax and black abdomen tip . Black-and-yellow when teneral and pruinose with maturity. However, abdominal segments 9-10 never become pruinose and segments 7-8 rarely so, being black.
- Very distinctive. In the northern and eastern parts of South Africa it may be confused with the Deceptive Widow, Palpopleura deceptor found in the same habitat. P. deceptor, has each forewing marked with a blackish streak and spot, and has bi-coloured pterostigmas, unlike the clear (or generally slightly smoky) wings of N. farinosa, with all yellow-brown pterostigmas.
- The pale stripe on the top of the thorax of the female may be confused with the stripe on the female Two-striped Skimmer, Orthetrum caffrum, but the wings of N. farinosa differs.
Distribution and habitat:
- Widespread in South Africa.
- Occurs mostly at low elevations but sometimes reaches 1 200 m elevation. Frequents pools, pans and especially sluggish reaches of rivers with an abundance of reeds and tall grasses.
- Very conspicuous as it perches on reeds and makes short powerful hunting flight before it returns to its perch. Chase other species