Guinea Skimmer (Orthetrum guineense)

Guinea Skimmer Guinese Skepper

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Short description:

Medium sized to fairly large, slender and aging into all pruinescent blue with dark, thin dark shoulder stripes.

Key identification features:

Male:

Frons is light greenish grey, spectacled with fine cream lines, with a small wide indentation below the median ocellus not stretching to far towards the antifrons (lower part of frons). The area surrounding the frons, vertex (with small pointed slightly darker conical peaks), and occipital triangle is golden brown. Frons at most with dorsal dark markings running down onto shields. Clypeus, labrum, gena and labium (without dark median line) light creamy grey fading to a golden brow at the edges.
Eyes are dark greyish turquoise with brownish purple mottles on grey below.
Thorax is creamy brown to brown with faint brown stripe becoming pruinescent dull blue with no side pattern, each shoulder with narrow, dark and sharply defined, wedge-shaped stripe that shows through pruinescence. Metepimeral carina often marked with black line
Wings clear, becoming slightly smoky with age. The underside of antenodal crossveins and costa is yellowish. Pterostigmas are yellowish brown bordered by dark brown, not swollen, usually 12.5% of Hw length or less
Abdomen is pruinescent blue. Usually shorter than Hw (if longer, S4-6 with transverse bands). At least S4-7 with pale longitudinal streaks, at most S9-10 all dark, although marking on S8 can be tiny; cerci always at least partially dark. For the description of the secondary genitalia refer to the sketch. Note space between hook and lobe of hamule usually wide

Female:

Orange brown.
Face and eyes light brown.
Head shallowly dimpled with small peaks, shiny brownish black above, cream at sides and back.
Thorax is pale brown on the sides with narrow, pointed, dark brown shoulder stripes and brown side stripe.
Abdomen is orange brown with very fine blackish line running the top length. Foliations are small, yellowish with black margins.

Credit to MJ Samways for the description.

Compared with other species:

General; appearance similar to Julia Skimmer O. Julia but with yellowish brown Pterostigmas.
Similar to Orthetrum machadoi but differs by labium often marked with black rather than all pale. Metepimeral carina marked with black line;. Hook of hamule narrow rather than broad, and turned outward and with straight anterior border.
The frons of O. julia has a narrow deep and longish indentation below the median ocellus compared to the wide shallow indentation on O. guineense.
Labium has no central, dark marking.
Secondary genitalia are very similar to but a wider space between hamule and genital lobe.
The yellow on the underside of the antenodal crossveins is very distinctive.

Distribution and habitat:

Distribution data is insufficient for Southern Africa to form a clear demographical picture but found on the higher elevation areas from
Brits in NWP, Vaalwater in the Limpopo area and further eastward to MP. Africa south f the Sahara
Streams, but possibly also rivers, in open landscapes or open areas in forest. Often with rocks and a soft (like muddy) bottom.
From 0 to 2100 m above sea level, but mostly below 1800.

Behaviour:

Perches on the rocks or occasionally on twigs over the clear water, where it darts out and then returns to its perch.