Savanna Riverjack Mesocnemis singularis Vlakterivierjuffer
Also known as the Common (Forest/Savanna) Riverjack
Medium sized, fairly robust, distinctly all pruinescent pale blue damselfly with an almost dusty appearance.
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Key identification features:
- Face pruinescent pale grey. Labrum pale blue. Head not very wide, about 2x as broad as deep, pruinescent, pale blue with black band running across from above.
- Eyes bright, light cobalt blue. Diagnostic
- Neck and thorax highly pruinescent, pale whitish blue very mottled. Legs also pruinescent.
- Wings clear with black veins. Pterostigmas brownish black, almost square. Tend to sit with the wing folded above the abdomen and angled slightly upwards.
- Abdomen robust, dark blue but made pale by dense pruinescence which becomes particularly strong and whitish on segments 8 to 10. Base of cerci bears two long finger- and thumb-like processes directed inwards, visible in dorsal view, paraprocts (lower Clasper) more quadrangular.
- Light grey to greenish brown
- Fine dark brown lines on thorax and on top of head,with some pruinescence on lower half of thorax
- Pterostigmas lightish brown, almost square.
- Abdomen segments 9 to 10 light brown, some pruinescence segments 1 and 2, and on the legs.
Compared with other species:
- Unmistakable, being robust and pruinescent, all very pale blue and with short, dark pterostigmas.
- Differs from Metacnemis valida (Blue Riverjack), by not having the distinctive blue and black markings, and also does not occur in the ECP.
- Appendages, which are pointed, readily distinguish it from any species.
Distribution and habitat:
Northern Cape and, NWP, LP, GP, MP, KZN other northern provinces Hot savanna and semi-arid areas. Mostly rivers,
but also streams and large lakes, mostly shaded by gallery forest, but also in open landscapes and open areas in forest.
Often faster sections (rapids, falls) with emergent vegetation, submerged roots, rocks and/or probably overhanging branches.
From 0 to 1400 m above sea level, but mostly between 100 and 1300.
- Powerful flyer that hawks out over fast flowing rivers or stream
Description by Michael J Samways from Dragonfly Biotic Index.