100 823 Mesocnemis singularis Riverjack Nwanedi Dec 2015 r 3 100 826 Mesocnemis singularis Savanna Riverjack Female Parys RSA DEC 2016r 4 102 014 2016 12 20 river jack savanna parys

Savanna Riverjack    Vlakterivierjuffer  Africa

Family Platycnemididae Yakobson & Bianchi, 1905
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100 825 Mesocnemis singularis Riverjack Nwanedi Dec 2015 r 9 Mesocnemis singularis, Savanna Riverjack Mal 100 822 Mesocnemis singularis Riverjack Nwanedi Dec 2015 r 5 100 826 Mesocnemis singularis Savanna Riverjack Female Parys RSA DEC 2016r 4
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Short description:

Medium sized, fairly robust, distinctly all pruinescent pale blue damselfly with an almost dusty appearance.

Key identification features:

Male: Mesocnemis singularis, Savanna Riverjack Mal

  • 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. 100 265 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 15  100 264 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 13  100 262 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 10  
  • Eyes bright, light cobalt blue. Diagnostic  100 265 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 15 100 264 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 13
  • Neck and thorax highly pruinescent, pale whitish blue very mottled. Legs also pruinescent. 100 262 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 10  100 263 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 11 
  • Wings clear with black veins. Pterostigmas brownish black, almost square. Tend to sit with the wing folded above the abdomen and angled slightly upwards. 100 268 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 19
  • Abdomen robust, dark blue but made pale by dense pruinescence 100 268 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 16 which becomes particularly strong and whitish on segments 8 to 10. 100 266 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 17 Base of cerci bears two long finger- and thumb-like processes directed inwards, visible in dorsal view, paraprocts more quadrangular. 100 267 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 18

Female: 100 826 Mesocnemis singularis Savanna Riverjack Female Parys RSA DEC 2016r 4

  • Light grey to greenish brown 100 826 Mesocnemis singularis Savanna Riverjack Female Parys RSA DEC 2016r 4 
  • Fine dark brown lines on thorax and on top of head,with some pruinescence on lower half of thorax 100 828 Mesocnemis singularis Savanna Riverjack Female Parys RSA DEC 2016r 3
  • Pterostigmas lightish brown, almost square.
  • Abdomen segments 9 to 10 light brown, some pruinescence  segments 1 and 2, and on the legs.100 832 Mesocnemis singularis Savanna Riverjack Female Parys RSA DEC 2016r 10

Description by Machael J Samways from Dragonfly Biotic Index.

Compared with other species:
  • Unmistakable, being robust and pruinescent, all very pale blue and with short, dark pterostigmas.
  • Differs from Metacnemis valida (Blue Riverjack), 105 518A M valida Mzamba River 2016 11 12 10 46 43 4089c 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. 100 266 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 17 100 267 Mesocnemis singularis Savanna Riverjack Male Close up Nwanedi LP RSA Dec 2018r 18
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.
Behaviour:

Powerful flyer that hawks out over fast flowing rivers or stream 

Further reading:
http://vmus.adu.org.za/vm_map_afr.php?&database=odonata&grid=2&outline=1&key=0&map=4&spp=661640 Books
A Guide to Dragonflies and Damselflies of South Africa   p. 56

Dragonflies and Damselflies of South Africa   p. 69
Dragonfly Biotic Index   p, 61
Websites
Tarboton 
A Visual Guide to the Damselflies and Dragonflies of South Africa
Odonata Atlas of Africa VMU Number 661640
Dragonflies & Damselflies Online 
The IUCN Red List of Threatened Species
Other Information:
Size Comparison Diagram 
Dragonflies, Damselflies
Morphology of a
Dragonfly,  Damselfly
Map of South Africa

 

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