118 517 Orthetrum robustum Kosi Bay 1 118 516 Orthetrum robustum Kosi Bay 6 1 100 1246 Orthetrum robustum Robust SkimmerMale Banga Neck KZN Mch 2017r 12

Robust Skimmer.     Forse Skepper    Africa

Family: Libellulidae; Rambur, 1842

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100 1246 Orthetrum robustum Robust SkimmerMale Banga Neck KZN Mch 2017r 12 100 1222 Orthetrum robustum Robust Skimmer Male Close up Banga Neck KZN Mch 2017r 2 100 1085 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 2
Images Male Male
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Short description:

Llarge ( together with O. trinacria the largest in the southern African region), powerfully built, with a green brown mottled aging to pruinescent grey brown thorax and blue pruinescent abdomen with very long slender append.

Key identification features:

Male 

  • Lenght 50 - 56 - 58mm, wingspan 76 - 83 - 86mm, pterostigmas 2.5 - 4mm  100 3026 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 54   100 3027 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 55
  • Face mostly lighter bluish grey. Labium is dull yellow with dark brown central marking not quite reaching anterior margin. Labrum is dull yellow. Anteclypeus, postclypeus and front of frons is light bluish grey, not spectacled.  100 3018 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 30  Sides and top of frons adjacent to eyes is dark brown.  100 3017 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 26  Head dimpled above, black with two small sharp peaks, without groove. 100 2061 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 24
  • Eyes light greenish grey with blackish mottled marking in the lower area.  100 3018 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 30
  • Thorax indistinctly marked, light bluish grey on top  100 1400 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 20   100 1096 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 16   (brownish green and brown when young), 100 1086 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 10 mottled brown and dark brown at sides. With aging, it develops some thin pruinosity, hence appearing mainly brown.
  • Wings are clear to slightly smoky.  100 3024 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 48  with a small amber patch in hind margin.of hind wing only. 2 cell-rows in radial planate, sum of cell-doublings in all wings 11-29, rarely down to only 4. Pterostigmas yellowish brown with dark brown anterior margins. More than 3 mm and 10% of hindwing length  100 3025 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 51   
  • Abdomen has well tapered waist. 100 3020 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 37  100 3021 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 42  All pale pruinescent blue with possible yellowish brown indistinct markings on the dorsal area when young. Segment 8 - 10 (½ S 8 hind margin) black. Clapers (appendages) black with creamy  yellow at the tip of the cercus ( upper clasper). 100 3022 rthetrum robustum Robust Skimmer Male Kozi bay KZN RSA Mch 2019r 44

Female

  • Indistinctly marked light and dark brown, wings slightly smoky. 2 yellowish brown stripes either side of thin black stripe on dorsal carina. Foliations small yellowish brown bordered in dark brown.
Similarities with other species:
  • In contrast to O. trinacria, O. robustum is robust, not slender and the abdomen is shorter than the hindwing. O. robustum easily distinguished from male O. trinacria by pruinose blue colour.
  • Final identification should by by inspection of the secondary genitalia and measurement.
Distribution and habitat:
  • Northern KZN coastal area. Visible in Botswana, Namibia, DRC and Zambia but should be visible in Zimbabwe and Mozambique
  • Prefers standing and often temporary waters. Marshy verges of pans, lakes, and floodplains, in open landscapes, but sometimes in open areas in forest. Usually with emergent and often aquatic vegetation, often with a soft (like muddy) bottom.
  • From 900 to 1500 m above sea level, but near sea level in South Africa.
Behaviour:
  • Very conspicuous as it perches on reeds and makes short hunting flight before it returns to its perch.
Further reading:
http://vmus.adu.org.za/vm_map_afr.php?&database=odonata&grid=2&outline=1&key=0&map=4&spp=%20668060
Books:
The Dragonflies and Damselflies of Eastern Africa ... p.182
Dragonfly Biotic Index ... p. 151
Dragonflies of Namibia. ...p. 209
Dragonflies and Damselflies of South Africa ... p. 159
Websites:
Odonata Atlas of Africa Number 668060
Warwick Tarboton
A Visual Guide to the Damselflies and Dragonflies of South Africa
The IUCN Red List of Threatened Species  Least Concern
African Dragonflies & Damselflies Online

Other Information:
Size Comparison Diagram
Dragonflies, Damselflies
Morphology of a
Dragonfly,  Damselfly
Map of South Africa

 

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