Genus Gynacantha Rambur, 1842
true duskhawkers

Type species: Gynacantha nervosa Rambur, 1842

Introduction

Pantropical genus with over 80 species. Thirteen occur in continental Africa, which fall in three distinctive groups that may become separate genera in the future. The africana-group is easily recognised by the black metastigma and includes mostly large (hindwing 44-56 mm) rather dull olive brown species, sometimes with a rufous or green tinge, and plain orange-brown legs. The bullata-group species are generally small (hindwing 35-48 mm) and often more colourful, e.g. with yellow legs and/or cream, green, blue or black markings. The medium-sized (hindwing 44-47 mm) and plain greenish brown G. immaculifrons is the only continental member of the Indian Ocean island bispina-group, known only locally from eastern Tanzania, Katanga and northern Malawi. All species have large eyes and are crepuscular, flying at dawn, dusk and during rain, and may come to light at night. The large species fly fast and erratically in clearings, small species hover cautiously along edges or low above the ground. They rest inside vegetation during the day. Males may wind through tangled vegetation in search of females. Reproduction takes place in stagnant, often seasonal, swamps and pools in or near dense vegetation. Most species prefer (some) forest, G. manderica occurring in drier habitats. Good places to look for adults are thick undergrowth along dry streambeds and bordering forested swamps, but they are perhaps easiest to catch as they hunt along narrow forest paths during the half hour around sunset (and to some degree at sunrise). Discoloration after death may dull all colour and obscure pale markings. The presence of small black denticles on the abdominal carinae is often characteristic. View these from below: the lateral carinae lie on the outside and the ventral carinae on the inside. [Adapted from Dijkstra & Clausnitzer 2014]

Diagnosis

Males of genus are closest to Heliaeschna by (a) frons at most 2/5 as wide as head (dorsal view); (b) auricles present; (c) IR3 clearly forked proximal to Pt; (d) IR2 usually extends proximally more than halfway under Pt; (e) R3 not or only weakly arched forward near distal end of Pt; (f) distal end of Rspl directed at wing tip or point posterior of it; (g) Hw tornus angled; (h) Hw cubital field often of 1 cell-row at base; (i) membranule small, only touching extreme base of anal triangle; (j) anal triangle and falls short of tornus by at least 1/3 of its length. However, differs by (1) brace veins often present; (2) mainly 2-5 rows in fork of IR3, rather than only 2 cell-rows; (3) no secondary Ax present proximal to proximal primary Ax; (4) no cross-veins in median spaces, although very rarely 1 or 2. [Adapted from Dijkstra & Clausnitzer 2014]


Gynacantha (B) bullata Karsch, 1891. Male © Adolfo Cordero

Map citation: Clausnitzer, V., K.-D.B. Dijkstra, R. Koch, J.-P. Boudot, W.R.T. Darwall, J. Kipping, B. Samraoui, M.J. Samways, J.P. Simaika & F. Suhling, 2012. Focus on African Freshwaters: hotspots of dragonfly diversity and conservation concern. Frontiers in Ecology and the Environment 10: 129-134.


References

  • Fraser F.C. (1962). The Gynacanthas of tropical Africa. Revue de Zoologie et de Botanique Africaines, 65, 1-28. [PDF file]
  • Dijkstra, K.-D.B. (2005). Taxonomy and identification of the continental African Gynacantha and Heliaeschna species (Odonata: Aeshnidae). International Journal of Odonatology, 8, 1-32. [PDF file]
  • Dijkstra, K.-D.B, and Clausnitzer, V. (2014). The Dragonflies and Damselflies of Eastern Africa: handbook for all Odonata from Sudan to Zimbabwe. Studies in Afrotropical Zoology, 298, 1-264.
  • Ris, F. (1921). The Odonata or Dragonflies of South Africa. Annals South African Museum, XVIII, 245-452. [PDF file]
  • Schouteden, H. (1934). Annales Musee Congo belge Zoologie 3 Section 2, 3, 1-84. [PDF file]

Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2017-04-30].