Genus Onychogomphus Selys, 1854
claspertails

Type species: Libellula forcipata Linnaeus, 1758

Introduction

Heterogeneous genus with over 50 species in Eurasia and Africa. The placement of about ten Afrotropical species in Onychogomphus is dubious and all are likely to be allocated to other genera in the near future. Probably only the four North African species (O. costae, O. forcipatus, O. uncatus and the recently discovered O. boudoti) represent the true genus Onychogomphus. At least seven species belong to the distinctive supinus-group, recognised by the male’s four-pronged epiproct and double-toothed cerci. Unfortunately they are rarely collected, leaving their taxonomy unresolved: identification is now based largely on markings and the female head structure, and males of (for example) O. seydeli and O. styx cannot be reliably separated. In some regions where the group occurs it is unclear which species is present, e.g. in eastern Zimbabwe probably one of the paler and in southern Malawi one of the darker taxa. Whether the true O. supinus occurs outside South Africa is unclear. Members of this group are medium-sized (hindwing 24-32 mm) and inhabit streams and smaller rivers, often in highlands, both in open landscapes (pale species) and forest (dark ones). Males perch low on bank-side rocks or vegetation. The other Afrotropical taxa, including the enigmatic ‘Onychogomphus’ bwambae, are reminiscent of Libyogomphus. [Adapted from Dijkstra & Clausnitzer 2014]

Diagnosis

Recognised best in North Africa by the male’s large appendages: the upper and lower appendages are both distinctly longer than S10 and are curved strongly towards one point, like pincers. With the exception of the brown, faintly-marked O. costae, all species have a yellow abdomen ringed with black, and a yellow thorax with black stripes. The hindwing has a small anal loop of 1-3 cells; therefore there is not a straight perpendicular vein running directly to the wing’s hind margin from the last thick lengthwise vein in the wing base. The males can hardly be misidentified because of their appendages, but females may be mistaken for Gomphus and Paragomphus. Paragomphus genei is smaller; male has broad flaps on S8-9 and females have a row of small black denticles on the rear of the occiput. Gomphus is marked differently, the abdomen appearing blacker and longitudinally striped, rather than ringed. [Adapted from Dijkstra & Lewington 2006]

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

• Dijkstra, K.-D.B. (in prep). Notes on the genus Notogomphus, with the descriptions of new pecies and a key to the species (Odonata: Gomphidae). Zoologische Mededelingen. [PDF file]
• Pinhey, E.C.G. (1964). Dragonflies (Odonata) of the Angola-Congo borders of Rhodesia. Publicacoes culturais Companhia Diamantes Angola, 63, 95-130. [PDF file]
• Ris, F. (1921). The Odonata or Dragonflies of South Africa. Annals South African Museum, XVIII, 245-452. [PDF file]
• Pinhey, E.C.G. (1961). Dragonflies (Odonata) of Central Africa. Occasional Papers Rhodes-Livingstone Museum, 14, 1-97. [PDF file]
• Calvert, P. P. (1899) Neuropterous insects collected by Dr. A. Donaldson Smith in Northeastern Africa. Ecological Entomology 51: 228-244 [PDF file]

Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2024-10-30].