Genus Olpogastra Karsch, 1895
Type species: Olpogastra lugubris Karsch, 1895
Monotypic and endemic to tropical Africa, the genus is unmistakeable by its large size (hindwing 37-42 mm), very elongate abdomen with bulbous base, and glossy black body with bold yellow spots. O. lugubris perches conspicuously along open rivers (sometimes streams and lakes), being very aggressive towards other dragonflies. [Adapted from Dijkstra & Clausnitzer 2014]
Male of genus is similar to Zygonoides by (a) size, Hw 37-45 mm; (b) occipital triangle smaller with rather concave borders, eyes touching over distance of at least half its length; (c) frons and vertex of different colour (e.g. brown or red), more uniform (e.g. less contrasting yellowish dorsally and brown ventrally), or dorsum darkest; (d) Pt never black-and-white and wings at most with dark tips or bases or with overall yellowish infusion; (e) Fw triangle of 2-3 cells; subtriangle of 3-6 cells and without cross-veins; (f) Fw discoidal field of 3-4 rows at base; (g) 11½-17½ Ax in Fw; (h) all wings with 2-8 cell-doublings in radial planate; count those cells touching Rspl, but not IR3. However, differs by (1) subtriangle of 5 rather than 3 cells [4-6]; (2) anterior lamina anteriorly bare, rather than with long hairs; genital lobe sickle-shaped rather than rounded; (3) Abd longer than Hw, S1-3 bulbous, S4-10 slender, cylindrical and of even width: S3 much deeper than long, S4 about 8x longer than wide. [Adapted from Dijkstra & Clausnitzer 2014; this diagnosis not yet verified by author]
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.
- Dijkstra, K.-D.B., Suhling, F., and Müller, O. (2006). Review of the genus Zygonoides, with description of the larvae and notes on ‘zygonychine’ Libellulidae (Odonata). Tijdschrift voor Entomologie, 149, 275-292. [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]
- Pinhey, E.C.G. (1961). Dragonflies (Odonata) of Central Africa. Occasional Papers Rhodes-Livingstone Museum, 14, 1-97. [PDF file]
- Fraser, F.C. (1955). Odonata. Exploration Parc National Upemba. Mission G F de Witte, 38, 1-34. [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/ [2018-12-10].