Genus Zygonoides Fraser, 1957
riverkings

Type species: Olpogastra fuelleborni Grünberg, 1902

Introduction

Previously the three continental African species, and a fourth endemic to Madagascar, were placed in Olpogastra. They are large (hindwing 38-45 mm) and robust species with ringed abdomen, thus appearing superficially like Zygonyx torridus. That species has dark brown eyes with maturity, while those of Zygonoides are bluish or green. They are also similar in behaviour, patrolling aggressively over faster sections of rivers, but perching more frequently and with abdomen raised rather than hanging. Z. fuelleborni also inhabits rocky lakeshores, while Z. occidentis appears to favour huge forest rivers like the Congo and Ubangui. It patrols rapidly over these far from the banks and thus will not perch: its presence is more easily evidenced by the large spiny exuviae. [Adapted from Dijkstra & Clausnitzer 2014]

Diagnosis

Male of genus is similar to Olpogastra 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) Abd shorter than Hw, S1-3 triangular, S4-10 broad, flattened and widest at S6-7: S3 about as deep as long, S4 about 3x longer than wide; (2) subtriangle of 3 cells; (3) anterior lamina anteriorly bears long hairs; genital lobe rounded. [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.

References

• 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.
• Pinhey, E.C.G. (1961). Dragonflies (Odonata) of Central Africa. Occasional Papers Rhodes-Livingstone Museum, 14, 1-97. [PDF file]

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