Genus Trithetrum Dijkstra & Pilgrim, 2007
African darters

Synonyms:

• scientific: formerly placed in genus Sympetrum Newman, 1833

Type species: Sympetrum navasi Lacroix, 1921

Introduction

This genus was recently described for two tropical African species that were formerly placed in Sympetrum but are genetically and morphologically very distinct. Males are medium-sized (hindwing 23-29 mm) and diagnostically uniform and unmarked. T. navasi is widespread and locally common along sunned grassy verges of rivers, ponds and lakes; T. congoense occurs with it from central DR Congo to south-eastern Gabon, favouring similar but smaller water bodies like small rivers, streams and pools. Both species may be mistaken for Trithemis, T. congoense especially recalling T. grouti, but have a different posture, sitting with abdomen held low and wings flat or slightly raised, often on leaves. [Adapted from Dijkstra & Clausnitzer 2014]

Diagnosis

Male of genus is similar to Sympetrum by (a) size, Hw 23-35 mm; (b) all wings with 0 cell-doublings in radial planate [0-2]; (c) Pt never black-and-white and wings at most with dark tips or bases or with overall yellowish infusion; (d) Fw supratriangles without cross-veins; (e) Fw triangle of 2-3 cells, subtriangle of 3-6 cells; (f) Fw discoidal field of 3-4 rows at base; (g) 6½-8½ Ax in Fw; (h) arculus between Ax1-2, usually closest to Ax1; (i) if Abd ventrally red or orange, then dorsum similarly coloured. However, differs by (1) body parts uniform: thorax unmarked; frons without band; mid and hind femur all black; S1-10 unmarked; (2) venation blackish; (3) Fw discoidal field 5-8 cells wide on wing border. [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., and Pilgrim, E.M. (2007). Trithetrum, a new genus of African dragonflies formerly placed in Sympetrum (Odonata, Libellulidae). Journal of Afrotropical Zoology, 3, 77-81. [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.

Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2024-11-15].