The wing venation of Odonata alt-text


Abstract

Existing nomenclatures for the venation of the odonate wing are inconsistent and inaccurate. We offer a new scheme, based on the evolution and ontogeny of the insect wing and on the physical structure of wing veins, in which the veins of dragonflies and damselflies are fully reconciled with those of the other winged orders. Our starting point is the body of evidence that the insect pleuron and sternum are foreshortened leg segments and that wings evolved from leg appendages. We find that all expected longitudinal veins are present. The costa is a short vein, extending only to the nodus, and the entire costal field is sclerotised. The so-called double radial stem of Odonatoidea is a triple vein comprising the radial stem, the medial stem and the anterior cubitus, the radial and medial fields from the base of the wing to the arculus having closed when the basal sclerites fused to form a single axillary plate. In the distal part of the wing the medial and cubital fields are secondarily expanded. In Anisoptera the remnant anal field also is expanded. The dense crossvenation of Odonata, interpreted by some as an archedictyon, is secondary venation to support these expanded fields. The evolution of the odonate wing from the palaeopteran ancestor – first to the odonatoid condition, from there to the zygopteran wing in which a paddle-shaped blade is worked by two strong levers, and from there through grade Anisozygoptera to the anisopteran condition – can be simply explained.

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