Morphology of exophytic ovipositors in dragonflies (Odonata: Gomphidae, Corduliidae, Libellulidae), with particular reference to ovipositor muscles and sensilla 00

Abstract

A comparative study of female external genitalia was carried out in representatives of three dragonfly families that lay eggs exophytically, with special emphasis placed on skeletal musculature and sensilla. Female external genitalia are characteristically represented by the vulvar lamina and rudiments on the 9th sternum. In a gomphid, Gomphus vulgatissimus, and a corduliid, Cordulia aenea, the vulvar laminae bear numerous styloconic sensilla and sparse campaniform sensilla. In addition, the rudiments of C. aenea are richly furnished with basiconic sensilla, each with an apical pore. In corduliids and libellulids the ovipositor musculature is formed by two antagonistic muscles, contractions of which cause up- and downward movements of the middle part of the 9th sternum, where rudiments are usually located. Characteristically, gomphid females lack both the ovipositor-related muscles and rudiments. Based on the present results, the rudiments may be reasonably homologized with the gonapophyses of the 9th segment of the plesiomorphic well-developed ovipositor. The proposed functional interpretations of the ovipositor derivatives in Odonata with exophytic oviposition are discussed in light of their egg laying behaviour.

Keywords: female genitalia, musculature, vulvar lamina, gonapophysis, exophytic oviposition, homology, heterochrony, Odonata, Insecta

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