Wing spine distribution: a new character for sexual differentiation in Lestidae (Zygoptera)

The ratio between the number of spines in the cubito-anal fields of the fore and hind wings of Lestes barbarus, L. dryas, Chalcolestes viridis, and Sympecma fusca is significantly higher in the females and constitutes a sexual distinction analogous to what is found in Calopterygoidea. This ratio is much less pronounced in L. virens vestalis.