Scanning electron microscopy of pruinosity in Odonata

The structure of the supracuticular pigment of Mnais pruinosa (Calopterygidae), Bayadera indica (Euphaeidae), Lestes sponsa (Lestidae), Libellula depressa, Orthetrum albistylum, O. anceps, O. cancellatum and O. triangulare (Libellulidae) were examined using scanning electron microscopy. On the base of pruinescence micromorphology, 2 groups of families can be distinguished, viz. Lestidae+Libellulidae, with lamellar pruinosity, and Calopterygidae+Euphaeidae, with filamentous pruinosity. Differences in the microstructure of the pruinescent colouration result from some solid morphological (structure of porous canals of the cuticle) and/or biochemical (structure of cuticular waxes) differences between the odon. groups. The structures are interpreted both as sunlight reflectors and as colour patterns useful in intraspecific communication.