Comparative morphology of the forewing base articulation in Sternorrhyncha compared with a representative of Fulgoromorpha (Insecta, Hemiptera).

The forewing articulation of single species from each of the four subgroups of Sternorrhyncha (Aleyrodomorpha, Aphidomorpha, Coccomorpha, Psyllomorpha) was examined by optical and scanning electron microscopy. The species were compared with a species of Cixiidae (Fulgoromorpha), as an outgroup of Sternorrhyncha. We present the results of a comparative analysis of the forewing articulation in these five groups, propose a standardized terminology and compare our findings with those previously reported. The wing base of all examined species is composed of the following structures: anterior and posterior notal wing process, first, second, and third axillary sclerites, tegula, and axillary cord. The number of elements included in the wing base and the surrounding area is the greatest in Cacopsyllamali, the most complicated species from Sternorrhyncha. Based on the shape of axillary sclerites and the number of elements forming the wing base environment, Orthezia urticae (Coccomorpha) and Cixius nervosus (Fulgoromorpha) are the most similar. Among Sternorrhyncha, the most similar axillaries are those of Aphis fabae and Orthezia urticae, which is congruent with existing classifications. In this paper we show that the four groups from Sternorrhyncha exhibit their own distinct wing base morphology.