Comparative exploration of antennae in Pseudopontia, and antennal clubs of the tribes Leptideini and Dismorphiini (Lepidoptera: Pieridae).

Abstract

We examined antennal ultrastructure in species of Dismorphiinae and Pseudopontiinae (Pieridae) using scanning electron microscopy (SEM). We examined two species of Pseudopontia (Pseudopontiinae) and more than 30 species in seven genera of two tribes in the subfamily Dismorphiinae: Leptidea, Enantia, Pseudopieris, Lieinix, Moschoneura, Dismorphia, and Patia. We focused on the scaleless terminal area of the antenna where there are many types of sensilla, some of which are clustered together and constitute specialized organs. We measured, described, and illustrate at different magnifications structures including the antennal club, antennomeres, sulci, pseudosulci, and chaetic, trichoid, coeloconic, basiconic, and auriculate sensilla, as well as other previously unnamed sensilla. From these antennal features, we created a matrix of characters that allowed us to recognize divergence between the tribes Leptideini and Dismorphiini. The antennae of Leptideini have fewer scaleless antennomeres in the antennal club than those of Dismorphiini, a greater number of pseudosulci disaggregated or dispersed (in Leptidea), and fewer types of sensilla and microtrichia (a more homogeneous antennal morphology), as well as a reduction in the density of sensilla. In Leptidea the antennal form is more specialized: it is shorter in comparison to genera of other Papilionoidea families. We also created a matrix of general morphological characters of Dismorphiinae and Pieridae from the taxonomic literature. This matrix confirms the marked character divergence between the tribes and allows for a more meaningful discussion regarding the relationships between Dismorphiinae and the other subfamilies of Pieridae (i.e., Pseudopontiinae, Coliadinae, and Pierinae). We argue that Pseudopontiinae cannot be considered the least derived subfamily among Pieridae because pupal features, wing venation, and antennal characters exhibit a combination of primitive and specialized states. In addition, we discuss our results from the perspective of patterns of food plant usage in pierid subfamilies, specifically the diversification of several Dismorphiinae genera on Hologalegina and Ingeae (Fabaceae).