Antennal morphology and ultrastructural sensilla characterization in Caligo illioneus illioneus Cramer (Lepidoptera, Nymphalidae) adults

Abstract

In the present study, we investigated the antennal morphology and the distribution and typology of sensilla in antennae of male and female Caligo illioneus illioneus Cramer (Lepidoptera: Nymphalidae), examined by scanning electron microscopy—SEM. The insect was identified by morphological and molecular means, and the COI gene of this subspecies was sequenced and deposited in GenBank. The SEM results showed that antennae of both sexes do not present dimorphism, as they cannot be distinguished from each other in terms of morphology. In addition, the ventral region of the flagellum has longitudinal carinae. In both sexes, seven types of sensilla were identified along the scape, pedicel and flagellum: Böhm’s bristles and sensilla auricillica, basiconica, chaetica, coeloconica, squamiformia, and trichodea. Subtypes I and II were characterized for Böhm's bristles and sensilla basiconica and chaetica according to the length, because morphometric result was statistically different among individuals of the same sex. In addition, the flagellum contains the vast majority of sensilla and their subtypes, except for Böhm’s bristles, present only in the basal region. This study provides valuable information about the antennal morphology and sensilla typology in C. i. illioneus, contributing with morphological evidence on the sensory system of butterflies, mainly in the genus Caligo, which is helpful to assist behavioral and electrophysiological studies.