Comparative Analysis of Antennal Surfaces in Adult Caddisflies of the Genus Ecnomus McLachlan (Trichoptera, Ecnomidae)

Abstract

Investigation of the antennal surfaces in four species of the family Ecnomidae (Ecnomus insularis, E. maheensis, E. jethet, and E. tenellus) has revealed the presence of antennal structures including long trichoid, curved trichoid, mushroom-like pseudoplacoid, basiconic, styloconic, and chaetoid sensilla, as well as Böhm’s bristles. The mean number and diversity of the sensilla decrease toward the antenna apex. Interpopulation differences in the size and numbers of sensilla, mostly the curved trichoid ones, were observed in the widespread species Ecnomus tenellus, for the first time in insects. Quantitative differences in the composition of sensilla were found between all the studied species; these differences are probably adaptive. The evolutionary significance of the revealed divergence is discussed.