Comparative morphology of the external scent efferent system of dorsal abdominal glands in nymphs of Pentatomidae (Hemiptera: Heteroptera)

A remarkable characteristic of Heteroptera is the release of highly odoriferous substances, and the associated complex structures and chemicals are apomorphic to the true bugs. Studies on the structures of the scent efferent system (SES) have shown a correspondence between morphology and phylogeny or classification. The external SES of dorsal abdominal scent glands in nymphs of 27 representative species of Pentatomidae and eight species of other six families of Pentatomoidea are analyzed. Even though Pentatomoideans have three pairs of serially homologous SES, the anterior SES has a particular and simplified morphology compared to the median and posterior SES. Morphology of SES within the superfamily varies from simplified to conspicuous ornamentation. The complexity of SES has already been tentatively related to living habits, instance gregariousness, and arboreal or fossorial behaviour. Some structures are correlated to subfamilial level in Pentatomidae. We were able to find consistent similarities between taxa, but cuticular structures of SES are diverse and probably have evolved multiple times across lineages in Pentatomidae. The characters present on SES constitute an interesting source for evolutionary analyses in Pentatomoidea.