External morphology of the abdominal glands in Asopinae (Hemiptera: Heteroptera: Pentatomidae)

Abstract

Heteropterans communicate chemically through thoracic or abdominal glandular complexes. The dorso-abdominal scent glands (DAGs) are externalized by cuticular specialized structures forming the external scent efferent system (SES). Different groups in Heteroptera present other glands, such as the Asopinae (Pentatomidae), whose males can have ventral abdominal pheromonal glands externalized by cuticular modifications, called glandular patches (GPs). Here we describe the SES of DAGs and, for the first time, the GPs of 22 Asopinae genera. The ostioles of SES 1 vary in shape. SES 2 and SES 3 were restricted to scars, indicating that only the SES 1 remains functional in adults. The GPs are found mostly in segments V and VI. We have not found any difference in the morphological pattern between the SES of species bearing GPs and those lacking it, meaning that the acquisition of GPs is likely related to some sexual behavior, thus not as a complex structure replacing any role of the DAGs. The cuticle of the GPs is microsculptured, bearing many pores surrounding the base of sensilla being the pathway for the secretions to reach the outside of the exoskeleton. The sensilla may be adaptations to increase the contact surface, assisting rapid evaporation of the volatile secretions from the pores.