Morphology of the prosternal glands of Heliconius erato (Lepidoptera: Nymphalidae)

Abstract

Two types of exocrine glands, located midventrally on the prosternum, are described for the larval stage of Heliconius erato (Linnaeus) (Lepidoptera: Nymphalidae). The first type, formed by a single, flat secreting pouch, opens as a transverse slit on the anterior portion of the prosternum. The second, composed of a pair of ellipsoid secreting units, opens laterally by fine ducts on the distal portion of a cone-shaped sac, which is protruded by hemostatic pressure posteriorly between the prothoracic legs. The morphology of these glands is described and illustrated by light, scanning, and transmission electron microscopy. The varied terminologies adopted in the literature for describing these glands are discussed, and we propose a single term, prosternal glands.