Ultrastructure of the spines and neck gland of Abananote hylonome Doubleday, 1844 (Lepidoptera: Nymphalidae)

The external morphology of the cuticular spines, and the ultrastructure of the spines and neck gland in fifth instar Abananote hylonome larvae was studied. The larvae are spiny along the length of their bodies. Along the length of the spines are setae with a swelling towards the apical region. Internally, in the base of each seta there is a complex of secretory cells surrounding a large vacuole continuous with the seta. The neck gland is eversible, composed of a pair of oval internal sacks connected to the exterior via an extracellular canal produced by an invagination of the cuticle. The sack cells surround a reservoir containing an amorphous substance. In both the spines and neck gland the nuclei are large and irregularly shaped, typical of defensive glands of Lepidoptera. The border of the cells adjacent to the vacuoles (spines) and the reservoir (neck gland) is made up of numerous microvilli. We suggest that defensive compounds are produced in the gland cells and then later released via the vacuoles in the spines and the extracellular canal in the neck gland.