The fully formed intermoult cuticle and associated structures of Podura aquatica (Collembola)

Specializations of the epidermis in the regions of ocelli, setae, muscle insertions, and the vesicles of the ventral tube are described, along with modifications of the overlying cuticle.

Abstract

ABSTRACT The cuticle overlying most of the body consists of 2 major layers only, the lamellate endocuticle and the epicuticle, and is very thin (1 to μ). Three major cuticular layers are found in the slightly thicker cuticle of certain areas (2 to 3 μ thick) and in the thickest regions (8 to 10μ)a distinct sclerotized exocuticle is present. The epicuticle consists of 1 to 4 laminae, the ‘inner’, ‘cuticulin’, ‘wax’, and ‘cement’ layers, and the distribution of these laminae is described. The outer surface of the cuticle is thrown into major tubercles of approximately 3 μ pitch, with minor tubercles super-imposed upon them. Modification of the cuticle at the bases of setae is described and related to the mechanical requirements of the setal insertion and suspension. The nature of the muscle insertion is also considered. The epidermis is fully cellular and the cells contain the granules of black pigment which impart the black coloration to the insect. Specializations of the epidermis in the regions of ocelli, setae, muscle insertions, and the vesicles of the ventral tube are described, along with modifications of the overlying cuticle.