The cuticle redesigned: showcasing the larval cuticle of Sabatinca chalcophanes, one of the most aberrant insect cuticles

The multilayered insect cuticle is highly adaptive chemically and structurally, allowing for a wide range of mechanical, chemical and tribological properties of great survival value. Almost all known structural cuticular specializations are achieved through the shaping of the epicuticle providing an almost endless array of cuticular surface sculptures, but structural specializations of the underlying cuticle layers can also occur. The Micropterigidae (Lepidoptera) are one of the most basal of the lepidopteran families. Micropterigid Larvae are very distinct due to their soil dwelling, sometimes angiosperm-independent biology and sluglike movement and by exhibiting an array of autapomorphic morphological characteristics. The chambered, hence non-solid, cuticle of micropterigid larvae is a striking example of an internal structural cuticular specialization that so far appears to be unparalleled within arthropods. The exocuticle of the dorsal and lateral integument of the larvae is composed of fluid filled chambers arranged in of honeycomb pattern. This chambered exocuticle is separated from the endocuticle by an intracuticular space. The exocuticular chambers have proved to be connected to the intracuticlular space and the exterior environment through chamber pores. The newly discovered connection between the chamber content and the exterior larval surface may potentially lead to new insights into the function and composition of the mucous like pellicle that surrounds the larvae. A detailed description of this cuticlular design is instrumental for understanding the function of the specialized micropterigid cuticle and the exterior pellicle, and hence ultimately the biology of these larvae.