Forum: The Subelytral Cavity of Desert Tenebrionids

Michael L. Draney

Abstract


Tenebrionid beetles are a conspicuous component of the world's hot deserts. Different species exhibit considerable variability in physiology, morphology, behavior, and life history; most aspects of their biology are influenced by the interrelated problems of excess heat and insufficient moisture which all desert organisms face. This paper is a review of research and thought concerning an adaptation characteristic of desert tenebrionids, an air space between fused elytra and the dorsum of the abdomen called the subelytral cavity. The subelytral cavity may be seen as a hermetic seal which reduces transpiration regardless of its size, and as a protected space within the beetle which, whether airtight or not, allows the abdomen to expand to store food, water, or eggs. I hypothesize that the cavity itself is probably an architectural constraint resulting from the need for abdominal expansion within the heavily sclerotized, fused elytra that evolved primarily as a water conservation adaptation.

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