Tegmen

A tegmen (plural: tegmina) designates the modified leathery front wing on an insect particularly in the orders Dermaptera (earwigs), Orthoptera (grasshoppers, crickets and similar families), Mantodea (praying mantis), Phasmatodea (stick and leaf insects) and Blattodea (cockroaches). A tegmen (plural: tegmina) designates the modified leathery front wing on an insect particularly in the orders Dermaptera (earwigs), Orthoptera (grasshoppers, crickets and similar families), Mantodea (praying mantis), Phasmatodea (stick and leaf insects) and Blattodea (cockroaches). It is also a term used in botany to describe the delicate inner protective layer of a seed, and in zoology to describe a stiff membrane on the upper surface of the crown of a crinoid. In vertebrate anatomy it denotes a plate of thin bone forming the roof of the middle ear. The term tegmen refers to a miscellaneous and arbitrary group of organs in various orders of insects; they certainly are homologous in the sense that they all are derived from insect forewings, but in other senses they are analogous; for example, the evolutionary development of the short elytra of the Dermaptera shared none of the history of the development of tegmina in the Orthoptera, say. Also, in some other insects fore- and hindwings differ both in texture and their role in flight, but are not universally regarded as tegmina. For example, the hemelytra of some Hemiptera have been called tegmina by some authorities, but not by most modern authors. Entomologists do not customarily refer to the forewing of a beetle as a tegmen; the term for beetles' forewings is elytra. Probably the major role of tegmina in general is that of protecting the hindwings when folded. In many insects they also are important in camouflage and in displays, especially defensive display, where the tegmina are drab, but cover aposematic displays that are startling when suddenly uncovered. Sometimes, as in some mantids, the tegmina crossed over the back are not striking, but when suddenly raised, act as a threatening display resembling a pair of eyes.