A number of closely related cockroach taxa unassociated with caves can show as much variation as Paratemnop-teryx. Wing condition is therefore of little value as a diagnostic generic character unless it occurs in conjunction with one or more stable and distinctive characters (Hebard, 1929; Rehn, 1932b). The three native species of the genus Ectobius in Great Britain clearly depict an evolutionary trend in female wing reduction. Males are macropterous in all three species. Females of E. pallidus also have fully developed wings, but in E. lapponicus the tegmina of the female are about two-thirds the length of the abdomen and the wings are reduced. In E. panzeri the tegmina of the female are just a little longer than wide and the wings are micropterous (Kramer, 1956). The subfamily Tryonicinae illustrates the degree of wing variation that can occur at higher taxonomic levels. Table 2.3 displays the genera of these blattids arranged to exhibit a detailed gradient of wing development from one extreme (macropterous) to the other (apterous).
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