MORPHOMETRIC ANALYSIS OF VARIATION IN NALA LIVIDIPES (DUFOUR) AND LABIDURA TRUNCATA KIRBY (DERMAPTERA: LABIDURIDAE)

Two male morphs occur in populations of Nala lividipes (Dufour), the black field earwig, and of Labidura truncata Kirby, the common brown earwig, distinguished by the presence or absence of a tooth at the mid‐point on each forceps branch. Multivariate morphometric analyses using discriminant function analysis applied to measurements of various body parts of wild‐caught specimens showed that the morphs were statistically separate in both species. In each species female size is intermediate to that of the 2 male morphs. The results are discussed on the basis of natural selection, and possible reasons given for the maintenance of 2 male morphs but only 1 female morph.