The Inheritance of Brachypterous and Macropterous Wings in Sitona hispidula

Abstract

IN the genus Sitona some of the species are fully winged, but in others the wings are so reduced in size that flight is impossible. In at least two species wing dimorphism occurs. One, S. humeralis Steph., is described by Grandi from Italy as having brachypterous wings, but all the specimens of this species which I have examined from England are macropterous; in the other, S. hispidula F., I find that fully winged and brachypterous individuals are common and widely distributed throughout Britain. In the brachypterous form the wings are very small and have a truncated appearance owing to the absence of the apical portion which, in the normal wing, is bent under in repose. Examples of wing dimorphism have been recorded in other beetles, usually in genera which contain both macropterous and brachypterous species, but no investigation appears to have been made to ascertain whether the two forms interbreed, and if so, how the wing condition is inherited.