Elytron length and sexual dimorphism in <i>Zonocerus elegans</i> (Thunb.), (Orthoptera: Pyrgomorphidae)

Abstract

Adults of the African pyrgomorphid grasshopper, Zonocerus elegans Thunberg, exhibit strong alar polymorphism, especially in the male sex, with wings either vestigial or fully developed. Analysis of body and elytron lengths of about 400 insects revealed sexual dimorphism, females being larger than males, and showed a bimodal distribution for wing length. The difference in average wing length between long-winged and short-winged forms was 14 mm. Since the two distributions (short and long) do not overlap, they would correspond closely to the subsidiary infra-subspecific categories f. brachyptera and f. macroptera, respectively, although even wings of the lower macroptera range seem to be vestigial, i.e. imperfectly developed and useless for flight.