Acoustic and Morphometric Differences between Allopatric Populations of Pterophylla beltrani (Orthoptera: Tettigoniidae: Pseudophyllinae)

Abstract

Pterophylla beltrani(Bolivar & Bolivar 1942) is an important forest pest in north-eastern Mexico. The species exhibits green and pink morphs. Allopatric populations differ greatly in size, wing venation and colour. To gain insight into the status of different populations, we studied variation in acoustic signals and morphometric characters within and between three allopatric populations of P. beltrani. Some divergence in acoustic signals has occurred but a discriminant analysis of the signals failed to separate the populations completely. Despite the divergence in acoustic signals males and females from all populations still recognize each other as mates and readily mate if brought together. Divergence in morphology has ocurred more rapidly than in acoustic signals as the populations can be completely separated by a morphometric analysis. Indications of genetic incompatibilities between the populations were revealed by lower numbers of eggs laid, reduced percentage of egg hatch and distorted sex ratios of interpopulation crosses. From these results we suggest that P. beltrani is one species consisting of several subspecies which are in the process of developing into separate species (