The neo-XY system of Catantops humilis (Acrididae: Catantopinae) in Malaysia

Abstract

Catantops humilis lives on the leguminous covercrop in young rubber and oil palm plantations on the coastal plains of Peninsular Malaysia. The grasshopper has high dispersal capability, and migrates when the trees mature, so distribution of populations changes regularly. Southern populations have normal 2n=23, XO/24, XX complements. In Selangor State two morphologically indistinguishable chromosomal forms comprising XO and neo-XY males with basic homozygote and fusion heterozygote females, exist sympatrically in the same microhabitat in eight localities. In one population where occasional sharp reduction in numbers and migration occur, the centric rearrangement has attained a 40–50% frequency. A further mixed population was found 300 km north. Consideration is given to the possibilities that these mixed populations are part of a broad region of hybridization between two chromosomal races, or that they represent a widespread polymorphism.