Stalk-Eyed Flies: Caprices of Evolution?

Abstract

A report is given on the species of stalk-eyed flies found around the Kuala Belalong Field Studies Centre (Brunei Darussalam, Borneo) during the Brunei Rain Forest Project 1991-92 of the University of Brunei and the Royal Geographical Society. Twelve of thirteen species of stalk-eyed flies found belong to the family Diopsidae. Ten of these are new species which are yet to be described. Local diversity of that family is much higher than hitherto assumed. Some of the species closely resemble their sister species present on the Malay Peninsula but do not interbreed with them. Allometric data of body length and eyespan are given for two species; some features of their behaviour are described. The only non diopsid stalk-eyed fly found, Themara hirtipes (Rondani), belongs to the family Tephritidae. Here only males have eyestalks. Allometric data of males are presented, together with field observations on territoriality, mating behaviour and reproductive behaviour.