Observations on the external morphology and behaviour of Pteroptyx tener and Pteroptyx bearni in Malaysia

Abstract

Colonies of Pteroptyx tener and smaller colonies of Pteroptyx bearni can be found along the Kerteh River in Terengganu while only the latter is found 42 km to the south at Cherating River, Pahang. Aspects of the external morphology, habitat and behaviour of these firefly species were studied at these two locations. At the Kerteh River, P. tener was found in the brackish region while P. bearni was found in more saline regions near the estuary, with some overlap in the area of occurrence. Body length of P. bearni is smaller than P. tener and also differs in coloration. P. tener flashes synchronously while P. bearni does not flash synchronously. The two species also differ in flash communication behaviour, including duration and intensity. P. bearni males produce a brighter light than P. tener. Both firefly species display on the vegetation commonly found at their display site. P. tener and P. bearni share the same trees when both species were sympatric. Colony size and density were much lower in P. bearni compared to P. tener.