Studies in Australian amphibia II..Taxonomy, ecology and evolution of the genus Heleioporus Gray (Anura : Leptodactylidae)

Abstract

The status of the five existing species of the genus Heleioporus Gray, H. albopunctatus Gray, H. australiacus (Shaw), H. eyrei (Gray), H. inornatus Lee & Main, and H. psammophilus Lee & Main are confirmed on the basis of morphological and behavioural criteria and the results of interpopulation in vitro crosses. The Western Australian population, formerly included under H. australiacus, is raised to species status on the basis of consistent differences in morphology and mating call. Each species is redescribed, and descriptions of the larvae and juveniles are included. The results of in vitro crosses support the recognition of two species groups, a bassian group comprising H. australiacus, the H. australiacus-like frog, and H. inornatus, and an eyrean group comprising H. albopunctatus, H. eyrei, and H. psammophilus. The breeding biology of all of the western species appears closely tied to the Mediterranean climate of south-western Australia. All species breed in April and May. Rain sufficient to moisten the soil, and declining temperatures are the two most obvious environmental factors influencing the timing of breeding. Breeding sites include ephemeral ponds and water courses, and the edges of coastal lakes. Breeding occurs before these are covered by water, in winter. Males call from burrows, and copulation, oviposition, and embryonic development all occur at the bottom of these burrows. Where they occur together, the burrows of H. albopunctatus, H. eyrei, and H. psammophilus are found scattered through the centre of a swamp and those of H. inornatus, around the periphery. The eggs are laid in froth, and development to hatching takes between 1 and 3 weeks. Hatching may be delayed by withholding the eggs from water. The period between the onset of calling and hatching of the embryos roughly corresponds to the period between the onset of winter rain and the flooding of larval sites. The larvae of H. albopunctatus, H. eyrei, and H, psammophilus are found in ponds, those of H. inornatus in collapsed, flooded breeding burrows, and those of H. australiacus and the H. australiacus-like frog in creeks.