New records of the diving beetle Rhantus simulans Régimbart, 1908 in south-western Australia (Coleoptera, Dytiscidae, Colymbetinae)

New distributional records of the rarely collected diving beetle Rhantus simulans Régimbart, 1908, an endemic species of south-western Australia, are presented. We also summarize what is known about its habitat. The occurrence of R. simulans indicates a high conservation value of the sampled wetland. For easier identification, we provide photographs of the habitus and male genitalia of R. simulans and R. suturalis (Macleay, 1825). Rhantus simulans is now recorded from 17 localities along the coast of south-western Australia. Furthermore, data on the location of other 31 diving beetle species are provided.