Revision of the genus Chalcasthenes Arrow (Coleoptera: Scarabaeidae: Dynastinae: Oryctoderini) from the Solomon Islands

Abstract

The genus Chalcasthenes Arrow (Dynastinae: Oryctoderini), a scarab beetle genus endemic to the Solomon Islands, is reviewed. Based on examination of type specimens, the genus Strehlia Frey (Rutelinae: Rutelini: Parastasiina) is a new junior synonym of Chalcasthenes. The historical classification of these genera (either in the subfamily Dynastinae or Rutelinae) and character-based criteria for assigning the taxa to the Dynastinae are provided. We discuss character states that support the monophyly of members of the genus Chalcasthenes, comment on the distribution and biogeography of species in the genus and provide a key to species. The genus includes four species: Chalcasthenes divinus Endrödi, Chalcasthenes pulcher Arrow, Chalcasthenes squamigerus Frey new combination and Chalcasthenes styracoceros Jameson and Ratcliffe n. sp. Species hypotheses are corroborated based on evidence from Pleistocene geological reconstructions of the Solomon Islands, geographic variation of bird species in the region, and development in scarab beetles.