Exocelina baliem sp. n., the only known pond species of New Guinea Exocelina Broun, 1886 (Coleoptera, Dytiscidae, Copelatinae)

Exocelina baliem sp. n. is described from the Baliem Valley in the Central Mountain Range of New Guinea (Papua Province, Indonesia). Having striolate elytra, different structure and setation of the male and female genitalia and tarsomeres, and inhabiting swampy ponds, the new species differs from all known New Guinea species, which have smooth elytra and are stream associated. It forms a monophyletic group with the Australian Exocelina ferruginea (Sharp, 1882) and New Caledonian Exocelina inexspectata Wewalka, Balke & Hendrich, 2010, based on shape of the paramere and structure of the male tarsi. Habitus, protarsomeres, and male and female genitalia are illustrated, comparing some structures with Exocelina ferruginea and two New Guinea stream species. We briefly discuss the biogeographic relevance of this discovery.