A new species of Chasmogenus Sharp, 1882 and new records of Hydrophilidae (Coleoptera) from Northeastern Brazil.

Chasmogenus cajuina sp. nov., a new species of the water scavenger beetle (Hydrophilidae: Acidocerinae) is described and illustrated, based on adult males, collected in the Lower Parnaíba River Basin, north of Piauí, Northeast Region of Brazil.