An extraordinary new genus and species of horseshoe crab beetle (Ptiliidae: Cephaloplectini) from the Brazilian Atlantic biome

Abstract Clepsammia gaia Chaul & Lopes-Andrade gen. et sp. n. is described herein, representing the first new taxon of Cephaloplectini (Ptiliidae) proposed in more than 80 years. The species is blind and flightless, as are all other known members of the tribe, but it exhibits a highly distinctive morphology, characterized by a conspicuous mid-body constriction bearing spongiform setae. The description is based on five specimens collected from a single locality in the Brazilian Atlantic Forest, found 30–40 cm deep below the soil surface. An updated identification key to the genera of Cephaloplectini is provided. We also compile an extensive list of putative or confirmed ant hosts of Cephaloplectini species, which indicates a broad host spectrum, spanning multiple ant subfamilies and genera across the tribe’s geographic range. Finally, we discuss possible explanations for the morphological modifications observed in C. gaia relative to other members of the tribe.