Interceptions from the underground: The subterranean ant (Hymenoptera) and beetle (Coleoptera) fauna of Virginia, West Virginia, and North Carolina

Subterranean traps selectively target taxa living and foraging several inches to several feet below the soil surface. They have been increasingly used to collect soil-dwelling invertebrates in tropical and subtropical areas, however, studies from the Nearctic region are largely lacking. We utilized two subterranean trap designs, slotted pipe traps and buried conventional pitfall traps, to explore the belowground ant and beetle fauna of Virginia, North Carolina and West Virginia. These traps allowed us to collect invertebrates active between 2.5 cm (~1 in) and 50.5 cm (~20 in) below the soil surface. In the period 2017-2020, we placed traps at 21 North Carolina, Virginia, and West Virginia sites. Trap locations were chosen because of the known, or suspected, presence of rare soil-dwelling carabid beetles. Both trap types captured ants and beetles, including rarely collected species and undescribed forms. In total, we collected 14,135 ants (Formicidae) and 826 beetles in twelve families (Agyrtidae, Carabidae, Ciidae, Chrysomelidae, Curculionidae, Hydrophilidae, Leiodidae, Ptiliidae, Ptilodactylidae, Scarabaeidae, Staphylinidae, and Teredidae). Noteworthy ant finds include the rarely collected hypogaeic Proceratium chickasaw and Lasius plumopilosus, as well as a yet undescribed species of Myrmecina. Notable hypogaeic beetles include Arianops thornei (Staphylinidae), Pterostichus hypogeus (Carabidae), seven species of anilline carabids, four species of Catopocerus (Leiodidae), and three species of eyeless Lathrobium (Staphylinidae); over half of these are newly discovered undescribed species. These results indicate that subterranean traps are effective at sampling hypogaeic ants and beetles in the Nearctic region, including rare species not captured by traditional methods.