Open Access

Curt W. Harden, Michael S. Caterino

• The small, eyeless beetles of the genus Anillinus Casey (Coleoptera: Carabidae: Trechinae: Anillini) comprise a diverse, ubiquitous, but poorly known component of insect biodiversity in the southeastern United States. Their limited dispersal capabilities make them ideal subjects for biogeography, but taxonomic problems and undescribed species diversity hamper such studies. In this paper, we redescribe four enigmatic species, Anillinus docwatsoni Sokolov and Carlton, Anillinus elongatus Jeannel, Anillinus pecki Giachino, and Anillinus turneri Jeannel, and consider their relationships. The elongatus species group is revised, with descriptions of four newly discovered species, Anillinus arenicollis Harden and Caterino, new species, Anillinus montrex Harden and Caterino, new species, Anillinus pittsylvanicus Harden and Caterino, new species, and Anillinus uwharrie Harden and Caterino, new species. Two species previously considered part of the elongatus group are determined to not belong here, Anillinus cavicola Sokolov and Anillinus turneri Jeannel. The exact placement of A. turneri remains uncertain, but it shares some character states with the sinuaticollis group. We erect the pecki group for A. docwatsoni and A. pecki, which are likely sister species. We provide a key to the eastern species groups of Anillinus and the species of the elongatus and pecki species groups. Anillinus pecki is broadly distributed in the southern Appalachian Mountains northeast of the French Broad River basin, while A. docwatsoni is apparently endemic to the Hickory Nut Gorge in western North Carolina. Anillinus pecki is reported for the first time from Tennessee and Virginia. All members of the elongatus group have small geographic ranges and are difficult to sample without special techniques, hinting that many more species await discovery in the densely populated Piedmont region of North Carolina, where natural habitats are rapidly being lost. Our sampling was not dense enough to test biogeographic hypotheses, but distributions of the elongatus group species suggest that hydrochory might have played an important role in passive dispersal and reproductive isolation. These taxonomic contributions will facilitate future studies on the genus and serve to highlight the rich insect biodiversity that remains to be discovered in the southeastern United States. ZooBank registration. urn:lsid:zoobank.org:pub:DE12672F-A328-41A3-90E2-EE62ABDD5ECF