Medusapyga LaBonte and Maddison, a New Genus of Anillini (Coleoptera: Carabidae: Trechinae) from the Pacific Northwest of the United States Author LaBonte, James R. 1570 Kenard Street NW, Salem, OR 97304, USA. Author Maddison, David R. Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA. text Proceedings of the California Academy of Sciences 2023 2023-02-15 67 18 401 432 journal article 299337 10.5281/zenodo.11067222 1cb742f7-205f-4cc5-9136-b613d5ab059d 0068-547X 11067222 Key to the Genera of North American (North of Mexico ) Anillini 1. Mandibles extremely long and narrow, much longer than head behind the antennal insertions ( Fig. 3 ); sides of head behind antennal insertions more-or-less parallel and straight; frontal furrows deep and long, extending to occiput ( Fig. 3 ); lateral explanation of elytron very broad in anterior half, abruptly narrowing thereafter ( Fig. 3 ); geographic range Sierra Nevada, California ............ Anillaspis Casey – Mandibles shorter and stouter, shorter than head behind the antennal insertions ( Fig. 2 ); sides of head behind antennal insertions rounded; frontal furrows shallow and short, extending no more than halfway to occiput ( Fig. 2 ); lateral explanation of elytra much narrower and broadest only near the humeri or in the anterior quarter, gradually narrowing until terminating before the apex ( Fig. 2 )............... 2 2. Mentum with a pair of setae near apex of anteromedial tooth; geographic range California, Oregon , and Washington ........................................................................ 3 – If two setae are present on mentum tooth, then they are at base of tooth, well posterior of apex; geographic range eastern United States west to Missouri and Texas .............................. 4 3. Male profemur with a spine on ventrobasal face ( Fig. 4A, C ); male protarsus with tarsomeres 1 and 2 strongly asymmetrically dilated ( Fig. 5 ); female genitalia with a field of long bifurcate setae scattered throughout the apical region of laterotergite IX ( Fig. 6 ); geographical range Pacific Northwestern United States ( Oregon and Washington )........................ Medusapyga LaBonte and Maddison – Male profemur without a spine on ventrobasal face; male protarsus with only tarsomere 1 dilated; each lateral tergite of female genitalia with a field of simple setae on the venter along medial or apical edges; geographical range California ............................................ Anillodes Jeannel 4. Both sexes with apical margin of last visible abdominal ventrite evenly arcuate; right paramere present; geographic range eastern United States west to Missouri and Texas ............... Anillinus Casey – Male with apical margin of last visible abdominal ventrite toothed; right paramere apparently absent; geographic range southeastern United States ................................. Serranillus Barr