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