Key to US Stigmatomma species

Key to the species of Stigmatomma from the United States.

1

 * Lobes of frontal carinae contiguous or fused => Stigmatomma orizabanum
 * Lobes of frontal carinae separated by a distinct gap => 2

2

 * Inner borders of mandible angularly produced, so that the blades are trianglular in shape without apices; large double teeth with rounded apices; genal teeth reduced to inconspicuous obtuse angles (N Carolina, U.S.A.) => Stigmatomma trigonignathum
 * Inner borders of mandibles straight to convex, not angularly produced, blades linear; large double teeth prominently acute; genal teeth acute and projecting => 3

3

 * Inner borders of mandibles and anterior clypeal margin straight (N California to British Columbia) => Stigmatomma oregonense
 * Inner borders of mandibles, and usually also the anterior clypeal margin, convex in outline (temperate N. America at least to Arizona) => Stigmatomma pallipes