Cremastocheilus excavatus

One of about thirty-five species of myrmecophilous Cremastocheilus. The host ant is unknown.

Key to Trinodia species
This species most closely resembles Cremastocheilus saucius but can be readily distinguished by its more robust shape, opaqueness, irregular sculpturing throughout, and by its lateral deeply excavated hind pronotal margin.

Distribution
Mexico

Nomenclature
Holotype male in the collection of the United States National Museum, collected by H.F. Wickham at Durango, Mexico. Paratype male collected at Tlalnepantla, Mexico by O.W. Barrett.

Description
Medium sized; dark red, opaque. Head shallowly, indistinctly, irregularly punctate; clypeus as broad as head, impunctate, front margin reflexed, median carina small, not extending to upper clypeal margin; mentum somewhat cupuliform, side angles not reflexed, remainder with reflexed margins. Pronotum widest a apical third, sides evenly rounded to auriculate apical angles and to deep sinuation anterior to acutely pointed basal angles; surface deeply trilobed, a deep excavation inside and anterior to each basal angle; surface with irregular, indistinct, shallow impressions. Elytra with sides subparallel; disk shallowly concave, surface with rather dense, irregular, shallow, angulate punctures and lines, sparsely clothed with short brown pile. Beneath sparsely punctate and pilose; all femora wide, compressed, anterior tibiae moderately convex, middle and posterior tibiae compressed, all tibiae subpedunculate, anterior pair bidentate externally, middle and hind pairs with acute tooth about middle of outer edge, tarsi short, rounded, segments subequal; pygidium large subcylindrical, irregularly lined on surface. Length 10 mm., width 4.1 mm.