A single species from Mexico, ant host unknown.
Mexico: Durango State: 9 m E. of El Palmit, 7500 ft. elev.
Common host is unknown.
Description (holotype, female). — Approximate length 14.5, width 6, height 4 mm. Colour black, opaque, derm shagreened. Pilosity black. Habitus, plate ι fig. 17. Cephalic contours, fig. 1. Clypeopleuron (fig. 7) narrow, shiny, with reflexed superior border; clypeofrontal disc distinctly hemipunctate in front, with long erect pilosity, diameters of punctures and length of setae decreasing caudad; diameters of clypeal punctures ca. 0.075 mm, their densities 7-10/0.1 sq. mm. Maximum width of head 3.85 mm. Pronotal contours, fig. 2; notal-pectoral transition abrupt, even near anterolateral angle; posterolateral angle distinct, acute; basal-lateral trichome a fringe of closely set, coarse black setae. General surface of pronotum evenly convex, with numerous fine punctures, several with fine recurved seta; anterolateral surface hemipunctate, with coarser setae; diameters of central punctures ca. 0.025 mm, their densities 7-10/0.1 sq. mm. Maximum length of pronotum 4.70, maximum width 3.20 mm; ratio 1/w 1.47. Scutellum, fig. 3. Elytral contours, fig. 3; posthumeral emargination shallow; disc remarkably deplanate, with numerous evenly distributed horseshoe-shaped striolae, their size rapidly decreasing towards elytral base and apical declivity; shortest (transverse) diameters of striolae ca. 0.125 mm, their densities ιο-15/sq. mm; lateral declivity and paradiscal costa with numerous fine punctures, some of them with extremely fine seta, their diameters 0.05 mm or slightly less, separated by many times this diameter. Maximum length of elytron 8.4, suturai length 6.3, maximum width of elytra combined 6.0 mm; ratio maximum 1/w 1.40. Mentum, fig. 7; surface of backward extension with arcuate-striolate sculpture, densely covered with short setae, posterior border with long setae. Antennal scape, fig. 6. Prosternai apophysis relatively short; anterior border of prosternum with brown setae. Lateral surface of propectus longitudinally striolate, sparsely setiferous, posterolateral region slightly scabrous, weakly shiny. Lateral parts of mesopectus and metapectus (except for metepimeron), and hind coxae with numerous horseshoe-shaped striolae, many of them with a seta; diameters of these striolae ca. 0.2 mm. Proximal abdominal sternites with similar sculpture, striolae rather unevenly distributed; distal sternites with small hemipunctures; abdominal pilosity sparse; anteapical sternite with shallow basal-lateral impression. Propygidial spiracles very weakly elevated; propygidial surface with dense cover of arcuate striolae. Pygidium sparsely set with annulate striolae, their diameters centrally ca. 0.1 mm, densities ca. 6/0.25 sq. mm. Fore tibia (fig. 4) with vague setiferous longitudinal ridge on superior side; both sides with erect to semierect short setae in poorly pronounced hemipunctures or short striolae, only internal border of tibia with longer setae; terminal denticle of inferior ridge very distinct; terminal spur of fore tibia acuminate, just reaching tarsal segment 3. Fore tarsi (fig. 4) distinctly setiferous. Middle and hind tibia (fig. 5) with spiniform external elevation at about one-third from apex; terminal spurs long and slender, weakly acuminate, both reaching tarsal segment 2; visible femoral and tibial surfaces of middle and hind leg with numerous seta-bearing hemipunctures and striolae. Middle and hind tarsi also distinctly setiferous.
Material examined. — Holotype, female, from Mexico: Durango State: 9 mi E. of El Palmito, 7500 ft, 15-17.vi.1971, H . F. Howden (Howden collection, Ottawa).
- Alpert, Gary D. 1994. A Comparative Study of the Symbiotic Relationship Between Beetles of the Genus Cremastocheilus (Coleoptera: Scarabaeidae) and their Host Ants (Hymenoptera:Formicidae). Sociobiology 25(1).