Cremastocheilus constricticollis

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

Key to Trinodia species
This species belongs with the species in the Trinodia group but is apparently only distantly related to any previously described. It can be separated from all other species by its narrow pronotum, and the transverse impression on the front of the head.

Distribution
Arizona (Duquesne Road east of Rio Rico, Santa Cruz County), Cochise County, Graham County.

Habitat
Common host is Myrmecocystus mexicanus.

Biology
Obligate myrmecophile in nest of Myrmecocystus species ants. Adults feed on ant brood.

Nomenclature
Holotype female in the collection of Mark Robinson, collected at Bonita, Graham Co., Arizona, from the collection of Charles Schaeffer.

Description
Medium sized, elytra moderately robust, pronotum slightly more than one-half as wide as elytra; thorax and elytra piceous, head and legs reddish. Head with vertex moderately densely punctate, punctures separated by about their own widths, front with transverse impression in front of eyes, front and impression clothed with golden pile, median carina prominent, glabrous dorsally, sides with pile behind and a tomentose patch on either side in front but behind reflexed clypeal margin; clypeus impunctate, as wide as head and strongly reflexed, median reflexed portion extending posteriorly and connecting with carina; mentum cupuliform, front and side margins evenly rounded, posterior margin medially produced into an acute point. Pronotum slightly more than one-half as wide as elytra, side margins evenly, obtusely rounded, anterior angles auriculate, inner notch moderately deep, posterior angles acute, straight; surface with median portion opaque, impressed, sparsely, irregularly punctate. Elytra opaque, side margins subparallel, evenly rounded to apex, surface densely covered with elongate punctures, which are nerly coalescent longitudinally and separated by about their own widths transversely. Beneath bare, sparsely punctate, anterior tibiae bidentate, posterior tooth distad to middle, tarsi five-segmented, laterally flattened; pygidium roughened, without regular punctures, dorsal two-thirds opaque, ventral one-third shining. Length 11mm., width 4.5 mm.