Pheidole imbrilis

This species occurs in cloud forest. Minor and major workers recruit to ground baits, and workers occur in Winkler samples of sifted litter and rotten wood.

Identification
face smooth and shining; promesonotal groove absent; entire mesosoma smooth and shiny except for faint foveolation on dorsal face of propodeum; anterior and dorsal faces of pronotum separated by a single transverse carina; propodeal spines short triangular denticles; gaster smooth and shining; mesosomal and gastral dorsum with abundant flexuous erect setae; tibiae lack erect setae; color light yellow brown.

Major: inner hypostomal teeth very reduced, inconspicuous tubercles about half way between midline and outer hypostomal teeth; scape base terete; face mostly smooth and shining, with longitudinal carinulae on anterior third; propodeal spines short triangular denticles; gastral dorsum smooth and shining; side of head with erect setae; mesosomal and gastral dorsum with abundant flexuous erect setae; tibiae with 0-2 erect setae.

Measurements, minor worker: HW 0.42, HL 0.46, SL 0.42, EL 0.10, WL 0.54, PSL 0.01, PTW 0.08, PPW 0.11, CI 92, SI 99, PSLI 4, PPI 136 (n=2).

Measurements, major worker: HW 0.87, HL 0.97, SL 0.48, EL 0.12, WL 0.76, PSL 0.02, PTW 0.15, PPW 0.24, CI 90, SI 55, PSLI 2, PPI 159 (n=2).

This species is very similar to Pheidole laselva and Pheidole laselvoides, differing in the broader head (HW 0.87 vs. < 0.8) and reduced facial carinulae of the major worker, and the overall lighter color of both worker castes.

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica.

Nomenclature

 *  imbrilis. Pheidole imbrilis Longino, 2019: 38, fig. 7 (w.) COSTA RICA.

Type Material

 * HOLOTYPE: 1 major worker, Costa Rica, Limón: Cerro Platano, 26km WSW Limón, 9.86713 -83.24141 ±20 m, 1130 m, 18-Jun-2015, mature cloud forest, night foragers (J. Longino, JTL9329-s) [MUCR, unique specimen identifier CASENT0637137].
 * PARATYPES: major, minor workers: same data as holotype [MUCR, MCZC]; same data except 9.86439 -83.24371 ±50 m, 1050 m, 19-Jun-2015, at bait (ADMAC, Ba-E-03-2-04-05) [CAS, JTLC, USNM].

Etymology
Latin, "of rain," in reference to the incessant and voluminous rain that occurred during field sampling at the type locality.

References based on Global Ant Biodiversity Informatics

 * Longino J. T. 2019. Pheidole (Hymenoptera, Formicidae) of Middle American wet forest. Zootaxa 4599: 1-126