Pheidole caliginosa

This species occurs in lowland to lower montane wet forest. Minor and major workers recruit to ground baits, and workers occur in Winkler samples of sifted litter and rotten wood. A few minor workers have been collected in beating samples.

Identification
Minor: face smooth and shining; head rounded behind; promesonotal groove present, distinctly impressed; pronotum entirely smooth and shining; katepisternum foveolate; propodeal spines about half length of posterior face of propodeum; gaster smooth and shining; mesosomal and gastral dorsum, tibiae with abundant erect dark amber setae; color dark brown to black.

Major: inner hypostomal teeth widely spaced, acicular; scape base terete; face mostly smooth and shining, with longitudinal carinulae between eye and antennal fossa, a few longitudinal carinulae medial to frontal carinae; propodeal spines about one third length of posterior face of propodeum; gastral dorsum smooth and shining; side of head with erect setae; mesosomal and gastral dorsum, tibiae with abundant erect dark amber setae.

Measurements, minor worker: HW 0.75, HL 0.88, SL 1.10, EL 0.18, WL 1.16, PSL 0.11, PTW 0.18, PPW 0.26, CI 86, SI 147, PSLI 14, PPI 145 (n=2).

Measurements, major worker: HW 1.46, HL 1.51, SL 1.08, EL 0.23, WL 1.46, PSL 0.13, PTW 0.31, PPW 0.42, CI 96, SI 74, PSLI 9, PPI 137 (n=2).

This species is similar to Pheidole hector and Pheidole hectornidita. Compared to both species, the head of the minor worker is more rounded behind, with less developed occipital carina. Both it and P. hector have dark amber setae.

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

Nomenclature

 *  caliginosa. Pheidole caliginosa Longino, 2019: 29, fig. 55 (w.) COSTA RICA.

Type Material

 * HOLOTYPE: 1 major worker, Costa Rica, San José: Cerro Plano, 9.48141 -83.96276 ±100 m, 1070 m, 6-Jul-2015, ridgetop cloud forest, at bait (ADMAC, Ba-E-06-1-03-11) [MUCR, unique specimen identifier CASENT0631248].
 * PARATYPES: major, minor workers: same data as holotype [MCZC, MUCR]; same data except Ranchos Tinamu, 9.48686 -83.95215 ±100 m, 720 m, 9-Jul-2015, montane wet forest, near pasture, at bait (ADMAC, Ba-E-07-1-03-03) [CAS]; Ba-E-07-1-03-04 [JTLC, DZUP]; Ba-E-07-1-03-08 [JTLC, USNM].

Etymology
Latin for dark.

References based on Global Ant Biodiversity Informatics

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