Pheidole costaricensis

This species occurs in lowland rain forest to lower cloud forest habitats. Minor and occasional major workers recruit to ground baits. Workers occur in Winkler samples. One nest was observed in soil beneath a stone.

Identification
Minor: face and mesosoma foveolate, anteroventral katepisternum smooth and shining; promesonotum evenly convex, promesonotal groove absent; propodeal spines one fourth length of posterior face of propodeum; gaster smooth and shining; abundant erect setae on mesosomal dorsum and gaster; tibiae with 2-3 erect setae; color orange.

Major: inner hypostomal teeth stout, closely spaced; scape base terete; face with distinct scrobes, delimited dorsally by frontal carinae and forming concave trough below them, ventral and posterior margins less delimited, surface of scrobe smooth and shiny; head weakly depressed posteriorly; face surface generally smooth and shiny, with sparse, feeble longitudinal carinulae; propodeal spines one fourth length of posterior face of propodeum; gastral dorsum smooth and shining; sides of head with abundant erect setae; abundant flexuous erect setae on mesosomal dorsum, tibiae, and gaster. 32 · Zootaxa 4599 (1) © 2019 Magnolia Press LONGINO

Measurements, minor worker: HW 0.48, HL 0.51, SL 0.48, EL 0.11, WL 0.63, PSL 0.04, PTW 0.09, PPW 0.14, CI 93, SI 102, PSLI 7, PPI 161 (n=4).

Measurements, major worker: HW 1.03, HL 1.24, SL 0.48, EL 0.14, WL 0.98, PSL 0.07, PTW 0.18, PPW 0.36, CI 83, SI 47, PSLI 7, PPI 200 (n=3).

This species remains poorly delimited. The type locality is a cloud forest site southwest of Limón, where minor workers were definitively associated with major workers. At La Selva Biological Station and the lower Barva transect above it, many minor workers that have been collected at baits and in Winkler samples are tentatively identified as P. costaricensis. However, no major workers have been collected from this area. Three of the minor workers have DNA barcodes and form a tight cluster, near the cluster of Pheidole corniclypeus. Given the inability to morphologically distinguish minor workers of P. costaricensis and P. corniclypeus, and the proximity of true P. corniclypeus, there is the possibility that both species could occur on the Barva transect. A population was sampled on the Pacific slope of Costa Rica, in lower montane forest above the Rio Savegre, and minors were associated with major workers. These major workers are somewhat intermediate between P. costaricensis and P. corniclypeus, with more pronounced facial carinae, and small bulges on the lateral clypeus where the large teeth are on P. corniclypeus. Finally, BOLD has a tight cluster of specimens from the lowland dry forest of Guanacaste, close to the clusters for P. corniclypeus and P. costaricensis. Images of these specimens include a lateral view of a major worker, and there is no evidence of a clypeal bulge or tooth. See additional comments under Pheidole andersoni.

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

Nomenclature

 *  costaricensis. Pheidole costaricensis Longino, 2019: 31, fig. 19 (w.) COSTA RICA.

Type Material

 * HOLOTYPE: 1 major worker, Costa Rica, Limón: Cerro Platano, 26km WSW Limón, 9.86439 -83.24371 ±50 m, 1050 m, 19-Jun-2015, mature cloud forest, under stone (J. Longino, JTL9332) [MUCR, unique specimen identifier CASENT0637143].
 * PARATYPES: major, minor workers: same data as holotype [MCZC, MUCR]; same data except 9.86621 -83.24203 ±50 m, 1110 m, at bait (ADMAC, Ba-E-03-1-04-06) [CAS]; 9.86439 -83.24371 ±50 m, 1050 m, at bait (Ba-E-03-2-05-16) [USNM].

Etymology
From the type locality.