Pheidole kelainos

This species occurs in lowland rainforest. It is known from two collections. At La Selva Biological Station a single minor worker was collected at a ground bait. At Hitoy Cerere, the type locality, a nest was found at a stream edge in forest. The nest was in rocky, sandy soil of a steep shaded bank, near the water. The entrance was an irregular hole, leading to a nest chamber about 10 cm deep. The chamber contained adult males, major and minor workers, and brood.

Identification
Minor: face smooth and shining; head somewhat tapering posteriorly; occipital carina moderately developed; promesonotal groove present, distinctly impressed; lateral pronotum smooth and shiny; katepisternum uniformly foveate; propodeal spines long, similar in length to posterior face of propodeum; gaster smooth and shining; coarse, black, erect setae on mesosomal dorsum, tibiae, and gastral dorsum; color black.

Major: inner hypostomal teeth widely spaced, acicular; scape base subterete, narrower than apical portion; face irregularly and shallowly rugulose foveolate over entire surface, rugulae fading posteriorly; propodeal spines long and thin, similar to minor; gastral dorsum shallowly foveolate on anterior third; abundant erect setae on sides of head, mesosomal dorsum, tibiae, gastral dorsum.

Measurements, minor worker: HW 0.62, HL 0.79, SL 1.1, EL 0.16, WL 1.06, PSL 0.15, PTW 0.11, PPW 0.19, CI 79, SI 177, PSLI 24, PPI 165 (n=2).

Measurements, major worker: HW 1.34, HL 1.42, SL 1.14, EL 0.21, WL 1.44, PSL 0.19, PTW 0.24, PPW 0.36, CI 95, SI 85, PSLI 14, PPI 151 (n=2).

This species is most similar to Pheidole indagatrix, with which it is sympatric. It differs in darker, coarser pilosity and longer propodeal spines (mean PSLI 24 vs. 14).

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

Nomenclature

 *  kelainos. Pheidole kelainos Longino, 2019: 41, fig. 46 (w.) COSTA RICA.

Type Material

 * HOLOTYPE: 1 major worker, Costa Rica, Limón: Res. Biol. Hitoy Cerere, 9.66773 -83.02953 ±50m, 150m, 13-Jun-2015, rainforest stream edge, nest in soil (J. Longino, JTL9268) [MUCR, unique specimen identifier CASENT0646308].
 * PARATYPES: major, minor workers: same data as holotype [CAS, DZUP, JTLC, MCZC, MUCR, USNM].

Etymology
Greek for black, in reference to the black setae.