Pheidole bicornisculpta

This species is known from one collection from a cloud forest site. The nest was in a myrmecophytic Piper, identified as P. fimbriulatum. The ants inhabited the clasping petiolar chambers and the hollow stems. The colony was polygynous or there were multiple colonies in the same plant, because four dealate queens occurred in the collection.

Identification
Minor: head subquadrate, posterior margin weakly emarginate; face fully foveolate, overlain with faint rugulae; promesonotal groove absent; dorsal pronotum foveolate rugulose, fading to smooth on dorsal mesonotum; lateral pronotum and katepisternum smooth and shining medially, foveolate peripherally; propodeal spines triangular, about one third length of posterior face of propodeum; gaster smooth and shining; abundant, flexuous setae on mesosomal and gastral dorsum; tibiae with abundant short suberect setae; color yellow brown. Major: inner hypostomal teeth distinct, closely spaced; scape base terete; frontal carinae produced anteriorly as elevated, triangular teeth, most visible in profile; head elongate rectangular; scrobes shallowly impressed; face heavily sculptured, reticulate rugose throughout; propodeal spines triangular, about one third length of posterior face of propodeum; gastral dorsum smooth and shiny; abundant erect setae on sides of head; mesosomal and gastral pilosity similar to minor worker.

Measurements, minor worker: HW 0.59, HL 0.68, SL 0.37, EL 0.13, WL 0.86, PSL 0.05, PTW 0.16, PPW 0.21, CI 87, SI 63, PSLI 9, PPI 130 (n=1).

Measurements, major worker: HW 0.72, HL 0.92, SL 0.40, EL 0.14, WL 0.99, PSL 0.07, PTW 0.20, PPW 0.25, CI 78, SI 55, PSLI 10, PPI 128 (n=1).

Measurements, queen: HW 0.61, HL 0.70, SL 0.40, EL 0.22, WL 1.16, PSL 0.10, PTW 0.24, PPW 0.35, CI 87, SI 66, PSLI 16, PPI 146 (n=1).

The minor workers of this species are unusual in exhibiting characteristics of the major worker, with subquadrate heads and foveolate/rugose face sculpture. The close relatives of this species, Pheidole bicornis and Pheidole passivaeferox, have typical minor workers with rounded heads and mostly smooth faces. Nevertheless, the worker castes of P. bicornisculpta are fully dimorphic. The major workers of this species have a single median ocellus on the face. Minor workers also have faint vestiges of a median ocellus. See further discussion under P. passivaeferox.

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

Nomenclature

 *  bicornisculpta. Pheidole bicornisculpta Longino, 2019: 27, fig. 39 (w.q.) COSTA RICA.

Type Material

 * HOLOTYPE: 1 major worker, Costa Rica, San José: 8km S Santa Maria, 9.56866 -83.95125 ±50 m, 1550 m, 29-Jun-2015, cloud forest, in ant Piper (J. Longino, JTL9379) [MUCR, unique specimen identifier CASENT0637206].
 * PARATYPES: major, minor worker, alate queen; same data as holotype [CAS, DZUP, JTLC, MCZC, MUCR, USNM].

Etymology
Similar to P. bicornis but with more sculptured face.