Pheidole tenuicephala

Pheidole tenuicephala occurs in cloud forest habitats on the Cordillera Volcánica Central and the Cordillera de Tilarán in Costa Rica. On the Barva Transect it is a narrow elevation specialist, being common at 1100m elevation, but not recorded from 1500m or 500m collecting sites. In the Cordillera de Tilarán collections have been made from 800-1400m elevation. Workers have been collected in Winkler samples, Malaise traps, pan traps, at cookie baits, and as foragers in a refuge clearing. Minor and major workers recruit to cookie baits. A nest was found beneath a stone in the lower Bajo del Tigre forest of Monteverde, a moist forest area just below the continental divide on the upper Pacific slope of the Cordillera de Tilarán. (Longino 2009)

Identification
Longino (2009) - With the habitus of Pheidole madrensis and Pheidole insipida. Minor worker: head relatively narrow, CI 79-85, versus broader, CI > 83 (madrensis, insipida); vertex margin rounded versus flattened (madrensis) (variable in insipida); pronotum completely smooth and shining versus with mixture of smooth shiny areas and faint foveolate sculpture (madrensis); pilosity relatively longer and more abundant versus shorter and sparser (madrensis). Major worker: head relatively narrow, CI 82-88, versus broader, CI > 89 (madrensis, insipida); face almost entirely smooth and shining versus with rugose foveate sculpture extending over anterior two thirds to three fourths (madrensis).

This is a Costa Rican variant of the P. insipida complex. The very narrow head of the major worker, with nearly flat sides, is highly distinctive within the complex.

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

Worker
Minor

Images from AntWeb
Major

Nomenclature

 *  tenuicephala. Pheidole tenuicephala Longino, 2009: 84, fig. 24 (s.w.) COSTA RICA.

Worker
Minor Measurements (paratype): HL 0.76, HW 0.63, HLA 0.28, SL 0.76, EL 0.15, ML 0.94, PSL 0.06, PMG 0.02, SPL 0.03, PTW 0.12, PPW 0.17, CI 83, SI 121, PSLI 8, PMGI 3, SPLI 4, PPI 137.

Measurements (n=10): HL 0.68-0.76, HW 0.55-0.63, SL 0.73-0.86, CI 79-85, SI 121-143.

Mandible, clypeus, and face smooth and shining; margin of vertex rounded; occipital carina narrow, not visible in full face view; scape with abundant erect setae longer than maximum width of scape; promesonotal groove present, conspicuous; propodeal spines present; pronotum largely smooth and shining with narrow region of faint foveolae and rugulae on anterior margin; katepisternum, lateral face of propodeum, and dorsal face of propodeum foveolate; abundant setae on promesonotal dorsum; dorsal (outer) margin of hind tibia with abundant, long, suberect setae; first gastral tergum smooth and shining; gastral dorsum with abundant, long, suberect setae; color dark red brown.

Major Measurements (holotype): HL 1.30, HW 1.14, HLA 0.36, SL 0.71, EL 0.18, ML 1.15, PSL 0.04, PMG 0.03, SPL 0.04, PTW 0.19, PPW 0.25, IHT 0.42, OHT 0.48, CI 88, SI 62, PSLI 3, PMGI 2, SPLI 3, PPI 131, HTI 88.

Measurements (n=6): HL 1.20-1.30, HW 1.04-1.14, SL 0.69-0.74, CI 82-88, SI 62-71.

Mandibles smooth and shiny; clypeus smooth and flat with strong anterior notch; face with longitudinal rugae from anterior margin to about level of compound eye and antennal insertion, rest of head completely smooth and shining; head with abundant short subdecumbent setae projecting from sides of head in face view; scape smooth and shining, terete at base, with abundant suberect setae about as long as maximum width of scape; hypostomal margin gently curved, hypostomal sclerite narrow, meeting genal bridge at obtuse angle; median tooth absent; inner hypostomal teeth sharply pointed, widely-spaced, much closer to outer hypostomal teeth than to midline; promesonotal groove present, conspicuous; propodeal spines present; pronotum smooth and shiny, katepisternum and propodeum generally shiny, with irregular rugulae and foveolae; dorsal (outer) margin of hind tibia with abundant suberect setae subequal in length to maximum length of tibia; pilosity abundant on mesosomal dorsum; postpetiole in dorsal view globular, sides rounded; first gastral tergite smooth and shining, with abundant suberect setae; color dark red brown.

Type Material
Holotype major worker. Costa Rica, Puntarenas: Monteverde, 10.30000°N 84.80000°W, ±2000m, 1400m, 21 Jun 1999 (J. Longino#4042), unique specimen identifier CASENT0609054.

Paratypes: major and minor workers. Same data as holotype, , , , , , , , , , , ].

Etymology
The name is in reference to the relatively narrow head of the major worker.

References based on Global Ant Biodiversity Informatics

 * Basset Y., L. Cizek, P. Cuenoud, R. K. Didham, F. Guilhaumon, O. Missa, V. Novotny, F. Odegaards, T. Roslin, J. Schmidl et al. 2012. Arthropod diversity in a tropical forest. Science 338(6113): 1481-1484.
 * Longino J. T. 2009. Additions to the taxonomy of New World Pheidole (Hymenoptera: Formicidae). Zootaxa 2181: 1-90.
 * Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
 * Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/