Pheidole mesomontana

This species occurs in mature mid-elevation wet forest. It is known from only one locality but it is relatively abundant at that locality. The Project ALAS survey at the 1070m site on the Barva transect yielded numerous collections in Malaise traps, pan traps on the ground, and Winkler samples of sifted leaf litter from the forest floor. (Longino 2009)

Identification
Each caste separately with the morphometric profile of many species, but the combination of minor and major worker measurements and general habitus are similar to the allopatric Pheidole hedlundorum (a montane species from Venezuela), and the sympatric Pheidole umphreyi and Pheidole erratilis. Minor worker: not readily distinguishable from similar species; the propodeal spines are spiniform versus somewhat more triangular in erratilis. Major worker: face with faint foveolate sculpture covering entire vertex lobes versus smooth and shining (hedlundorum, umphreyi); head with convex sides but not diverging, versus relatively more cordate (hedlundorum, umphreyi); hypostomal margin curved and inner hypostomal teeth stout, versus hypostomal margin relatively flat and inner hypostomal teeth reduced to inconspicuous denticles (hedlundorum, umphreyi). (Longino 2009)

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

Worker
Minor

Images from AntWeb
Major

Nomenclature

 *  mesomontana. Pheidole mesomontana Longino, 2009: 54, fig. 15 (s.w.) COSTA RICA.

Worker
Minor Measurements (paratype): HL 0.66, HW 0.63, HLA 0.20, SL 0.67, EL 0.15, ML 0.83, PSL 0.06, PMG 0.01, SPL 0.03, PTW 0.13, PPW 0.19, CI 96, SI 106, PSLI 9, PMGI 1, SPLI 5, PPI 149.

Measurements (n=6): HL 0.60-0.66, HW 0.58-0.63, SL 0.64-0.67, CI 93-97, SI 106-114.

Mandible striate at base, grading to smooth and shiny on rest of dorsal surface; clypeus and face smooth and shiny; posterior margin of vertex flattened; occipital carina narrow, visible in full face view; scape rugulose, with abundant erect setae longer than maximum width of scape; promesonotal groove indistinct; propodeal spines present; pronotal humerus developed as an angular boss, with faint foveolate sculpture around boss, rest of pronotum smooth and shining; katepisternum and side of propodeum irregularly rugulose foveate; dorsal face of propodeum faintly foveolate; abundant setae on promesonotal dorsum; dorsal (outer) margin of hind tibia with erect setae subequal in length to maximum width of tibia; first gastral tergum smooth and shining; gastral dorsum with abundant erect setae; color dark red brown.

Major Measurements (holotype): HL 1.20, HW 1.18, HLA 0.26, SL 0.68, EL 0.20, ML 1.01, PSL 0.11, PMG 0.00, SPL 0.05, PTW 0.19, PPW 0.30, IHT 0.25, OHT 0.39, CI 99, SI 57, PSLI 9, PMGI 0, SPLI 4, PPI 159, HTI 64.

Measurements (n=3): HL 1.13-1.20, HW 1.12-1.18, SL 0.63-0.68, CI 99-101, SI 56-59.

Mandible striate at base, grading to smooth and shiny on rest of dorsal surface; clypeus smooth and shallowly concave, with shallow anterior notch; face with median groove, widely-spaced longitudinal rugae between frontal carinae and compound eye, obliquely radiating rugae between frontal carinae, grading to faint foveolate sculpture on vertex lobes; head with abundant suberect setae projecting from sides of head in face view; scape foveolate rugulose, not shining, slightly curved and flattened at base (but width at base still less than maximum width of scape at apex), with abundant erect setae longer than maximum width of scape; hypostomal margin strongly concave medially; median tooth broad, blunt; inner hypostomal teeth stout, slightly closer to outer hypostomal teeth than to midline; promesonotal groove absent; propodeal spines present; pronotal humerus developed as blunt tubercle; anterodorsal face of pronotum with widely-spaced, transverse rugulae; lateral face of pronotum smooth and shining; katepisternum, anepisternum, and side of propodeum coarsely and irregularly rugose; mesonotal dorsum broad, flat, with smooth spaces and irregular rugulae; dorsal face of propodeum with faint irregular rugulae; dorsal (outer) margin of hind tibia with abundant suberect setae subequal in length to maximum width of tibia; pilosity abundant on mesosomal dorsum; postpetiole in dorsal view weakly trapezoidal; first gastral tergite smooth and shining, with abundant erect setae; color dark red brown.

Type Material
Holotype major worker. Costa Rica, Heredia: 16km SSE La Virgen, 10.26667°N 84.08333°W, ±2000m, 1100m, 19 Mar 2001 (ALAS#11/WF/03/36), unique specimen identifier INB0003214187.

Paratypes: major and minor workers. Same locality as holotype but 18 Feb 2001 (R. Vargas#01-RVC-037), 17 Mar 2001 (R. Vargas#01-RVC-063), 16 Mar 2001 (M. Paniagua#11/RG/MPG/006), 20 Feb 2001 (ALAS#11/WF/01/13 and 11/WF/01/all), 19 Mar 2001 (ALAS#11/WF/03/24 and 11/WF/03/36), , EAPZ, ECOSCE, , , , , , , , , MEL, , UNAM, ICN,.

Etymology
The name is in reference to the narrow mid-elevation range of the species.

References based on Global Ant Biodiversity Informatics

 * 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/