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Costa Rica: mid-elevation Atlantic slope and Cordillera de Tilaran.
The elongate head of the major is a very distinctive feature of this species, relative to variegata and other similar species. It keys to aciculata in Wilson (2003) but the scapes are shorter and it is generally smaller.
Holotype major worker. Costa Rica, Puntarenas: Monteverde, 10.30000°N 84.80000°W, ±2000m, 1400m, 21 Jun 1999 (J. Longino#4042) [INBC, unique specimen identifier CASENT0609054].
Paratypes: major and minor workers. Same data as holotype [BMNH, CAS, FMNH, INBC, JTLC, LACM, MCZ, MHNG, MIZA, MZSP, UCD, USNM].
With the habitus of P. madrensis and P. mooreorumHNS. Minor worker: head relatively narrow, CI 79-85, versus broader, CI> 83 (madrensis, mooreorumHNS); vertex margin rounded versus flattened (madrensis) (variable in mooreorumHNS); 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, mooreorumHNS); face almost entirely smooth and shining versus with rugose foveate sculpture extending over anterior two thirds to three fourths (madrensis).
Description of minor worker
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.
Description of major worker
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.
Pheidole tenuicephalaHNS occurs in cloud forest habitats on the Cordillera Volcanica Central and the Cordillera de Tilaran 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 Tilaran 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 Tilaran.
The name is in reference to the relatively narrow head of the major worker.
Additional material examined
COSTA RICA: Alajuela, Poco Sol, 10°20'44"N, 84°40'28"W, 800m (J. Longino); Heredia, 16km SSE La Virgen, 10°16'N, 84°05'W, 1100m (multiple collectors and collections).
Found most commonly in these habitats: 23 times found in montane wet forest, 4 times found in moist forest, 12 times found in cloud forest, primary, along steep ridge near peak, 3 times found in evergreen forest, 5 times found in cloud forest, primary, near ridgetop, 3 times found in montane wet forest, in matrix of pasture and forest, probabl old 2nd growth, 1 times found in cloud forest, 2 times found in wet forest, 2 times found in pasture fencerow edge, 2 times found in riparian forest, cloud forest along stream, near dairy farm pasture, 2nd growth or disturbed primary, ...
Found most commonly in these microhabitats: 22 times at bait, 2 times nest under stone, 11 times ex sifted leaf litter, 5 times Hojarasca, 3 times bajo de M/19, 3 times bajo de M/10, 5 times at ground bait, 2 times bajo de M/09, 1 times in refuge clearing, 2 times bajo de M/17, 2 times bajo de M/08, ...
Collected most commonly using these methods: 5 times search, 21 times baiting, 15 times flight intercept trap, 7 times bait, 6 times miniWinkler, 3 times maxiWinkler, 5 times Mini Winkler, 2 times Winkler, 1 times Malaise.
Elevations: collected from 800 - 1580 meters, 1204 meters average
Type specimens: Holotype Pheidole tenuicephala: casent0609054; Paratype: fmnhins0000050047, fmnhins0000050048; Paratype Pheidole tenuicephala: casent0609055, casent0609056, casent0609057, casent0609058, casent0609059, casent0609060, casent0609061, casent0609062, casent0609063, casent0609064, casent0609065, casent0609066, casent0609067, casent0609068, casent0609069, casent0609070, casent0609071, casent0609072, lacment143534, lacment143535