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Wilson (2003) discussed character variation in a broadly-defined P. rhinoceros. Subsequent evidence supported the existence of two sharply parapatric species that separate by elevation. There are a few areas where the two species co-occur in the same forest. On the Atlantic slope of the Cordillera de Tilarán in Costa Rica, both species were collected at a single bait line at the Poco Sol field station at the lower end of the Peñas Blancas valley, at 800m elevation. At Refugio Eladio, further up the valley but at about the same elevation, extensive collections have yielded only P. rhinomontana. In Monteverde, in the cloudforest-covered ridges that rise to 1800m at the head of the valley, only P. rhinomontana occurs. On the Barva Transect on the Atlantic slope of the Cordillera Volcánica Central, P. rhinoceros is common from La Selva Biological Station at 50m to the El Ceibo Station at 500m. Both species co-occur at this elevation. At the 1070m station and above only P. rhinomontana occurs. This pattern may also occur as far north as Honduras and south into Panama. Although specimen data were not captured, a visit to the MCZ revealed Honduras specimens of P. rhinoceros from a 650m elevation site and Honduras specimens of P. rhinomontana from a 1040m elevation site. In Panama, the type specimens of P. rhinoceros are from Bugaba, below 500m elevation, while the MCZ specimens of P. rhinomontana examined by Wilson were from Volcán Chiriquí, 900m, and Cerro Campana, 800-950m.
Holotype major worker. Costa Rica, Alajuela: Penas Blancas Valley, Guindon cabin, 10.30000°N 84.70000°W, ±2000m, 940m, 5 Jul 1984 (J. Longino#5Jul84/0854) [INBC, unique specimen identifier CASENT0610082].
Paratypes: major and minor workers. Same data as holotype [BMNH, CAS, FMNH, INBC, LACM, MCZ, MHNG, MIZA, MZSP, UCD, ICN, USNM].
Costa Rica, Panama.
With the habitus and morphometric profile of P. rhinocerosHNS. Minor worker: katepisternum largely foveolate versus smooth and shining ( rhinocerosHNS). Major worker: basal one third to one half of mandible coarsely striate versus largely smooth and shining; clypeus usually with longitudinal to oblique rugulae lateral to medial horn versus clypeus completely smooth and shining lateral to medial horn ( rhinocerosHNS).
Description of minor worker
Measurements (paratype): HL 0.60, HW 0.56, HLA 0.21, SL 0.55, EL 0.11, ML 0.77, PSL 0.03, PMG 0.00, SPL 0.03, PTW 0.08, PPW 0.14, CI 94, SI 97, PSLI 5, PMGI 0, SPLI 5, PPI 175.
Measurements (n=9): HL 0.54-0.65, HW 0.50-0.60, SL 0.50-0.59, CI 90-94, SI 97-105.
Mandible smooth and shining; clypeus smooth and shining with faint medial longitudinal carina; face largely smooth and shining with variable degree of concentric carinulae around antennal insertion and faint foveolate sculpture between frontal carinae and compound eye; margin of vertex rounded with slight median impression; occipital carina narrow, not or barely visible in full face view; scape with abundant erect setae, longest about as long as maximum width of scape; promesonotal groove absent; propodeal spines present; pronotum smooth and shiny dorsally and laterally, with foveolae on humerus and strip of foveolae and transverse carinulae anterodorsally; katepisternum largely to entirely foveolate; sides and dorsum of propodeum foveolate; abundant setae on promesonotal dorsum; dorsal (outer) margin of hind tibia with abundant suberect setae, longest about as long as maximum width of tibia; first gastral tergum smooth and shining; gastral dorsum with abundant erect setae; color red brown.
FIGURE 20. Pheidole rhinomontanaHNS. Major worker: A, face view; B, lateral view; C, dorsal view; D, hypostomal margin. Minor worker: E, face view; F, lateral view; G, dorsal view; H, hind tibia. A-C, Holotype major worker; D, non-type major worker; E-H, Paratype minor worker. Scale bar 0.5mm for E, 1mm for others.
Description of major worker
Measurements (holotype): HL 1.55, HW 1.32, HLA 0.40, SL 0.64, EL 0.17, ML 1.33, PSL 0.09, PMG 0.01, SPL 0.05, PTW 0.21, PPW 0.38, IHT 0.21, OHT 0.58, CI 85, SI 48, PSLI 6, PMGI 1, SPLI 3, PPI 180, HTI 35.
Measurements (n=10): HL 1.29-1.74, HW 1.12-1.44, SL 0.60-0.71, CI 83-87, SI 48-53.
Mandible with coarse longitudinal rugae on basal one third to one half, remaining surface smooth; medial clypeus forming a differentiated, somewhat concave surface, sharply delimited by strong oblique carinae extending from anterior apices of frontal carinae; clypeus obsolete or absent lateral to these carinae, not differentiated from coarsely rugose anterior head capsule; medial clypeus with a pronounced acute laminar horn; usually with several weak longitudinal to oblique carinulae on the clypeal surface lateral to horn; anterior clypeal margin flat to weakly emarginate; anterolateral head capsule with longitudinal rugae, grading to reticulate rugae over foveolae between antennal insertion and compound eye, grading to faint foveolate sculpture on scrobal area beneath scapes, grading to smooth and shining on vertex lobes; area between frontal carinae with longitudinal carinulae; head with abundant suberect setae projecting from sides of head in face view; scape smooth and shining, terete at base, with abundant erect setae about as long as maximum width of scape; hypostomal margin flat; median tooth absent; inner hypostomal teeth pointed, stout, closer to midline than to outer hypostomal teeth; promesonotal groove absent; propodeal spines present; mesosoma largely smooth and shining, with faint transverse etchings on pronotum, faint foveolate sculpture on dorsal face of propodeum; dorsal (outer) margin of hind tibia with abundant erect setae, these not quite as long as maximum width of tibia; pilosity abundant on mesosomal dorsum; postpetiolar dorsum smooth and shining, in dorsal view broader than long, weakly conulate; first gastral tergite smooth and shining, with abundant erect setae; color red brown.
This species inhabits mature montane wet forest habitats, from 500-1600m elevation. Workers are frequently visitors at baits on the ground and are common in Winkler samples of sifted leaf litter. Nests are in or under dead wood on the ground, often in shallow chambers near the surface or under loose bark. Incipient colonies with single queens are often encountered, and colonies can become quite populous.
Wilson (2003) discussed character variation in a broadly-defined P. rhinocerosHNS. New evidence supports the existence of two sharply parapatric species that separate by elevation. The morphological differences outlined in the Diagnosis are subtle but consistent. There are now two known areas where the two species co-occur in the same forest. On the Atlantic slope of the Cordillera de Tilaran in Costa Rica, both species were collected at a single bait line at the Poco Sol field station at the lower end of the Penas Blancas valley, at 800m elevation. At Refugio Eladio, further up the valley but at about the same elevation, extensive collections have yielded only P. rhinomontanaHNS. In Monteverde, in the cloudforest-covered ridges that rise to 1800m at the head of the valley, only P. rhinomontanaHNS occurs. On the Barva Transect on the Atlantic slope of the Cordillera Volcanica Central, P. rhinocerosHNS is common from La Selva Biological Station at 50m to the El Ceibo Station at 500m. Both species co-occur at this elevation. At the 1070m station and above only P. rhinomontanaHNS occurs. This pattern may also occur as far north as Honduras and south into Panama. Although specimen data were not captured, a visit to the MCZ revealed Honduras specimens of P. rhinocerosHNS from a 650m elevation site and Honduras specimens of P. rhinomontanaHNS from a 1040m elevation site. In Panama, the type specimens of P. rhinocerosHNS are from Bugaba, below 500m elevation, while the MCZ specimens of P. rhinomontanusHNS examined by Wilson were from Volcan Chiriqui, 900m, and Cerro Campana, 800-950m.
Additional material examined
COSTA RICA: Alajuela, Casa Eladio, Rio Penas Blancas, 10°19'N, 84°43'W, 800m (J. Longino); Poco Sol, 10°20'44"N, 84°40'28"W, 800m (J. Longino); Guanacaste, 3km N Santa Elena, 10°20'N, 84°50'W, 1500m (R. Burtoft); Heredia, 16km SSW Pto. Viejo, 10°19'03"N, 84°02'56"W, 500m (TEAM); 16km N Vol. Barba, 10°16'N, 84°05'W, 1020m (J. Longino); 17km N Vol. Barba, 10°17'N, 84°05'W, 800m (J. Longino); 10km SE La Virgen, 10°20'N, 84°05'W, 500m (August Longino and Lisa Schonberg); 16km SSE La Virgen, 10°16'N, 84°05'W, 1100m (J. Longino) Vara Blanca, 10km NE Vara Blanca, 10°14'00"N, 84°05'00"W, 1500m (J. Longino); Puntarenas, Monteverde, 10°18'N, 84°48'W, 1500m (J. Longino); Wilson Botanical Garden, 4km S San Vito, 8°47'N, 82°58'W, 1200m (L&A Alonso).
Found most commonly in these habitats: 74 times found in cloud forest, 17 times found in wet forest, 29 times found in ridgetop cloud forest, 18 times found in montane rainforest, 21 times found in cloud forest, old second growth forest, 10 times found in montane wet forest, 12 times found in ridgetop cloud forest, isolated peak with oak trees, 9 times found in cloud forest, primary, near ridgetop, 6 times found in hardwood forest nr stream, 2 times found in tropical wet forest, ...
Found most commonly in these microhabitats: 98 times ex sifted leaf litter, 96 times at bait, pheidole colony in soft rotten stump times wet forest, around Guindon cabin. 0854, 7 times ex sifted leaf litter on ground, 1 times under dead wood in refuge clearing, 2 times at bait at night, 1 times pecan sandie bait, 3 times ex sifted litter, 4 times beating vegetation, 2 times at cookie bait, 1 times at bait on branchfall, ...
Collected most commonly using these methods: 95 times Baiting, 59 times MiniWinkler, 34 times Winkler, 20 times search, 21 times MaxiWinkler, 6 times bait, 5 times Beating, 1 times Baiting on ground, 1 times hand collected, 1 times Malaise, 1 times nest under stone, ...
Elevations: collected from 500 - 1830 meters, 1189 meters average
Type specimens: Holotype Pheidole rhinomontana: casent0610082; Paratype Pheidole rhinomontana: casent0610063, casent0610064, casent0610065, casent0610066, casent0610067, casent0610068, casent0610069, casent0610070, casent0610071, casent0610072, casent0610073, casent0610074, casent0610075, casent0610076, casent0610077, casent0610078, casent0610079, casent0610080, casent0610083, inbiocri002279575, inbiocri002279576; Paratypes: fmnhins0000050049