Taxonomic History (provided by Barry Bolton, 2015)
Costa Rica (Atlantic and northern Pacific lowlands).
Occurs in both seasonal dry forest and lowland rainforest; recruits to baits; does not occur in Winkler samples, which implies that it neither nests nor forages in forest leaf litter.
Taxonomic Treatment (provided by Plazi)
Wilson, E. O.:
Etymology L scalaris , of a ladder, alluding to the strong ladder-like pattern on the dorsum of the major head. diagnosis Close to transversostriata but distinguished from it and other members of the transversostriata group by the broad occipital zone of rugoreticulum on the dorsal surface of the head of the major, surmounting a wide "ladder" of parallel transverse carinulae that reach the frontal lobes, where they curve anteriorly to the ends of the lobes; also, the premesonotal dorsum is completely covered by transverse carinulae. Also, see the distinctive color of the minor (below).
This species is possibly synonymous with P. transversostriata var. nigridens Forel of Colombia, which has been provisionally synonymized with transversostriata ; nigridens has rugoreticula on the occipital corners and more carinulae on the pronotal dorsum, and is intermediate between scalaris and transversostriata . However, scalaris also differs from transversostriata by the more elongate head of the major (Head Length 1.3X Head Width versus 1.2X in transversostriata ) and smooth sides of the pronotum of the minor. Measurements (mm) Holotype major: HW 0.64, HL 0.84, SL 0.32, EL 0.10, PW 0.36. Paratype minor: HW 0.42, HL 0.46, SL 0.36, EL 0.08, PW 0.26. Color Major: concolorous medium yellow.
Minor: overall light brownish yellow, with medium brown vertex, occiput, and dorsum of promesonotum, and medium yellow appendages.
Range Atlantic and northern Pacific lowlands of Costa Rica; and Arima Valley, Trinidad.
Biology Longino (1997) found P. scalaris in both seasonal dry forest and evergreen forest. The workers were recruited to baits on the forest floor.
Figure Upper: holotype, major. Lower: paratype, minor. COSTA RICA: La Selva Biological Station, near Puerto Viejo, Heredia (Stefan Cover). Scale bars = 1 mm.
Specimen Habitat Summary
Found most commonly in these habitats: 3 times found in SAT, 3 times found in La Selva, 2 times found in 2nd growth dry forest, 2 times found in dry forest, 1 times found in Puesto19,158G. 10m., 1 times found in house clearing, 3 times found in mature wet forest, 3 times found in montane wet forest, 3 times found in STR, 2 times found in lowland rainforest, ...
Collected most commonly using these methods or in the following microhabitats: 4 times search, 4 times Winkler, 7 times Berlese, 3 times bait, 6 times baiting, 5 times Lure/Bait, 4 times flight intercept trap, 3 times miniWinkler, 1 times Unknown, 2 times Fogging, 2 times Malaise, ...
Elevations: collected from 50 - 610 meters, 123 meters average
Type specimens: paratype Pheidole scalaris: jtlc000016522
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