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Three named species are known to be in this complex, all described as new by Wilson (2003): P. acamata, P. potosiana, and P. psilogaster. Across all material the major workers are very uniform in habitus and there are no consistent differences in pilosity or sculpture that differentiate the three species. Thus, at this time the majors of the three species cannot be identified without associated minor workers. Two of the species, P. potosiana and P. psilogaster, have minor workers with smooth and shiny faces. The minor worker of P. acamata has a densely and uniformly foveolate face. The minor worker of P. potosiana has the dominant sculpture of the pronotum foveolate, with variable degrees of shiny patches and rugulae. The minor worker of P. psilogaster has the pronotum entirely smooth and shiny or largely smooth with some development of transverse rugulae anterodorsally.
The types of P. acamata from the Atlantic coastal lowlands of Nicaragua are identical to numerous collections from sites in the lowlands of northern Chiapas State, Mexico. The face and pronotum have reticulate rugae overlaying the foveolate sculpture, weak on the face and stronger on the pronotum, and the color is orange yellow. Some specimens from one site in Chiapas near Salto de Agua are somewhat different: the minor workers have a duskier coloration and the foveolation on the face and pronotum are much reduced to absent. These characters are more like P. potosiana. This form and typical acamata occur together at Salto de Agua and are very similar there, differing only in the presence or absence of foveolate sculpture on the face.
Relatively few collections of P. potosiana have been examined. The types are from the state of San Luis Potosí, Mexico. The minor workers are uniformly red brown. The pronotum is largely foveolate, with smooth shiny patches on the side and dorsum. Collections from northern Chiapas lowlands are identical to the types or with pronotum more uniformly foveolate, with shiny patches reduced to absent. A collection from Santa Rosa National Park in the Costa Rica, in the dry forest of the northwestern lowlands, is nearly identical to the types, differing only in a somewhat darker brown coloration and slightly more developed transverse rugulae on the anterior pronotum. A few minor workers from further south in Costa Rica's Pacific lowlands are tentatively identified as P. potosiana.
Pheidole psilogaster, as here interpreted, shows considerable geographic variation in color of the body and sculpture of the pronotum. The types of P. psilogaster from Veracruz State, Mexico are nearly identical to material from the Atlantic lowlands of Costa Rica. The coloration is dark red brown and the pronotum is completely smooth and shining. Collections from the Osa Peninsula, on the southwest Pacific coast of Costa Rica, and from the northern Chiapas lowlands are yellow orange and the pronotum has faint rugulae and sometimes traces of faint foveolate sculpture overlaying the generally smooth and shining surface.
DNA barcoding shows equivocal results that do not correlate well with morphology. One cluster (less than 3% sequence divergence) contains a large number of Belize specimens and one specimen from the central Atlantic coast of Honduras. These all match typical acamata morphology. Another cluster contains specimens from central coastal Honduras, La Mosquitia area of Honduras, multiple sites in Nicaragua, and lowland Atlantic Costa Rica. In this latter group the morphology is interdigitated, with the central coastal Honduras and Nicaraguan specimens looking like typical acamata, while the La Mosquitia and Costa Rica specimens have typical psilogaster morphology.
In northern Chiapas there are two common forms, both yellow and very similar except for the smooth versus foveolate face. Most have foveolate faces and are identified as acamata; a smaller number have shiny faces and are identified as psilogaster.
On the lower slopes of Cerro Saslaya in Nicaragua, the dark shiny form (psilogaster) and the yellow foveolate form (acamata) are similarly abundant and there are no intermediates.
Minor workers in this complex can be very similar to other species outside of the complex. For example, in the northern Chiapas lowlands Pheidole acamata and P. gulo, both very common, have currently indistinguishable minor workers.
|Pheidole acamata||new species||Wilson, E. O., 2003, Pheidole in the New World. A dominant, hyperdiverse ant genus., Cambridge, MA: Harvard University Press: 258, (download)||258||20017|
|Pheidole acamata||Longino, J. T., 2009, Additions to the taxonomy of New World Pheidole (Hymenoptera: Formicidae)., Zootaxa 2181, pp. 1-90: 11-12, (download)||11-12||22820|
Found most commonly in these habitats: 76 times found in tropical wet forest, 102 times found in 2º lowland rainforest, 63 times found in lowland wet forest, 46 times found in mesophil forest, 38 times found in tropical rainforest, 44 times found in tropical moist forest, 21 times found in mature wet forest, 16 times found in 2º wet forest, 15 times found in 2º tropical rainforest, 15 times found in montane rainforest, ...
Found most commonly in these microhabitats: 370 times at bait, 96 times ex sifted leaf litter, 1 times nest in rotten stick, 1 times nest in clay soil, 1 times nest in dead wood, 1 times beating vegetation, 1 times nest in clay bank, 1 times Malaise trap.
Collected most commonly using these methods: 371 times Baiting, 67 times MiniWinkler, 28 times MaxiWinkler, 3 times search, 1 times Berlese, 1 times beating, 1 times Malaise.
Elevations: collected from 20 - 1600 meters, 373 meters average