Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Range
Widespread in mainland Neotropics, from southern USA (Louisiana) to northern Argentina; also in Jamaica. Costa Rica: widespread in lowland forest, sea level to about 500m elevation, wet and dry forest habitats.
Identification
Mesosomal dorsum with erect hairs; opening of propodeal spiracle viewed perpendicularly slit-shaped, more than twice as long as wide; mandible with approximately 9 teeth; in side view, dorsal outline of mesosoma forms a continuous convexity including mesonotum, metanotum and propodeal dorsum; propodeal groove obsolete or nearly so, and not strongly impressed; cheeks without a distinct carina between lateral clypeal wing and eye margin; stridulatory file absent; arolia absent; head width less than 2.0mm; mesosoma less than 3.6mm long; dorsolateral margin of pronotum with or without a distinct carina.
Most harpax from Costa Rica have a humeral carina (a ridge on the dorsolateral margin of the pronotum). However, in Corcovado National Park there are workers similar to typical harpax in all respects except they lack the humeral carina (figure), and they are sympatric with workers that have the carina. See below under Taxonomic Notes.
Similar species: impressa and purpurascens are similar but much larger, and they always lack the humeral carina.
Natural History
This species is one of the most common Pachycondyla species in Costa Rica. Foragers are common on the ground, never arboreal, and relatively more abundant at night. They occur in most samples of sifted leaf litter (Winkler samples), and I collected them once at a tuna bait. In Corcovado, I once observed a mid-morning mating swarm inside an insectary.
I have never found a nest of this common species. The nest must be subterranean. If they nested in the leaf litter or in dead wood, nests would be more frequently encountered.
Garcia-P. et al. (1997) observed harpax preying on termites (Gnathamitermes tubiformans) in the wild.
When pursued with forceps, workers release a stream of clear viscous secretion from the top of the abdomen (Overal 1987). Overal suggests these are defensive secretions employed in tunnels, where room is lacking in which to wield the sting.
Type Data
Formica harpax Fabricius 1804:401. Type worker: South America.
Taxonomic Notes
Six names have been synonymized under harpax (Brown 1950):
concinna: Brazil
dibullana: Colombia
irina: Guatemala
montezumia: Mexico
amplinoda: USA
orizabana: Mexico
As mentioned above, there are two discrete forms of harpax sympatric in Corcovado. It is unknown whether this results from distinct genotype clusters at this site (different species) or from an intraspecific polymorphism. Given that there is the possibility of two sympatric species of harpax in Costa Rica, there is the possibility that harpax is a species complex with multiple species throughout the Neotropics. If further research resolves harpax into multiple species, some of the above synonyms may be removed from synonymy and applied to the Costa Rican forms.
Notes from Emery collection, July 1990: All of the material that Emery called montezumia, from Texas to Brazil, has the sharp pronotal carina. Of two workers he called harpax, one (Matto Grosso) has a carina and looks like the other montezumia. The other specimen (Bragansa) lacks the carina but has a larger head than the carina-less form from Costa Rica. A Staudinger worker from Bolivia is set aside with pencil label "var." It most closely matches the Costa Rican carina-less form.
Literature Cited
Brown, W. L., Jr. 1950. Morphological, taxonomic, and other notes on ants. Wasmann J. Biol. 8(2):241-250.
Fabricius, J. C. 1804. Systema Piezatorum secundum ordines, genera, species, adjectis synonymis, locis, observationibus, descriptionibus. Brunswick: C. Reichard, xiv + 15-439 + 30pp. Ants - p. 395-428.
Garcia P., J. A., A. Blanco P., R. Mercado H., and M. Badii 1997. The predatory behavior of Pachycondyla harpax Fabr. on Gnathamitermes tubiformans Buckley in captivity conditions. Southwestern Entomologist 22:345-353 [Spanish].
Overal, W. L. 1987. Defensive chemical weaponry in the ant Pachycondyla harpax (Formicidae, Ponerinae). Journal of Entomological Science 22:268-269.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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