Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Costa Rica (type locality), Mexico. Costa Rica: in wet forested habitats throughout the country, at low and mid-montane elevations.
Puncta on face faint, widely spaced, intervals smooth and shining (Brown 1960).
Two studies have been carried out on the behavior of P. amabilis, based on several captive colonies from La Selva Biologica Station in Costa Rica (Hoelldobler and Wilson 1986, Hoelldobler et al. 1992). The following account is based on those studies:
Colonies are polydomous, occupying many small chambers in dead wood fragments. They may contain over 700 workers, and 1 or 2 reproductive queens (active ovaries, filled spermatheca). Workers all appear capable of producing trophic eggs, which may be the main food of the queen. Workers attack live prey and transport it back to the larvae. When presented with a "cafeteria" of diverse prey types, they strongly prefer campodeid diplurans, but will occasionally take other small arthropods. Workers produce a trail pheromone from specialized glands in the hind basitarsus. They exhibit a characteristic behavior, a rapid up and down vibration, which appears to excite or attract other workers, and they drag their hind legs along the surface, apparently leaving a pheromone trail. These behaviors are used to recruit nestmates when prey is discovered. Workers exhibit a simple temporal caste polyethism, in which young workers attend primarily to brood care, while older workers undertake a broader range of behaviors, including brood care, tending the queen, and foraging. Workers have a "wall-papering" behavior, in which they use cocoon fragments to cover the walls of chambers containing pupae, a behavior thought to aid in keeping the pupal chamber dry. Trophallaxis and adult transport have not been observed, and there appears to be no alarm pheromone (Hoelldobler and Wilson 1986, Hoelldobler et al. 1992).
I know this species from Hitoy Cerere Biological Reserve, Tortuguero, Turrialba, the north slope of Volcan Barba from La Selva Biological Station (where it is common) to 600m, the Penas Blancas Valley from 800-1000m, Pitilla station in Guanacaste Conservation Area, Sirena in Corcovado National Park, and Wilson Botanical Garden near San Vito. It is a very common species in wet forested habitats. I most often encounter it in Winkler samples of sifted litter from the forest floor, but it is also quite easy to encounter nests in rotten wood and under loose bark. Colonies can be large, with many hundreds of workers.
I once observed alate queens flying in a downpour in Corcovado National Park; they were falling down my shirt and stinging my neck. Colony founding may be pleometrotic: I lifted the loose bark from a rotten log in Penas Blancas, and found three different pairs of dealate queens, each pair separated from the next by about 30cm. The queen pairs were in small chambers and had small brood piles. In the 1986 Hoelldobler and Wilson study they found single queens in the two colonies they examined in detail, but in the 1992 Hoelldobler et al. study they found two reproductive queens in a colony. Could it be that this species regularly has two queens? The single queens observed by Hoelldobler and Wilson could be due to undersampling; locating all portions of a polydomous colony in the leaf litter can never be achieved with certainty.
Prionopelta amabilis Borgmeier 1949:203. Type worker: Costa Rica, Santa Clara Prov. [=Limon Prov.], Hamburg Farm.
At present the species Prionopelta antillana Forel 1909, with type locality in the Antilles (Saint Vincent), is not separable from amabilis (Brown 1960). The name antillana tends to be used for material from South America, and amabilis for material from Central America. Further research is needed to determine whether amabilis is a valid species distinct from antillana, or a junior synonym of antillana.
Borgmeier, T. 1949. Formigas novas ou pouco conhecidas de Costa Rica e da Argentina (Hymenoptera, Formicidae). Rev. Bras. Biol. 9:201-210.
Brown, W. L., Jr. 1960. Contributions toward a reclassification of the Formicidae. III. Tribe Amblyoponini (Hymenoptera). Bull. Mus. Comp. Zool. 122:143-230.
Forel, A. 1909. Ameisen aus Guatemala usw., Paraguay und Argentinien (Hym.). Dtsch. Entomol. Z. 1909:239-269.
Hoelldobler, B., Obermayer, M., Wilson, E. O. 1992. Communication in the primitive cryptobiotic ant Prionopelta amabilis (Hymenoptera: Formicidae). J. Comp. Physiol. A. Sens. Neural Behav. Physiol. 171:9-16.
Hoelldobler, B., Wilson, E. O. 1986. Ecology and behavior of the primitive cryptobiotic ant Prionopelta amabilis (Hymenoptera: Formicidae). Insectes Soc. 33:45-58.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.email@example.com
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