Pachycondyla dismarginata Mackay and Mackay 2010

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker face view

worker lateral view


Costa Rica (mid-elevation wet forest, Cordillera de Tilaran to Cordillera de Talamanca).


Mesosomal dorsum with erect hairs; opening of propodeal spiracle viewed perpendicularly slit-shaped, more than twice as long as wide; mandible with approximately 17 teeth; dorsal outline of mesosoma interrupted by a distinct, impressed propodeal groove, so that the mesonotum forms a convexity separate from the more or less convex propodeal dorsum; in full-face view, a line drawn through the centers of the eyes falls near head mid-head, crossing near posterior limits of frontal carinae; cheeks with a distinct carina reaching from clypeal wing to eye margin; anterior face of petiolar node somewhat sloping to rounded apex, dorsolateral margins absent; antennal scapes long, SI greater than 120.

Natural History

I have encountered this species in three areas: the upper Penas Blancas Valley in the Cordillera de Tilaran, between 500 and 1000m elevation in Braulio Carrillo National Park north of Volcan Barba, and at the Wilson Botanical Gardens near San Vito. I most often encounter the species as foraging workers, often at night.

The species has relatively small colonies, with no more than two dozen or so workers in a nest, based on four nests I have observed: (1) In a small clearing surrounded by rainforest, in the upper Penas Blancas Valley, a nest was in a thick, soft, wet, dead Piper stem near the ground; (2) another nest was in a live branch, 5-10cm outer diameter, of a small shrub that had live and dead hollow stems; (3) another nest was in a soft rotten stump, in chambers left by a large wood-boring beetle larva; (4) on a forest trail at Wilson Botanical Gardens, a nest was in a Cecropia trunk that had fallen across the trail. The trunk was mostly still live, with a dead apex. The nest was in internodes at the live to dead transition zone.


This was a Bill Brown manuscript name based on material I sent to Brown in 1988. It was formally described by Mackay and Mackay (2010). The Biology section of Mackay and Mackay is somewhat misleading, by first stating that it nests in Cecropia insignis. The species is an opportunistic cavity nester. It may be found in necrotic or abandoned internodes of Cecropia stems, but is in no way an ant-plant specialist.

Literature Cited

Mackay, W. P., and E. E. Mackay 2010. The Systematics and Biology of the New World Ants of the Genus Pachycondyla (Hymenoptera: Formicidae). Edwin Mellon Press, Lewiston.

Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505

Date of this version: 24 December 2010.
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