Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Note: The above images are of material from the Barva Transect in Braulio Carrillo National Park, at the 2000m site. They replace the previous page's images. We are using the name umphreyi to refer to this population of ants on the top of Volcan Barva, although the determination is by no means certain. The umphreyi types are from Boquete, Panama, a montane site very near the Costa Rican border. The Barva specimens are similar but not identical to the Boquete specimens. The conspecificity of these and the other collections listed below is very uncertain.
Identification
Minor worker: head length 0.58mm, head width 0.56mm, scape length 0.51mm, Webers length 0.72mm (n=1). Head flattened behind; mesonotal suture absent; humeri somewhat produced; propodeal spines of moderate length; face and pronotum smooth and shining; katepisternum, anepisternum, and propodeum punctatorugose; gaster smooth and shining; dorsal pilosity abundant, long, flexuous; color red brown.
Major worker: head length 1.12mm, head width 1.07mm, scape length 0.56mm (n=1). Anterior two thirds of face with longitudinal, subparallel rugae, posterior fourth and vertex lobes smooth and shining; antennal scrobes present in the form of broad, shallow depressions beneath apices of scapes, dorsally margined by posterior extensions of frontal carinae; hypostomal margin gently curved, with no median tooth, and pair of minute teeth about half distance to recessed teeth flanking mandible bases; dorsal pilosity abundant; head with abundant, suberect setae projecting from sides of head in face view.
Range
Costa Rica, Panama.
Natural History
The population on Volcan Barva nests in rotten wood, and workers are moderately common in Winkler samples of sifted litter from the forest floor. The one nest I have observed was in a rotten log in an old treefall gap. The nest was in the side of the log where there was a vertical wall of humus. I found small chambers about 1cm deep, and the center of the nest about 10cm deep. There were probably several hundred workers, numerous soldiers (in the deepest part of the nest), about a dozen adult males, brood, and one dealate queen. The outer chambers had small plant seeds, thinly spread on the walls and floor.
A collection from Monteverde was in a patch of dry scrub at 1100m elevation. Workers were scattered over the surface of a dead tree being sawn up for lumber.
A colony at Sirena in Corcovado National Park was in a tall dead tree. The tree was largely barkless and had recently fallen. Workers were abundant on the surface, often entering small beetle holes.
Given the strongly contrasting habitats and behaviors of these records, a re-evaluation of the identities of these ants is needed.
Page authors:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
Stefan Cover, Museum of Comparative Zoology, Harvard University, Cambridge MA 02138 USA. scover@oeb.harvard.edu
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