Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Costa Rica to northern South America (Lattke 1995). Costa Rica: Osa Peninsula, Atlantic lowlands.
Large, light orange species; HW without eyes greater than 2.0mm; sculpture finely striate.
Gnamptogenys concinna is known from two locations in Costa Rica: Corcovado National Park on the Osa Peninsula, and the La Selva Biological Station in the Atlantic lowlands. In Corcovado it is moderately common; at La Selva it is extremely rare. It nests in the canopy but will forage on the ground. It exhibits group raiding behavior, and preys on a wide variety of often heavily armored insects. Prey records include Platypodidae, Cerambycidae, Histeridae, Passalidae, Chrysomelidae, Curculionidae, Tenebrionidae, Aradidae, and Pentatomidae. In general, workers are observed either carrying prey alone, or hunting in groups of 10-40. The following are observations from field notes, all from Corcovado:
I saw a line of 10 workers moving along a vine. They traveled together about 10m to the side of a large liana lying on the ground. They milled about for a few minutes; then it appeared that one worker was chased off by the other workers. It rapidly ran back the way it had come. Suddenly one worker began struggling with a pentatomid bug near the ground. Soon, two other workers joined in. After awhile the prey was pulled up onto the liana. Three workers pulled from different sides, and it appeared that a tug-of-war ensued for several minutes. One of the workers was larger than the others, and this one eventually took the prey and began to return along the same path. Two workers followed, clamped onto the pentatomid's legs. I collected this group, and the larger ant turned out to be a dealate queen. A similar scenario was occurring with a second pentatomid close by. It was soon relinquished to one forager, which held the prey above its head. The workers returned along their original path to where I first saw them; then they continued up lianas and into the trees. The cluster of foragers that went out had split up and returned separately or in small groups around the prey. The foragers characteristically walked with their gasters curled and touching the substrate. When they were together near the prey I could often make out a tiny white area (gland?) exposed at the very tip of the gaster, which other foragers would investigate. These observations were made between 1000 and 1040hrs. The pentatomid prey were robust, cryptically colored, with truncate wing tips and a proboscis longer than the body.
At 0910hrs a foraging column of 40 single-file workers walked along a vine and up a liana out of site. At 0940 the first workers began returning along the same path, singly or in pairs. One worker carried a chrysomelid beetle. At 1000 a cluster of three ants came down carrying an aradid bug. For a long time one ant remained motionless at the juncture of two vines as the other ants passed by. When the second prey item came down, this ant suddenly "woke up" and went with it, and another worker that had just come down "froze" in place about 5 cm above the former ant's position. More ants passed this one for about 10 min. A pair of ants came down and the motionless ant suddenly "woke" and went with them. At 1013 three more workers came down. I could see no more coming down the vine at that point, and I ended the observations.
Mature forest; canopy of tall Licania (Chrysobalanaceae) tree, about 20m up. I offered a foraging worker a freshly killed tabanid. It at first ignored the fly, walked on top of it and then walked on, but later it returned and picked it up. The ant walked in ever widening circles on the branch until it encountered a particular side branch. The ant then walked along the side branch directly to the nest entrance. The nest was inside a large, deep knothole, leading into the center of a branch.
A single worker was walking along a fallen log with a beetle in its mandibles. The beetle was an elongate, cylindrical histerid.
A single worker carrying a cerambycid in its mandibles.
Workers attacking passalid beetle embedded in rotten log (observation by J. Mallet).
A large branch-fall; a worker pulling a platypodid beetle out of a hole and stinging it.
Single worker carrying tenebrionid prey along downed log.
A single worker carrying an aradid bug across a root in the trail. Earlier I had seen several foragers moving along the root.
A worker carrying a cerambycid adult about 1/2 its size.
Seven workers were moving in a group on the trail. They were in the same area I have seen workers with prey before. These had no prey.
At La Selva Biological Station, a worker was collected by Project ALAS in a canopy fogging sample from a Virola koschnyi tree. I collected a worker from a sidewalk in the laboratory clearing.
Ectatomma concinna F. Smith 1858:103.
Lattke, J. E. 1995. Revision of the ant genus Gnamptogenys in the New World (Hymenoptera: Formicidae). Journal of Hymenoptera Research 4:137-193.
Smith, F. 1858. Catalogue of hymenopterous insects in the British Museum. VI. Formicidae. 216pp., 14 pls.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.email@example.com
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