Formicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Additional images: dorsal view of worker gaster (original, reduced).
Costa Rica: Lowland to montane habitats throughout country.
Minor worker: Propodeum lacking spines or tubercles of any kind; propodeum somewhat box-like, dorsal and lateral faces flat or nearly flat and meeting at an approximate right angle; dorsal face of propodeum subrectangular; pubescence on first gastral tergite dilute, appressed to suberect, not obscuring integument; color black; propodeum not strongly projecting, forming part of continuous dorsal profile of mesosoma; in face view side of head mostly lacking erect setae, a few setae near mandibular insertion and posterior to eye; dorsal and posterior faces of propodeum meeting at relatively shallow angle; propodeum not elevated.
Similar species: excisus.
This species is common in lowland wet or dry habitats, and can be found at mid to upper elevations (e.g. 1200m elevation around Las Alturas, to 900m on road to Monteverde). In lowland sites it can occur in both mature and second growth forest, but at higher elevations is increasingly restricted to open or disturbed habitats. The workers are commmon diurnal foragers on vegetation, often visiting extrafloral nectaries, and the species is common in canopy fogging samples from La Selva Biological Station. I have observed nests five times, and all have been in dead wood. One was in a standing fencepost, one was in branches of a 5m tall Cecropia angustifolia tree, and the others have been in dead branches of various trees.
One of the nests was in Corcovado National Park. A small dead tree had fallen across the trail, and highly agitated workers on the surface revealed the presence of a nest inside. The trunk varied from 3 to 4.5cm diameter, of white fairly hard wood. The core was a corky pith about 1.5 cm diameter. The workers had tunneled out the pith and there were pockets of small brood in the center. There were flat chambers just under the bark which had many pupae. The workers were weak biters. I found a single queen in the center of the nest.
One colony was in a recent branchfall in the lab clearing at La Selva. The branch was covered with epiphytes, and the branch itself was riddled with cavities. Workers were scattered in cavities throughout the branch, in dead stems and among epiphyte roots. Some of the nest chambers were packed with adult males, but no colony queen and no alate queens were found.
When I found the species in the Cecropia angustifolia tree, there were several widely separated nests. These were probably parts of one polydomous colony.
Four times I have found lone founding queens in dead sticks in vegetation.
These observations all suggest that the species is monogynous and polydomous, maintaining a central nest with the single colony queen and transporting brood to satellite nests.
For many years I referred to this species as C. canescens. Alex Wild examined the types of canescens and concluded that they were unlike the Costa Rican species. Click here for Alex Wild type images.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.email@example.com
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