Formicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
|
|
|
|
|
|
Additional images: dorsal view of gaster of worker from La Selva (reduced, original); worker from Corcovado (reduced, original).
Range
Mexico to southern Brazil. Costa Rica: Atlantic and southern Pacific lowlands.
Identification
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; first gastral tergite with very dense, long, bright gold appressed pubescence; abundant gold erect setae cover mesosoma and head; erect setae on first gastral tergite relatively long, intermediate between planatus and brettesi; uniformly dark brown to dark red brown; side of mesosoma densely punctate, not shining; mesosomal profile relatively flat (makes nests of leaves sewn together with silk).
I tentatively identify as senex two workers from Corcovado National Park. However, they do not have the same mesosomal profile as the senex from La Selva. The propodeal shape is like brettesi (dorsal face more sloping, meeting posterior face at more obtuse angle), but the strong golden pubescence and pilosity is like La Selva senex. Also, the surface sculpture on these two workers is duller than either La Selva senex or brettesi. Image of worker: (reduced, original).
Similar species: JTL-045.
Natural History
This species inhabits mature rainforest canopy, where it builds nests by sewing leaves together with larval silk (Schremmer 1979, Holldobler and Wilson 1983). This is one of four Camponotus species I know in Costa Rica that exhibit this behavior (see chartifex, JTL-045, nitidior).
I have only seen the silk nests once. At La Selva Biological Station there is a large foot bridge that crosses the Rio Puerto Viejo. On each side of the river the bridge goes through the crowns of canopy trees growing on the banks of the river. One of these is an Inga, and for a while it contained nests of C. senex. From the side of the bridge I could see two or three of the nests, each a cluster of leaves and silk about the size of a baseball. This was in the early 1990's, but in recent years (late 1990's) I have not seen them.
The species does not seem very common. The only record of C. senex in 52 canopy fogging samples at La Selva is one dealate queen, and a worker was collected in one Malaise trap sample. I also collected two workers of C. senex at Sirena in Corcovado National Park. These two workers were stray workers on tree trunks, not associated with silk nests, and given their differences from La Selva senex (see above) may not be conspecific. In general senex seems to be a low density species in Costa Rica, but may have higher densities elsewhere in the Neotropics.
Literature Cited
Holldobler, B., and E. O. Wilson. 1983. The evolution of communal nest-weaving in ants. American Scientist 71:490-499.
Schremmer, F. 1979. Das Nest der neotropischen Weberameise Camponotus (Myrmobrachys) senex Smith (Hymenoptera, Formicidae). Zoologischer Anzeiger 203:273-282.
Smith, F. 1858. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
Go back to top
