Attini, Myrmicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Guatemala to Amazonian Brazil. Costa Rica: Atlantic slope.
Body covered with lanose pubescence, like Sericomyrmex. All other Costa Rican Trachymyrmex have short, stout setae. This species is most easily confused with the genus Sericomyrmex. Sericomyrmex has a more broadly heart-shaped head and less strongly developed mesosomal tubercles. Recent phylogenetic studies suggest Sericomyrmex is a derived Trachymyrmex (T. Schultz, pers. comm.).
This species inhabits wet forest. Nests are in the soil. Mayh and Brandao (2002) describe the biology as follows:
The first information is from Mann (1922:49) on the type series: "...large colony. The nest was in the ground, alongside a trail in thick woods. The entrance was in the form of a turret, loosely constructed of earth and about 6 inches in height; a foot beneath the surface was a large cavity, containing a fungus garden, pendulous and 4 or 5 inches in diameter." Gabriel A. R. Melo has collected in Manaus three workers following a forage trail, carrying dry leaves ... Antonio Mayh and Jose V. Hernandez found two nests in Aroa, Venezuela, in a secondary forest, at 865m of altitude. The entrance of the first ... was at the side of a human trail and presented a turret made by rigid earth coming out of the litter, 1cm diameter and 3 cm height; the [single] ... chamber was 20 cm deep. The second one ... presents also a turret, although smaller, and its [single] ... irregular chamber was 16 cm deep, with the fungus garden hanging from the roof. ...The ants feign death when disturbed, in a conspicuous cryptic behavior.
I know the species from two localities in Costa Rica: La Selva Biological Station, and Refugio Eladio in the Penas Blancas Valley east of Monteverde. At La Selva I observed workers entering a small clay turret in a trail. At Eladio's I observed a second nest, also with a turret-like tumulus in the middle of a trail. The tumulus was fairly large, about 10cm diameter. The main nest chamber, with queen and fungus garden, was about 10cm deep below the surface. It was spherical, about 5cm in diameter. I observed a worker returning with a caterpillar dropping.
Sericomyrmex opulenta Mann 1922:48, fig. 21. Worker: Honduras. Combination in Trachymyrmex: Weber, 1958:51.
Mann, W. M. 1922. Ants from Honduras and Guatemala. Proceedings of the United States National Museum 61:1-54.
Mayh-Nunes, A. J., and C. R. F. Brandao. 2002. Revisionary studies on the attine ant genus Trachymyrmex forel. Part 1: Definition of the genus and the Opulentus group (Hymenoptera : Formicidae). Sociobiology 40:667-698.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.firstname.lastname@example.org
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