Gnamptogenys hartmani (Wheeler 1915)

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker face view

worker lateral view

Range

Southern United States south to Peru and Bahia, Brazil (Lattke 1995). Costa Rica: Pacific lowlands.

Identification

Promesonotal suture absent; scapes just barely reach, but do not distinctly surpass, margin of vertex when laid back; dorsal surfaces of mandibles striate on basal fourth or less, rest smooth and shining; head width across eyes less than 1.0mm.

Notes

Gnamptogenys hartmani was formerly treated as three species: hartmani, nigrifrons, and turmalis (see Lattke 1995, Brown and Kempf 1968).

Scattered observations suggest that the species may be a specialized predator on Trachymyrmex. J. C. Moser observed several colonies in nests of Trachymyrmex in Louisiana (cited in Brown and Kempf 1968). Echols (1964) also reported it as a predator on Trachymyrmex in northwestern Louisiana, as follows:

Colonies were discovered on 4 separate occasions while nests of Trachymyrmex septentrionalis (McCook) were being examined, but only one colony contained a queen with developing brood. In all cases G. hartmani had killed most or all of the Trachymyrmex workers, and were occupying the entire nest. Ten nearyby nests of T. septentrionalis with deteriorating fungus gardens were devoid of workers and brood, presumably as a result of action by G. hartmani. However, there were many active unmolested nests in the area. ... The colony containing a queen and brood was placed in ... the laboratory for study. Brood continued to increase, although egg laying was not observed. Adults readily fed on immature stages of T. septentrionalis that were placed in the container. They did not eat fungi taken from gardens, or adults that were vigorously attacked and killed by repeated stinging. In the laboratory, adults of G. hartmani also destroyed workers and fed on brood of the Texas leaf-cutting ant, Atta texana (Buckley). Even the largest workers were killed from multiple stings in a few minutes. Although G. hartmani were adept in avoiding the crushing mandibles of A. texana, one was occasionally caught and killed.

The type colony of turmalis was found on Barro Colorado Island in Panama, and Brown and Kempf state "it is believed that the ants were raiding a nest of the attine genus Trachymyrmex."

In Costa Rica, this species is rarely encountered. I have observed it at three localities: Puntarenas: Curu Wildlife Refuge, 947'N, 8455'W, 5m (J. Longino); Sirena, Corcovado National Park, 829'N, 8336'W, 5m (J. Longino); 19km S Ciudad Neily, 829'N, 8258'W, 20m (J. Longino). The first site is dry forest at the tip of the Nicoya Peninsula; the second and third sites are wet forest on the Osa Peninsula. At Curu I collected a nocturnal forager on the ground surface. At the site near Ciudad Neilly I collected workers in a Winkler sample of sifted leaf litter from the forest floor. At Sirena I observed workers carrying brood in a loose, 3m long column on a rotten log. Dana Meyer, a student working at Sirena, found a colony in the leaf litter, amidst the remains of a Trachymyrmex nest. There were cut-up workers and a cut-up queen of Trachymyrmex, and many wounded Gnamptogenys workers.

At the northernmost limits of its range, in Texas and Louisiana, the species is either extremely rare or very cryptic in its habits. Wheeler (1915) named hartmani from a single specimen from eastern Texas. The species remained unknown for many years, which led Brown (1961) to speculate that Wheeler's worker was mislabeled or an adventive from shipping. But then Echols (1964) reported several colonies from Louisiana, establishing the species as part of the native ant fauna. In 1984 I collected a single worker in south Texas near Brownsville. The lone worker was on the surface of the ground at night, in a scrubby forested area, and intense search in the area failed to reveal any additional workers. In 1987 MacKay and Vinson (1988) encountered a single worker in a pitfall trap near the type locality, in an open grassy area near postoak woods.

Type data

Ectatomma (Parectatomma) hartmani (Wheeler 1915:390). Type worker: USA, Texas: Huntsville.

Literature Cited

Brown, W. L., Jr. 1961. A note on the ant Gnamptogenys hartmani Wheeler. Psyche 68:69.

Brown, W. L., Jr., and W. W. Kempf 1968. Report on some neotropical ant studies. Papeis Avulsos de Zoologia, Sao Paulo 22:89-102.

Echols, H. 1964. Gnamptogenys hartmani discovered in Louisiana. Annals of the Entomological Society of America 57:137.

Lattke, J. E. 1995. Revision of the ant genus Gnamptogenys in the New World (Hymenoptera: Formicidae). Journal of Hymenoptera Research 4:137-193.

MacKay, W. P., and S. B. Vinson 1988 (1989). Rediscovery of the ant Gnamptogenys hartmani (Hymenoptera: Formicidae) in eastern Texas. Proceedings of the Entomological Society of Washington 91:127

Wheeler, W. M. 1915. Some additions to the North America ant fauna. Bulletin of the American Museum of Natural History 34:389-421.


Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu


Date of this version: 18 December 1998
Previous versions of this page: 4 December 1998
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