Poneracantha triangularis

A millipede feeder that is found in humid forests. The USA record (Deyrup, et. al. 1989:93) is undoubtedly a recent introduction and they have apparently found prey in the local species of millipedes, as they are well established. (Lattke 1995)

Identification
A member of the rastrata complex (in the rastrata subgroup of the rastrata species group). Promesonotal suture weakly impressed; node dorsum with transverse costulae and subquadrate costulae and subquadrate subpetiolar process; first gastric sternum with transverse costulae; metacoxal tooth long and thin. Piceous body. (Lattke 1995)

Distribution
Introduced into Alabama and Florida (Dade and Escambia counties) from Central or South America. It is not as yet common there, but seems well established. First published Florida record: Deyrup et al. 1989; earlier specimens: 1985. (Deyrup, Davis & Cover, 2000.)

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Argentina, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Peru, Uruguay.

Biology
This species was studied in Venezuela by Lattke (1990). He found nests in fallen logs and branches, inhabited by 80-120 individuals. In the four nests examined he found only the remains of millipedes, in the form of disarticulated segmental rings, surrounding the area of the nest. Larvae were found with their heads thrust into the body of a dead millipede. Many millipedes secrete powerful defensive secretions, including cyanide. Lattke found that both adults and larvae of P. triangularis are resistant to cyanide, surviving for three hours in a potassium cyanide killing jar that killed other ants in less than five minutes. Even the P. triangularis were dead in twelve hours.

A colony from Homestead, Florida, had many millipede fragments in the nest (Gary Umphrey 1987, pers. comm.; Deyrup, Davis & Cover, 2000).

Nomenclature

 * . Ectatomma (Gnamptogenys) triangulare Mayr, 1887: 544 (q.) URUGUAY.
 * Type-material: holotype queen.
 * Type-locality: Uruguay: (no further data) (C. Berg).
 * Type-depository: NHMW.
 * Emery, 1906c: 113 (w.).
 * Combination in E. (Parectatomma): Emery, 1911d: 44;
 * combination in Gnamptogenys: Brown, 1958g: 230;
 * combination in Poneracantha: Camacho, Franco, Branstetter, et al. 2022: 11.
 * Status as species: Dalla Torre, 1893: 26; Emery, 1896g: 46 (in key); Emery, 1906c: 113; Emery, 1911d: 44; Bruch, 1914: 213; Santschi, 1916e: 366; Gallardo, 1918b: 39; Luederwaldt, 1918: 34; Borgmeier, 1923: 59; Kusnezov, 1953b: 336; Brown, 1958g: 229, 323; Kusnezov, 1969: 35 (in key); Kempf, 1972a: 116; Zolessi, et al. 1988: 2; Bolton, 1995b: 211; Lattke, 1995: 190; Deyrup, 2003: 45; Lattke, et al. 2004: 349; MacGown & Forster, 2005: 68; Lattke, et al. 2007: 263 (in key); Lattke, et al. 2008: 100; MacGown & Wetterer, 2011: 1; Feitosa, 2015c: 98; Guénard & Economo, 2015: 226; Deyrup, 2017: 21; Feitosa & Prada-Achiardi, 2019: 673; Camacho, et al. 2020: 461 (in key); Camacho, Franco, Branstetter, et al. 2022: 11.
 * Senior synonym of aculeaticoxae: Lattke, 1995: 190; Camacho, Franco, Branstetter, et al. 2022: 11.
 * Senior synonym of richteri: Brown, 1958g: 230, 323; Kempf, 1972a: 116; Bolton, 1995b: 211; Lattke, 1995: 190; Camacho, Franco, Branstetter, et al. 2022: 11.
 * Distribution: Argentina, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Panama, Peru, Suriname, Uruguay, U.S.A., Venezuela.
 * aculeaticoxae. Ectatomma (Parectatomma) aculeaticoxae Santschi, 1921g: 82 (w.m.) FRENCH GUIANA.
 * Type-material: 2 syntype workers, 1 syntype male.
 * Type-locality: French Guiana: Haute Carsevenne, 1898 (F. Geay).
 * Type-depositories: MNHN, NHMB.
 * Wheeler, G.C. & Wheeler, J. 1971b: 1201 (l.).
 * Combination in E. (Poneracantha): Santschi, 1929h: 476;
 * combination in Gnamptogenys: Brown, 1958g: 227.
 * Status as species: Santschi, 1929h: 476; Brown, 1958g: 227, 300; Kempf, 1961b: 491; Kempf, 1972a: 111; Deyrup, et al. 1989: 93; Lattke, 1990b: 5; Brandão, 1991: 345; Bolton, 1995b: 208; Deyrup, et al. 2000: 295 (error).
 * Junior synonym of triangularis: Lattke, 1995: 190; Camacho, Franco, Branstetter, et al. 2022: 11.
 * richteri. Ectatomma (Parectatomma) triangulare r. richteri Forel, 1913l: 203 (w.) ARGENTINA (Buenos Aires).
 * Type-material: syntype workers (number not stated).
 * Type-localities: Argentina: Buenos Aires, Belgrano (Richter), Buenos Aires, Rojas (Weiser).
 * Type-depositories: MHNG, NHMB.
 * Forel, 1914d: 265 (q.).
 * Subspecies of triangularis: Forel, 1914d: 265; Bruch, 1914: 213; Gallardo, 1918b: 41.
 * Junior synonym of triangularis: Brown, 1958g: 230, 323; Kempf, 1972a: 116; Bolton, 1995b: 210; Lattke, 1995: 190; Camacho, Franco, Branstetter, et al. 2022: 11.

Lattke (1995) - The number of transverse costulae on the petiolar dorsum can vary from 8 to 14, and those on the pronotum from 13 to 23. Specimens from Argentina tend to have a higher count but there is no gap separating the values. The length of the coxal teeth is variable and bears no relation to the number of petiolar costulae. Propodeal teeth also show variation form a low mound to the usual low, sharp teeth. Occasional specimens can have up to 4 transverse costulae on the anterior pronotal face, and rarely longitudinal costulae on the petiolar node. Other traits used by Santschi to separate Gnamptogenys aculeaticoxae, such as degree of impression of the promesonotal suture, gastric constriction and gauge of hairs, length vs. width of petiolar node and the mandibular costulation all show continuous variation that is best described as infraspecific.

References based on Global Ant Biodiversity Informatics

 * Basset Y., L. Cizek, P. Cuenoud, R. K. Didham, F. Guilhaumon, O. Missa, V. Novotny, F. Odegaards, T. Roslin, J. Schmidl et al. 2012. Arthropod diversity in a tropical forest. Science 338(6113): 1481-1484.
 * Borgmeier T. 1923. Catalogo systematico e synonymico das formigas do Brasil. 1 parte. Subfam. Dorylinae, Cerapachyinae, Ponerinae, Dolichoderinae. Archivos do Museu Nacional (Rio de Janeiro) 24: 33-103.
 * Brown W. L., Jr. 1958. Contributions toward a reclassification of the Formicidae. II. Tribe Ectatommini (Hymenoptera). Bulletin of the Museum of Comparative Zoology 118: 173-362.
 * Cuezzo, F. 1998. Formicidae. Chapter 42 in Morrone J.J., and S. Coscaron (dirs) Biodiversidad de artropodos argentinos: una perspectiva biotaxonomica Ediciones Sur, La Plata. Pages 452-462.
 * Donoso D. A., G. Onore, G. Ramon, and J. E. Lattke. 2014. Invasive ants of continental Ecuador, a first account. REMCB 35: 133-141.
 * Emery C. 1911. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118: 1-125.
 * Favretto M. A., E. Bortolon dos Santos, and C. J. Geuster. 2013. Entomofauna from West of Santa Catarina State, South of Brazil. EntomoBrasilis 6 (1): 42-63.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Forster J.A. 2005. The Ants (hymenoptera: Formicidae) of Alabama. Master of Science, Auburn University. 242 pages.
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
 * Gallardo A. 1918. Las hormigas de la República Argentina. Subfamilia Ponerinas. Anales del Museo Nacional de Historia Natural de Buenos Aires 30: 1-112.
 * INBio Collection (via Gbif)
 * Kaspari M., D. Donoso, J. A. Lucas, T. Zumbusch, and A. D. Kay. 2012. Using nutritional ecology to predict community structure: a field test in Neotropical ants. Ecosphere 3(11): art.93.
 * Kempf W. W. 1961. A survey of the ants of the soil fauna in Surinam (Hymenoptera: Formicidae). Studia Entomologica 4: 481-524.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Kusnezov N. 1953. La fauna mirmecológica de Bolivia. Folia Universitaria. Cochabamba 6: 211-229.
 * Lattke J. E. 1995. Revision of the ant genus Gnamptogenys in the New World (Hymenoptera: Formicidae). Journal of Hymenoptera Research 4: 137-193
 * Lattke J. E., F. Fernández, T. M. Arias-Penna, E. E. Palacio, W. Mackay, and E. MacKay. 2008. Género Gnamptogenys Roger. Pp. 66-100 in: Jiménez, E.; Fernández, F.; Arias, T.M.; Lozano-Zambrano, F. H. (eds.) 2008. Sistemática, biogeografía y conservación de las hormigas cazadoras de Colombia. Bogotá: Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, xiv + 609 pp.
 * Lattke, J. E. 1990b. Revisión del género Gnamptogenys Roger en Venezuela (Hymenoptera: Formicidae). Acta Terramaris 2: 1-47
 * Luederwaldt H. 1918. Notas myrmecologicas. Rev. Mus. Paul. 10: 29-64.
 * MacGown J. A., and J. K. Wetterer. 2011. Geographic spread of Gnamptogenys triangularis (Hymenoptera: Formicidae: Ectatomminae). Psyche 2012: Article ID 571430, (doi:10.1155/2012/571430):4 pp.
 * Pires de Prado L., R. M. Feitosa, S. Pinzon Triana, J. A. Munoz Gutierrez, G. X. Rousseau, R. Alves Silva, G. M. Siqueira, C. L. Caldas dos Santos, F. Veras Silva, T. Sanches Ranzani da Silva, A. Casadei-Ferreira, R. Rosa da Silva, and J. Andrade-Silva. 2019. An overview of the ant fauna (Hymenoptera: Formicidae) of the state of Maranhao, Brazil. Pap. Avulsos Zool. 59: e20195938.
 * Rosa da Silva R. 1999. Formigas (Hymenoptera: Formicidae) do oeste de Santa Catarina: historico das coletas e lista atualizada das especies do Estado de Santa Catarina. Biotemas 12(2): 75-100.
 * Salazar F., and D. A. Donoso. 2013. New ant (Hymenoptera: Formicidae) records for Ecuador deposited at the Carl Rettenmeyer ant collection in the QCAZ Museum. Boletín Tecnico 11, Serie Zoológica 8-9: 151  177.
 * Santoandre S., J. Filloy, G. A. Zurita, and M. I. Bellocq. 2019. Ant taxonomic and functional diversity show differential response to plantation age in two contrasting biomes. Forest Ecology and Management 437: 304-313.
 * Santschi F. 1921. Ponerinae, Dorylinae et quelques autres formicides néotropiques. Bulletin de la Société Vaudoise des Sciences Naturelles 54: 81-103.
 * Santschi F. 1929. Révision du genre Holcoponera Mayr. Zoologischer Anzeiger. 82: 437-477.
 * Zolessi L. C. de, Y. P. Abenante, and M. E. de Philippi. 1988. Lista sistematica de las especies de Formicidos del Uruguay. Comun. Zool. Mus. Hist. Nat. Montev. 11: 1-9.
 * Zolessi L. C. de; Y. P. de Abenante, and M. E. Philippi. 1989. Catálogo sistemático de las especies de Formícidos del Uruguay (Hymenoptera: Formicidae). Montevideo: ORCYT Unesco, 40 + ix pp.