Neivamyrmex swainsonii

Due to its large size and relative abundance N. swainsonii is easily one of North America’s most conspicuous army ants.

Identification
Key to the Neivamyrmex species of the United States

Distribution
United States: Kansas, Louisiana and Texas, west to California; Mexico: border states south to Chiapas and Yucatán; south to Argentina.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Argentina, Brazil, Colombia, Costa Rica, Ecuador, Guatemala, Mexico, Panama, Paraguay, Trinidad and Tobago, Venezuela.

Nomenclature

 *  swainsonii. Labidus swainsonii Shuckard, 1840a: 201 (m.) BRAZIL. Combination in Eciton: Forel, 1895b: 121; in E. (Acamatus): Emery, 1900a: 187; in E. (Neivamyrmex): Borgmeier, 1948b: 462; in Neivamyrmex: Borgmeier, 1953: 15. Senior synonym of arizonense: Borgmeier, 1955: 454; of fallax, mexicanus: Snelling, G.C. & Snelling, R.R., 2007: 490..
 * mexicanus. Labidus mexicanus Smith, F. 1859b: 7 (m.) MEXICO. Forel, 1899c: 27 (w.); Reichensperger, 1939: 297 (q.). Combination in Eciton: Dalla Torre, 1893: 4; in E. (Labidus): Emery, 1895c: 260; in E. (Acamatus): Emery, 1900a: 187; in E. (Neivamyrmex): Smith, M.R. 1942c: 544; in Neivamyrmex: Borgmeier, 1953: 8. Subspecies of pilosus: Borgmeier, 1936: 59. Junior synonym of pilosus: Smith, M.R. 1942c: 544. Revived from synonymy as subspecies of pilosus: Borgmeier, 1953: 14; Borgmeier, 1955: 361. Senior synonym of clavicornis: Mayr, 1886b: 120; of subsulcatum: Dalla Torre, 1893: 4; of aztecum: Borgmeier, 1936: 60; of militarium: Borgmeier, 1953: 14. Junior synonym of swainsonii: Snelling, G.C. & Snelling, R.R., 2007: 490. See also: Borgmeier, 1955: 361.
 * aztecum. Eciton aztecum Forel, 1901h: 49 (m.) GUATEMALA. Subspecies of mexicanus: Emery, 1910b: 26; of pilosus: Wheeler, W.M. 1921d: 314. Junior synonym of mexicanus: Borgmeier, 1936: 60.
 * arizonense. Eciton (Acamatus) arizonense Wheeler, W.M. 1908e: 414, pl. 26, fig. 5 (m.) U.S.A. Combination in E. (Neivamyrmex): Smith, M.R. 1942c: 581; in Neivamyrmex: Borgmeier, 1953: 18. Subspecies of swainsonii: Borgmeier, 1953: 19. Junior synonym of swainsonii: Borgmeier, 1955: 454.
 * fallax. Neivamyrmex fallax Borgmeier, 1953: 48, figs. 31, 33 (w.) U.S.A. See also: Borgmeier, 1955: 425. Junior synonym of swainsonii: Snelling, G.C. & Snelling, 2007: 490.

Snelling and Snelling (2007) - We have determined that N. fallax is the worker of N. swainsonii. The evidence for this association is scanty: it is based on a worker of N. fallax found attached to the leg of a male collected in Arizona. Although throughout the United States and Mexico the ranges of these two taxa overlap nicely, N. fallax is unknown south of Guatemala.