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Species: Neivamyrmex opacithorax   (Emery, 1894) 

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Neivamyrmex opacithorax castaneum

Taxonomic History (provided by Barry Bolton, 2015)

Eciton californicum subsp. opacithorax Emery, 1894d PDF: 184 (diagnosis in key) (w.) U.S.A. Nearctic. AntCat AntWiki

Taxonomic history

Wheeler & Long, 1901 PDF: 163, 173 (m.q., respectively); Wheeler & Wheeler, 1984a PDF: 273 (l.).
Combination in Neivamyrmex (Neivamyrmex): Smith, 1942c PDF: 555; in Neivamyrmex: Borgmeier, 1953 PDF: 5.
Raised to species: Emery, 1900e: 186.
Senior synonym of Neivamyrmex castaneum: Borgmeier, 1955 PDF: 502.


collected from the Chiricahua Mtns, Cochise Co.


Habitat: Open, upland forest and woodlands, savannas, prairies, also parks and spacious campuses.

Natural History: Also relatively common and well-known, the habits of N. opacithorax are quite similar to those of N. nigrescens. Males are bicolored, black with a reddish-brown gaster, and may be seen flying on calm, cool, sunny, late summer or early fall days.



Taxonomic Treatment (provided by Plazi)

Ward, P. S., 2005:

Snelling, G. C., 2007:
Figures 108, 109, 120, 134, 145
Eciton (Acamatus) californicum subsp. opacithorax Emery , 1894: 184 (w, in key).U. S. A. , Missouri , Doniphan ( MHNG ). Emery, 1895 b: 259. Pergande, 1895: 874. Forel, 1899: 28 .
Eciton (Acamatus) opacithorax : Emery, 1900 a: 524; Emery, 1910: 25. Wheeler & Long, 1901: 163, 173 (w, q). Wheeler, 1908 b: 411 (m). M. R. Smith, 1924: 84. Mallis, 1941: 62.
Eciton (Acamatus) carolinense : Wheeler, 1921: 314 (q). Misidentification
Eciton (Neivamyrmex) opacithorax : M. R. Smith, 1932: 555 (w, q, m). M. R. Smith, 1951 [in Muesebeck, et al.]: 781. Buren, 1944: 180. Creighton, 1950: 74.
Eciton (Acamatus) opacithorax var. castaneum Borgmeier , 1939 a: 416 (w).COSTA RICA , San Jose ( MCSN ) .
Eciton (Acamatus) californicum : Mallis, 1941: 62 (w). Misidentification
Eciton (Neivamyrmex) californicum : M. R. Smith, 1942: 560 (w). Misidentification
Eciton (Neivamyrmex) opacithorax subsp. castaneum : Borgmeier, 1948: 191 (w, q m). COSTA RICA, San Jose.
Neivamyrmex opacithorax : Borgmeier, 1953: 6. Watkins, 1972: 349; Watkins, 1976: 16, 22. Watkins, 1985: 482, 484.
UNITED STATES: Virginia and Tennessee, south to Florida, west to California; MEXICO (Baja California, Jalisco); GUATEMALA; COSTA RICA. SPECIMENS EXAMINED
We have 51 records from within the United States.
Although N. opacithorax is a widespread species it is not as commonly encountered as other members of the N. nigrescens group. Within the group it is readily recognized by the distinctively shaped mandible and the shiny head. It is presumably a raider on other ant species. Workers of this species were discovered during the processing of a number twig cuttings which contained a colony of Pseudomyrmex championi (Forel) in Guatemala. It is unknown if the Neivamyrmex were actively entering the colony while it was intact or if the raiding began as the twigs were cut and collected for processing (P. S. Ward, pers. comm.).
Automontage images of N. opacithorax may be viewed at antweb. org.

Specimen Habitat Summary

Found most commonly in these habitats: 1 times found in road edge in mesophyl forest, 2 times found in 2Âș wet forest, 1 times found in oak pine juniper woodland, 1 times found in grazed creosote desert, 1 times found in pine-oak forest, 2 times found in swamp forest, 1 times found in leaf litter, 1 times found in oak-pine-juniper forest, 1 times found in old sawdust amid slabs, 1 times found in Ponderosa Pine for. 50' tall. Dry creekbed w / shrubby lonicera + Robinia unders, ...

Collected most commonly using these methods or in the following microhabitats: 4 times search, 2 times Baiting, 2 times Berlese, 1 times Search, subterranean raid, 0 times under rock, 1 times general collecting, 1 times Malaise trap

Elevations: collected from 6 - 1960 meters, 1206 meters average

Type specimens: syntype of Eciton californicum opacithorax: casent0903735

(-1 examples)

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