Neivamyrmex mandibularis

Males have been collected from early July to late August.

Identification
Snelling and Snelling (2007) - When M. R. Smith (1942) described this species as a subspecies of N. pilosus he did so primarily on similarities in the shape of the mandible. This difference is consistent throughout the range of this species, a range that lies almost entirely within the much more extensive range of N. pilosus. Were this the only difference between the two, there is no doubt that they would be regarded as conspecific. However, there is a difference, too, in the shape of the paramere. Although quite variable in shape, the paramere of N. pilosus is narrowly rounded at the apex; in N. mandibularis the paramere is blunt and broadly rounded. Additionally, the hairs of the compound eyes in N. mandibularis are generally longer and more flexuous than they are in most populations of N. pilosus, but in areas where both forms are present, they are more consistent in this difference.

Distribution
United States: Arizona and New Mexico; Mexico: border states south to Chiapas and Colima.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Castes
Only known from the male caste.

Nomenclature

 * . Eciton (Neivamyrmex) pilosum subsp. mandibulare Smith, M.R. 1942c: 548, pl. 3, fig. 14 (m.) U.S.A. (Arizona).
 * Type-material: holotype male, 2 paratype males.
 * Type-locality: U.S.A.: Arizona, Pima County, 30 mi. E Quijotoa (no collector’s name).
 * Type-depositories: USNM (holotype); CUIC, USNM (paratypes).
 * Combination in Neivamyrmex: Borgmeier, 1955: 375.
 * Subspecies of pilosus: Creighton, 1950a: 76; Smith, M.R. 1951a: 781; Borgmeier, 1955: 375 (redescription); Smith, M.R. 1958c: 109; Smith, M.R. 1967: 345; Watkins, 1972: 352 (in key); Hunt & Snelling, 1975: 21; Smith, D.R. 1979: 1332; Bolton, 1995b: 290; Mackay & Mackay, 2002: 63.
 * Status as species: Snelling, G.C. & Snelling, 2007: 478.
 * Distribution: Mexico, U.S.A.

Snelling and Snelling (2007) - Workers of N. pilosus are relatively large and are conspicuous when that species is present. No workers of N. pilosus have been found in southern Arizona, even though this is one of the most heavily collected areas for ants in the United States. While absence of proof is not proof of absence, we have allowed this consideration to influence our thinking. Additionally, workers of another species, N. melanocephalus, are available as a possible match for N. mandibularis. At present, we are reluctant to do more than suggest this match-up since recently examined material of N. graciellae (Mann, 1926), has raised the possibility that this might be the worker of N. mandibularis. That species was originally described from Ototonilco, Jalisco, Mexico, well within the range of N. mandibularis, and this species is another member of the N. pilosus group. For the present, then, we leave the question unresolved. But, in any case, we have concluded that N. mandibularis is best regarded as a species apart from N. pilosus.

Male
Length 13 mm.

Head one and eight-tenths to one and nine-tenths times as broad as long. Ocelli large, placed on protuberance above general surface of head, summit of protuberance concave; space between inner border of eye and lateral ocellus less than half diameter of ocellus. Antenna short; scape robust, slightly shorter than combined length of first 4 funicular segments; funiculus very distinctly tapering from base toward apex, clearly wider through segments 2 to 5 inclusive than elsewhere. Toothlike convexity on superior border of mandible very faint, hardly discernible. Frontal carinae sharply margined but farther apart and more nearly parallel than with pilosum, and apparently also more deeply grooved. Clypeus excised. Eye large, convex, strongly protuberant. The large eye, in profile, occupies all of the side of the head except a narrow area above the base of the mandible, and a much larger area posterodorsad of the eye. Region of head posterior to ocelli smooth, concave, with well-defined occipital flange. Head, from above, with well-rounded posterior corners which merge into eyes without forming perceptible angles. Thorax strongly projecting anteriorly over head. Prothorax, from above, more truncate anteriorly, narrower, and with better defined humeri than in pilosum. Mesonotum with anteromedian and parapsidal lines. Epinotum with distinct longitudinal median groove where base and declivity meet, declivity concave. Tarsal claws faintly toothed. Dorsal surface of petiole in profile, most convex very far posteriorly; ventral surface with protuberance. Gaster elongate, moderately slender. Intermediate tooth of seventh gastric sternum short but somewhat more acute than that of pilosum. Paramere differing from that of pilosum in having a more truncate apex, and a more feebly developed tooth on the dorsal border.

Most of the head, the legs, and anterior portion of each gastric segment shining; remainder of body including appendages less shining, especially funiculi. Entire body with coarser punctate-shagreening than in pilosum.

Hairs yellowish, dense, and rather appressed on body; longer and more suberect to erect on head, legs, and venter of petiole. Hairs apparently longer and less appressed than those of pilosum.

Head, legs, and seventh gastric sternum darker than remainder of body and appenda:ges, which are yellowish brown. Color deeper than that of pilosum. Wings distinctly yellowish, with brownish veins and stigma.

Type Material
A holotype and one paratype in the United States National Museum bear U.S.N.M. No. 55464. The other paratype is in the collection of Cornell University. Thirty miles east of Quijotoa, Pima County, Ariz.

References based on Global Ant Biodiversity Informatics

 * Borgmeier T. 1955. Die Wanderameisen der neotropischen Region. Studia Entomologica 3: 1-720.
 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Fernandes, P.R. XXXX. Los hormigas del suelo en Mexico: Diversidad, distribucion e importancia (Hymenoptera: Formicidae).
 * Johnson R. Personnal Database. Accessed on February 5th 2014 at http://www.asu.edu/clas/sirgtools/resources.htm
 * Mackay W. P., and E. E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Lewiston, New York: Edwin Mellen Press, 400 pp.
 * Mackay, W.P. and E. *Mackay, W. P. and E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, NY.
 * Smith M. R. 1942. The legionary ants of the United States belonging to Eciton subgenus Neivamyrmex Borgmeier. American Midland Naturalist 27: 537-590.
 * Snelling G. C. and R. R. Snelling. 2007. New synonymy, new species, new keys to Neivamyrmex army ants of the United States. Memoirs of the American Entomological Institute 80: 459-550
 * Vasquez-Bolanos M. 2011. Checklist of the ants (Hymenoptera: Formicidae) from Mexico. Dugesiana 18(1): 95-133.
 * Vasquez-Bolanos M., and J. L. Navarrete-Heredia. 2004. Checklist of the ants (Hymenoptera: Formicidae) from Jalisco State, Mexico. Sociobiology 43(2): 351-365
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Watkins II, J.F. 1982.The army ants of Mexico (Hymenoptera: Formicidae: Ecitoninae). Journal of the Kansas Entomological Society 55(2): 197-247.