Neivamyrmex mandibularis

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

 *  mandibularis. Eciton (Neivamyrmex) pilosum subsp. mandibulare Smith, M.R. 1942c: 548, pl. 3, fig. 14 (m.) U.S.A. Combination in Neivamyrmex: Borgmeier, 1955: 375. Raised to species: Snelling, G.C. & Snelling, R.R., 2007: 478.

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.