Novomessor albisetosus

This is the second most common species of the genus in the arid regions of the Southwestern United States and northern México (after Novomessor cockerelli). Nests are usually found under stones with the entrance surrounded by gravel. These ants are very aggressive and although they cannot sting, their bite is irritating (Mackay and Mackay 2002).

Identification
This species can be distinguished from species of Aphaenogaster by the poorly marked metanotal suture, long legs and well-developed spines on the propodeum. Most workers can be distinguished from the closely related Novomessor cockerelli as they have a less elongate head. Specimens of these two species are often difficult to separate. It can be easily separated from the Mexican species Novomessor ensifera by the lack of a constricted neck.

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



Biology
Habitats range from Chihuahuan Desert to oak forests. When found in arid ecosystems, it usually occurs in the bottoms of arroyos or in areas near water. The soil in these areas is often rocky with boulders.

Wheeler and Creighton (1934) - It is unlikely that anyone who has seen the nests of these insects could have failed to be impressed with their extraordinary coarseness of construction. There is not a single feature of the nest which does not appear abnormally large in view of the size of the insects themselves. The irregular central opening of the nest may be three or four inches across. Through this one looks down into a steeply descending, roughly constructed tunnel which more nearly resembles a rat's burrow than the entrance to an ant's nest. Around the central opening the insects ordinarily build a disc of very coarse gravel mixed with excavated soil. This disc may be six feet in diameter in Novomessor cockerelli but is usually smaller and sometimes absent in N. albisetosus. Toward the center of the disc there is often a thicker pile of soil and gravel which has been formed into a rude crater. Nests of albisetosus whick lack the disc and crater are generally constructed under stones but otherwise do not differ from the nests of the more common type.

During the summer months the foraging activities of these insects begin late in the afternoon and continue through the night hours.... As a rule by the middle of the morning the workers have returned to the nest where they remain during the midday hours. When foraging the workers do not form files. Each stalks slowly about in a deliberate manner, which gives it a ludicrous air of bland solemnity. It may be doubted if these insects are capable of quick movement since, even when disturbed, their best efforts at speed are neither rapid nor sustained. The workers show no particular preference for seeds since, in addition to these, they gather small bits of plant tissue, pieces of fruit, and the disarticulated parts of insects. The latter are probably secured from insects which are dead or in a moribund condition since the slow movements of Novomesser would scarcely permit successful predatism. Little if any of the various substances brought into the nest are stored there.

Nomenclature

 *  albisetosus. Aphaenogaster albisetosa Mayr, 1886d: 446 (w.) U.S.A. Wheeler, W.M. & Creighton, 1934: 350 (q.m.); Wheeler, G.C. & Wheeler, J. 1953b: 70 (l.). Combination in Stenamma (Aphaenogaster): Emery, 1895c: 306; in Novomessor: Emery, 1915d: 73; in Aphaenogaster: Brown, 1974b: 47; in Novomessor: Demarco & Cognato, 2015: 5. Senior synonym of minor Enzmann: Brown, 1949a: 49. See also: Hölldobler, Stanton & Engel, 1976: 32; Hölldobler, Stanton & Markl, 1978: 163; Smith, D.R. 1979: 1360; Bolton, 1982: 340.
 * minor. Novomessor cockerelli var. minor Enzmann, J. 1947b: 148, pl. 8 (w.) U.S.A. [Unresolved junior secondary homonym of Aphaenogaster minor André, 1883b: 355, above.] Junior synonym of albisetosus: Brown, 1949a: 49.