Novomessor cockerelli

A common and abundant species in some parts of its range, and the most common member of the genus in New Mexico. Nests are usually found in the soil with the entrance surrounded by a circle of pebbles with a diameter of about 50 cms. Even nests under stones usually have the entrance surrounded by pebbles. Most nests are found in rocky soil, although they may nest in sandy soils, even dunes. Individual foragers are usually found during early morning and late afternoon or evening, and occasionally during the night. Foraging occurs throughout the day during the cool part of the year or even on cloudy days during the summer. These ants are omnivorous. Prey usually consists of dead or dying insects, parts of plants and seeds. This species is very aggressive, but cannot sting; the bite is very fastidious when large numbers are attacking.

Identification
This ant is easily distinguished, as it is a large, elongate species with long legs and two well-developed spines on the propodeum. The metanotal suture is poorly marked on the dorsum of the mesosoma. Its elongate head usually distinguishes it from the closely related Novomessor albisetosus, although the two species can be difficult to separate. It can be easily separated from the similar Mexican species, Novomessor ensifera, by the lack of the constricted neck.

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



Biology
Known from habitats including Creosotebush scrub, the most arid of habitats, fluff grass, open areas with annuals, usually at elevations below 1500 m.

Nests are usually found in the soil with the entrance surrounded by a circle of pebbles. Even nests under stones usually have the entrance surrounded by pebbles. Most nests are found in rocky soil, although they may nest in sandy soils, even dunes. Individual foragers are usually found during early morning and late afternoon or evening, and occasionally during the night. Foraging occurs throughout the day during the cool part of the year or even on cloudy days during the summer. These ants are omnivorous. Prey usually consists of dead or dying insects, parts of plants and seeds. This species is very aggressive but cannot sting. (Mackay and Mackay 2002)

Wheeler and Wheeler (1986) summarized previous published accounts about the biology of these ants:

"In the dry deserts of western Texas, I have seen ... cockerelli bring its larvae and pupae out onto the large crater of the nest about 9 P.M. and carry them leisurely to and fro" (W.M. Wheeler, 1910:69). He also (1910:178) saw straggling workers "returning from all directions to their nests just as the cold December twilight was setting in. Each worker bore in her slender jaws a fellow worker that she had picked up while on her way home.

"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.... Toward the center of the disc there is often a thicker pile of soil and gravel which has been formed into a rude crater" (Wheeler and Creighton, 1934:346-347).

"There is little structural modification and practically no trophic adaptation which would mark them as well developed xerophiles" (Wheeler and Creighton, 1934:344).

"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 ... would scarcely permit successful predatism. Little if any of the various substances brought into the nest are stored there" (Wheeler and Creighton, 1934:346-347).

Nevada, Wheeler and Wheeler (1986) - We have 10 records from 7 localities. All are in the Hot Desert in the southern tip of the state. Nest entrances huge and irregular, 12-50 mm across and surrounded by a disc or low crater or half-crater of gravel about 60 cm in diameter (see Fig. 22). Workers bit but did not sting. R.C. Bechtel collected nymphs of Arenivaga sp. (Orthoptera: Polyphagidae) at Searchlight (Clark Co.) in a nest.

Nomenclature

 *  cockerelli. Aphaenogaster (Ischnomyrmex) cockerelli André, 1893b: 150 (w.) MEXICO. Wheeler, W.M. & Creighton, 1934: 350 (q.m.); Wheeler, G.C. & Wheeler, J. 1960b: 10 (l.). Combination in Stenamma (Ischnomyrmex): Forel, 1901c: 128; in Novomessor: Emery, 1915d: 73; in Aphaenogaster: Brown, 1974b: 47; in Novomessor: Demarco & Cognato, 2015: 5. Senior synonym of sonorae: Wheeler, W.M. & Creighton, 1934: 352. See also: Wheeler, G.C. & Wheeler, J. 1972b: 239; Hölldobler, Stanton & Engel, 1976: 32; Hölldobler, Stanton & Markl, 1978: 163; Smith, D.R. 1979: 1360; Bolton, 1982: 340.
 * sonorae. Aphaenogaster sonorae Pergande, 1893: 34 (w.) MEXICO. Combination in Novomessor: Emery, 1915d: 73. Junior synonym of cockerelli: Wheeler, W.M. & Creighton, 1934: 352.