Novomessor

A small genus of xeriphilous ants that inhabit the desert southwest of North America.

Identification
Demarco and Cognato (2015) - Morphological characters that separate Novomessor from Aphaenogaster include a head width and length each of greater than 2mm, and a striated frontal triangle above the clypeus. The intraocular distance is 1.4mm or greater. The distance between the tips of the spines is greater than 0.56mm and the spine length is 1mm or longer. The Weber’s length is 3mm or greater, and the promesonotal suture is indistinct or absent. Characters that diagnose Messor from Novomessor include a large metasternal process in Messor, which is smaller in Novomessor, and a quadrate head in Messor, which is elongate in Novomessor. In addition, Novomessor has no constriction of the postpetiole at the gaster, Messor and Veromessor have a slight constriction, and Aphaenogaster has a strong constriction.

Distribution
Demarco and Cognato (2015) - Novomessor albisetosus and Novomessor cockerelli occur in southeastern Arizona, southern New Mexico, southwestern Texas, and northern Mexico at elevations from 150 to 300 m. N. cockerelli is found on the desert floor, with large, crater-like nest entrances surrounded by coarse gravel. N. albisetosus is found near N. cockerelli, but their nests occur in the desert foothills, under flat rocks or stones, and are surrounded by gravel. Novomessor ensifer has only been found in Mexico, in sandy soil with large stones present (Kannowski 1954).

Biology
Demarco and Cognato (2015) - Both Novomessor cockerelli and Novomessor albisetosus forage late in the day and into evening, and feed upon small insects, seeds, and bits of plant tissue (Cook, 1953). Kannowski (1954) describes a different foraging pattern for Novomessor ensifer. He observed them foraging in the early morning and late afternoon, and also only observed them feeding on insects, but no plant material. He also found no plant pieces or seeds in their nests.

Nomenclature

 * NOVOMESSOR [junior synonym of Aphaenogaster]
 * Novomessor Emery, 1915d: 73. Type-species: Aphaenogaster (Ischnomyrmex) cockerelli, by original designation.
 * Novomessor junior synonym of Aphaenogaster: Brown, 1974b: 47.
 * Novomessor revived from synonymy: Hölldobler, Stanton & Engel, 1976: 32.
 * Novomessor junior synonym of Aphaenogaster: Bolton, 1982: 364 (discussion pp. 339-341); Bolton, 1994: 106.
 * Novomessor revived from synonymy: Demarco & Cognato, 2015: 5.

Description
Demarco and Cognato (2015) - Workers in Novomessor are 8–8.5mm in length and reddish brown. The head in all three species is longer than it is wide, the mesosoma has long transverse rugae, and the gaster is darker than the head. Novomessor albisetosus and Novomessor cockerelli have long hairs under the head resembling a psammophore, while Novomessor ensifer has only short hairs. They have well-developed propodeal spines, averaging 1mm in length. N. albisetosus and N. cockerelli can be difficult to distinguish from each other, but the long wavy rugae on the head end at the top of the eyes in N. cockerelli and extend to the occiput in N. albisetosus.