Veromessor chamberlini

Identification
Superficially chamberlini resembles a small worker of Veromessor andrei but it may be easily distinguished from that species by the flattened base of the antennal scape, broader head, shorter epinotal spines, uniformly feebler sculpture, and notably sparser pilosity.

Identification Keys including this Taxon
Key to Veromessor species

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

Nomenclature

 *  chamberlini. Messor chamberlini Wheeler, W.M. 1915b: 410 (w.) U.S.A. Wheeler, G.C. & Wheeler, J. 1972b: 240 (l.). Combination in Veromessor: Wheeler, W.M. & Creighton, 1934: 366; in Messor: Bolton, 1982: 341; in Veromessor: Ward et al., 2014: 13. Subspecies of andrei: Enzmann, J. 1947b: 152. Revived status as species: Creighton, 1950a: 159.

Worker
Wheeler and Creighton (1934) - Length 4 mm.

Head, exclusive of the mandibles, as broad as long, the sides very slightly narrowed from a point just posterior to the eyes to the insertion of the mandibles. Occiput flat, its angles very broadly rounded. Anterior border of the clypeus virtually straight, the median lobe very shallowly impressed in front and with two feeble carinae. Mandibles large, their external border strongly curved; masticatory margin with two sharp, prominent, terminal teeth and a row of denticles along the rest of the margin. Frontal carinae prominent, moderately divergent anteriorly and strongly divergent behind. The antennal scapes in :repose fail to reach the occipital border by a distance less than their greatest thickness; the proximal end of the scape flattened and forming a spatulate portion which is wider than the feebly clavate tip. First funicular joint slightly shorter than the following two together; funicular joints 2-7 all longer than broad though gradually increasing in thickness, the remaining four joints much more thickened and forming a distinct club. Eyes rather small, feebly convex, suboval, situated at the middle of the side of the head.

Promesonotum in profile strongly though somewhat irregularly convex, with the mesonotum descending abruptly to the much lower epinotum, the mesoepinotal suture feebly impressed. Dorsum of the epinotum very feebly sinuate and much longer than the declivous face, the angle between them armed with two long, feebly arcuate spines which are thin toward the tips but rather thick toward the base. Seen from above, the promesonotum is sub pyriform and notably wider than the remainder of the thorax, with the promesonotal suture obsolescent but rather clearly visible in certain lights. Sides of the thorax not constricted at the mesoepinotal suture, the epinotal spines only moderately divergent and approximately as long as the distance between their tips. Petiole in profile with a long anterior peduncle, which lacks a ventral tooth and increases slightly in diameter toward the node. The sloping anterior face of the node meets the peduncle in a very wide angle, the summit of the node is rounded, the posterior face short and abrupt. The posterior peduncle is short and forms a distinct angle at its junction with the node. Postpetiole in profile with a bluntly angular dorsum and a sinuate ventral face. Seen from above the peduncle of the petiole is compressed anteriorly by two semicircular constrictions, posterior to which it gradually increases in width. Postpetiole from above subpyriform only slightly less than twice as wide as the node of the petiole. Gaster small, oval. Head entirely covered with fine rugae which diverge from the median line toward the occipital angles; interrugal spaces feebly granulose and somewhat shining. Mandibles with coarse longitudinal striae, feebly shining. Clypeus granulose, opaque except for the median lobe which is rather strongly shining. Frontal area opaque. Antennal scapes smooth, strongly shining. Thorax, except for the pronotum where the rugae are transversely arcuate, entirely covered with strong irregular longitudinal rugae, somewhat more shining than the head. Petiolar nodes very feebly granulose, somewhat shining. Gaster very smooth and shining, the small piligerous punctures scarcely visible. Hairs very irregular both in length and thickness. Gular ammo chaetae very poorly developed, consisting of only a few, fine, long hairs. Clypeus with a fringe of rather stout, golden hairs of irregular length. Front, vertex, and occiput with a number of short, fine, whitish hairs many of which are suberect. Thoracic hairs abundant over the entire dorsum and very irregular in length. Petiole, postpetiole, and gaster with abundant whitish hairs which are more uniform in length than those of the thorax. Femora with a few short erect hairs, those of the tibiae, tarsi, and antennal scapes finer, more numerous, and sub erect. Head and thorax dear, ferruginous red, nodes of the pedicel a duller red, base of the gaster yellowish red, femora, tibiae, and posterior gastric segments piceous brown.

References based on Global Ant Biodiversity Informatics

 * Adams T. A., W. J. Staubus, and W. M. Meyer. 2018. Fire impacts on ant assemblages in California sage scrub. Southwestern Entomologist 43(2): 323-334.
 * Johnson R. Personnal Database. Accessed on February 5th 2014 at http://www.asu.edu/clas/sirgtools/resources.htm
 * Mallis A. 1941. A list of the ants of California with notes on their habits and distribution. Bulletin of the Southern California Academy of Sciences 40: 61-100.
 * Smith M. R. 1956. A key to the workers of Veromessor Forel of the United States and the description of a new subspecies (Hymenoptera, Formicidae). Pan-Pacific Entomologist 32: 36-38.
 * Staubus W. J., E. S. Boyd, T. A. Adams, D. M. Spear, M. M. Dipman, W. M. Meyer III. 2015. Ant communities in native sage scrub, non-native grassland, and suburban habitats in Los Angeles County, USA: conservation implications. Journal of Insect Conservervation 19:669–680
 * Wetterer, J. K.; Ward, P. S.; Wetterer, A. L.; Longino, J. T.; Trager, J. C.; Miller, S. E. 2000. Ants (Hymenoptera: Formicidae) of Santa Cruz Island, California. Bulletin of the Southern California Academy of Sciences 99:25-31.
 * Wetterer, J.K., P.S. Ward, A.L. Wetterer, J.T. Longino, J.C. Trager and S.E. Miller. 2000. Ants (Hymenoptera:Formicidae) of Santa Cruz Island, California. Bulletin of the Southern California Academy of Science 99(1):25-31.
 * Wheeler W. M. 1915. Some additions to the North American ant-fauna. Bull. Am. Mus. Nat. Hist. 34: 389-421.
 * Wheeler W. M., and W. S. Creighton. 1934. A study of the ant genera Novomessor and Veromessor. Proceedings of the American Academy of Arts and Sciences 69: 341-387.
 * Wheeler W.M. 1935. Check list of the ants of Oceania. Occasional Papers of the Bernice Pauahi Bishop Museum 11(11):1-56.