Veromessor andrei

Although built in open areas the nests are not particularly conspicuous. There is usually no crater, but the nest entrance is surrounded by an area of gravel which, because of its irregularity, can hardly be called a disc. The workers forage in files and collect seeds which are apparently stored in the nest, to judge from the chaff which surrounds the nest entrance. This chaff is scattered about and not formed into a crescent or ring as in the case of pergandei. Very little is known of the mating habits of andrei. Sexual forms which we have examined have been collected from June to September 15. In view of the occurrence of the species in the northern part of California, it seems likely that the marriage flight takes place early in the spring. (Wheeler and Creighton 1934)

Identification Keys including this Taxon
Key to Veromessor species

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

Foraging
Plowes et al (2014) - Three Nearctic seed harvesting ants in the genus Veromessor (Veromessor pergandei, Veromessor  andrei, and Veromessor  julianus) employ column foraging to guide workers leaving and returning to the nest. for distributing workers searching for food outside the nest. When foraging first begins for the day, thousands of V. andrei workers emerge from their colony and move along a narrow path away from the nest. These paths, the foraging column, extend from 3 to more than 40 m. At the location where the foraging column comes to an end, workers then disperse in a foraging fan, i.e., individuals leave the trail and forage independently, then return to the column after they have collected a food item (Went et al. 1972; Bernstein 1975; Wheeler and Rissing 1975). Columns may form trunk trails when they lead to a more stable resource (Plowes et al. 2013). The direction taken by a column is determined at the beginning of each foraging bout. Columns always originate at the nest and direction may change between morning and evening and between subsequent days (e.g., Clark and Comanor 1973). In V. andrei, foraging columns often follow the same direction for several successive foraging bouts. The columns function to direct workers to harvesting sites while simultaneously avoiding neighbors (Ryti and Case 1988; Plowes et al. 2014). Inter-colony aggression occurs when columns from neighboring colonies intersect (Wheeler and Rissing 1975; Brown and Gordon 2000).

Plowes et al (2014) combined behavioral analyses in the laboratory and field to investigate chemical communication in the formation of foraging columns in two Nearctic seed harvesting ants, Veromessor pergandei and Veromessor andrei. In the laboratory, V. pergandei were found to use poison gland secretions to lay recruitment trails. GCMS analysis of V. andrei poison glands revealed several volatile substances. Their mass spectra and retention time matched those of (1) 1-phenylethanol (1PE); (2) tridecane; (3) E2-hexadecen-1-ol; (4) pentadecane; (5) hexadecenoic acid; (6) oleic acid; (7) 2-propenoic acid, [3-(4-methoxyphenyl)-, 2-ethylhexyl ester]. A 3 μl of a 0.5–1 ppm solution of 1-phenyl ethanol drawn out along a 40 cm long trail released trail following behavior.

Nomenclature

 *  andrei. Aphaenogaster andrei Mayr, 1886d: 448 (w.) U.S.A. Emery, 1895c: 306 (q.); Wheeler, G.C. & Wheeler, J. 1972b: 240 (l.); Taber & Cokendolpher, 1988: 95 (k.). Combination in Stenamma (Messor): Emery, 1895c: 306; in Novomessor: Emery, 1915d: 73; in N. (Veromessor): Forel, 1917: 235; in Veromessor: Wheeler, W.M. & Creighton, 1934: 362; in Messor: Bolton, 1982: 341; in Veromessor: Ward et al., 2014: 13. Senior synonym of castaneus (and its junior synonym flavus): Creighton, 1953a: 3. See also: Smith, D.R. 1979: 1364.
 * castaneus. Veromessor andrei subsp. castaneus Wheeler, W.M. & Creighton, 1934: 365 (w.) U.S.A. Senior synonym of flavus: Creighton, 1950a: 159. Junior synonym of andrei: Creighton, 1953a: 3.
 * flavus. Veromessor andrei subsp. flavus Wheeler, W.M. & Creighton, 1934: 366 (w.) U.S.A. Junior synonym of castaneus: Creighton, 1950a: 159.

Worker
Wheeler and Creighton (1934) - Length: 4.5-7 mm.

Head, exclusive of the mandibles, four-fifths as broad as long, slightly wider behind the eyes than in front of them, the sides in front of the eyes straight, behind the eyes slightly convex and meeting the occiput in a broadly rounded angle. Occipital border with a broad though very shallow median concavity. Border of the clypeus straight or at most very feebly convex, the median portion feebly sulcate, the lateral portions raised into a narrow ridge or welt which bounds the anterior edge of the antennal fossa. Frontal area opaque. Frontal carinae very narrow and welt-like, slightly divergent above the insertion of the scapes, much more divergent posteriorly where they fuse with the sculpture of the head at a point just behind the posterior border of the antennal fossae. Eyes of moderate size, oval in outline, strongly eon vex, with about sixteen facets in their greatest diameter, their posterior border lying at a point half way between the insertion of the mandible and the occipital border. Antennal scapes slender, the proximal portion dilated to form a trumpet-shaped expansion, distal to this the median portion of the scape somewhat constricted, the apical end only slightly swollen and no larger in diameter than the flared proximal end. When in repose the tip of the scape just reaches the occipital border. Funicular joints, with the exception of the last three, all longer than broad, especially the first joint, which is more than twice as long as broad; joints ten and eleven only slightly longer than broad and notably thicker than the preceding joints, the terminal joint bluntly pointed, longer but no thicker than the preceding two. Mandibles large and stout with the evenly curved outer edge meeting the masticatory margin in a powerful two-cusped terminal tooth. The remaining six or seven teeth much smaller, forming a concave serrated edge to the masticatory margin, the latter meeting the straight inner margin of the mandible at a right angle.

Thorax, seen in profile, with a gibbous promesonotum, the promesonotal suture marked by a somewhat flattened area but not forming a distinct depression; epinotum greatly depressed, the mesoepinotal suture broad and strongly impressed; basal face of the epinotum virtually flat, sloping slightly backward, terminating in two large, straight, divergent spines, which slightly exceed the length of the basal face of the epinotum; declivous face of the epinotum short and concave. Seen from above, the promesonotum is pyriform and notably wider than the rest of the thorax, the sides of the thorax very slightly constricted at the mesoepinotal suture, sides of the epinotum virtually parallel. First joint of the petiole with a rather thick peduncle, which gradually increases in thickness from its anterior end to the base of the node, its ventral surface with a sharp anterior tooth and a low, rounded lamella at its midpoint. Node of the petiole small, its height no greater than the thickness of the peduncle, its anterior face forming a continuous feebly concave slope with the dorsum of the peduncle, the summit acute, the posterior face very declivous and strongly convex, posterior peduncle extremely short. Postpetiole in profile lower than the petiole, the node low and rounded above, with the anterior face longer though less declivous than the posterior face, ventral surface with a prominent V-shaped median impression. Seen from above, the rather narrow petiole is scarcely two-thirds as wide as the campanulate postpetiole. Gaster large. Legs long, the femora slightly swollen.

Head sub opaque, completely covered with rather coarse, wavy rugae which diverge toward the occiput. The interrugal spaces finely granulose and feebly shining. Mandibles shining, with moderately prominent longitudinal striae. Antennal scapes feebly granulose, more shining than the head. Thorax somewhat more opaque than the head, completely covered with irregular rugae, except at the front and lateral edges of the pronotum where they are subparallel. Petiole and postpetiole strongly granulose, with a few short rugae. Gaster smooth and shining, with numerous fine piligerous punctures.

Entire insect covered with glistening whitish hairs which are very unequal in length; the gular hairs forming rather poorly developed ammochaetae, longer than the majority of hairs on the head and thorax but almost equalled in length by a few long hairs which occur on the upper surface of the head, the pronotum, and the coxae of the fore legs. Dorsum of the first gastric segment entirely covered with hairs which are relatively short and more nearly of equal length than those on the head and thorax. Hairs on the remaining abdominal segments confined to the posterior border of each segment. Antennal scapes, femora, and tibiae with numerous, short, erect hairs; those on the tarsi somewhat finer and subappressed; funicular hairs very fine, short, and subappressed, except on the last four joints where they are replaced by golden pubescence.

Color variable. In some specimens the entire insect is reddish black, except for the nodes of the petiole which are reddish. In other specimens only the posterior part of the gaster is black, the first gastric segment castaneous and the remainder of the insect clear, deep red. Not infrequently both the head and gaster are infuscated, leaving only the thorax and nodes of the petiole red.