Veromessor julianus

This species uses column foraging to guide workers leaving and returning to the nest, as explained in the biology sections of Veromessor pergandei and  Veromessor andrei.

Identification Keys including this Taxon
Key to Veromessor species

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Nomenclature

 *  julianus. Aphaenogaster juliana Pergande, 1894: 164 (w.) MEXICO. Combination in Stenamma (Messor): Emery, 1895c: 308; in Aphaenogaster (Messor): Forel, 1899c: 59; in Novomessor: Emery, 1915d: 73; in Novomessor (Veromessor): Forel, 1917: 235; in Veromessor: Wheeler, W.M. & Creighton, 1934: 368; in Messor: Bolton, 1982: 341; in Veromessor: Ward et al., 2014: 13. Current subspecies: nominal plus clarior, manni. See also: Wheeler, W.M. & Creighton, 1934: 368.

Worker
Wheeler and Creighton (1934) – Length 5-8 mm.

Head in the largest workers sub quadrate, the length from the flat occipital border to the anterior margin of the clypeus very slightly exceeding the greatest width. Head widest just behind the eyes, the width slightly decreasing from that point to the insertion of the mandibles, sides straight or very slightly convex. In the smaller workers the head is somewhat more narrow, widest at the eyes, with the sides feebly convex and the occipital angles more broadly rounded, which gives the occipital border a slightly convex appearance. Clypeus short, scarcely projecting, the anterior edge with an irregular median impression, the median lobe not clearly marked off, the entire middle portion of the clypeus longitudinally striate. Frontal carinae narrow and rather short, feebly divergent in front, their lateral margins only moderately divergent behind and fusing with the head at a point on a level with the frontal area; the latter moderately depressed, and subopaque. Mandibles powerful, their exterior margin strongly and evenly curved; teeth poorly developed, the apical two much rounded and forming a terminal lobe at the junction of the outer and masticatory margins, the remainder of the masticatory margin serrate rather than toothed. Eyes oval, moderately convex, surrounded by a shallow and narrow groove. Antennal scapes straight and slender, the tips not noticeably swollen, the entire scape gradually increasing in diameter from base to apex. In repose the scape surpasses the occipital border by a distance slightly in excess of its greatest thickness. Funicular joints all notably broader than long, joints 2-6 of approximately the same diameter, the remaining joints increasing in thickness and forming a poorly developed terminal club.

Promesonotum seen from above subpentagonal, with the anterior border strongly convex, the two lateral and posterior borders more nearly straight. Promesonotal suture obsolete. Epinotum from above notably narrower than the pronotum, rectangular in outline, the sides not constricted at the mesoepinotal suture. Spines strongly divergent, straight, the apical two-thirds rather thin, the basal third decidedly thickened; length from base to apex slightly less than the distance between their tips. Seen in profile, the dorsum of the pronotum is feebly convex, that of the mesonotum virtually straight and sharply sloping, the epinotum much depressed, with straight basal and declivous faces which meet at a sharp angle. Declivous face of the epinotum approximately two-thirds as long as the basal face, the spines at their junction only slightly elevated, forming an angle of about twenty degrees with the plane of the basal face. Mesoepinotal suture not impressed.

Petiole in profile with a long, thick, tapering anterior peduncle which has neither ventral tooth nor lamella. Anterior face of the node sloping forward to form a broad angle with the dorsum of the peduncle. Posterior face of the node strongly convex, meeting the anterior face in a sharp angle at the summit of the node. Posterior peduncle very short. Postpetiole in profile with a rather long and narrow anterior peduncle, the node low, feebly convex above, its posterior face not constricted into a posterior peduncle but broadly applied to the first gastric segment. Seen from above, the petiole is narrow, bluntly cuneate in outline, with the broadest portion at the base of the node. Postpetiole trapezoidal, much narrowed in front and not at all constricted where it joins the gaster, which is large and oval.

Head shining, entirely covered with fine and rather even striae which are interrupted at intervals by small, shallow punctures. The striae on the front diverge from the midline toward the occipital angles where they are met by longitudinal striae which extend from the insertion of the mandibles to the occipital angles. Mandibles shining, with coarse longitudinal striae. Clypeus somewhat duller, the striae more irregular. Thorax subopaque, the pronotum with close-set, transverse rugae, those on the mesonotum and epinotum more widely separated and irregular. The interrugal spaces densely granulose over the entire thorax, especially on the sides of the pronotum where the granulation largely replaces the rugae. Lower portions of the petiole and postpetiole opaque, very finely granulose, the summits of the nodes, especially the postpetiole, shining. Gaster shining, feebly shagreened, with very small piligerous punctures. Hairs rather sparse. Gular ammochaetae consisting of about half a dozen long curved hairs on either side of the head. Anterior border of the clypeus with a few long hairs, the remaining hairs on head and thorax all shorter and very uneven in length. Abdominal hairs short and more nearly uniform in length. Femora, tibiae, and tarsi covered with numerous fine erect hairs. Those of the scapes and funiculi very fine but erect or suberect, except on the terminal funicular joints where they grade into pubescence.

Head dingy blackish red, the thorax somewhat clearer red, petiolar nodes and gaster piceous brown. Mandibles, antennae, and legs yellowish brown.

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Emery C. 1895. Beiträge zur Kenntniss der nordamerikanischen Ameisenfauna. (Schluss). Zoologische Jahrbücher. Abteilung für Systematik, Geographie und Biologie der Tiere 8: 257-360.
 * Johnson, R.A. 2000. Reproductive biology of the seed-harvester ants Messor julianus (Pergande) and Messor pergandei (Mayr) (Hymenoptera: Formicidae) in Baja California, Mexico. Journal of Hymenoptera Research 9(2):377-384.
 * Johnson, R.A. and P.S. Ward. 2002. Biogeography and endemism of ants (Hymenoptera: Formicidae) in Baja California, Mexico: a first overview. Journal of Biogeography 29:10091026/
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133