Messor denticornis

Identification
A distinctive species amongst those with uniformly distributed pilosity on the first gastral tergite, denticornis is immediately isolated by its relatively large eyes. Only a few workers of Messor tropicorum approach even the lower end of its eye size range but in the latter species the clypeus has a conspicuous posteromedian tumulus or welt and the propodeum is shorter and higher in profile than is the case in denticornis. (Bolton 1982)

Distribution based on Regional Taxon Lists
Afrotropical Region: Botswana, Namibia, South Africa.

Nomenclature

 * . Messor denticornis Forel, 1910f: 14 (w.q.m.) NAMIBIA.
 * Type-material: syntype workers, syntype queens (numbers not stated), 1 syntype male.
 * Type-locality: Namibia (“German Southwest Africa”): Lüderitzbucht, 1903 (L. Schultze).
 * [Note: Forel records other specimens (not syntypes?) from Namibia: Little Namaland, Kamaggas (L. Schultze), and Little Namaland, Steinkopf (L. Schultze).]
 * Type-depositories: BMNH, MHNG.
 * Status as species: Arnold, 1920a: 411; Emery, 1921f: 74; Wheeler, W.M. 1922a: 806; Stitz, 1923: 148; Bolton, 1982: 349 (redescription); Marsh, 1986: 341; Bolton, 1995b: 253.
 * Senior synonym of brunni: Bolton, 1982: 349; Bolton, 1995b: 253.
 * Senior synonym of parvidens: Bolton, 1982: 349; Bolton, 1995b: 253.
 * Distribution: Botswana, Namibia, South Africa.
 * brunni. Messor denticornis var. brunni Forel, 1910e: 444 (w.) NAMIBIA, SOUTH AFRICA.
 * Type-material: syntype workers (number not stated).
 * Type-localities: Namibia (“Afrique Sud-Ouest”): (no further data) (Brunn), South Africa: Cape Prov., Steckstown (Wartmann).
 * Type-depository: MHNG.
 * Subspecies of denticornis: Arnold, 1920a: 413; Emery, 1921f: 74; Wheeler, W.M. 1922a: 806.
 * Junior synonym of denticornis: Bolton, 1982: 349; Bolton, 1995b: 253.
 * parvidens. Messor denticornis var. parvidens Forel, 1910f: 15 (w.) NAMIBIA, SOUTH AFRICA.
 * Type-material: syntype workers (number not stated).
 * Type-locality: Namibia (“German Southwest Africa”): Great Namaland, Kubub, 1903 (L. Schultze).
 * [Note: Forel records other specimens (not syntypes?) from South Africa: Cape Prov., Steckstown (Wartmann).]
 * Type-depository: MHNG.
 * Subspecies of denticornis: Arnold, 1920a: 413; Emery, 1921f: 74; Wheeler, W.M. 1922a: 806.
 * Junior synonym of denticornis: Bolton, 1982: 349; Bolton, 1995b: 256.

Worker
Bolton (1982) - Medium to Large, HW 2.48- > 3.10.

Anterior clypeal margin usually evenly convex medially, only rarely with the faintest trace of a central indentation. With the head in full-face view the sides more or less straight and diverging anteriorly, but sometimes the sides more nearly parallel. Occipital margin broadly but shallowly concave, this feature fading out in smaller workers where the margin is approximately transverse. In HW range 2.48-3.16 the maximum diameter of the eye is 0.56-D.70, about 0.21-0.25 x HW, and the CI range is 100-106. Propodeum in profile relatively long and low, resembling that of striatifrons. Propodeal armament very variable, the junction of dorsum and declivity being rounded, acutely angled or distinctly bidentate. These variants are commonly seen in the same series and are in fact shown by the type-series of denticornis itself. Basic sculpture of the head finely densely packed parallel longitudinal rugulae with punctulate ground-sculpture between them. Frequently the sculpture much reduced, either by suppression of the ground-sculpture so that the rugulae stand out from a smooth surface or by reduction of the rugulae in number and intensity so that the head is mostly or wholly punctulate. In smaller individuals the surface may be almost smooth. Dorsal alitrunk rugulose to rugose, the sculpture sometimes partially or totally effaced from the pronotum. First gastral tergite smooth and shining or at most with faint superficial pattering. All dorsal surfaces of head and body with numerous standing hairs. Colour mid-brown to black, sometimes with the gaster darker than the head and alitrunk.

References based on Global Ant Biodiversity Informatics

 * Arnold G. 1920. A monograph of the Formicidae of South Africa. Part IV. Myrmicinae. Annals of the South African Museum. 14: 403-578.
 * Bolton B. 1982. Afrotropical species of the myrmicine ant genera Cardiocondyla, Leptothorax, Melissotarsus, Messor and Cataulacus (Formicidae). Bulletin of the British Museum (Natural History). Entomology 45: 307-370.
 * Branstetter M. G. 2012. Origin and diversification of the cryptic ant genus Stenamma Westwood (Hymenoptera: Formicidae), inferred from multilocus molecular data, biogeography and natural history. Systematic Entomology 37: 478-496.
 * Campbell H., M. D. E. Fellowes, and J. M. Cook. . Species diversity and dominance-richness relationships for ground and arboreal ant (Hymenoptera: Formicidae) assemblages in Namibian desert, saltpan, and savannah. Myrmecological News 21: 37-47.
 * Forel A. 1910. Zoologische und anthropologische Ergebnisse einer Forschungsreise im westlichen und zentralen Südafrika ausgeführt in den Jahren 1903-1905 von Dr. Leonhard Schultze. Vierter Band. Systematik und Tiergeographie. D) Formicidae. Denkschriften der Medizinisch-Naturwissenschaftlichen Gesellschaft zu Jena 16: 1-30.
 * IZIKO South Africa Museum Collection
 * Koch F., and K. Vohland. 2004. Ants along a southern African transect - a basis for biodiversity change monitoring (Insecta, Hymenoptera, Formicidae). Zoosystematics and Evolution 80(2): 261-273.
 * Marsh A. C. 1985. Forager abundance and dietary relationships in a Namib Desert ant community. S. Afr. J. Zool. 20: 197-203.
 * Marsh A. C. 1986. Ant species richness along a climatic gradient in the Namib Desert. Journal of Arid Environments 11: 235-241.
 * Marsh A. C. 1986. Checklist, biological notes and distribution of ants in the central Namib Desert. Madoqua 14: 333-344.
 * Robertson H. G. 2000. Formicidae (Hymenoptera: Vespoidea). Cimbebasia Memoir 9: 371-382.
 * Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bulletin of the American Museum of Natural History 45: 711-1004