Anoplolepis steingroeveri

One of a few species of common, abundant Anoplolepis species in southern Africa that are well known - as pugnacious ants - to people living in areas where these ants occur. Anoplolepis steingroeveri are agressive, fast moving ants. When sensing anything that can be perceived as a threat workers will swarm and attack. Honeydew is part of their diet and Anoplolepis steingroeveri tending of honeydew producing pest species can lead to these ants causing problems in some agricultural settings.

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

Nomenclature

 *  steingroeveri. Plagiolepis steingroeveri Forel, 1894b: 72 (w.) NAMIBIA. Emery, 1895h: 44 (q.); Arnold, 1922: 591 (q.m.). Combination in Plagiolepis (Anoplolepis): Santschi, 1914b: 123; in Plagiolepis (Zealleyella): Arnold, 1922: 590; in Anoplolepis: Emery, 1925b: 18; in Anoplolepis (Zealleyella): Santschi, 1926a: 14. Senior synonym of braunsi: Prins, 1982: 217. Current subspecies: nominal plus gertrudae, parsonsi.
 * braunsi. Plagiolepis braunsi Forel, 1913a: 141 (w.) SOUTH AFRICA. Combination in Plagiolepis (Anoplolepis): Santschi, 1914b: 123; in Plagiolepis (Zealleyella): Arnold, 1922: 592; in Anoplolepis: Emery, 1925b: 17. Junior synonym of steingroeveri: Prins, 1982: 217.

Worker
Prins (1982) - TL 2,9-8,0 mm; L 1,80-3,90 mm; HL 0,76-1,80 mm; ED 0,52-1,36 mm; CL 0,22-0,60 mm; SL 0,88-1,64 mm; WL 1,16-2,24 mm; MFL 0,76-1,64 mm; HFL 1,04-2,08 mm; PL 0,14-0,36 mm; CI 100,0-111,1; SI 82,0-115,8; CLI 213,3-272,7; CTI 65,5-80,4; TI 41,4-55,4; PI 142,9-188,9; HFI 89,7-92,9.

Polymorphic as in case of the common pugnacious ant and usually somewhat darker in colour, varying from reddish-brown to almost piceous-brown or blackish-brown, and also more shiny. In major workers sides of the head, seen from above, more convex than in Anoplolepis custodiens; clypeus in lateral view also more convex medially, its anterior border, seen from above, more arcuate. The major workers are fairly easily distinguished from those of A. custodiens by the absence of the chequered pattern on the abdomen due to the fact that the pubescent hairs are arranged only in one direction on each side of the median line. On the abdomen of the minors, however, there are less pubescent hairs and they are also more shiny; they are therefore sometimes confused with the workers of the black sugar-ant Acantholepis capensis, or even with those of the brown house ant, Pheidole megacephala. A few pilose hairs occur on the body of all workers, as in the case of the other species.

Queen
Prins (1982) - Wing-span about 24,9 mm; TL 11,6-12,6 mm; L 5,2-6,4 mm; HL 1,76-1,96 mm; EK 1,56-1,70 mm; CL 0,44-0,52 mm; SL 1,6-1,7 mm; WL 3,6-4,6 mm; MFL 1,92-2,1 mm; HFL 2,36-2,6 mm; PL 0,4 mm; CI 113,6-117,4; SI 73,9-80,0; CLI 300,0-318,2; CTI 42,6-48,9; TI 58,7-63,9; PI 250,0; HFI 56,5-65,6.

Rather similar to female of A. custodiens, but smaller, and usually darker in colour, mostly brown to dark-brown; abdomen devoid of any chequered pattern, pubescent hairs arranged in one direction only on each side of median line. Generally somewhat more shiny than in the latter species and as in the case of the workers, the clypeus more convex, its anterior border more arcuate when seen from above.

Scale of petiole deeply emarginate above, emargination V-shaped; hind wing similar to that of Anoplolepis nuptialis, vein m + cua long, in most specimens seen, almost as long as the cell la. In specimens at hand, discoidal (or subdiscoidal) vein in front wings more weakly developed than in both A. custodiens and nuptialis and usually indistinct or even obsolete.

Male
Prins (1982) - Wing-span about 15,7 mm; TL 6,6-6,9 mm; L 3,6 mm; HL 1,12-1,16 mm; ED 0,80-0,84 mm; CL 0,28 mm; SL 1,30-1,36 mm; WL 2,6-2,7 mm; MFL 1,80 mm; HFL 1,92 mm; PL 0,24-0,28 mm; CI 110,7-117,2; SI 100,0-104,8; CLI 300,0-328,6; CTI 42,9-43,1; TI 61,5-62,2; PI 228,6-250,0; HFI 71,1-73,l.

Smaller than male of A. custodiens, sombre coloured, abdomen without chequered pattern, pubescent hairs more or less arranged as in female. Scale of petiole deeply emarginate, emargination V-shaped; clypeus and wings more or less as in female. In some specimens seen the marginal and cubital veins in front wings connected by a short stem to first cubital cell, rather similar to that of A. nuptialis.

External male genital organs

Differ from those of both A. custodiens and nuptialis in the longer penis lobes, which are longer than vol sellae and gonostipes; latter short and seen from side almost resembling those of A. nuptialis. Both digiti and cusp ides equally developed and more or less of same length. Each digitus with fine denticles or tubercles on its external side; cuspides each with a row of fine denticles on its distal half. Volsellae in this case flattened and only slightly convex on inner side; also covered with a few fine hairs as in case of the other two species.

References based on Global Ant Biodiversity Informatics

 * Arnold G. 1922. A monograph of the Formicidae of South Africa. Part V. Myrmicinae. Annals of the South African Museum 14: 579-674.
 * 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.
 * Dean, W. R. J. and Bond, W. J. 1990. Evidence for Rapid Faunal Changes on Islands in a Man-Made Lake. Oecologia. 83:388-391.
 * Emery C. 1895. Voyage de M. E. Simon dans l'Afrique australe (janvier-avril 1893). 3e mémoire. Formicides. Annales de la Société Entomologique de France 64: 15-56.
 * Forel A. 1910. Note sur quelques fourmis d'Afrique. Annales de la Société Entomologique de Belgique 54: 421-458.
 * 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.
 * Forel A. 1913. Fourmis de Rhodesia, etc. récoltées par M. G. Arnold, le Dr. H. Brauns et K. Fikendey. Annales de la Société Entomologique de Belgique 57: 108-147.
 * Hanrahan S. A., M. J. Steinbauer, and F. D. Duncan. 2014. Ant assemblages in a poorly sampled part of the arid Nama Karoo. African Entomology 22(2): 448453.
 * IZIKO South Africa Museum Collection
 * Lach, L. 2008. Argentine ants displace floral arthropods in a biodiversity hotspot. Diversity and Distributions 14:281-290
 * 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.
 * Mgocheki N., and P. Addison. 2010. Spatial distribution of ants (Hymenoptera: Formicidae), vine mealybugs and mealybug parasitoids in vineyards. Journal of Applied Entomology 134: 285295.
 * Prins A. J. 1967. The ants of our National Parks. Koedoe - African Protected Area Conservation and Science 10(1): 63-81.
 * Prins A. J. 1982. Review of Anoplolepis with reference to male genitalia, and notes on Acropyga (Hymenoptera, Formicidae). Annals of the South African Museum 89: 215-247.
 * Robertson H. G. 2000. Formicidae (Hymenoptera: Vespoidea). Cimbebasia Memoir 9: 371-382.
 * Santschi, F. "Résultats de la Mission scientifique suisse en Angola, 1928-1929. Formicides de l'Angola." Revue Suisse de Zoologie 37 (1930): 53-81.
 * Stitz H. 1923. Hymenoptera, VII. Formicidae. Beiträge zur Kenntnis der Land- und Süsswasserfauna Deutsch-Südwestafrikas 2: 143-167.
 * 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