Tetraponera ambigua

This species is a generalist inhabitant of dead twigs, and appears to be more common in semi-arid environments than in rainforest.

Identification
A member of the Tetraponera ambigua-group.

Ward (2006) - Within the T. ambigua-group the worker of this species is characterized by its intermediate size, relatively small eyes (REL2 0.54 - 0.60), relatively flat profile of the mesosoma dorsum, and abundant standing pilosity. There is some variability in the configuration of the median clypeal lobe, shape of the petiole and details of sculpture – as might be expected in a widespread species – but the variation appears to be continuous and is consistent with the hypothesis of a single polytypic species. Of course, a more detailed genetic and phenotypic analysis might reverse this judgment.

Distribution
This widespread species is found from the Arabian Peninsula and the Sahara south to South Africa.

Distribution based on Regional Taxon Lists
Afrotropical Region: Angola, Botswana, Cameroun, Democratic Republic of Congo, Djibouti, Gabon, Kenya, Mozambique, Namibia, Saudi Arabia, Senegal, Somalia, South Africa, Sudan, United Arab Emirates, United Republic of Tanzania, Yemen, Zimbabwe. Palaearctic Region: Algeria, Egypt, Ethiopia, Israel, Libya.

Biology
It is dimorphic with soldiers and workers. Found nesting in dead twigs in dry habitats.

Nomenclature

 *  ambigua. Sima ambigua Emery, 1895h: 23 (w.q.) SOUTH AFRICA. Forel, 1910f: 5 (m.). Combination in S. (Tetraponera): Arnold, 1916: 185; in Tetraponera: Wheeler, W.M. 1922a: 796. [Sima ambigua Forel, 1894b: 89. Nomen nudum, attributed to Emery.] Senior synonym of angolensis, bifoveolata, encephala, erythraea, maculifrons, occidentalis, rhodesiana, syriaca: Ward, 2006: 123.
 * bifoveolata. Sima bifoveolata Mayr, 1895: 146 (w.) MOZAMBIQUE, TANZANIA (Zanzibar I.).
 * [Misspelled as foveolata by Santschi, 1912b: 162.]
 * Menozzi, 1926a: 37 (q.).
 * Combination in S. (Tetraponera): Arnold, 1916: 184; Emery, 1921f: 27;
 * combination in Tetraponera: Wheeler, W.M. 1922a: 796.
 * Status as species: Mayr, 1904b: 4; Arnold, 1916: 184; Emery, 1921f: 27; Wheeler, W.M. 1922a: 796; Menozzi, 1926a: 37; Menozzi, 1930b: 81; Santschi, 1935b: 266; Finzi, 1936: 157; Collingwood, 1985: 240; Kugler, J. 1988: 256; Bolton, 1995b: 417; Collingwood & Agosti, 1996: 312; Taylor & McGavin, 2020: 14.
 * Junior synonym of ambigua: Ward, 2006: 123; Collingwood, et al. 2011: 421.
 * erythraea. Sima ambigua subsp. erythraea Emery, 1895h: 23 (w.) YEMEN.
 * [Sima ambigua susbp. erythraea Emery, 1893f: 256. Nomen nudum.]
 * Combination in S. (Tetraponera): Emery, 1921f: 27;
 * combination in Tetraponera: Wheeler, W.M. 1922a: 796.
 * Subspecies of ambigua: Stitz, 1917: 335; Emery, 1921f: 27; Wheeler, W.M. 1922a: 796; Finzi, 1940: 156.
 * Status as species: Collingwood, 1985: 242; Bolton, 1995b: 418; Collingwood & Agosti, 1996: 312 (in key); Taylor & McGavin, 2020: 15.
 * Junior synonym of ambigua: Ward, 2006: 123.
 * maculifrons. Sima bifoveolata st. maculifrons Santschi, 1912b: 162 (w.) SOMALIA. [Name misspelled as foveolata in original description.] Combination in Sima (Tetraponera): Emery, 1921f: 27; in Tetraponera: Wheeler, W.M. 1922a: 796. Junior synonym of ambigua: Ward, 2006: 123.
 * rhodesiana. Sima ambigua r. rhodesiana Forel, 1913a: 112 (w.) ZIMBABWE. Arnold, 1914: 31 (s.w.); Arnold, 1916: 187 (q.). Combination in S. (Tetraponera): Arnold, 1916: 186; in Tetraponera: Wheeler, W.M. 1922a: 796. Junior synonym of ambigua: Ward, 2006: 123.
 * syriaca. Sima bifoveolata var. syriaca Wheeler, W.M. & Mann, 1916: 167 (w.) SYRIA. Combination in S. (Tetraponera): Emery, 1921f: 27; in Tetraponera: Ward, 1990: 489. Junior synonym of ambigua: Ward, 2006: 123.
 * encephala. Sima encephala Santschi, 1919h: 84 (q.) SENEGAL. Combination in Tetraponera: Wheeler, W.M. 1922a: 797. Junior synonym of ambigua: Ward, 2006: 123.
 * angolensis. Tetraponera ophthalmica st. angolensis Santschi, 1930b: 61, fig. 1 (w.) ANGOLA. Junior synonym of ambigua: Ward, 2006: 123.
 * occidentalis. Tetraponera ambigua var. occidentalis Menozzi, 1934: 154 (w.) ALGERIA. [First available use of Sima ambigua r. erythraea var. occidentalis Stitz, 1917: 336. Unavailable name (Ward, 1990: 489).] Junior synonym of ambigua: Ward, 2006: 123.

Taxonomic Notes
Sima bifoveolata

Taylor & McGavin (2020) treat the junior synonym Sima bifoveolata as a valid species. However, they provide no evidence to support this conclusion, stating that it is a "A fairly small ant, minor TL 3.8-4.2 mm, major TL 4.5-5.0 mm. The minor exactly matches the alitrunk and gaster of the type. This appears to be the first finding of a major worker and Ward gave no indication of a major for T. ambigua." This proposal is not followed here.

Tetraponera erythraea

Taylor & McGavin (2020) treat this taxon as a valid species. They found that "T. erythraea has the alitrunk profile in three shallow convexities, with quite abundant erect hairs, whereas the alitrunk on the T. ambigua type is near flat and there are few, very short, erect hairs [based on the type image on AntWeb.org at CASENT0904033]. The junior synonym of T. ambigua, rhodesiana is identical." They note that Ward (2006) states that T. ambigua has "abundant standing pilosity" and then note "that the types of T. ambigua and rhodesiana do not show abundant standing pilosity". The T. ambigua type specimen imaged by AntWeb (CASENT0904033) clearly shows several elongate hairs. As this is an older specimen it might be expected to have suffered damage since being collected and thus may not have a full complement of hairs. Relying on a single specimen (the type) to characterise an entire species may lead to incorrect conclusions as it is not possible to gauge variation within the species or detect damage to a single specimen. Until T. ambigua and all related forms can be reassessed, it seems prudent to retain T. erythraea as a junior synonym of T. ambigua.

Worker
Ward (2006) - (n = 14). HW 0.61 - 0.71, HL 0.86 - 0.99, LHT 0.55 - 0.63, CI 0.69 - 0.79, FCI 0.19 - 0.25, REL 0.41 - 0.45, REL2 0.54 - 0.60, SI 0.52 - 0.60, SI3 0.89 - 1.07, FI 0.43 - 0.51, PLI 0.56 - 0.76, PWI 0.47 - 0.59, LHT / HW 0.84 - 0.94, CSC 18 - 40, MSC 12 - 44.

Masticatory margin of mandible with four teeth; anterior margin of median clypeal lobe varying from convex and crenulate to obtusely tridentate; median lobes of antennal sclerites expanded laterally and covering most of the antennal insertions; ocelli absent or represented by a pair of weak lateral ocelli; pronotum laterally submarginate; mesosoma dorsum more or less flat in profile, mesosonotum weakly convex and not separated from anterior margin of propodeum by prominently raised metanotal spiracles; dorsal face of propodeum subequal in length to declivitous face, the two surfaces better differentiated than in other T. ambigua-group species; petiole relatively robust, less than twice as long as high; metabasitarsal sulcus absent. Integument coriarious/puncticulate and sublucid; a pair of more coarsely sculptured patches of cuticle variably developed on posterolateral corners of head; side of propodeum with varying amounts of weak irregular longitudinal carinulae, extending onto adjacent mesopleuron. Standing pilosity common (see CSC and MSC values), present on mesonotum and propodeum; scattered appressed pubescence on most of body, moderately dense on abdominal tergite 4 (hairs separated by less than their lengths). Pale yellowish-orange to orange-brown.

Type Material
Ward (2006) - Syntypes, 1 worker, Hammans Kraal, South Africa (leg. Simon), 1 dealate queen, Makapan, South Africa (leg. Simon) [examined].

References based on Global Ant Biodiversity Informatics

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