Tetraponera

Widespread in the Old World tropics, Tetraponera contains just over 100 taxa, occurring in Africa, Madagascar, India, south-east Asia and Australia. Five species have been described from Baltic amber, and one from Oligocene deposits in France. Although less diverse than its New World counterpart Pseudomyrmex, Tetraponera is nevertheless a conspicuous element of the ant fauna in some regions, especially Madagascar where there are about 30 species (mostly undescribed). Most species are unspecialized arboreal nesters, living in dead twigs, branches, insect bored cavities or domatia of living plants (Ward 1990, 1991). In the latter case these species typically have co-evolved with their hosts and provide protection from herbivores (Ward, 1991).

Identification
Ward (1990):

Worker Monomorphic or (rarely) polymorphic, variable in size (worker HW 0.42-2.25). Basal and masticatory margins of mandibles usually distinct, occasionally meeting at a rather oblique angle; basal margin with 0-2 teeth, proximal tooth always lacking; masticatory margin with 3-6 teeth, usually 3 or 4, subequal in size. Venter of mandible with a single ridge or weak rise, which is continuous and broadly rounded behind the masticatory and basal margins (sometimes this ridge is very reduced). Palp formula: 6,4 in all species, except T. tessmanni where reduced to (4p3.3). Distal margin of labrum usually with a narrow, notch-like cleft; prominent teeth or protuberances sometimes present on the labrum. Anterodorsal surface of median clypeal lobe continuous, non-truncate; anterior margin often toothed or crenulate. Antennae 12-segmented. Median lobes of antennal sclerites rather strongly expanded laterally, covering most of the basal condyles of the antennae (ASI 0.75-1.00). Frontal carinae separated by more than basal scape width (FCI 0.08-0.25). Compound eyes relatively large, width two-thirds or more the length. Number of ocelli: 3, with reductions to 2 and (commonly) 0. Metanotal groove usually distinctly impressed, sometimes preceded by a distinct, flattened, metanotal (or mesoscutellar?) plate. Hind basitarsal sulcus nearly always present, becoming rather reduced in some species and absent in three. Mid basitarsal sulcus less frequently developed. Mid and hind tarsi each with a pair of apical spurs, the anterior spur sometimes very reduced, the posterior spur pectinate. Median connection of spiracular plates (of sting apparatus) membranous.

Queen Deciduously winged (ergatoid and brachypterous forms known only in Tetraponera tessmanni). Similar in most respects to workers; mandibles often modified, e.g. with a much expanded apicobasal area or basally geniculate. Genal pit often present, just above mandibular insertions. Ocelli (3) always present. Mid and hind basitarsal sulci more prominent than in workers. Forewing typically with two cubital cells; reductions to one cell occur.

Male Basal margin of mandibles two-thirds or more the length of the masticatory margin, the two often meeting at a rounded corner rather than a sharp apico-basal angle; basal margin with 0, rarely 1, teeth; masticatory margin with 2-6 teeth, generally subequal in size (6 teeth occurring only in larger species, with HW ≥ 1.00). Palp formula and labrum as in workers. Anterior margin of clypeus straight to broadly convex, rarely emarginate; clypeal lobe sometimes dorsomedially protuberant. Antennal sclerites often projecting anterodorsally over the frontal triangle; antennal insertions situated relatively close to the posterior margin of the clypeus (separated by less than the maximum diameter of the antennal fossa). Tibial spurs as in workers. Volsella a small, setose, finger-like lobe; in some species even further reduced and fused to the inner wall of the paramere (where it is quite inconspicuous). Internal face of inner valve (aedeagus) lacking a differentiated, plate-like structure which is separated from the dorsal margin. Wing venation as in queen. Antennae in pupa passing laterally on either side of the mandibles.

Species groups

 * Tetraponera allaborans species group: Africa, Madagascar, India to China, south to northern Australia
 * Tetraponera ambigua species group: Africa, Arabian Peninsula, Madagascar
 * Tetraponera grandidieri species group: Madagascar
 * Tetraponera natalensis species group: Africa, northwestern Madagascar
 * Tetraponera nigra species group: Oriental, Indo-Australian region
 * Tetraponera pilosa species group: Indo-Australian region
 * Tetraponera rufonigra species group: West and central Africa; Indian subcontinent to southeast Asia

Biology
Ward (2001) - Some species of Tetraponera can show remarkable variation in size and shape, both within populations and over larger geographical scales. Thus, progress on the species-level taxonomy of these ants requires the analysis of geographically extensive population samples, and an appreciation of the potential for species to show substantial phenotypic variation.

Most collections of Indo-Australian Tetraponera consist of isolated workers, unassociated with sexual alates, and often lacking biological data. Our knowledge of the ecology and behavior of these ants would be enhanced if more emphasis were placed on the procurement of nest series. This would also allow the accumulation of worker-associated queens and males, whose characteristics may prove to be more reliable for delimiting species. Males are known for only about half the species (and in small sample sizes for some of these) but the available data indicate that the genitalia provide good diagnostic traits for some species and clades.

Nomenclature

 *  TETRAPONERA [Pseudomyrmecinae]
 * Tetraponera Smith, F. 1852: 44. Type-species: Tetraponera atrata (junior synonym of Eciton nigrum), by subsequent designation of Wheeler, W.M. 1911f: 173.
 * Tetraponera junior synonym of Pseudomyrma: Roger, 1863b: 24; Mayr, 1863: 451.
 * Tetraponera junior synonym of Sima: Dalla Torre, 1893: 53; Bingham, 1903: 107; Emery, 1917a: 95.
 * Tetraponera subgenus of Sima: Emery, 1900d: 673; Emery, 1915b: 266; Emery, 1921f: 24.
 * Tetraponera as genus: Smith, F. 1877b: 68; Donisthorpe, 1916b: 244; Wheeler, W.M. 1922a: 654; Taylor & Brown, D.R. 1985: 17; Ward, 1990: 470.
 * Tetraponera senior synonym of Sima: Smith, F. 1877b: 68; Donisthorpe, 1916b: 244; Wheeler, W.M. 1920: 47; Wheeler, W.M. 1922a: 105.
 * Tetraponera senior synonym of Pachysima, Parasima, Sima, Viticicola: Ward, 1990: 470.
 * PACHYSIMA [junior synonym of Tetraponera]
 * Pachysima Emery, 1912b: 97 [as subgenus of Sima]. Type-species: Tetraponera aethiops, by monotypy.
 * Pachysima raised to genus: Wheeler, W.M. 1918c: 308 (footnote); Wheeler, W.M. 1922a: 112, 654.
 * Pachysima subgenus of Sima: Emery, 1921f: 22.
 * Pachysima junior synonym of Tetraponera: Ward, 1990: 470.
 * PARASIMA [junior synonym of Tetraponera]
 * Parasima Donisthorpe, 1948d: 592 [as subgenus of Tetraponera]. [Unnecessary replacement name for Sima in the sense of Emery, 1921f: 23.]
 * Parasima junior synonym of Tetraponera: Ward, 1990: 470.
 * SIMA [junior synonym of Tetraponera]
 * Sima Roger, 1863a: 178. Type-species: Sima compressa (junior synonym of Pseudomyrma allaborans), by monotypy.
 * [Type-species not Eciton rufonigrum, unjustified subsequent designation by Emery, 1915b: 266, repeated in Emery, 1917a: 95 Emery, 1921f: 22.]
 * Sima revived status as genus: Dalla Torre, 1893: 53; Emery, 1917a: 95; Forel, 1917: 240; Emery, 1921f: 21.
 * Sima junior synonym of Tetraponera: Smith, F. 1877b: 68; Donisthorpe, 1916b: 244; Wheeler, W.M. 1920: 47; Wheeler, W.M. 1922a: 105; Ward, 1990: 470.
 * VITICICOLA [junior synonym of Tetraponera]
 * Viticicola Wheeler, W.M. 1919i: 130. Type-species: Sima tessmanni, by original designation.
 * Viticicola junior synonym of Tetraponera: Ward, 1990: 470.
 * [ Viticola Donisthorpe, 1943g: 735, incorrect subsequent spelling.]

Ward (2001) - Tetraponera is one of three genera in the ant subfamily Pseudomyrmecinae. The workers of this genus have the following characteristics:

1. Mandible short, usually with 3-4 (rarely 5-6) teeth on the masticatory margin and 0-2 small teeth on the basal margin; basal margin lacking proximal tooth (Figs 6-7).

2. Palp formula 6,4 (reduced to 4,3 in one African species).

3. Posteromedial margin of clypeus not prolonged backwards between the frontal carinae.

4. Anterodorsal surface of median portion of clypeus continuous, non-truncate (in contrast to Pseudomyrmex), its anterior margin with a line of clypeal setae, and varying from straight and entire to protruding and dentate (e.g. Figs 8-18, 61-64).

5. Median lobe of antennal sclerite expanded laterally and covering most of the basal condyle of the antenna when head is observed in full-face view.

6. Antenna 12-segmented.

7. Scape short, less than three-quarters ofhead length (SI2 0.38-0.68 in Oriental/Australian species).

8. Frontal carinae relatively well separated, the minimum distance between them greater than basal scape width (FCI 0.08-0.20 in Oriental/Australian species).

9. Compound eye relatively large (REL 0.25-0.53 in Oriental/ Australian species), width of eye two-thirds or more of length.

10. Ocelli present (usually 3) or absent.

11. Pronotum and mesonotum not fused, freely articulating with one another.

12. Mesopropodeal impression usually well marked, sometimes containing a plate-like sclerite, apparently of metanotal origin.

13. Propodeal spiracle circular to elongate, located well forward on upper third of propodeum.

14. Metapleural gland well developed, the opening directed ventrolaterally or posterolaterally, and preceded by an impression along the lower margin of the metapleuron, whose dorsal margin is marked by an oblique longitudinal carina.

15. Metabasitarsal sulcus nearly always present, reduced in some species (absent in three African species).

16. Meso- and metatibiae each with a pair of the apical spurs, the posterior spur well developed and pectinate, the anterior spur smaller, sometimes very reduced.

17. Terga and sterna of abdominal segments II (petiole), III (postpetiole) and IV not laterally fused.

18. Postpetiole distinctly developed.

19. Pupa naked.

20. Larva with trophothylax (food pocket) on ventral surface of thorax.

For practical purposes workers of Tetraponera can be distinguished from those of all other ants by the combination of well-developed postpetiole, short mandibles, large oval eyes, and a flexible promesonotal suture.