Tetraponera sahlbergii (Forel)

Ward, Philip S., 2022, The ant genus Tetraponera (Hymenoptera: Formicidae) in the Afrotropical region: taxonomic review and key to species, Zootaxa 5102 (1), pp. 1-70 : 42-43

Tetraponera sahlbergii (Forel)

( Fig. 21 )

Sima Sahlbergii Forel 1887: 386 . Holotype worker (by monotypy), Bois d’Ivondro pr. Tamatave, Madagascar (C. Keller) (MHNG) [examined]. Imaged on AntWeb : CASENT0101052.

Sima sahlbergi r. spuria Forel 1897: 199 . Syntypes, 18 workers, 1 male, Nosy Be [as “Nosibé” and “Nossibé”], Madagascar (Völtzkow) ( MSNG, MHNG, NMHV) [examined] . 6 syntype workers, 1 syntype male from MHNG imaged on AntWeb: CASENT0101055, CASENT0101056, CASENT0101057, CASENT0101058, CASENT0101059, CASENT0101060, CASENT0101063 . 1 syntype worker from MSNG imaged on AntWeb: CASENT0102036. Syn. nov .

Sima (Tetraponera) plicatidens Santschi 1926: 26 . Syntypes, 2 alate queens, 2 males, Ankaratra , 2000m, Madagascar (Descarpentries) ( NHMB) [examined] . 1 syntype queen, 2 syntype males imaged on AntWeb : CASENT0101149, CASENT0101150, CASENT0101151. Syn. nov .

Sima Sahlbergi Forel ; Forel 1892: 260. Description of queen.

Sima (Tetraponera) sahlbergi Forel ; Emery 1921: 28. Combination in Sima (Tetraponera) .

Tetraponera sahlbergi (Forel) ; Wheeler 1922c: 1015. Combination in Tetraponera .

Tetraponera sahlbergii (Forel) ; Chomicki et al. 2015: figure S1. Placement in molecular phylogeny.

Sima (Tetraponera) sahlbergi subsp. spuria Forel ; Emery 1921: 28. Combination in Sima (Tetraponera) .

Tetraponera sahlbergi subsp. spuria (Forel) ; Wheeler 1922c: 1016. Combination in Tetraponera .

Tetraponera plicatidens (Santschi) ; Ward 1990: 489. Combination in Tetraponera .

Worker measurements (n = 17). HW 0.49–0.77, HL 0.69–1.01, LHT 0.48–0.70, CI 0.69–0.76, FCI 0.08–0.14, REL 0.29–0.34, REL2 0.38–0.47, SI 0.55–0.65, SI3 1.31–1.56, FI 0.40–0.45, PLI 0.46–0.62, PWI 0.34–0.52, LHT/ HW 0.84–1.02, CSC 2–3, MSC 2–6.

Worker diagnosis. Relatively small species, with somewhat elongate head (CI 0.69–0.76), and eyes of moderate size (see ocular indices); minimum distance between frontal carinae only slightly exceeding basal scape width (FCI 0.08–0.14); scape moderately long, greater than one-half head width and less than one-half head length (SI 0.55–0.65, SI2 0.41–0.45); median clypeal lobe broadly convex, denticulate, furnished with a small median tooth and flanked by one or two pairs of weak lateral teeth, sometimes reduced to crenulations ( Fig. 21a ); profemur moderately robust (FI 0.40–0.45); mesosoma with a differentiated, transverse metanotal plate, about one third the length of the mesonotum; dorsal face of propodeum flat to weakly convex (posterior view), about as long as declivitous face and rounding into the latter; petiole slender (PLI 0.46–0.62, PWI 0.34–0.52), with a well differentiated anterior peduncle, the node with relatively shallow and similar anterodorsal and posterodorsal faces, as seen in profile ( Fig. 21b ); postpetiole longer than broad. Head and mesosoma sublucid, with fine reticulate-coriarious sculpture and scattered small punctures. Standing pilosity relatively sparse; head usually with 1 pair of supraocular setae (CSC 2–3); mesosoma with 1–2 pairs of standing hairs on the pronotum and 0–1 pair on the mesonotum (MSC 2–6); standing pilosity absent from dorsal face of propodeum. Dark brownish-black, antennae, mandibles and distal portions of legs lighter.

Comments. This is a widespread and somewhat variable species, recognizable in the worker caste by the combination of (1) relatively small size, (2) a moderately elongate head (CI 0.69–0.76), (3) a broadly convex anterior clypeal margin, that is crenulate or denticulate but lacks prominent teeth, (4) a slender petiole, and (5) sparse standing pilosity. In western populations the sheen of the integument is somewhat dulled by the fine reticulate-coriarious sculpture, compared to similar congeners. T. sahlbergii workers from mesic localities in eastern Madagascar tend to have a shinier head and more robust petiole than those from drier habitats on the western half of the island, but intermediate phenotypes occur, and the variation is here treated as intraspecific.

Distribution and biology. This is a common species that occurs in spiny forest, tropical dry forest and disturbed open habitats almost throughout the island of Madagascar. It is a generalist inhabitant of dead twigs or stems of woody plants.

Figures

FIGURES 19–21. Tetraponera allaborans group, workers, full-face (dorsal) view of head (a) and lateral profile of body (b). 19, T. mandibularis, Madagascar (CASENT0012845); 20, T. morondaviensis, Madagascar (CASENT0012835); 21, T. sahlbergii, Madagascar (CASENT0012851). Images from AntWeb (www.antweb.org); photographer April Nobile.