Tetramorium uelense

Hita Garcia & Fisher (2014) - T. uelense is known from a few collections in savannah habitats throughout a relatively wide geographical range from West to Central Africa. Compared to most other Afrotropical Tetramorium species, there is a wealth of information about the natural history of T. uelense (Longhurst, 1979). Longhurst et al. (1979) provided important observation data about nests, foraging, recruitment, and predation on termites. Tetramorium uelense live in subterranean nests difficult to locate without observing foraging workers. At least in the area observed by Longhurst et al. (1979), the main prey of T. uelense consisted of various species of Microtermes Wasmann, and T. uelense exerted great predation pressure on these small termites. Scouting is performed by solitary workers that search the leaf litter, fallen grass stems or pieces of wood for prey. After locating termites the scouts return to the colony for recruitment of groups between 10 to 30 workers. These groups locate, immobilise, and retrieve the prey. For more details refer to Longhurst et al. (1979).

Identification
Hita Garcia & Fisher (2014) - The following character combination separates T. uelense from the other species of the Tetramorium decem species group: relatively larger species (WL 0.98–1.06); propodeum armed with short triangular to elongate-triangular teeth (PSLI 16–18); petiolar node in profile around 1.1 times higher than long (LPeI 88–93); dorsum of mesosoma conspicuously longitudinally rugose with distinctive reticulate-punctate ground sculpture; strongly bicoloured with dark brown to black gaster contrasting with light brown to reddish brown remainder of body.

Tetramorium uelense can be easily distinguished from the remainder of the T. decem species group. The presence of longitudinally rugose sculpture on the dorsum of the mesosoma separates T. uelense immediately from Tetramorium decem, Tetramorium ultor, and Tetramorium venator. In the latter three the mesosomal dorsum is completely unsculptured, smooth, and very shiny. The only other species with sculpture on the dorsum of the mesosoma, which could be confused with T. uelense, is T. raptor. Nevertheless, both are well separable in morphology and ecology. Most obviously, T. uelense is a larger species (WL 0.98–1.06) with distinct bicolouration while T. raptor (WL 0.88–0.93) is smaller and a uniform dark brown colour. In addition, T. uelense has longer and better developed propodeal teeth (PSLI 16–18) compared to T. raptor (PSLI 10–11), even though this might be difficult to see and may require measurements to confirm. Another, more visible character is the sculpture on the mesosomal dorsum, which is strongly longitudinally rugose with distinct punctate ground sculpture in T. uelense versus longitudinally rugulose with very little ground sculpture in T. raptor. Also, the lateral pronotum of the latter is mostly unsculptured, smooth, and shiny while in T. uelense the lateral pronotum is strongly rugose with conspicuous ground sculpture.

Despite the broad distribution range, we did not observe any significant intraspecific variation in T. uelense.

Key to Tetramorium decem species group

Distribution
The known distribution spans Guinea through Ghana and Nigeria to the northeast of the D. R. Congo close to South Sudan and Uganda.

Distribution based on Regional Taxon Lists
Afrotropical Region: Congo, Democratic Republic of Congo, Ghana, Guinea , Nigeria.

Habitat
Savannah

Nomenclature

 *  uelense. Tetramorium (Decamorium) decem st. uelense Santschi, 1923e: 258 (w.q.) DEMOCRATIC REPUBLIC OF CONGO. Combination in Decamorium: Bolton, 1976: 298; in Tetramorium: Hita Garcia & Fisher, 2014: 87. Raised to species and senior synonym of nimba: Bolton, 1976: 298. See also: Longhurst, Johnson & Wood, 1979: 83.
 * nimba. Decamorium decem r. nimba Bernard, 1953b: 250 (w.) GUINEA. Junior synonym of uelense: Bolton, 1976: 298.

Worker
Hita Garcia & Fisher (2014) - (N=6). HL 0.67–0.72 (0.70); HW 0.54–0.59 (0.57); SL 0.39–0.42 (0.41); EL 0.19–0.20 (0.20); PH 0.36–0.38 (0.37); PW 0.43–0.47 (0.45); WL 0.98–1.06 (1.02); PSL 0.11–0.13 (0.10); PTL 0.27–0.29 (0.28); PTH 0.29–0.32 (0.31); PTW 0.21–0.23 (0.22); PPL 0.24–0.26 (0.25); PPH 0.28–0.34 (0.31); PPW 0.30–0.33 (0.31); CI 80–83 (81); SI 69–74 (72); OI 34–35 (35); DMI 43–44 (44); LMI 35–37 (36); PSLI 16–18 (17); PeNI 48–49 (49); LPeI 88–93 (90); DPeI 77–81 (79); PpNI 69–70 (70); LPpI 75–86 (80); DPpI 122–125 (124); PPI 141–145 (143).

Head much longer than wide (CI 80–83); posterior head margin weakly concave. Anterior clypeal margin with distinct, but often shallow median impression. Frontal carinae strongly developed and noticeably raised forming dorsal margin of very well-developed antennal scrobes, curving down ventrally and anteriorly halfway between posterior eye margin and posterior head margin and forming posterior and ventral scrobe margins; antennal scrobes very well developed, deep and with clearly defined margins, but ventral margin less strongly developed, median scrobal carina absent. Antennal scapes short, far from reaching posterior head margin (SI 69–74). Eyes relatively large (OI 34–35). Mesosomal outline in profile relatively flat, elongate and low (LMI 35–37), moderately to strongly marginate from lateral to dorsal mesosoma; promesonotal suture absent; metanotal groove present, distinct, but relatively shallow. Propodeum armed with short, triangular to elongate-triangular, and acute teeth (PSLI 16–18), propodeal lobes reduced, short, and well rounded, usually shorter than propodeal teeth. Tibiae and femorae strongly swollen. Petiolar node nodiform with moderately rounded antero- and posterodorsal margins, in profile around 1.1 times higher than long (LPeI 88–93), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins situated at about same height and equally angled, petiolar dorsum clearly convex; node in dorsal view around 1.2 to 1.3 times longer than wide (DPeI 77–81), in dorsal view pronotum between 2.0 and 2.1 times wider than petiolar node (PeNI 48–49). Postpetiole in profile globular, approximately 1.2 to 1.3 times higher than long (LPpI 75–86); in dorsal view between 1.2 and 1.3 times wider than long (DPpI 122–125), pronotum around 1.4 times wider than postpetiole (PpNI 69–70). Postpetiole in profile more or less of same volume as petiolar node, postpetiole in dorsal view around 1.4 times wider than petiolar node (PPI 141–145). Mandibles and clypeus unsculptured, smooth, and shining; cephalic dorsum between frontal carinae with fine irregularly longitudinally rugulose/ rugose sculpture, rugulae/rugae often interrupted, meandering, or with cross-meshes, cephalic dorsum also puncticulate to punctate throughout its length; scrobal area strongly reticulate-punctate; lateral head mainly reticulate-rugose with weak to moderately well developed punctate ground sculpture. Ground sculpture on head usually weak, except scrobal area (see above). Dorsum of mesosoma densely longitudinally rugose on top of strong punctate ground sculpture; lateral mesosoma longitudinally rugose and very conspicuously reticulate-punctate. Forecoxae unsculptured, smooth, and shining. Petiolar node and postpetiole superficially longitudinally rugulose or irregularly rugulose superimposed on conspicuous but relatively weak reticulate-punctate ground sculpture. Mesosoma and waist segments appearing matt. First gastral tergite unsculptured, smooth, and shiny. Pilosity and pubescence greatly reduced: head with few pairs of moderately long, standing hairs, anterior pronotum with one long pair, waist segments sometimes with one long pair each, and sometimes first gastral tergite with one long pair; appressed pubescence present everywhere on body, but noticeable only on antennae, cephalic dorsum, legs, and first gastral tergite. Anterior edges of antennal scapes and dorsal (outer) surfaces of hind tibiae with appressed hairs. Body strongly bicoloured with dark brown to black gaster contrasting with light brown to reddish brown remainder.