Tetramorium boehmei

The types were collected in Kakamega Forest in Western Kenya where it was sampled in primary forest sites. Considering the high sampling effort to assess the ant fauna of the Kakamega Forest (Hita Garcia et al. 2009) yielded only two specimens of T. boehmei, it seems to be a rather rare species. Little information is available on its biology. One specimen was found in a Winkler leaf litter extraction sample and one was hand collected from the ground. T. boehmei is either a rare terrestrial species, living either in the ground or the leaf litter, or it may inhabit the lower vegetation or the canopy and the two specimens were only accidentally collected. The former seems more probable. The two workers are consistent with Tetramorium typically found in the leaf litter than in the canopy where species tend to have larger eyes and scapes. It is also notable that T. boehmei was sampled in the two least disturbed primary forest sites examined in the Kakamega Forest (FHG, unpublished data). This may indicate that the new species prefers undisturbed primary forest and reacts negatively to anthropogenic disturbance like selective logging. (Hita Garcia et al. 2010).

Identification
Hita Garcia et al. (2010) -The highly reduced cephalic and mesosomal sculpturation renders Tetramorium boehmei straightforwardly recognizable within the Tetramorium camerunense species group.

Within the T. camerunense species group it obviously belongs to the T. camerunense species complex because of the unsculptured petiole and postpetiole. Second, and more importantly, T. boehmei shows a remarkable character combination that varies significantly from the other members of the species group, and allows an easy and clear identification. The single best diagnostic character to separate T. boehmei from the rest of the group is the almost completely reduced sculpturation on head and mesosoma. This reduction to a few weak rugulae on the cephalic dorsum, and even less sculpturation on the mesosomal dorsum, is unique in the species group. All other species possess a distinctly longitudinally rugose or rugulose head and mesosoma, though variable from species to species, and sometimes irregularly shaped.

It has to be mentioned that the holotype and paratype differ in some aspects that could be considered as sufficient enough to divide them into two different species. First, the mandibular sculpturation is completely smooth and shiny in the holotype while it is longitudinally striate in the paratype. This character is usually species-specific and could be considered as a good diagnostic tool to divide them. Second, the paratype is larger and possesses more sculpture on head and mesosoma than the holotype which appears generally much more smooth and shining. Furthermore, the clypeal notch is distinct in both species but stronger developed in the paratype. However, at present, the observed variation is considered as intraspecific variation until more material becomes available. Apart from the noted differences there is a striking morphological similarity between both specimens and also the morphometric measurements of both are very close.

Distribution based on Regional Taxon Lists
Afrotropical Region: Kenya, Uganda.

Nomenclature

 *  boehmei. Tetramorium boehmei Hita Garcia & Fisher, in Hita Garcia, Fisher, Kück, et al. 2010: 363, figs. 1-6 (w.) KENYA.

Worker
HL 0.700–0.772; HW 0.633–0.711; SL 0.533–0.578; EL 0.122–0.139; PW 0.450–0.489; WL 0.822–0.900; PSL 0.150–0.189; PTL 0.194–0.200; PTH 0.211–0.239; PTW 0.178–0.189; PPL 0.189–0.200; PPH 0.194–0.222; PPW 0.250–0.267; CI 90–92; SI 82–84; OI 19–20; PSLI 21–24; PeNI 39–40; LPeI 84–92; DPeI 91–94; PpNI 55–56; LPpI 90–97; DPpI 132–133; PPI 141 (2 measured).

Head longer than wide (CI 90–92). Anterior clypeal margin with small but distinct median notch. Frontal carinae fine and relatively weak, even weaker behind eye level and significantly not reaching occipital margin. Antennal scrobe very weakly developed, nearly vestigial. Antennal scape of moderate length, not reaching posterior margin of head (SI 82–84). Eyes small to moderate (OI 19–20), with 8 to 9 ommatidia in longest row. Metanotal groove not impressed. Propodeal spines moderately sized (PSLI 21–24), relatively thin, spinose and straight. Propodeal lobes small, elongate-triangular and acute, always shorter than propodeal spines. Petiolar node nodiform, in profile weakly higher than long (LPeI 84–92), in dorsal view slightly longer than wide (DPeI 91–94) and posteriorly wider than anteriorly. Postpetiole rounded, in dorsal view around 1.3 times wider than long (DPpI 132–133), and around 1.4 times wider than petiole (PPI 141); in lateral view weakly higher than long (LPpI 90–97). Sting appendage triangular.

Mandibles either unsculptured, smooth and shining or finely striate. Clypeus with three longitudinal rugae, median ruga stronger developed than lateral rugae. Cephalic sculpturation greatly reduced, laterally with only weak partial rugulation, mostly smooth and shining; cephalic dorsum with 5–6 very weak and fine, widely spaced longitudinal rugulae between frontal carina, most of them broken along their length and never reaching occipital margin, occipital region unsculptured. Cephalic ground sculpturation absent, generally smooth and shining. Lateral mesosoma anteriorly mostly unsculptured, smooth and shiny, posteriorly with weak irregular rugulation; dorsum of mesosoma unsculptured or with few weak rugulae, or traces of rugulae only, generally smooth and shining. Petiole either completely unsculptured or with traces of sculpture; postpetiole and gaster completely unsculptured, smooth and shiny.

All dorsal surfaces of head, mesosoma, both waist segments and gaster with numerous long, simple, suberect to erect hairs. Fine pubescence on antennal scapes and tibia appressed to subdecumbent.

Head, mesosoma, waist segments, and gaster very dark brown to black, antennae, mandibles, and legs of lighter brownish colour.

Type Material
Holotype worker, KENYA, Western Province, Kakamega Forest, Colobus, 00° 21’ 16’’ N, 34° 51’ 36’’ E, 1650 m, primary rain forest, hand collected, VII.2009, leg. G. Fischer (: CASENT0217238). Paratype worker, KENYA, Western Province, Kakamega Forest, Salazar, 00° 19’ 36’’ N, 34° 52’ 14.6’’ E, 1650 m, Kakamega Forest survey 2007, Transect 6, primary forest, Winkler leaf litter extraction, 21.VI.2007, leg. M. Peters (: CASENT0217239).

Etymology
The new species is dedicated to Prof. Dr. Wolfgang Böhme from Bonn, Germany, in honour of his nearly four decades of passionate herpetological work at the Zoological Research Museum Koenig in Bonn. Furthermore, with his encouraging, and always interesting, lectures, courses and excursions he had a significant positive influence on the authors leading to their scientific dedication with zoological systematics and the Afrotropical zoogeographical region.