Tetramorium schoutedeni

Only known from the worker holotype.

Identification
The following combination of characters separates Tetramorium schoutedeni from the rest of of the species complex: small eyes (OI 22); mandibles unsculptured; all dorsal surfaces with simple long, erect to suberect hairs; bicoloured with orange-brown head, mesosoma, petiole, and postpetiole, while gaster of darker colour.

Distribution
This taxon was described, and is only known, from Democratic Republic of Congo.

Nomenclature

 *  schoutedeni. Tetramorium schoutedeni Santschi, 1924b: 213, fig. 9 (w.) DEMOCRATIC REPUBLIC OF CONGO. See also: Bolton, 1980: 231; Hita Garcia, Fischer & Peters, 2010b: 39.

Hita Garcia et al. (2010) - We agree with Bolton in placing Tetramorium schoutedeni in the weitzeckeri species group. Although the antennal count is unknown, all other characters fit the definition of the weitzeckeri species group, and the general overall similarity with related species like T. pinnipilum or T. philippwagneri is quite evident. The latter and T. schoutedeni are morphologically very similar and, as already stated above, both might in fact be the same species. However, considering that the mandibular sculpturation in T. schoutedeni is smooth and shiny while it is conspicuously longitudinally rugose in T. philippwagneri both are considered as distinct species. Furthermore, the SI in T. schoutedeni (SI 75) seems to be slightly shorter than in T. philippwagneri (78 - 83). Note that this has to be treated with caution since only the holotype, and the only known specimen, of T. schoutedeni was measured, generally not enough to get a good impression of its real morphometric range. Additionally, the standing hairs on head and mesosoma are shorter in the T. schoutedeni holotype than in all the examined T. philippwagneri material although this difference is difficult to measure (more diagnostic differences are provided above in the description of T. philippwagneri). Tetramorium pinnipilum is also relatively close to T. schoutedeni but can be well separated since the latter shows simple pilosity as opposed to the bizarre pilosity in the first. The same simple pilosity distinguishes T. schoutedeni from T. mkomazi, T. rogatum, and T. zonacaciae, which all have modified or reduced pilosity. Additionally, the other species of the complex, T. edouardi, T. robertsoni, and T. rubrum, are all uniformly coloured and possess larger eyes (OI 23 - 30) while T. schoutedeni is distinctly bicoloured with small eyes (OI 22).

Worker
Hita Garcia et al. (2010) - HL 0.878; HW 0.850; SL 0.639; EL 0.183; PW 0.600; WL 1.078; PSL 0.289; PTL 0.233; PTH 0.344; PTW 0.289; PPL 0.244; PPH 0.344; PPW 0.356; CI 97; SI 75; OI 22; PSLI 33; PeNI 48; LPeI 68; DPeI 124; PpNI 59; LPpI 71; DPpI 146; PPI 123 (1 measured).

Head slightly longer than wide (CI 97), posterior margin of head deeply and broadly concave. Anterior clypeal margin with median impression. Frontal carinae well developed, growing weaker behind eye level, fading out shortly before posterior margin of head. Antennal scrobe shallow, narrow, and without defined posterior and ventral margins, ending before posterior margin of head. Antennal scape of moderate length, not reaching posterior margin of head (SI 75). Eyes relatively small (OI 22), with 9 ommatidia in longest row. In profile metanotal groove barely impressed. Propodeal spines long, spinose, and acute (PSLI 33). Propodeal lobes small and triangular. Petiolar node high nodiform, in dorsal view only slightly wider than long (DPeI 124), in profile around 1.5 times higher than long (LPeI 68). Postpetiole in dorsal view around 1.5 times wider than long (DPpI 146); in lateral view weakly antero-posteriorly compressed, around 1.4 times higher than long (LPpI 71). Mandibles unsculptured, smooth and shiny. Clypeus with more than 5 irregularly arranged longitudinal rugae. Head mostly longitudinally rugose with 10 widely spaced rugae between frontal carinae, most reaching posterior margin of head unbroken. Spaces between rugae and scrobal area with fine punctate ground sculpturation, generally shiny. Mesosoma mostly longitudinally rugose, spaces between rugae and propodeal declivity unsculptured and shiny. Petiole and postpetiole with few longitudinal rugae, but generally smooth and shiny. Gaster unsculptured, smooth and shiny. All dorsal surfaces of head, mesosoma, both waist segments and gaster with abundant, long, suberect to erect simple hairs. Fine pubescence on tibiae and antennal scapes appressed to decumbent. Head, mesosoma, petiole, and postpetiole orange-brown, gaster of darker brown.

Type Material
Hita Garcia et al. (2010) - Holotype worker, D.R. CONGO, Kunungu, 6.IV.1921, leg. H. Schouteden (: ZFMK_HYM_2009_6177) [examined]. As already noted in Bolton (1980), both antennae of the holotype are damaged, the funiculi are broken and only the scapes remain.

Additional References

 * Hita Garcia, F.; Fischer, G.; Peters, M. K. 2010. Taxonomy of the Tetramorium weitzeckeri species group (Hymenoptera: Formicidae) in the Afrotropical zoogeographical region. Zootaxa 2704:1-90.