Tetramorium edouardi

Other than showing a preference for open areas, little is known about the biology of Tetramorium edouardi.

Identification
Tetramorium edouardi can be best separated from other members of the weitzeckeri group by the following combination of characters: anterior clypeal margin with small median impression; clypeus with distinct median longitudinal carina; CI 90 - 96; antennal scape of moderate length (SI 76 - 83), eyes moderate to relatively large (OI 26 - 30); metanotal groove in profile distinctly impressed; whole body with simple subdecumbent to erect pilosity; coloration dark brown.

There is a relatively high intraspecific variability observable in sculpture. Specimens from the same sampling event showed a remarkable variation in mandibular sculpturation, ranging from smooth and shiny mandibles to partly or fully rugose. The same applies to the sculpturation on the pronotal or petiolar dorsum, although to a lesser extent. In contrast to this high intraspecific variation in sculpturation at local level, geographic variation seems to be of minor relevance.

Tetramorium rubrum differs from T. edouardi in having longer antennal scapes and head, different coloration, and development of the metanotal groove. An additional species morphologically close to T. edouardi is Tetramorium robertsoni but the median area of the clypeus is unsculptured in the latter while it is distinctly longitudinally rugose in the first. Furthermore, the metanotal groove in T. robertsoni is barely impressed in lateral view whereas in T. edouardi it is distinctly so.

A member of the Afrotropical edouardi species complex, which is part of the weitzeckeri species group.

Key to weitzeckeri-group species.

Distribution
This taxon was described from Ethiopia. It is also found in Kenya and Ivory Coast.

Nomenclature

 *  edouardi. Tetramorium (Xiphomyrmex) edouardi Forel, 1894b: 82 (w.) ETHIOPIA. Santschi, 1919a: 344 (q.). Combination in Xiphomyrmex: Santschi, 1919a: 344; in Tetramorium: Bolton, 1980: 225. Senior synonym of atrinodis, kivuense, tersum: Hita Garcia, Fischer & Peters, 2010b: 23.
 * kivuense. Tetramorium (Xiphomyrmex) kivuense Stitz, 1911b: 386, fig. 6 (w.) DEMOCRATIC REPUBLIC OF CONGO. Santschi, 1924b: 216 (q.). Combination in Xiphomyrmex: Wheeler, W.M. 1922a: 907. Junior synonym of tersum: Bolton, 1980: 233; of edouardi: Hita Garcia, Fischer & Peters, 2010b: 23.
 * tersum. Tetramorium tersum Santschi, 1911c: 357, fig. 1 (w.) KENYA. Senior synonym of atrinodis, kivuense: Bolton, 1980: 233. Junior synonym of edouardi: Hita Garcia, Fischer & Peters, 2010b: 23
 * atrinodis. Xiphomyrmex kivuense st. atrinodis Santschi, 1928f: 208 (w.) KENYA. Junior synonym of tersum: Bolton, 1980: 233; of edouardi: Hita Garcia, Fischer & Peters, 2010b: 23.

Worker
Hita Garcia et al. (2010) - HL 0.800 - 1.050 (0.942); HW 0.744 - 0.989 (0.876); SL 0.589 - 0.789 (0.698); EL 0.206 - 0.272 (0.240); PW 0.539 - 0.756 (0.668); WL 0.944 - 1.270 (1.135); PSL 0.244 - 0.344 (0.307); PTL 0.222 - 0.300 (0.267); PTH 0.322 - 0.433 (0.384); PTW 0.267 - 0.367 (0.316); PPL 0.244 - 0.344 (0.288); PPH 0.300 - 0.422 (0.365); PPW 0.322 - 0.467 (0.404); CI 90 - 96 (93); SI 76 - 83 (80); OI 26 - 30 (27); PSLI 29 - 36 (33); PeNI 44 - 51 (47); LPeI 62 - 76 (70); DPeI 111 - 127 (118); PpNI 57 - 67 (61); LPpI 71 - 90 (79); DPpI 126 - 158 (141); PPI 118 - 138 (128) (37 measured).

Head longer than wide (CI 90 - 96). Anterior clypeal margin with small median notch. Frontal carinae strongly developed, becoming weaker behind eye level, reaching posterior margin of head. Antennal scrobe shallow, narrow, without defined posterior and ventral margins, ending before posterior margin of head. Antennal scape of moderate length, not reaching posterior margin of head (SI 76 - 83). Eyes moderate to relatively large (OI 26 - 30), with 11 to 15 ommatidia in longest row. In profile metanotal groove distinctly impressed. Propodeal spines long and spinose (PSLI 29 - 36). Propodeal lobes small, triangular and acute. Petiolar node high nodiform, in dorsal view only slightly wider than long (DPeI 111 - 127) and in profile around 1.3 to 1.6 times higher than long (LPeI 62 - 76), posterodorsal angle of node less strongly developed than anterodorsal and generally more rounded, dorsal face sloping faintly downwards posteriorly. Postpetiole in dorsal view between 1.2 to 1.6 times wider than long (DPpI 126 - 157) and much more voluminous than petiole; in lateral view rounded dorsally, around 1.1 to 1.4 times higher than long (LPpI 71 - 90). Mandibular sculpturation variable, generally smooth and shiny, sometimes partially and rarely completely longitudinally rugose. Clypeus usually with 3 to 5 longitudinal rugae, median ruga always strongly developed and unbroken. Head mostly longitudinally rugose with widely spaced rugae, 8 to 11 longitudinal rugae (usually 9) between frontal carinae, almost all running unbroken to posterior margin of head, sometimes with cross-meshes around posterior margin of head. Spaces between rugae and scrobal area usually unsculptured. Mesosoma dorsally and laterally with distinct, mostly longitudinal, widely spaced rugae, spaces between them and propodeal declivity unsculptured and shiny. Petiole generally distinctly rugo-reticulate, often with a less sculptured dorsal area; postpetiole less strongly sculptured than petiole, usually weakly rugose to rugo-reticulate; gaster completely unsculptured, smooth and shiny. All dorsal surfaces of head, mesosoma, both waist segments and gaster with abundant, long, and simple suberect to erect hairs. Fine pubescence on tibiae and antennal scapes appressed to decumbent. Coloration dark brown to nearly black [note that the coloration of the holotype is of a pale reddish brown but this might be due to its age and preservation].

Type Material
Hita Garcia et al. (2010):

Holotype worker, ETHIOPIA, Harar, leg. Ilg (: ZFMK_HYM_2009_6175) [examined].

Tetramorium tersum Holotype worker, KENYA, Rift Valley, Naivasha, 1904, leg. C. Allaud (MNHN) [examined].

Tetramorium (Xiphomyrmex) kivuense Holotype worker, D.R. CONGO, Lake Kivu, Kwidschwi I., 1907-08, leg. Mecklenburg (: GBIF D/FoCol 2105) [examined].

Xiphomyrmex kivuense st. atrinodis Holotype worker, KENYA, Naivasha, 1900m st., 14.XII.1911, leg. Allaud & Jeannel [examined].

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.