Tetramorium renae

Only known from the island of São Tomé.

Identification
Tetramorium renae can be well distinguished from the remaining species of the complex by the following character set: dorsum of mesosoma with weak rugulation only, often partly unsculptured; ground sculpturation on head and mesosoma generally smooth and shiny; standing hairs present on first gastral tergite; generally bicoloured with head, appendages, and gaster of yellowish brownish colour contrasting with reddish brown mesosoma, petiole, and postpetiole.

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

Distribution based on Regional Taxon Lists
Afrotropical Region: São Tomé & Principe.

Nomenclature

 *  renae. Tetramorium renae Hita Garcia, Fischer & Peters, 2010b: 75, figs. 17A, 85-87 (w.) SÃO TOMÉ & PRINCIPE.

Morphologically  Tetramorium renae can be placed together with Tetramorium boltoni, Tetramorium snellingi, and Tetramorium weitzeckeri. Nevertheless, not considering the differences in coloration, the single best diagnostic character to distinguish T. renae from them is the sculpturation on the mesosoma. Generally, the mesosomal sculpturation of T. renae is reduced, consisting dorsally of weak irregular rugulae only, and laterally mostly unsculptured, while T. boltoni, T. snellingi, and T. weitzeckeri all show a strongly longitudinally rugose mesosoma throughout their whole distribution ranges. In addition, T. renae cannot be confused with Tetramorium guineense since the latter possesses a very prominent cephalic reticulate-punctate ground sculpturation that is absent in T. renae, and much longer propodeal spines (PSLI 28 - 43). Finally, the group of species without standing hairs on the first gastral tergite and a squamiform postpetiole differs significantly from T. renae in which hairs are present on all dorsal surfaces and the postpetiole is only weakly antero-posteriorly compressed.

An extraordinary variation in coloration can be observed in the type material of T. renae. The holotype and most other specimens are bicoloured with the gaster, appendages, and head significantly of lighter colour than the mesosoma and waist segments, whereas few specimens showed a much darker uniformly reddish brown coloration. However, more specimens are necessary to decide if this observed colour variation is consistent in this species or only a rarity.

Worker
HL 0.633 - 0.744 (0.687); HW 0.600 - 0.700 (0.641); SL 0.467 - 0.533 (0.503); EL 0.128 - 0.161 (0.143); PW 0.422 - 0.489 (0.461); WL 0.778 - 0.878 (0.810); PSL 0.144 - 0.194 (0.174); PTL 0.089 - 0.100 (0.094); PTH 0.278 - 0.322 (0.302); PTW 0.233 - 0.294 (0.271); PPL 0.167 - 0.217 (0.191); PPH 0.256 - 0.317 (0.289); PPW 0.256 - 0.322 (0.294); CI 90 - 96 (93 ); SI 75 - 81 (78); OI 21 - 24 (22); PSLI 23 - 28 (25); PeNI 54 - 62 (59); LPeI 29 - 35 (31); DPeI 261 - 311 (287); PpNI 61 - 66 (64); LPpI 64 - 69 (66); DPpI 146 - 163 (154); PPI 104 - 113 (109 ) (13 measured).

Head longer than wide (CI 90 - 96). Anterior clypeal margin with median impression. Frontal carinae well developed, becoming weaker behind eye level, fading out shortly before posterior margin of head. Antennal scrobe narrow, shallow, and without defined posterior and ventral margins, ending before posterior margin of head. Antennal scape of medium length (SI 75 - 81). Eyes relatively small to moderate (OI 21 - 24), with 7 to 9 ommatidia in longest row. Metanotal groove usually weakly impressed. Propodeal spines moderate to long (PSLI 23 - 28), elongate-triangular to spinose, and acute. Propodeal lobes small, triangular and acute. Node of petiole squamiform, quite thin and transverse, in dorsal view between 2.6 to 3.1 times wider than long (DPeI 261 - 311) and in profile 2.8 to 3.5 times higher than long (LPeI 29 - 35). Postpetiole in lateral view weakly antero-posteriorly compressed, around 1.5 times higher than long (LPpI 64 - 69), in dorsal view around 1.5 times wider than long (DPpI 146 - 163) and much more voluminous than petiole. Mandibles finely longitudinally striate, sometimes weakly developed but always present. Clypeus usually with 3 longitudinal rugae, median ruga always strongly developed and unbroken, while lateral rugae sometimes weaker developed. Head longitudinally rugose with widely spaced rugae, cephalic dorsum with 7 to 9 longitudinal rugae between frontal carinae, most running unbroken to posterior margin of head. Spaces between rugae and scrobal area with very weak, nearly effaced ground sculpture or completely unsculptured, generally shiny. Dorsum of mesosoma with weak, mostly irregular, longitudinal rugulation, often partly unsculptured; most of lateral mesosoma unsculptured, rarely with partial weak rugulation. Petiole, postpetiole, and gaster completely unsculptured, smooth and shiny. All dorsal surfaces with abundant, long, fine, and simple suberect to erect hairs. Fine pubescence on antennal scapes and tibiae appressed to decumbent. Holotype and most other specimens noticeably bicoloured, gaster, appendages, and usually head, pale yellowish brown, contrasting with the reddish brown mesosoma, petiole, and postpetiole, sometimes head of same colour as mesosoma; few specimens uniformly very dark reddish brown, appendages of lighter brown.

Type Material
Holotype worker, SÃO TOMÉ & PRINCIPE, Isla São Tomé, Ôbó N.P., 1.63 km WSW Bom Successo, 00° 16' 34 N, 06° 36' 20 E, 1351m, 5.-8.V.2001, #562, leg. J.M. Ledford (: CASENT0095412). Paratypes, 7 workers with same data as holotype (CASC: 5 workers CASENT0095382, CASENT0095421, CASENT0095423, CASENT0095427; : 1 worker CASENT0095426; : 2 workers CASENT0095383, CASENT0095425); 1 worker from SÃO TOMÉ & PRINCIPE, Ilha São Tomé, Ôbó N.P., 1.63 km WSW Bom Successo, 00° 16' 34 N, 06° 36' 20 E, 1351m, 9.-16.IV.2001, leg. C.E. Griswold (CASC: CASENT0096829); 2 workers from SÃO TOMÉ & PRINCIPE, Ilha São Tomé, Ôbó N.P., between Lagoa Ameila & Bom Successo, 00° 16' 48 - 00° 17' 10 N, 06° 25' 29 - 06° 36' 40 E, 1200m - 1500m, 5.-15.V.2001, #563, leg. J.M. Ledford (CASC: 2 workers CASENT0096115, CASENT0096119); 2 workers from SÃO TOMÉ & PRINCIPE, Isla São Tomé, Ôbó N.P., between Lagoa Ameila & Bom Successo, 00° 16' 48 - 00° 17' 19 N, 06° 25' 29 - 06° 36' 45 E, 1200m - 1500m, 5.-8.V.2001, #564, leg. J.M. Ledford (CASC: 1 worker CASENT0096916; : 1 worker CASENT0096940).

Etymology
The new species is dedicated to Rena Denzer from Bonn, Germany, for her enduring support of and patience with the first author.

References based on Global Ant Biodiversity Informatics

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