Tetramorium kakamega

Only known from the type specimens.

Identification
The combination of medially impressed anterior clypeal margin, impressed metanotal groove, long and spinose propodeal spines (PSLI 27 - 28), postpetiole in lateral view dorsally rounded and relatively low (LPpI 77 - 83), and in dorsal view only slightly wider than petiole (PPI 103 - 113), render T. kakamega recognizable within the muralti complex.

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

Key to weitzeckeri-group species.

Distribution based on Regional Taxon Lists
Afrotropical Region: Kenya.

Nomenclature

 *  kakamega. Tetramorium kakamega Hita Garcia, Fischer & Peters, 2010b: 50, figs. 8A, 58-60 (w.) KENYA.

It has to be pointed out that T. kakamega seems to be very close to T. occidentale and was at first misidentified as this species (Hita Garcia et al. 2009). However, close examination and comparison with the T. occidentale type and non-type material from West and Central Africa provided sufficient evidence to describe it as new species. First, T. kakamega possesses an impressed metanotal groove, not very strongly so but distinct in lateral and dorsal view, which is absent in T. occidentale and other species of the complex. Apart from this they also differ in postpetiolar shape. The postpetiole in T. kakamega is strongly rounded dorsally and relatively low in lateral view (LPpI 77 - 83) and usually less than 1.5 times wider than long in dorsal view (DPpI 143 - 151), while the postpetiole of T. occidentale in lateral view is cuneiform and distinctly higher (LPpI 62 - 71), and in dorsal view between 1.5 to 1.8 times wider than long (DPpI 153 - 182). Another species split from T. occidentale and relatively close to T. kakamega, too, is T. akengense. However, the long and spinose propodeal spines (PSLI 27 - 28) in T. kakamega strongly contrast with the smaller sized spines measured in T. akengense (PSLI 20 - 21). The latter also shows no trace of a metanotal groove in profile whereas this is distinct in T. kakamega. The other species in the muralti complex all have an entire anterior clypeal margin and are thus directly separable from T. kakamega.

Worker
HL 0.756 - 0.778 (0.770); HW 0.722 - 0.756 (0.0.742); SL 0.478 - 0.500 (0.493); EL 0.144 - 0.156 (0.153); PW 0.533 - 0.567 (0.549); WL 0.856 - 0.911 (0.874); PSL 0.206 - 0.217 (0.211); PTL 0.122 - 0.139 (0.132); PTH 0.311 - 0.322 (0.313); PTW 0.289 - 0.322 (0.304); PPL 0.222 - 0.233 (0.226); PPH 0.267 - 0.289 (0.282); PPW 0.328 - 0.344 (0.332); CI 96 - 97 (96); SI 65 - 68 (66); OI 20 - 22 (21); PSLI 27 - 28 (27); PeNI 54 - 57 (55); LPeI 39 - 43 (42); DPeI 221 - 236 (230); PpNI 59 - 61 (61); LPpI 77 - 83 (80); DPpI 143 - 151 (147); PPI 103 - 113 (109) (5 measured).

Head slightly longer than wide (CI 96 - 97). Anterior clypeal margin with median impression. Frontal carinae strongly developed and sinuate at first, becoming distinctly weaker behind posterior eye level and curving down ventrally shortly before posterior margin of head to form the posterior and ventral margins of antennal scrobe; posterior margin weak but distinct; otherwise scrobe well-developed and broad, with distinct and sharp dorsal and ventral margins. Antennal scape short (SI 65 - 68). Eyes relatively small (OI 20 - 22), with 10 to 11 ommatidia in longest row. Metanotal groove in profile impressed, weak but distinct. Propodeal spines long and spinose (PSLI 27 - 28). Propodeal lobes small and triangular with an acute apex. Petiolar node squamiform, in dorsal view generally around 2.3 times wider than long (DPeI 221 - 236), in lateral view around 2.3 to 2.5 times higher than long (LPeI 39 - 43). Postpetiole only weakly cuneiform, in profile distinctly rounded dorsally, in dorsal view around 1.5 times wider than long (DPpI 143 - 151) and only faintly wider than petiole (PPI 103 - 113); in profile relatively low, around 1.25 times higher than long (LPpI 77 - 83). Mandibles unsculptured, smooth and shiny. Clypeus with 3 longitudinal rugae, median ruga always strong and unbroken, lateral rugae sometimes interrupted. Head unsculptured except for median longitudinal ruga between frontal carinae and 2 short weak rugulae between median ruga and frontal carinae situated anteriorly, antennal scrobe with median longitudinal ruga anteriorly running at most to posterior eye level, cephalic dorsum with a nearly effaced punctate ground sculpturation, generally smooth and shiny. Mesosoma generally unsculptured, smooth and shiny, except for weak rugulation on anterior propodeal dorsum directly behind slope of metanotal groove. Both waist segments and gaster completely unsculptured, smooth and shiny. All dorsal body surfaces with simple, fine, long, and erect hairs. Fine pubescence on tibiae and antennal scapes appressed to decumbent. Colour uniformly very dark brown, nearly black, appendages of lighter brown.

Type Material
Holotype worker, KENYA, Kakamega Forest, Isecheno Forest Reserve, 00° 24' N, 34° 86' E, 1800m, 28.IV.2001, Equatorial rain forest, under bark of rotten wood, hand collected, leg. R.R. Snelling (: ZFMK_HYM_2009_6098). Paratypes, 4 workers with same data as holotype (: 1 worker ZFMK_HYM_2009_6097; : 1 worker ZFMK_HYM_2009_6095; NMK: 1 worker ZFMK_HYM_2009_6099; ZFMK: 1 worker ZFMK_HYM_2009_6096).

Etymology
The new species is named in reference to the Kakamega Forest in Western Kenya, which is an important biodiversity conservation area with a rich ant fauna, and was the temporary home to the authors during several ant field surveys. The species epithet is a noun in apposition and thus invariant.