Tetramorium pinnipilum

Found in the leaf litter of rainforests. In Western Kenya it is one of the most common species in leaf litter and is often abundantly present in pitfall traps and Winkler samples..

Identification
Tetramorium pinnipilum is the only species in the whole species group with pinnate, pectinate, or even plumose pilosity, thus easily identifiable. It shares many morphological similarities with Tetramorium philippwagneri and Tetramorium schoutedeni that separate them from the rest of the edouardi complex, especially the small eyes (OI 21 - 23 in all three species), and a very dark brown gaster that strongly contrasts with the yellowish or orange brown head, mesosoma, petiole, and postpetiole.

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

Distribution
Known from Angola and Kenya.

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

Nomenclature

 *  pinnipilum. Tetramorium pinnipilum Bolton, 1980: 230, figs. 3, 6 (w.) ANGOLA. See also: Hita Garcia, Fischer & Peters, 2010b: 31.

Worker
Hita Garcia et al. (2010) - HL 0.733 - 0.83 (0.778); HW 0.678 - 0.800 (0.735); SL 0.522 - 0.644 (0.571); EL 0.144 - 0.183 (0.166); PW 0.500 - 0.600 (0.544); WL 0.878 - 1.100 (0.950); PSL 0.189 - 0.267 (0.224); PTL 0.150 - 0.200 (0.181); PTH 0.294 - 0.367 (0.319); PTW 0.222 - 0.289 (0.257); PPL 0.178 - 0.256 (0.218); PPH 0.278 - 0.333 (0.307); PPW 0.267 - 0.356 (0.316); CI 89 - 97 (94); SI 73 - 83 (78); OI 21 - 23 (23); PSLI 25 - 32 (29); PeNI 44 - 51 (47); LPeI 50 - 61 (57); DPeI 135 - 150 (142); PpNI 53 - 62 (58); LPpI 62 - 78 (71); DPpI 131 - 159 (146); PPI 115 - 129 (123) (24 measured).

Head longer than wide (CI 89 - 97). Anterior clypeal margin with distinct median notch. Frontal carinae well developed, weakening behind eye level, nearly reaching 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 73 - 83). Eyes relatively small (OI 21 - 23), with 7 to 9 ommatidia in longest row. In profile metanotal groove weakly impressed. Propodeal spines long, spinose, and acute (PSLI 25 - 32). Propodeal lobes small, triangular and acute. Petiolar node high nodiform, in dorsal view between 1.3 and 1.5 times wider than long (DPeI 135 - 150) and in profile between 1.6 to 2 times higher than long (LPeI 50 - 61). Postpetiole in dorsal view around 1.5 times wider than long (DPpI 131 - 159); in lateral view antero-posteriorly compressed, around 1.3 to 1.6 times higher than long (LPpI 62 - 78). Mandibular sculpturation longitudinally rugose. Clypeus longitudinally rugose, usually with 3 to 5 rugae, often irregularly arranged, median rugae rarely unbroken and strong. Head with longitudinal rugulation, 9 to 12 widely spaced rugae between frontal carinae, most reaching posterior margin of head unbroken. Spaces between rugae and scrobal area with weak punctate ground sculpturation, appearing shiny. Mesosoma mostly longitudinally rugose, often irregularly, with strong widely spaced rugae; spaces between them and propodeal declivity unsculptured and shiny. Petiole, postpetiole, and gaster unsculptured, smooth and shiny. All dorsal surfaces of head, mesosoma, both waist segments and gaster with abundant, long, suberect to erect hairs, most of them conspicuously pinnate, pectinate, or plumose apically. Fine pubescence on tibiae and antennal scapes decumbent to subdecumbent. Head, mesosoma, petiole, and postpetiole orange-brown contrasting with very dark brown to black gaster.

Type Material
Hita Garcia et al. (2010) - Tetramorium pinnipilum Bolton, 1980:230. Holotype worker, ANGOLA, Salazar I.I.A.A., 9.-15.III.1972, leg. P.M. Hammond [examined]. Paratypes, 10 workers with same data as holotype (BMNH,, , ) [examined].

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1980. The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Ethiopian zoogeographical region. Bulletin of the British Museum (Natural History). Entomology 40: 193-384.
 * 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.
 * IZIKO South Africa Museum Collection
 * Ross S. R. P. J., F. Hita Garcia, G. Fischer, and M. K. Peters. 2018. Selective logging intensity in an East African rain forest predicts reductions in ant diversity. Biotropica 1-11.