Strumigenys nimbrata

Two collections records contain the only known clues regarding this ant's biology: littoral rainforest and primary forest litter-samples.

Identification
Bolton (1983) - A member of the nimbrata complex in the Strumigenys arnoldi-group. The size range of the non-paratypic material is HL 0.42-0.48, HW 0.31-0.37, CI 73-77, ML 0.17-0.21, MI 40-44, SL 0.22-0.26, SI 69-71. All this material matches the holotype. S. nimbrata is easily diagnosed by its very reduced funicular segments 2 and 3. Other characters aiding its recognition within the arnoldi-group include the cephalic pilosity, position of the proximal preapical teeth and size of the distals, development of the infradental lamellae and spongiform appendages, and minute size. The only other species sharing the character of very reduced funicular segments is Strumigenys bitheria, but in this species the flange bordering the upper scrobe margins is very broad, the distal preapical tooth of the mandible is longer, the pronotal dorsum has distinct punctate sculpture between the rugulae, the petiole node is as broad as long in dorsal view and the propodeal teeth are much longer than in nimbrata.

Distribution based on Regional Taxon Lists
Afrotropical Region: Gabon, Ghana, Ivory Coast.

Nomenclature

 *  nimbrata. Strumigenys nimbrata Bolton, 1983: 381 (w.q.) IVORY COAST. See also: Bolton, 2000: 594.

Worker
Holotype. TL 1.5, HL 0.43, HW 0.31, CI 72, ML 0.18, MI 42, SL 0.22, SI 71, PW 0.20, AL 0.37.

Outer margins of mandibles shallowly convex in full-face view, the blades narrowing basally and broadest at about the midlength. Apical fork of each mandible with 2 spiniform teeth, without intercalary teeth or denticles. Each mandible with 2 preapical teeth, a larger proximal tooth which is situated very close to the midlength of the blade, and a smaller distal preapical tooth which is close to the apical fork. The distance separating the bases of these two teeth is distinctly greater than the length of the distal preapical tooth. Upper scrobe margins with a narrow inconspicuous bordering rim or flange which is distinctly narrower than the maximum diameter of the eye. Eyes small, with only 4 ommatidia, the maximum diameter equal to or slightly less than the maximum width of the scape. Pre ocular notch absent, the ventral surface of the head without a pre ocular transverse groove or impression. Antennal scapes slender at the base and very weakly curved, the medial third slightly expanded and the leading edges with a row of apically curved narrow spoon-shaped hairs which are smaller than those fringing the upper scrobe margins. Funicular segments 2 and 3 vestigial and difficult to see, the separation of the two segments almost invisible and the length of segments 2 and 3 together less than half the length of segment 4 (the penultimate segment); under low magnification or in poor light the funiculus appears to consist of only 3 segments rather than the usual 5. Dorsum of head from posterior clypeal margin to about the midlength with conspicuous narrowly spoon-shaped pilosity which is curved anteriorly, and a double to triple row of these hairs border the upper scrobe margins. Behind the midlength the hairs are much smaller and sparser, narrow and inconspicuous; the pilosity of the two areas contrasting strongly. Dorsum of head with 6 standing hairs arranged in a transverse row of 4 close to the occipital margin and a more anteriorly situated pair. Dorsum of head reticulate-punctate. Pronotal humeri each with a single long fine flagellate hair. Mesonotum with a single pair of stout standing hairs. Ground-pilosity of dorsal alitrunk of sparse small hairs which are closely applied to the surface. Metanotal groove a feeble transverse line on the dorsum which is minutely impressed. Dorsum of mesonotum very shallowly concave in profile behind the level of the standing hairs, not sharply depressed. Propodeal teeth small and narrowly triangular, the infradental lamellae very narrow and petering out ventrally, broadest where they join the teeth. Sides of alitrunk unsculptured. Pronotal dorsum very weakly and irregularly longitudinally rugulose, the remainder of the dorsal alitrunk and the petiole node reticulate-punctate. Postpetiole smooth in centre of disc but elsewhere with faint superficial reticulation. Spongiform appendages of pedicel segments much reduced, the peduncle of the petiole with a narrow ventral strip and the lateral lobe of the node minute. Petiole node broader than long in dorsal view. Ventral spongiform lobe of postpetiole smaller than the exposed area of the postpetiolar disc in profile. Basigastral costulae widely spaced and short, but sharply defined. Petiole, postpetiole and gaster with stout standing hairs which are thickened apically. Colour dull yellow to brownish yellow.

Paratypes. TL 1.5-1.8, HL 0.42-0.46, HW 0.31-0.35, CI 72-77, ML 0.17-0.20, MI 40-45, SL 0.22-0.24, SI 68-73, PW 0.19-0.23, AL 0.35-0.43 (12 measured).

As holotype, the eyes with 4-6 ommatidia and the sculpture showing some variation in intensity. The postpetiole may be as described above, or wholly smooth, or even have a few faint longitudinal rugulae towards the outer edges of the disc.

Type Material
Holotype worker, Ivory Coast: Tai Forest, 17 .x.1980 (V Mahnert & J. -L. Perret). Paratypes. 31 workers and 1 female with same data as holotype (MHNG; ; ; ).

References based on Global Ant Biodiversity Informatics

 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research 3: 5-16.
 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research. 3: 5-16.
 * Bolton B. 1983. The Afrotropical dacetine ants (Formicidae). Bulletin of the British Museum (Natural History). Entomology 46: 267-416.
 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * IZIKO South Africa Museum Collection
 * Yeo K., T. Delsinne, S. Komate, L. L. Alonso, D. Aidara, and C. Peeters. 2016. Diversity and distribution of ant assemblages above and below ground in a West African forest–savannah mosaic (Lamto, Cote d’Ivoire). Insectes Sociaux DOI 10.1007/s00040-016-0527-6