Monomorium rufulum

According to Arnold (1916) this species, which he wrongly gives as Monomorium nitidiventre, is very agile and nests in loose sandy soil (Bolton 1987). A Namibia savannah study found this ant to be the dominant species at ground-baits (Campbell et al. 2015).

Identification
Bolton (1987) - A member of the M. bicolor complex in the M. salomonis species group. A distinctive and quite widespread member of the complex in southern Africa, rufulum is immediately diagnosed by its reduced basal mandibular tooth, numerous long arched ammochaete hairs on the ventral surface of the head, and densely hairy first gastral tergite contrasting to the hairless (or nearly hairless) dorsal alitrunk. Both alate and apterous females of rufulum are known.

Distribution based on Regional Taxon Lists
Afrotropical Region: Angola, Botswana, Namibia, South Africa, Zimbabwe.

Nomenclature

 * . Monomorium salomonis var. rufula Stitz, 1923: 156 (w.) NAMIBIA.
 * Type-material: 9 syntype workers.
 * Type-localities: Namibia: Windhoek, v.1911 (W. Michaelsen), Namibia: Omaruru, 21-22.v.1911 (W. Michaelsen).
 * Type-depository: MNHU.
 * Subspecies of salomonis: Ettershank, 1966: 92.
 * Status as species: Bolton, 1987: 359 (redescription); Bolton, 1995b: 266.
 * Senior synonym of monardi: Bolton, 1987: 359; Bolton, 1995b: 266.
 * Distribution: Angola, Botswana, Namibia, Zimbabwe.
 * monardi. Monomorium (Xeromyrmex) monardi Santschi, 1937d: 226, figs. 15, 16 (w.) ANGOLA.
 * Type-material: 2 syntype workers.
 * Type-locality: Angola: Osi, 1932-33, no. 16 (A. Monard).
 * Type-depository: NHMB.
 * Status as species: Ettershank, 1966: 90.
 * Junior synonym of rufulum: Bolton, 1987: 359; Bolton, 1995b: 264.

Worker
Bolton (1987) - TL 3.0-3.6, HL 0.76-088, HW 0.59-0.70, CI 75-80, SL 0.69-0.81, SI 112-120, PW 0.40-0.47, AL 0.98-1.16 (15 measured).

Fourth (basal) tooth of mandible reduced to a minute denticle which is only a fraction the size of the third tooth. Ventral surface of head with numerous very long anteriorly curved J-shaped or strongly arcuate hairs. Maximum diameter of eye 0.23-0.26 x HW, with 10-12 ommatidia in the longest row. Median portion of clypeus with its anterior margin transverse to shallowly convex in full-face view. Dorsum of head with a maximum of 3 pairs of hairs behind the level of the frontal lobes, but in full-face view the sides and occipital margin without projecting hairs. Dorsal alitrunk usually hairless but in Namibian specimens the pronotal humeri with a single hair on each side. Petiole node with 1-2 and postpetiole with 2-3 pairs of posteriorly projecting hairs. First gastral tergite densely pilose, with about 10 pairs in front of the apical transverse row. Colour dull orange to reddish orange on head, alitrunk, petiole and postpetiole; the gaster darker brown to blackish brown but frequently with a much paler spot or streak anteromedially. Dorsum and sides of head and entirety of alitrunk densely reticulate-punctate, the punctures small, crowded and sharply defined. Petiole and postpetiole reticulate-punctulate, the punctulae less well defined than on the alitrunk. Gaster feebly shagreened basally, the sculpture fading apically.

Type Material
Bolton (1987) - Syntype workers, Namibia: Windhoek, v.1911 (Michaelsen); Omaruru, 21-22.v.1911 (Michaelsen) [examined].

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1987. A review of the Solenopsis genus-group and revision of Afrotropical Monomorium Mayr (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History). Entomology 54: 263-452.
 * Campbell H., M. D. E. Fellowes, and J. M. Cook. . Species diversity and dominance-richness relationships for ground and arboreal ant (Hymenoptera: Formicidae) assemblages in Namibian desert, saltpan, and savannah. Myrmecological News 21: 37-47.
 * Ettershank G. 1966. A generic revision of the world Myrmicinae related to Solenopsis and Pheidologeton (Hymenoptera: Formicidae). Aust. J. Zool. 14: 73-171.
 * IZIKO South Africa Museum Collection
 * Santschi F. 1937. Résultats de la Mission scientifique suisse en Angola (2me voyage) 1932-1933. Fourmis angolaises. Revue Suisse de Zoologie. 44: 211-250.
 * Stitz H. 1923. Hymenoptera, VII. Formicidae. Beiträge zur Kenntnis der Land- und Süsswasserfauna Deutsch-Südwestafrikas 2: 143-167.