Monomorium drapenum

Collections of this species were noted as being hand collected in desert habitat and from Bushveld pitfall samples.

Identification
Bolton (1987) - A member of the M. subopacum complex in the M. salomonis species group. This distinctive small Namib Desert species is quickly identified by its sculpture, distribution of pilosity, and presence of a conspicuous lobate to dentiform subpetiolar process.

Distribution based on Regional Taxon Lists
Afrotropical Region: Namibia.

Nomenclature

 * . Monomorium drapenum Bolton, 1987: 342, fig. 48 (w.) NAMIBIA.
 * Type-material: holotype worker, 29 paratype workers.
 * Type-locality: holotype Namibia: Namib Desert, 23°04’S, 15°36’E, sample P 18,1984, pitfall (A.C. Marsh); paratypes: 8 workers with same data, 6 workers with same data but 23°06’S, 15°13’E, sample P 15, 3 workers with same data but 23°04’S, 15°36’E, sample P 14, 3 workers with same data but 23°04’S, 15°36’E, sample P 22, 3 workers with same data but 23°06’S, 15°18’E, sample P 23, 3 workers with same data but 23°06’S, 15°24’E, sample P 24, 3 workers with same data but 23°06’S, 15°24’E, sample P 25.
 * Type-depositories: BMNH (holotype); BMNH, MCZC, MHNG (paratypes).
 * Status as species: Bolton, 1995b: 261.
 * Distribution: Namibia.

Worker
Holotype. TL 2.4, HL 0.65, HW 0.50, CI 77, SL 0.50, SI 100, PW 0.32, AL 0.68.

Anterior free margin of median portion of clypeus shallowly convex. Eyes relatively large, the maximum diameter 0.28 x HW. Sides of head in full-face view evenly shallowly convex, broadest at the level of the eyes and narrowing slightly both anteriorly and posteriorly; occipital margin broadly but shallowly concave. With the alitrunk in profile the pronotal dorsal outline feebly convex, the mesonotum more or less fiat and sloping shallowly to the weakly impressed metanotal groove. Propodeum in dorsal view feebly transversely concave at the curvature where dorsum meets declivity. Petiole and postpetiole of approximately equal width in dorsal view; in profile the petiole node slightly higher than the postpetiole. Anterior peduncle of petiole ventrally with a broad blunt lamelliform process. Dorsum of head behind level of frontal lobes with appressed sparse pubescence and with four pairs of standing hairs, of which three pairs are close to the midline and the fourth is situated on the occipital margin close to the corners. Dorsal alitrunk without standing hairs, with fine sparse appressed pubescence present. Petiole with one pair and postpetiole with two pairs of backward directed hairs. First gastral tergite with hairs evenly distributed over the surface of the sclerite. Cephalic dorsum polished and shining, sculpture from level of eyes to occipital margin consisting only of an extremely fine superficial reticular patterning. Dorsal alitrunk more strongly sculptured than the head, the sculpture increasing in intensity from front to back. Pronotum superficially reticulate, grading on the mesonotum into raised reticulation and weak reticulate-punctate sculpture posteriorly; propodeal dorsum reticulate-punctate. Sides of pronotum polished and weakly reticulate-shagreenate, the remainder finely reticulate-punctate. Petiole and postpetiole reticulate to weakly reticulate-punctulate. First gastral tergite superficially reticulate, the patterning denser basally than apically. Head and gaster dark brown, alitrunk, petiole and postpetiole medium brown.

Paratypes. TL 2.4-2.6, HL 0.60-0.67, HW 0.46-0.52, CI 73-78, SL 0.46-0.51, SI 98-104, PW 0.32-0.34, AL 0.68-0.72 (18 measured). Maximum diameter of eye 0.28-0.32 x HW, with 8-10 ommatidia in the longest row. As holotype but some samples uniformly dark brown and some individuals with the subpetiolar process more acute than in the holotype, appearing more dentiform than lobate. Postpetiole sometimes with only a single pair of hairs.

Type Material
Holotype worker, Namibia: Namib Desert, 15°36' E, 23°04' S , sample P 18, pitfall, 1 984 (A. C. Marsh).

Paratypes. 8 workers with same data as holotype; 6 workers with same data but 15° 13' E, 23° 06' S, sample P 15; 3 workers with same data but 15° 36' E, 23° 04' S, sample P 14; 3 workers with same data but 15° 36' E, 23° 04' S, sample P 22; 3 workers with same data but 15° 18' E, 23° 06' S, sample P 23; 3 workers with same data but 15° 24' E, 23° 06' S, sample P 24; 3 workers with same data but 15° 24' E , 23° 06' S, sample P 25 (BMNH; ; ).

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.
 * IZIKO South Africa Museum Collection