Monomorium rotundatum

This species has been found in the leaf litter of a secondary forest.

Identification
Bolton (1987) - A member of the M. boerorum complex in the M. monomorium species group. In the original description Santschi placed rotundatum in the spurious subgenus Lampromyrmex, thus implying that the antennae had 11 segments. The antennae are poorly displayed in the three extant syntypes of this species, but those which are visible show 12 segments.

Of the six known African species which combined 12-segmented antennae with the characteristic form of eye described above, rotundatum is diagnosed by its pilosity, colour, eye size and scape length. Comparative measurements of the six species are as follows.


 * Monomorium floricola HW 0.33-0.37, CI 75-80, SI 86-94, Diameter of eye 0.21-0.24 x HW
 * Monomorium shilohense HW 0.30-0.34, CI 77-81, SI 80-85, Diameter of eye 0.23-0.24 x HW
 * Monomorium sryetum HW 0.32, CI 76, SI 84, Diameter of eye 0.25 x HW
 * Monomorium inquietum HW 0.38, CI 83, SI 76-79, Diameter of eye 0.16 x HW
 * Monomorium rotundatum HW 0.34-0.38, CI 77-81, SI 79-83, Diameter of eye 0.18-0.19 x HW
 * Monomorium trake HW 0.30, CI 79, SI 73, Diameter of eye 0.17-0.18 x HW

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

Nomenclature

 *  rotundatum. Monomorium rotundatum Santschi, 1920b: 14, fig. 2 (w.) SOUTH AFRICA. See also: Bolton, 1987: 409.

Worker
Bolton (1987) - TL 1.7-2.0, HL 0.44-0.48, HW 0.34-0.38, CI 77-81, SL 0.28-0.30, SI 79-83, PW 0.20-0.24, AL 0.44-0.52 (8 measured).

Clypeal carinae narrowly but quite strongly developed, divergent anteriorly. Anterior clypeal margin transverse to shallowly convex between the anterior points of the clypeal carinae. Eyes relatively small, their maximum diameter 0.18-0.19 x HW. Eye in profile seen to consist of an outer ring of ommatidia which encircles a single short longitudinal row, the encircled row of only 2-3 ommatidia so that the eye is only slightly longer than high. In full-face view the eye conspicuously in front of the midlength of the sides of the head. Antennal scapes, when laid straight back from their insertions, failing to reach the occipital margin. Promesonotum only shallowly convex in profile, the metanotal groove weakly and shallowly impressed. Propodeal spiracle small and pinhole-like. Petiole with a short stout anterior peduncle. Subpetiolar process a longitudinal strip which narrows posteriorly until it runs into the convex ventral border of the petiole node itself. Node of petiole low and broadly subconical in profile, bluntly rounded dorsally. Postpetiole smaller than petiole and dorsally much more broadly and shallowly convex. Standing pilosity sparse, showing signs of abrasion in all material examined, but apparently with 4-5 pairs on the promesonotum and a single pair on the propodeum. Sculpture absent except for short but distinct metanotal cross-ribs. Colour yellow, the apex of the first gastral tergite traversed by a band of brown, which may be indistinct in older samples.

Type Material
Bolton (1987) - Syntype workers, South Africa: Natal, Durban, 4.v. 1914, ex coil. Arnold (H. B. Marley) [examined].