Monomorium jacksoni

This species has been found numerous times in rainforest litter samples.

Identification
Bolton (1987) - A member of the hanneli species group. Very closely related to Monomorium invidium, which also occurs at the type-locality of jacksoni, but the latter with much stronger sculpture on the propodeal dorsum and sides of the alitrunk, and with smaller and less prominent clypeal teeth.

Distribution based on Regional Taxon Lists
Afrotropical Region: Cameroun.

Nomenclature

 * . Monomorium jacksoni Bolton, 1987: 427 (w.q.) CAMEROON.
 * Type-material: holotype worker, 12 paratype workers, 1 paratype queen.
 * Type-locality: holotype Cameroon: Nkoemvon, 12.i.1980 (D. Jackson); paratypes: 7 workers, 1 queen with same data, 5 workers with same data but 5.i.1980.
 * Type-depositories: BMNH (holotype); BMNH, MCZC, MHNG (paratypes).
 * Status as species: Bolton, 1995b: 263.
 * Distribution: Cameroon.

Worker
Holotype. TL 2.0, HL 0.46, HW 0.39, CI 85, SL 0.32, SI 82, PW 0.29, AL 0.55.

Mandibles unsculptured except for hair-pits. Median portion of clypeus flanked by a pair of short triangular denticles which are not strongly prominent, but the edges of the median clypeal bicarination V-shaped and very sharply defined. Eyes small, maximum diameter 0.15 x HW and with only 3 ommatidia in the longest row. Eye consisting of only 6 ommatidia in total, without central ommatidia surrounded by a peripheral ring. Promesonotum shallowly convex, the metanotal groove weakly impressed. Propodeal dorsum behind the metanotal groove sloping posteriorly; dorsum and declivity separated by a blunt angle. Dorsum of propodeum marginate laterally, the marginations diverging posteriorly. Petiole and postpetiole shaped as in invidium (Fig. 98). Cephalic dorsum smooth, unsculptured except for hair-pits and some short faint costulae behind the frontal lobes. Sides of head mostly unsculptured but the strip of cuticle between the eye and the mandibular insertion sculptured, this sculptured strip being slightly wider than the eye itself. Promesonotum glassy smooth everywhere, mesopleuron sculptured except for a smooth patch posterodorsally. Metapleuron completely sculptured as is the propodeal side except for a smooth area around the spiracle. Propodeal dorsum conspicuously transversely rugulose, the spaces between the rugulae punctate. Petiole, postpetiole and gaster unsculptured in dorsal view. All dorsal surfaces of head and body with numerous standing hairs. Colour of head and body blackish brown.

Paratypes. TL 1.8-2.0, HL 0.44-0.47, HW 0.38-0.40, CI 85-89, SL 0.30-0.34, SI 79-85, PW 0.27-0.30, AL 0.52-0.56 (12 measured). As holotype but eyes with maximum diameter 0.14-0.15 x HW and with 6-7 ommatidia in total. In some almost the upper third of the mesopleuron is unsculptured.

Type Material
Holotype worker, Cameroun: Nkoemvon, 12.i. 1980 (D. Jackson). Paratypes. 7 workers and 1 female with same data as holotype; 5 workers with same data but 5.i.1980 (BMNH; ; ).