Monomorium carbo

Only known from a single collection of a few workers.

Identification
Bolton (1987):

Worker. TL 2.3-2.4, HL 0.60-0.63, HW 0.43-0.45, CI 71-72, SL 0.44-0.48, SI 102-107, PW 0.30-0.31, AL 0.66-0.70 (2 measured).

Anterior margin of median portion of clypeus shallowly concave. With head in full-face view the sides weakly divergent from back to front, the occipital margin shallowly concave. Maximum diameter of eye 0-24-0-26 x HW and with 7 ommatidia in the longest row. The eyes very slightly in front of the midlength of the sides. Metanotal groove scarcely impressed in profile, the propodeal dorsum flattened to weakly depressed medially, without sharp lateral margins. Occipital margin of head with a pair of hairs straddling the midline and another pair closer to the occipital corners. Dorsal alitrunk without hairs. Petiole and postpetiole each with 1-2 pairs of backward directed hairs. First gastral tergite with numerous hairs which are evenly distributed over the surface in front of the apical transverse row. Dorsum of head opaque, shagreenate-punctulate everywhere. Dorsal alitrunk finely reticulate-punctate, the sides similarly sculptured but somewhat effaced on the sides of the pronotum. First gastral tergite shining, with superficial reticular patterning only. Colour uniform dark brown to blackish brown. This enigmatic Ethiopian species is only known from the type-series of a couple of workers.

At first glance it appears to be related to Monomorium minor, a yellow species from Namibia and Angola which itself seems to be intermediate between this complex and the viator-complex, but the wide separation of their habitats and the differences in their scape indices stand against this apparent relationship.

Fresh material will have to be obtained before a clear picture of what constitutes carbo can be developed.

Distribution based on Regional Taxon Lists
Afrotropical Region: Eritrea, Saudi Arabia, United Arab Emirates. Palaearctic Region: Ethiopia, Oman.

Castes
Queens and males are unknown.

Nomenclature

 *  carbo. Monomorium salomonis var. carbo Forel, 1910c: 251 (w.) ETHIOPIA. Combination in M. (Xeromyrmex): Wheeler, W.M. 1922a: 870. Raised to species: Bolton, 1987: 339.

Worker
Bolton (1987) - TL 2.3-2.4, HL 0.60-0.63, HW 0.43-0.45, CI 71-72, SL 0.44-0.48, SI 102-107, PW 0.30-0.31, AL 0.66-0.70 (2 measured).

Anterior margin of median portion of clypeus shallowly concave. With head in full-face view the sides weakly divergent from back to front, the occipital margin shallowly concave. Maximum diameter of eye 0.24-0.26 x HW and with 7 ommatidia in the longest row. The eyes very slightly in front of the midlength of the sides. Metanotal groove scarcely impressed in profile, the propodeal dorsum flattened to weakly depressed medially, without sharp lateral margins. Occipital margin of head with a pair of hairs straddling the midline and another pair closer to the occipital corners. Dorsal alitrunk without hairs. Petiole and postpetiole each with 1-2 pairs of backward directed hairs. First gastral tergite with numerous hairs which are evenly distributed over the surface in front of the apical transverse row. Dorsum of head opaque, shagreenate-punctulate everywhere. Dorsal alitrunk finely reticulate-punctate, the sides similarly sculptured but somewhat effaced on the sides of the pronotum. First gastral tergite shining, with superficial reticular patterning only. Colour uniform dark brown to blackish brown.

Type Material
Monomorium salomonis var. carbo Forel, 1910d: 251. Syntype workers, ETHIOPIA: Ghinda (K. Escherich) [examined].