Messor galla

Bolton (1982) - Without doubt the commonest, most successful and most widely distributed Messor species in the northern half of sub-Saharan Africa. Some aspects of the biology of galla have been investigated by Levieux & Diomande (1978) and Levieux (1979).

Identification
Key to Afrotropical Messor species

Of the four species in the region which lack dense gastral pilosity galla is separated from Messor collingwoodi and Messor luebberti by the extensive cephalic sculpturing of the last two. The separation of galla from its closest African relative, Messor angularis of Kenya, is tabulated under that name. (Bolton 1982)

Distribution
Ranges throughout the Sahelian zone across the entire width of the continent. On the eastern side it is found as far south as Kenya, and in the west it occurs coastally as well as in the drier northern parts of the West African states.

Distribution based on Regional Taxon Lists
Afrotropical Region: Burkina Faso, Chad, Eritrea, Ghana, Ivory Coast, Kenya, Mali, Niger, Nigeria, Saudi Arabia, Senegal, Somalia, Sudan. Palaearctic Region: Ethiopia, Iran, Oman.

Nomenclature

 *  galla. Stenamma (Messor) barbarum var. galla Mayr, 1904b: 5 (w.) ETHIOPIA. [First available use of Stenamma (Messor) barbarum subsp. caduca var. galla Emery, 1895a: 179; unavailable name.] Finzi, 1939a: 155 (q.m.). Combination in Messor: Santschi, 1914d: 335. Subspecies of barbarus: Santschi, 1910f: 234; Santschi, 1914d: 335. Raised to species: Santschi, 1923f: 326; Santschi, 1928f: 201. Senior synonym of latinoda: Viehmeyer, 1923: 87; Bolton, 1982: 350; of airensis, nobilis, rufula and material of the unavailable names armata, rufa, triempressa referred here: Bolton, 1982: 350. Current subspecies: nominal plus obscurus.
 * latinoda. Messor barbarus st. latinoda Santschi, 1917e: 93, fig. 2 (s.w.) EAST AFRICA. Junior synonym of galla: Viehmeyer, 1923: 87; Bolton, 1982: 350.
 * nobilis. Messor galla st. nobilis Santschi, 1928f: 201 (w.q.) ETHIOPIA. Junior synonym of galla: Bolton, 1982: 350.
 * rufula. Messor galla var. rufula Finzi, 1939a: 162 (w.) ETHIOPIA. [First avialable use of Messor barbarus r. semirufus var. rufula Forel, 1918b: 156; unavailable name.] Junior synonym of galla: Bolton, 1982: 350.
 * airensis. Messor galla var. airensis Bernard, 1950b: 286 (w.q.) NIGER. Junior synonym of galla: Bolton, 1982: 350.

Worker
Bolton (1982) - Medium to Large, HW 2.40- > 3.70.

Median portion of clypeus with anterior margin broadly but shallowly concave to more or less entire. With the head in full-face view the sides very shallowly convex to roughly straight, usually slightly convergent in front of the eyes. Occipital margin broadly indented medially. In HW range 2.40-3.76 the maximum diameter of the eye 0.44-0.68, about 0.17-0.20 x HW, and the CI range 102-114. Propodeum showing great variation; frequently with the dorsum rounding into the declivity but sometimes with a pair of broad teeth or lamellae. Between these two extremes is a range of intermediates including forms with a narrow to broad rim or flange following the curve of the surface, forms with a small to large salient angle and forms with the angle or flange projecting to various degrees. Dorsum of head smooth and shining, away from the median strip sculptured only with very widely scattered small pits or a faint superficial patterning. Median strip of head behind clypeus with longitudinal rugular sculpture which usually extends back at least as far as the level of the posterior margins of the eyes, and often distinctly further back than this; only very rarely is the rugular strip shorter. Intensity of rugulae on the median strip very variable and the width of the strip not usually exceeding the width across the frontal lobes and often narrower, only rarely slightly wider. Pronotum dorsally with weak transverse rugulae which may sometimes be very feeble or even partially effaced. Mesonotum varying from almost smooth to faintly rugulose. Propodeal dorsum generally sharply transversely rugose but in some samples the rugae diagonal, irregular or interrupted. First gastral tergite unsculptured but often showing a faint superficial patterning. With the head in full-face view the sides without projecting hairs, the occipital margin with 0-4 hairs on each side of the median impression. Generally hairs are present occipitally, specimens with zero count are very few and may be the result of abrasion. Dorsum of head sparsely hairy, the psammophore conspicuous ventrally. Parts of dorsal alitrunk with pilosity as follows; pronotum with 0-4 pairs, mesonotum with 4-10 pairs, metanotal groove with 1-2 pairs at least in large workers, propodeum with 1-5 pairs. Petiole with 1-3, postpetiole with 3-6 pairs of hairs. First gastral tergite without hairs or with a sparse transverse row at the extreme apex of the sclerite. Ventral surfaces of hind femora usually with hairs all along the shaft but in some they are denser proximally than distally. Colour reddish brown to blackish brown, usually with the gaster darker than the head and alitrunk. In some samples the head slightly more reddish than the alitrunk.