Polyrhachis lestoni

The type material was collected by canopy fogging in "primary forest."

Identification
Rigato (2016) - An easily recognizable alexisi group species, whose petiole is armed just with a pair of lateral teeth.

The weak transverse ridge separating the propodeal dorsum from declivity may be virtually absent in some specimens. In such cases dorsum and declivity are differently sculptured: the dorsum is longitudinally, posteriorly convergently striolate, the declivity superficially reticulate-punctate.

Distribution based on Regional Taxon Lists
Afrotropical Region: Central African Republic, Congo, Ghana, Kenya.

Nomenclature

 *  lestoni. Polyrhachis lestoni Bolton, 1973b: 349, figs. 48, 61 (w.) GHANA.

Worker
Holotype. TL 5.7, HL 1.34, HW 1.11, CI 83, SL 1.40, SI 126, PW 1.11, MTL 1.29.

Mandibles with four teeth; anterior margin of clypeus with a projecting, shallow rectangular lobe, the corners of which are minutely dentate and acute. In the centre of the lobe is a small, U-shaped notch. Head broader behind than in front, the sides weakly convex and converging anteriorly. Eyes convex, situated well up on the sides, not breaking the outline of the sides in full-face view. Alitrunk strongly antero-posteriorly compressed, almost as broad as long. Pronotum convex dorsally, armed with a pair of short, broad spines and marginate almost to the promesonotal suture, which is distinct. Mesonotum and propodeum fused, without the metanotal groove, but the limits of the two segments are discernible dorsally due to the direction of the sculpturation, discussed below. The fused mesonotum-propodeum is strongly convex, not marginate. Propodeum unarmed but with a weak transverse ridge separating the dorsum from the declivity, the latter deep and shallowly concave. Scale of petiole large, armed only with a small pair of teeth laterally. In front view the margin of the scale between the teeth is strongly convex and weakly sinuate dorsally. Anterior face of the first gastral segment strongly concave medially.

Dorsum of head and gaster with a few erect, white hairs, absent from the dorsum of the alitrunk and the first gastral tergite. Everywhere a sparse, greyish pubescence present.

Clypeus superficially reticulate, overlaid by extremely fine longitudinal striae. Head longitudinally striate. Pronotum finely striate, much more finely so than the head or the remainder of the alitrunk, the striae overlying a superficial reticulation. Some pronotal striae tend to arch from the spines towards the centre of the sclerite and then outwards again towards the promesonotal junction; the rest are longitudinal. The more coarse striae of the mesonotal region are divergent posteriorly, whilst those of the propodeum converge on a postero-median spot situated close to the weak ridge separating the dorsum from the declivity. Declivity, petiole and gaster finely, superficially reticulate. Sides of pronotum and the pleurae finely reticulate-rugose but the sides of the propodeum sculptured as the dorsum.

Paratype workers as holotype, but in one specimen the dorsal margin of the petiole is somewhat concave medially, giving the appearance of a pair of very broad, blunt, dorsolaterally situated tubercles. The range of dimensions of the paratypes is: TL 5.5-5.7, HL 1.29-1.33, HW 1.11-1.14, CI 84-85, SL 1.37-1.40, SI 123-126, PW 1.12-1.14, MTL 1.26-1.29 (3 measured).

Rigato (2016) - HL 1.25–1.35, HW 1.12–1.19, CI 86–90, SL 1.28–1.35, SI 112–121, FW 0.29–0.34, FI 26–30, PW 1.08–1.11, WL 1.45–1.60, HTL 1.19–1.30. (n=6)

Type Material
Holotype worker, GHANA: eastern region, Mt. Atewa, primary forest, by pyrethrum knock-down, sample A5/1, 12.vii.1969 (D. Leston) Paratypes. One worker with same data as holotype ; one worker with same data but sample A4/4 (UG, Legon); and one worker, GHANA : Eastern Region, Adeiso (P. M. Room), in coll. P. M. Room.