Polyrhachis alexisi

This rare, but distinctive species is only known from the original type specimens (Bolton, 1973) and a collection from the Central African Republic (Rigato, 2016).

Identification
The only species of the alexisi group with a combination of four petiolar spines or teeth and immarginate propodeum.

Distribution based on Regional Taxon Lists
Afrotropical Region: Central African Republic, Democratic Republic of Congo.

Nomenclature

 *  alexisi. Polyrhachis (Cyrtomyrma) alexisi Forel, 1916: 455, fig. 7 (w.q.) DEMOCRATIC REPUBLIC OF CONGO. Combination in P. (Pseudocyrtomyrma): Emery, 1925b: 206; in P. (Myrma): Bolton, 1973b: 346.

Description
Rigato (2016) - HL 1.25, HW 1.11, CI 89, SL 1.41, SI 127, FW 0.30, FI 27, PW 1.00, WL 1.56, HTL 1.35.

Bolton (1973) - TL 4.8, HL 1.19, HW 1.00, CI 84, SL 1.26, SI 126, PW 0.89, MTL 1.26.

Median portion of anterior clypeal margin projecting as a shallow, rectangular lobe, ending laterally in a pair of acute denticles. Sides of the head straight to weakly concave in front of the eyes, gradually converging anteriorly. Eyes convex, just breaking the outline of the sides of the head in full-face view. Alitrunk short, broad, convex dorsally. Pronotum armed with a pair of short spines, marginate for about half the distance between the base of each spine and the promesonotal suture. Remainder of alitrunk not marginate, the dorsum rounding without interruption into the sides. Promesonotal suture shallow but distinct, metanotal groove absent. Propodeum unarmed, the dorsum rounding into the declivity, the two surfaces not separated by a transverse ridge or margin. Declivity of propodeum very deep, concave in profile. Petiole with a pair of dorsal spines and a pair of lateral teeth. Anterior surface of the first gastral segment concave medially.

Erect hairs absent except on the clypeus, mandibles, and gastral apex. Pubescence extremely short and sparse.

Clypeus and gaster finely reticulate. Head finely, longitudinally striate. Dorsum of alitrunk with an exceedingly fine and dense striation overlying a superficial reticulation. In dorsal view the striae are longitudinal and somewhat arched on the pronotum, divergent on the mesonotum and posteriorly convergent on the propodeum. Sides of alitrunk finely reticulate apart from the propodeum which is striate as the dorsum. Colour black, the appendages brown, and with the antenna! funiculi yellow-brown.

Type Material
Bolton (1973) - Syntype workers, CONGO (KINSHASA) (H. Kohl) [examined].

References based on Global Ant Biodiversity Informatics

 * Rigato F. 2016. The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae). Zootaxa 4088: 1-50.