Polyrhachis esarata

The type specimens were obtained from a fogging sample.

Identification
Rigato (2016) - A medium sized militaris group species very similar to Polyrhachis decellei and separated by the latter mostly because of its comparatively larger and elliptical eyes in profile, and shorter scape (SI < 170 vs. SI > 170).

Polyrhachis esarata was described from a single worker. I consider as conspecific with it one worker and one gyne from Dem. Rep. of the Congo and Equatorial Guinea, respectively. The worker is a little larger than the holotype and lacks the distinctive couple of hairs on the head dorsum, but the corresponding hair pits are present. Also, the eyes are only moderately convex and not strongly protruding as in the type.

Bolton (1973) - This species, a member of the complex of species surrounding Polyrhachis concava and including Polyrhachis alluaudi and its allies, is closest related to Polyrhachis decellei. It may immediately be separated from concava and the more “normal” forms in the complex by the presence of a single pair of erect hairs on the dorsum of the head. This character is shared only with decellei, from which it can be separated by the shape of the anterior clypeal margin, the construction of the petiole and the outline shape of the propodeal margination seen in dorsal view.

Distribution based on Regional Taxon Lists
Afrotropical Region: Democratic Republic of Congo, Equatorial Guinea, Ghana.

Nomenclature

 *  esarata. Polyrhachis esarata Bolton, 1973b: 303, figs. 45, 55 (w.) GHANA.

Worker
Holotype. TL 7.2, HL 1.56, HW 1.20, CI 77, SL 1.91, SI 159, PW 1.08, MTL 1.92.

Anterior clypeal margin arcuate and entire. Eyes convex and protuberant. Sides of head in front of the eyes almost straight, very gently convex and somewhat convergent anteriorly. Behind the eyes the sides of the head round into the broadly convex occipital margin. Alitrunk marginate throughout its length, interrupted only at the sutures. Dorsal surfaces of pronotum and mesonotum flat, dorsal surface of propodeum convex. Pronotum armed with a pair of spines, the outer edges of which are continuous basally with the margination of the segment. Propodeum with a pair of minute, tuberculiform teeth. Promesonotal suture distinct; metanotal groove developed and impressed. In dorsal view the marginations of the alitrunk are convergent posteriorly on the pronotum and mesonotum. On the propodeum the marginations are convex, broadest at about the midlength of the segment and converging anteriorly towards the metanotal groove and posteriorly towards the propodeal teeth where they are terminated. Petiole with a dorsal pair of spines and a lateral pair of small teeth. The dorsal spines are weakly divergent and somewhat back-curved. Anterior face of first gastral segment not concave medially.

Erect hairs present on the anterior clypeal margin and the gastral apex, and with a single pair on the dorsum of the head, situated on a level with the posterior borders of the eyes, behind the posteriormost extension of the frontal carinae. Pubescence dense on alitrunk, long, with a pale brassy tint on the dorsum, rather more greyish on the sides. On the head, gaster and appendages the pubescence very short, fine, greyish in colour and moderately dense.

Sculpturation everywhere of a fine, dense reticulation.

Colour black, the legs, especially the tibiae, very dark brown-black. Palpi and extreme tip of apical funicular segment of antenna yellow-brown.

Rigato (2016) - Worker. HL 1.65, HW 1.30, CI 79, SL 2.13, SI 164, FW 0.38, FI 29, PW 1.08, WL 2.27, HTL 2.19.

Queen
Rigato (2016) - Gyne. HL 1.72, HW 1.40, CI 81, SL 2.08, SI 149, FW 0.42, FI 30, ScW 1.57, MnL 1.97, WL 2.87, HTL 2.34.

Type Material
Holotype worker, GHANA : Eastern Region, Bunso, by pyrethrum knock-down (sample B.3/8), 7.vii.1969 (D. Leston).

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.
 * Robson Simon Database Polyrhachis -05 Sept 2014