Polyrhachis andrei Emery

Rigato, Fabrizio, 2016, The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae), Zootaxa 4088 (1) : 10-11

Polyrhachis andrei Emery

Polyrhachis andrei Emery, 1921: 22 , figs. 1a, b, c. Holotype gyne, CAMEROUN (L. Conradt) (MSNG) [not seen].

Diagnosis. A distinctive militaris- group species with six petiolar spines or teeth and eyes placed at or just in front of the midlength of the head sides.

Worker (n=1). HL 1.63, HW 1.33, CI 82, SL 1.58, SI 119, FW 0.63, FI 47, PW, 1.30 WL 2.08, HTL 1.78.

Head somewhat rectangular, side subparallel and weakly convex; posterior corners broadly rounded. Anterior clypeal border with its median third straight and almost lobe-like. Frons relatively wide. Eyes protruding and placed slightly in front of the midlength of head sides. Mesosoma entirely laterally marginate; the margination overhanging the sides. Promesonotal and metanotal groove distinct, especially the latter which is also clearly incised in lateral view. Pronotum, mesonotum and propodeum wider than long. Pronotum with anterolaterally directed strong teeth at its anterior corners. Propodeal dorsum bearing at its posterior corners a pair of very stout upturned and weakly outward directed spines. Propodeal dorsum and declivity mostly confluent. Petiolar node with a pair of strong teeth medially and two pairs of long, mostly straight spines laterally. The spines of each lateral pair diverge: the anteriormost spine is slightly in front and dorsolaterally directed, the posteriormost one arises from a lower point and is more backward tilted.

Mandibles finely reticulate-punctate with overlaying weak striolation and several hair-bearing pits. Clypeus superficially shagreened with sparse hair pits. Head dorsum mostly longitudinally rugose, the rugae posteriorly diverging; around the eyes the sculpturation is mainly reticulate-rugose. Dorsum of mesosoma longitudinally rugose. Mesosoma laterally reticulate-rugose with a more longitudinal pattern on pronotal and propodeal sides. Petiole roughly reticulate. Gaster finely reticulate-punctate and moderately shining.

Standing, yellowish stiff hairs occur sparsely all over the body. Identical, subdecumbent hairs occur also on the apical half of scapes, tibiae and mid- and hind-femora. Pubescence very short and inconspicuous.

Body and appendages black

Gyne (n=2). HL 1.72–1.89, HW 1.32–1.54, CI 77–81, SL 1.59–1.70, SI 110–120, FW 0.68–0.75, FI 49–52, WL 2.70–3.07, ScW 1.52–1.76, MnL 1.93–2.13, HTL 1.85–2.13.

With the usual differences from the worker caste.

Comment. Emery’s (1921) description and figures of a queen are sufficient to identify this species. Polyrhachis andrei and P. decemdentata are the only known African species with six petiolar spines or teeth. Bolton (1973) based his diagnosis of P. andrei mostly on Emery’s (1921) description, and thought it could even be a synonym of P. decemdentata . I have seen two gynes and a single worker of andrei and some gynes and several workers of decemdentata from various localities. These species are easily distinguishable on the basis of the characters reported in the key, and pilosity as well: P. andrei has sparse, stiff standing hairs mostly apically located on tibiae and scapes, whereas P. decemdentata has abundant, thin hairs uniformly distributed on legs and scapes.

Material examined. GHANA: Kade, 17.ii.1971 (J. Majer) (1 g, BMNH). REPUBLIC of the CONGO: Niari Region, 2.28617 S 12.87004 E, 709 m, 29.vi.2013–9.vii.2013, primary forest, pitfall trapping (L. Niemand) (1 w, AFRC: LN-RC1-033, CASENT0250043). TANZANIA: 37 mi. north of Mpanda, 1200 m, 18.xi.1967 (E.S. Ross & A.R. Stephen) (1 g, CAS).