Polyrhachis wilmsi Forel

Rigato, Fabrizio, 2016, The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae), Zootaxa 4088 (1) : 46

Polyrhachis wilmsi Forel stat. n.

Polyrhachis cubaensis subsp. wilmsi Forel, 1910b: 30 . Holotype worker, MOZAMBIQUE: Lobombo Borges (F. Wilms) [not seen, not at MHNG]. [Junior synonym of P. cubaensis Mayr : Bolton 1973:325.]

Diagnosis. A viscosa -group species with standing hairs on frons and vertex, four similarly long petiolar spines, and a well developed median prominence along the ridge separating propodeal dorsum and declivity.

Comment. The type of P. cubaensis subsp. wilmsi has not been found in the MHNG collection, where it should have been preserved. Therefore, my interpretation of this taxon is based on the original description and a comparison with some more recently collected material.

Forel (1910b) briefly described Polyrhachis cubaensis subsp. wilmsi mentioning this important feature: a median triangular tooth (“dreieckigen Zahn”) on the ridge running between the propodeal spines (“Dornen” and not “Zähnen” as pointed out by Forel himself). Such a condition exactly matches the Bolton (1973) description of “ P. cubaensis ”. In addition, Forel (1910b) stated that wilmsi was 6.5 mm long and had a well developed longitudinal rugosity on head and mesosoma. All of these features correspond to Bolton’s cubaensis as well, and not to gerstaeckeri (see under this species), whose full size was reported as 5.4 mm.

As no other African Polyrhachis seems to share wilmsi ’s main features, I think that, in absence of the type, the best way to interpret any specimen with the above mentioned characters is to name them as P. wilmsi . Bolton (1973) based his description of cubaensis on some South African specimens I could examine and which are very similar to some Somalian specimens at MSNM. All of them well fit Bolton’s description, except that the Somalian specimens are slightly smaller, have a lower SI, and lack proximal hairs on the clypeal dorsum (a few ones occur in South African specimens) and on tergites II-III. South African and Somalian specimens look inseparable on the basis of all main features: head shape, mesosomal shape and proportions, propodeal spines and ridge, petiolar structure, sculpturation, pubescence length and density, and I consider them as conspecific. The measurements below refer to Somalian specimens for comparison with South African ones already given by Bolton (1973) (n=3). HL 1.70–1.72, HW 1.52–1.53, CI 89, SL 1.58–1.62, SI 104–106, FW 0.52–0.54, FI 34–36, PW 1.27–1.30, WL 2.08–2.18, HTL 1.70–1.76.

Material examined: SOMALIA: Mogadiscio, Afgoi, 22.iv–5.v.1984 (R. Mourglia) (3 w, MSNM). SOUTH AFRICA: Zululand (G. Arnold) (2 w, BMNH).