Polyrhachis cubaensis Mayr

Rigato, Fabrizio, 2016, The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae), Zootaxa 4088 (1) : 13-14

Polyrhachis cubaensis Mayr

Polyrhachis cubaensis Mayr, 1862: 687 . Holotype gyne [not worker as reported in Bolton, 1973], originally labeled CUBA, 1843; then corrected into SOUTH AFRICA, Port Natal [currently Durban] (see Mayr, 1893: 195, footnote) (NHMW) [examined].

Holotype gyne. HL 1.45, HW 1.24, CI 86, SL 1.40, SI 113, FW 0.47, FI 38, ScW 1.15*, MnL 1.60*, ML 2.34*, HTL 1.47. (*These measurements are imprecise because the specimen was pinned through the mesosoma; the mesoscutum is slightly misplaced and is missing most of its right and posterior portions.)

Clypeus medially faintly carinate and with its anterior margin moderately and evenly arched. Head in full face view oval, wider behind than in front, posterior margin wide, moderately and evenly convex without posterior corners; sides in front of the eyes anteriorly converging and feebly convex. Eyes relatively large and convex. Ocelli small. Pronotum laterally weakly marginate. Pronotal teeth anteriorly diverging, stout and blunt, their tips weakly upturned. Propodeal dorsum feebly marginate laterally, strongly arched in profile and weakly convex transversely, about twice as wide as long. Propodeal teeth minute and upturned. Propodeal dorsum and declivity divided by a sudden change of slope, no ridge occurs between them. Petiole with two pairs of spines, the mid pair looks stouter and slightly shorter than the lateral one; the mid pair a little more distant from one another than mid and lateral spine of the same side. All petiolar spines weakly backward tilted. First gastral tergite anteriorly slightly concave.

Mandibles shagreened and with sparse piligerous pits. Body mostly subopaque with a slightly shining gaster. Body and appendages finely reticulate-punctate, with no trace of rugosity. Clypeus, pronotal dorsum, mesonotum, mesanepisternum, propodeal dorsum and declivity, posterior petiolar surface and gaster mostly appearing more superficially and tidily sculptured.

Standing hairs mostly wanting, occurring only at the gastral apex, on gastral sternites I-IV, at the anterior clypeal margin and mandibular apex. Pubescence very short, inconspicuous on most of the body and moderately dense on gaster and appendages, but never hiding the sculpturation; on the gaster the distance between two adjacent elements is about equal to their length.

Colour mainly black, legs mostly brown with proximally darker tibiae, tarsi and coxae. Antennae piceous, except their dark brown funicular apices; mandibles apically ferrugineous. Wings moderately infuscated.

Comment. While examining a doubtfully identified P. cubaensis specimen I realized that Bolton (1973) did not see any of the types belonging either to cubaensis or to its synonyms (i.e. P. gerstaeckeri Forel, P. cubaensis var. striolatorugosa Mayr , and P. cubaensis subsp. wilmsi Forel ). As a consequence, he based his interpretation on the original, somewhat misleading, descriptions only. Bolton (1973) defined P. cubaensis on the basis of specimens he compared with Mayr’s description of P. cubaensis var. striolatorugosa (1893) , because the original description of cubaensis was too short (in Mayr’s own words too) and mostly useless.

Bolton (l.c.) thought the P. cubaensis holotype was a worker, yet it is actually a gyne (as one can infer from Mayr’s original description, which ends “Wings slightly brownish”, and from a comment in the description of var. striolatorugosa ). One of the main features Bolton (1973: 292, in key) reported for cubaensis was the occurrence of a transverse ridge running between the spines which is raised medially into a tooth or tubercle. The holotype gyne lacks this ridge. Mayr (1893) described P. cubaensis var. striolatorugosa as bearing a ridge between the propodeal teeth. Consequently, Mayr himself did not carefully compare his var. striolatorugosa with cubaensis s.str. and overlooked this very important difference, which is consistent in both female castes. The non-conspecificity between cubaensis var. striolatorugosa and cubaensis was therefore not hitherto ascertained. As a consequence, the current interpretation of cubaensis must be reviewed as well as its synonymies.

Both P. gerstaeckeri Forel and P. cubaensis subsp. wilmsi Forel have a ridge between the propodeal dorsum and the declivity and cannot be conspecific with P. cubaensis Mayr. At present, I cannot find either any synonym of P. cubaensis or any worker seemingly conspecific with the type gyne. Polyrhachis cubaensis apparently belongs in the viscosa -group, but an important feature of the species-group, the strength of the metanotal suture, cannot be inferred from gyne morphology. Among viscosa -group species, P. durbanensis Forel shares with cubaensis the lack of a ridge between the propodeal teeth, but durbanensis is definitely larger and has longer appendages. The P. cubaensis gyne is superficially similar to the rufipalpis gyne, but rufipalpis bears long pubescence on most of mesosomal sides and has more slender appendages. Therefore, P. cubaensis remains known from the type only and its actual taxonomic position is still doubtful.

The former cubaensis ’ synonyms must be assigned to two distinct species: P. gerstaeckeri Forel (senior synonym of P. cubaensis var. striolatorugosa Mayr ) and P. wilmsi Forel. They are discussed under their headings.