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WORKER (redescription of holotype). Measurements: HL 0.56, HW 0.46, HS 0.510, SL 0.38, PrW 0.34, WL 0.66, HFL 0.37, PeNL 0.14, PeH 0.30, PeNW 0.22, PeS 0.220. Indices: CI 82, SI 83, PeNI 65, LPeI 47, DPeI 157.
Eyes small but distinct, far forward on side, composed of a low but indeterminate number of partially fused small ommatidia (left eye depigmented). Mid-dorsal longitudinal impression on head terminates immediately behind the frontal lobes and does not extend to the midlength of the vertex or beyond. Apex of scape, when laid straight back from its insertion, fails to reach the midpoint of the posterior margin in full-face view by a distance that is less than the apical scape width; SL/HL 0.68. Cephalic dorsum extremely finely and superficially punctulate. Mesonotal-mesopleural suture absent. Metanotal groove conspicuously incised across dorsum of mesosoma; mesonotum with a well-defined posterior margin. Propodeal declivity bluntly rounded into the sides, without sharp marginations or carinae. Dorsum of mesosoma almost smooth, the minute punctulae that are present are superficial and inconspicuous. Upper half of mesopleuron with very fine superficial sculpture that is weaker than sculpture on side of propodeum; lower half of mesopleuron appears smoother (not clearly visible). Petiole in profile with the anterior and posterior faces of the node almost parallel; faces converge very slightly only at the apex, where they round into the weakly convex dorsum. Subpetiolar process in profile with an obtuse ventral angle. Maximum width of first gastral tergite in dorsal view less than the width of the second tergite at its midlength. Base of cinctus of second gastral tergite smooth and shining in dorsal view, without cross-ribs. Posttergite of second gastral segment, from posterior margin of cinctus to apex, much broader than long. Disc of second gastral tergite minutely superficially punctulate. Full adult colour a uniform dull yellow.
At first glance the holotype of nivarianaHNS appears to be a small, depigmented version of eduardiHNS that has lost most of its sculpture, but whose dimensions fall within the lower end of the punctatissimaHNS range. It is separated from these two species as follows.
It differs from eduardiHNS because in nivarianaHNS colour is dull yellow, dorsum of mesosoma is almost smooth, sculpture of mesopleuron is feeble and superficial, scape is shorter (SI 83, SL/HL 0.68) and fails to reach midpoint of posterior margin of head in full-face view (for comparison, in eduardiHNS SI 86 – 93, SL/HL 0.72 – 0.78). Overall size of nivarianaHNS is smaller (HL 0.56, HW 0.46, SL 0.38) when compared to eduardiHNS (HL 0.63 – 0.70, HW 0.54 – 0.59, SL 0.47 – 0.54).
It differs from punctatissimaHNS because in nivarianaHNS there is no elongate mid-dorsal cephalic impression, sculpture is present on the mesopleuron, the anterior and posterior faces of the petiole node in profile do not converge towards the apex and the subpetiolar process has an obtuse ventral angle.
H. nivarianaHNS is known from only five collections (Barquin Diez, 1981), all from Tenerife in the Canary Islands. The number of specimens from these five collections totals a mere 13 workers and a single queen, so nivarianaHNS cannot be considered a common or successful species. It may be a Canaries endemic, or an Afrotropical species that has not yet been discovered on the continent; or it may represent a hybrid between eduardiHNS and punctatissima . This last is highly speculative and without proof, though the fact that it possesses a strange mix of characters found in the two other species is suggestive. Its taxonomic history is short and the name nivarianaHNS has occurred in the literature very few times following Santschi’s original description. Wheeler (1927a), Wellenius (1955) and Hohmann, et al. (1993) all merely listed the species as present and endemic in the Canaries. Barquin Diez (1981) redescribed the species, added a few more details of morphology and correctly concluded that it was “ close to eduardiHNS ” but differed by its lighter colour, shorter scapes and more feeble dorsal sculpture.
Type specimens: syntype of Ponera nivariana: casent0915203