Probolomyrmex newguinensis

Probolomyrmex newguinensis has been collected only once from a nest under a rock in a regenerated rainforest in Papua New Guinea.

Identification
Petiolar node relatively long and narrow (best viewed dorsally), the dorsal face (in side view) moderately convex anteriorly and weakly convex posteriorly; posterodorsal margin of petiole in dorsal view produced medially into a rearward directed rounded projection; subpetiolar process reduced to a shallow convexity.

Probolomyrmex newguinensis is morphologically similar to Probolomyrmex watanabei from Malaysia, particularly in the shape of the petiole. It differs from that species in having the petiole more barrel-shaped in dorsal view rather than trapezoidal, and in having the anterior face of the node (in side view) more strongly convex, giving the petiole a higher appearance. Additionally, the head is more elongate (CI < 61 vs. > 62) and the scape is shorter (SI < 114 vs. > 124).

Key to Australian and Melanesian Probolomyrmex species

Distribution based on Regional Taxon Lists
Indo-Australian Region: New Guinea.

Nomenclature

 *  newguinensis. Probolomyrmex newguinensis Shattuck, Gunawardene & Heterick, 2012: 45, fig. 4 (w.m.) NEW GUINEA.

Description
Worker description. Body dark ferruginous brown. Head in full-face view with weakly convex sides and weakly and broadly concave posterior margin. Eyes absent. Antennae moderately long. Dorsal outline of mesosoma very weakly convex with a slight concavity at the metanotal groove; posterior margin of propodeal dorsum in dorsal view drawn posteriorly into a broad, rounded projection; posterior face of propodeum angled laterally and lacking a well-developed lamella. Petiole including subpetiolar process longer than high, its dorsal surface in profile relatively strongly convex anteriorly and rounding into a weakly convex to nearly flat surface posteriorly; subpetiolar process reduced to a weak convexity. Abdominal segment III (gastral segment I) in profile narrowed anteriorly, the ventral surface concave anteriorly and convex posteriorly.

Measurements. Worker (n=6)—CI 59–61; DPetW 0.21–0.24; HL 0.71–0.75; HTL 0.50–0.55; HW 0.43–0.46; LPetI 118–123; ML 0.97–1.03; PetH 0.30–0.31; PetNL 0.35–0.37; PronW 0.36–0.37; SI 110–114; SL 0.48–0.51