Probolomyrmex simplex

This species is presently known from a single small collection made many years ago in Northern Province, Papua New Guinea.

Identification
Petiolar node relatively long and narrow (best viewed dorsally), the dorsal face (in side view) uniformly convex and without a separation of the anterior and dorsal faces; posterior projection of the subpetiolar process in the form of a blunt tooth.

Probolomyrmex simplex is similar to the Australian species Probolomyrmex aliundus, Probolomyrmex salomonis from the Solomon Islands and the Malaysian Probolomyrmex maryatiae. It differs from P. aliundus in being smaller (HL < 0.59mm vs. > 0.59mm, HW < 0.38mm vs. > 0.38mm), having more strongly developed foveae and in having the posteroventral tooth of the subpetiolar process tooth-like rather than angular. It can be separated from P. salomonis in having the anteroventral tooth of the subpetiolar process narrow and tooth-like rather than broadly rounded, having relatively well developed lateral flanges on the posterior face of propodeum and in having the foveae on the mesosoma and gaster weakly rather than strongly developed. It differs from P. maryatiae in that the posterodorsal margin of the petiole in dorsal view is straight to weakly convex rather than concave as in P. maryatiae and in having the posterior face of the petiolar node in lateral view is much less convex.

Key to Australian and Melanesian Probolomyrmex species

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

Nomenclature

 *  simplex. Probolomyrmex simplex Shattuck, Gunawardene & Heterick, 2012: 47, fig. 6 (w.) NEW GUINEA.

Description
Worker description. Body ferruginous brown. Head in full-face view with weakly convex sides and weakly concave posterior margin. Eyes absent. Antennae relatively long. Dorsal outline of mesosoma essentially straight, the pronotum curving downwards slightly and the propodeal dorsum raised slightly; posterior margin of propodeal dorsum in dorsal view straight; posterior face of propodeum margined laterally with a well-developed, thin, translucent lamella. Petiole including subpetiolar process approximately as long as high, its dorsal surface in profile forming a relatively gentle and uniform curve with only a slightly stronger curve near the border of the anterior and posterior faces; subpetiolar process with conspicuous anteroventral and posteroventral projections, both in the form of a blunt tooth. Abdominal segment III (gastral segment I) in profile narrowed anteriorly, broadest near its posterior margin, the ventral surface uniformly convex.

Measurements. Worker (n=4)—CI 62–64; DPetW 0.16–0.17; HL 0.57–0.59; HTL 0.35–0.38; HW 0.35–0.38; LPetI 104–108; ML 0.73–0.79; PetH 0.24–0.26; PetNL 0.26–0.27; PronW 0.28–0.29; SI 96–102; SL 0.35–0.37