Proceratium politum

The holotype was collected in disturbed rainforest beside a stream.

Identification
A member of the silaceum clade. Proceratium politum and Proceratium caledonicum are the sole Proceratium species recorded from New Caledonia. They resemble each other by having a shining body and propodeal sides at most angulate. Differs from  caledonicum, in the worker, by the much broader frontal carinae and by the shorter erect hairs.

Distribution based on Regional Taxon Lists
Australasian Region: New Caledonia.

Nomenclature

 * . Proceratium politum De Andrade, in Baroni Urbani & De Andrade, 2003b: 324, fig. 131 (w.) NEW CALEDONIA.
 * Type-material: holotype worker, 1 paratype worker.
 * Type-locality: holotype New Caledonia: Toili River, Col d’Amieu Forest Station, 21.35S, 165.47E, 350 m., 21.ii.1977, disturbed rainforest, beside stream (P.S. Ward); paratype with same data.
 * Type-depository: ANIC.
 * Status as species: Liu, C., Fischer & Economo, 2015: 39 (in key).
 * Distribution: New Caledonia.

Worker
Head slightly longer than broad and with the sides gently diverging posteriorly. Vertex in full face view gently convex. Clypeus reduced and as long as the antennal sockets. Anterior border of the clypeus truncate. Frontal carinae very broad and weakly covering the antennal insertions. Lateral expansions of the frontal carinae broad, little raised, diverging on the two anterior fourths, converging on the third fourth, subparallel and carinate only on the posterior fourth. Frontal area concave and with a thin longitudinal carina faintly prolonging posteriorly. Head anterolaterally with a short, longitudinal carina. Genal carinae superficially marked but short, each carina corresponding to the external border of a superficial sulcus. Eyes visible as a dark dot below the integument, small and on the middle of the head sides. First funicular joint almost as broad as long. Funicular joints 2-10 broader than long. Last funicular joint as long as the sum of joints 6-10. Scapes short of the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 6-10 denticles before the pointed apical tooth. Palp formula 2,2.

Mesosoma weakly convex in profile and as long as the maximum head length (mandibles included). Pronotal and propodeal sutures absent. Basal face of the propodeum declivous posteriorly. Area between the basal and declivous faces of the propodeum weakly concave and poorly angulate on each side. Declivous face of the propodeum sloping posteriorly. Sides of the declivous face of the propodeum submarginate. Propodeal spiracle round and above mid height in lateral view.

Petiole subrectangular and not very thick. Anterior border of the petiole straight and anterolaterally carinate. Ventral process of the petiole large, subtriangular and pointed posteriorly. Postpetiole 1/3 shorter than gastral tergite II. Postpetiole in dorsal view with the sides gently convex. Postpetiolar sternite anteromedially with a marked subtriangular projection, gently convex posteriorly in side view. Constriction between postpetiole and gaster impressed. Gastral tergite I convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs not very elongate. All tibiae with a pectinate spur. Spurs of fore legs without basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/5 shorter than hind tibiae. Second tarsomere of hind legs shorter than pretarsus. Pretarsal claws simple. Arolia absent.

Sculpture. Body shining. Head minutely punctate, the punctures denser and mixed with irregular reticulation-rugosities below the eyes. Mesosoma, petiole, postpetiole, gaster and legs with minute piligerous punctures smaller than those on the head. Petiole with sparse, minute granulation.

Body covered by hairs of three main types: (1) short, dense, suberect or subdecumbent on the whole body, suberect and sparse on the funicular joints; (2) longer than type (1), erect on the whole body, shorter than in cnledonicum, absent from the antennae; (3) shorter than hair type (1), dense and decumbent on the funicular joints only. In addition the funicular joints bear whitish, thick, appressed, sparse hairs, and the scapes with sparse hairs similar to type (2) but shorter.



Colour. Ferrugineous-orange with slightly lighter legs.

Measurements in mm and Indices: TL 3.16-3.47; HL 0.69-0.74; HW 0.64-0.69; EL 0.04-0.05; SL 0.46-0.49; WL 0.91- 1.00; PeL 0.22-0.23; PeW 0.33-0.35; HFeL 0.54-0.57; WTiL 0.45-0.47; HBaL 0.35-0.38; LS4 0.35-0.39; LT4 0.69-0.76; CI 92.7-93.2; SI 66.2-66.6; 1GR 0.51.

Type Material


Holotype worker from New Caledonia labeled: "NEW CAL. Toili River, Col d'Amieu For. Stn. 21.35S, 165.47E, 21 Feb 1977 350 m, P. Ward, disturbed rainforest, beside stream", 1 paratype worker, same data and collection as the holotype.

Etymology
From the Latin politus (= smooth), referred to the integumental sculpture.

References based on Global Ant Biodiversity Informatics

 * Baroni Urbani C., and M.L de Andrade. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie 36: 1-480.
 * CSIRO Collection
 * Jennings J. T., L. Krogmann, and C. Burwell. 2013. Review of the hymenopteran fauna of New Caledonia with a checklist of species. Zootaxa 3736(1): 1-53.