Proceratium stictum

Specimens have been collected in rainforest habitat from a rotten log, litter and a ground nest.

Identification
A Proceratium species in an unresolved position within a three-species clade also containing Proceratium deelemani and Proceratium foveolatum (stictum clade). It resembles especially deelemani from which it differs by the frontal carinae less divergent posteriorly, by the longer hind basitarsi (HTiL/HBaL ≤ 1.19 instead of ≥ 1.28) and by the more superficial cephalic sculpture.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  stictum. Proceratium stictum Brown, 1958g: 336, figs. 45, 46 (w.) AUSTRALIA. Baroni Urbani & De Andrade, 2003b: 87 (m.).

Worker
Baroni Urbani and de Andrade (2003) - Head slightly longer than broad, narrower anteriorly than posteriorly. Vertex in full face view gently convex. Clypeus broad, convex, protruding anteriorly and surrounding the whole antennal insertions. Anteromedian margin of the clypeus with a notch. Frontal carinae far from each other, subparallel and not covering the antennal insertions. Floor of the frontal carinae concave medially. Lateral expansions of the frontal carinae narrow and slightly raised. Frons medially concave. Genal carinae present, strongly marked, prolonging towards the hypostomal bridge and bounding an impressed gular area. A superficial sulcus is present between the genal carinae and the gular area. Eyes present and composed of a small, clearly convex ommatidium slightly below the midline of the head. Scapes thick, distally incrassate, and not attaining the vertexal margin. First funicular joint about 1/4 longer than broad. Funicular joints 2-10 slightly broader than long. Last funicular joint as long as the sum of joints 7-10. Mandibles with 3 denticles before the apical tooth. Palp formula 4,3.

Mesosoma about as long as the head (mandibles included), convex in side view. Promesonotal and propodeal sutures absent. Promesopleural and meso-metapleural sutures impressed on the ventral half only. Basal face of the propodeum declivous posteriorly. Declivous face of the propodeum flat, sides of the declivous face weakly marginate, the margin more marked posteriorly. Propodeum with a pair of spines between basal and declivous faces. Propodeal lobes ventrally truncate and dorsally with a subround tooth protruding dorsally. Propodeal spiracle round and above the mid-height in lateral view.

Petiole about 0.1 longer than broad. Petiole in dorsal view subparallel in the anterior third and convex posteriorly. Anterior border of the petiole slightly concave, with a superficial margin denticulate on each side. Ventral process of the petiole lamellaceous and with 1-3 denticles of variable size. Postpetiole slightly shorter than gastral tergite I (LT4). Postpetiole in side view only slightly convex distally and in dorsal view with the sides gently convex. Postpetiolar sternite anteromedially with a marked subtriangular projection. Posterior half of the postpetiolar sternite slightly convex. Constriction between postpetiole and gastral segment I impressed. Gastral tergite I strongly convex on the curvature. Gastral sternite I very short medially. Remaining gastral tergites and sternites slightly curved ventrally.

Legs elongate. All tibiae with a pectinate spur. Spurs of fore legs with a basal spine. Fore basitarsi slightly longer than the mid ones. Hind basitarsi about 0.9 of the length of the hind tibiae. Second tarsomere of mid and hind legs longer than third and fourth tarsomeres, and slightly shorter than pretarsus. Pretarsal claws simple. Arolia present but small.

Sculpture. Head rugulose, granulopunctate, this sculptures superimposed by irregular foveae, the foveae very rare on the two anterior thirds of the head. Mesosoma, petiole and postpetiole granulopunctate and with variably impressed irregular foveae. Gaster with relatively large piligerous foveae, denser on the sides. Scapes and legs granulopunctate.

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

Colour ferrugineous.

Measurements in mm and Indices: TL 3.51-4.47; HL 0.83-1.04; HW 0.73-0.96; EL 0.06-0.07; SL 0.58-0.76; WL 0.97-1.28; PeL 0.40-0.51; PeW 0.34-0.46; HFeL 0.69-0.89; HTiL 0.56-0.72; HBaL 0.47-0.62; LS4 0.15-0.20; LT4 0.63-0.78; CI 87.9-92.3; SI 69.9-73.1; IGR 0.24-0.26.

Male
Baroni Urbani and de Andrade (2003) - Head about as long as broad. Vertex in full face view convex and in full dorsal view weakly flat. Vertexal margin medially narrowly carinate. Clypeus convex and superficially notched medially. Frontal carinae thin, low, parallel and far each other. Frons weakly impressed. Ocelli very large. Compound eyes also very large, larger than in any other male of the stictum clade, strongly convex and occupying almost the whole head sides. Scapes reaching the anterior border of the anterior ocellus. First funicular joint about 1/3 of the length of the second joint. Joints 2-11 longer than broad. Last funicular joint shorter than the sum of joints 10-11. Mandibles as in deelemani, longer than in foveolatum, edentate and only with a pointed apical tooth. Palp formula 4,3.

Mesosorna robust. Pronotum and anterior third of mesonotum almost perpendicular to the posterior two thirds of the mesonotum. Posterior two thirds of mesonotum almost flat. Parapsidal furrows superficially marked. Scutellum as high as the mesonotum, its posterior border subround. Sides of the basal face of the propodeurn converging posteriorly, ending in an angle and separated each other by a narrow, superficial incision. Declivous face of propodeum flat. Propleurae with a broad posterior incision. Metanotum with a median spine-like projection. Propodeal lobes small and subround. Propodeal spiracles small.

Petiole in side view convex, about 1/5 longer than broad. Sides of the petiole in dorsal view parallel in the anterior third and gently convex posteriorly. Anterior border of the petiole with a median concavity separated by a swelling on each side. Subpetiolar process absent. Postpetiole anteriorly slightly broader than the petiole; postpetiolar sides diverging posteriorly. Anterior border of the postpetiolar sternite with a projecting triangular edge connected to a short carina. Posterior half of the postpetiolar sternite with a broad swelling.

Gastral tergite I round. Gastral sternite I thicker than in foveolaturn. Remaining gastral tergites and sternites slightly curved ventrally.

Legs less stout than in the worker.

Fore wings of our type 3, hind wings of our type 2 as defined in the description of the genus.

Sculpture. Body largely smooth and with minute piligerous punctures, this sculpture larger and resembling small foveae between and around the ocelli, on the center of the mesosoma, on the whole scutellum, on the basal face of the propodeum and on the petiole. Pro- and rnesopleurae with sparse, superficial, small, foveae. Metapleurae with dense irregular foveae. Pilosity as in the worker but with the hair type (1) sparser and the hair type (2) shorter on the dorsum of the pronotum, of the mesonotum, of the petiole and or the postpetiole, and on the legs.

Colour. Brown with lighter antennae and legs.

Measurements in mm and Indices: TL 4.41-4.58; HL 0.74-0.76; HW 0.70-0.74; EL 0.52-0.53; SL 0.36-0.38; WL 1.56-1.64; PeL 0.47-0.49; Pew 0.40-0.44; HFeL 0.99-1.00; HTiL 0.80-0.81; HBaL 0.66-0.68; LS4 0.32-0.34; LT4 0.80-0.90; CI 94.6-97.4; ST 50.0; IGR 0.38-0.40.

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.