Proceratium gigas

Identification
A Proceratium species belonging to the silaceum clade and differing from all the other species of the clade, in the worker, by the following combination of characters: CI = 83.9, frontal carinae broad and strongly diverging, petiolar node thick, and erect long hairs sparse. Proceratium gigas shares with Proceratium hirsutum the broad, diverging frontal carinae, but gigas has sparser and shorter hairs and denser body sculpture. gigas resembles Proceratium gracile and Proceratium robustum for the shape of the gaster, strongly convex in profile. Among the 6 species of the silaceum group known from Australia, gigas is the largest one as exemplified by its TL = 3.72 mm (TL < 3.62 mm for the other 5 species).

Distribution
This taxon was described from Australia.

Nomenclature

 *  gigas. Proceratium gigas De Andrade, in Baroni Urbani & De Andrade, 2003b: 360, fig. 141 (w.) AUSTRALIA.

Worker
Head longer than broad and with parallel sides. Vertex in full face view gently convex. Clypeus reduced and slightly longer than the antennal sockets. Anterior border of the clypeus truncate. Frontal carinae broad and slightly covering the antennal insertions. Lateral expansions of the frontal carinae broad, raised, diverging on the two anterior fourths, converging on the third fourth, diverging and carinate only on the posterior fourth. Frontal area concave on the three anterior fourths and with a longitudinal carina starting from the last fourth and prolonging posteriorly. Head anterolaterally with a short, longitudinal carina. Genal carinae distinct, each carina corresponding to the external border of a deep sulcus. Eyes visible as a dark dot below the integument, small and on the middle of the head sides. First funicular joint about as broad as long. Funicular joints 2-10 broader than long. Last funicular joint as long as the sum of joints 7-10. Scapes short of the vertexal margin and gently thickening apically. Right mandible with masticatory margin with 4 denticles before the pointed apical tooth and left mandible minutely crenulate and with preapical and apical teeth. Palp formula 2,2.

Mesosoma convex and about as long as the maximum head length (mandibles included) in profile. Pronotal and propodeal sutures absent. Basal face of the propodeum declivous posteriorly. Area between the basal and declivous faces of the propodeum gently concave medially and with a dorsal carina ending in a small tooth on each side. Declivous face of the propodeum flat. Sides of the declivous face of the propodeum slightly marginate. Propodeal spiracle round and above mid height in lateral view.

Petiole rectangular and thick. Anterior border of the petiole straight and anterolaterally carinate. Ventral process of the petiole large, subtriangular and slightly pointed posteriorly. Postpetiole about 1/3 shorter than gastral tergite I, with gently diverging sides in dorsal view. Postpetiolar sternite anteromedially with a marked subround projection, 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 slightly 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 about as long as the pretarsus. Pretarsal claws simple. Arolia very small.

Sculpture. Head reticulate-punctate and rugulose. Mesosoma granulopunctate and with few, irregular rugosities, the rugosities more longitudinal on the pleurae. Petiole and postpetiole granulopunctate. Gaster and legs shining and with minute piligerous punctures, the punctures denser on the legs.

Body covered by hairs of three main types: (1) short, dense, suberect or subdecumbent on the whole body, sparser and erect on the funicular joints; (2) longer than type (1), sparse on the whole body, erect on the head and mesosoma, suberect or subdecumbent on the scapes, petiole, postpetiole, gaster and legs. absent on the funiculi; (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.

Colour. Light ferrugineous with slightly lighter antennae and legs.

Measurements in mm and Indices: TL 3.72; HL 0.87; HW 0.73; EL 0.04; SL 0.60; WL 1.04; PeL 0.25; Pew 0.35; HFeL 0.68; HTiL 0.56; HBaL 0.45; LS4 0.40; LT4 0.80; CI 83.9; SI 68.9; IGR 0.50.

Type Material
Holotype worker (unique) from New South Wales, Australia, labeled: "NSW: Dorrigo NP, E end Blackbutt Track, 710 m, 28.II-5.III.1980, subtrop. rainf., A. Newton, M. Thayer", in.

Etymology
From the Latin gigas (= giant), referred to large size of this species.