Proceratium microsculptum

Identification
Differing from all the other species of the genus, in the worker and gyne, by the following combination of characters: frontal carinae posteriorly contiguous, genal carinae strongly marked, second gastral tergite entirely foveolate, propodeal suture dorasally impressed and declivous face of the propodeum with lamellae.

Distribution
Malaysia (Sabah).

This taxon was described from Borneo.

Nomenclature

 *  microsculptum. Proceratium microsculptum De Andrade, in Baroni Urbani & De Andrade, 2003b: 199, fig. 84 (w.q.) BORNEO.

Worker
Head slightly longer than broad, its sides gently diverging posteriorly. Vertex in full face view almost straight. Clypeus anteriorly protruding, lamellaceous, relatively broad, subconvex and completely surrounding the antennal sockets. Anterior border of the clypeus subtruncate and crenulate. Frontal carinae fused posteriorly, not covering the antennal insertions. Lateral expansions of the frontal carinae narrow and raised. Genal carinae strongly marked, lamellaceous; each carina corresponding to the external border of a deep sulcus. Eyes absent. First funicular joint 1/2 longer than broad. Funicular joints 2-10 slightly broader than long. Last funicular joint about as long as the sum of joints 7-10. Scapes short of the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 2-3 denticles before the pointed apical tooth. Palp formula 4,3.

Mesosoma gently convex and slightly longer than the maximum head length (mandibles included) in profile. Propodeal suture superficially impressed. Basal face of the propodeum declivous posteriorly. Declivous face of the propodeum flat. Basal and declivous faces of the propodeum separated dorsally by a well marked, diverging carina, the carina connected to a subround, broad tooth on each side. Each side of the declivous face of the propodeum with a broad lamella, broader and round posteriorly. Propodeal spiracle round and over the mid height in lateral view.

Petiole strongly convex in profile, with the sides parallel on the anterior sixth and strongly convex posteriorly in dorsal view. Anterior border of the petiole concave and laterally carinate, the carina denticulate each side. Ventral process of the petiole triangular and pointed. Postpetiole anteriorly slightly broader than the petiole; its sides diverging and gently convex posteriorly. Postpetiolar sternite anteromedially with a marked subtriangular projection, almost straight in side view. Constriction between postpetiole and gaster impressed. Gastral tergite I slightly shorter than twice than the postpetiole, weakly angulate on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs slender and 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 subequal in size to the pretarsus. Pretarsal claws simple. Arolia present.

Sculpture. Head, mesosoma and petiole granulopunctate, irregularly rugulose-foveolate; the foveae very sparse on the head. Postpetiole punctate-foveolate. Gaster smooth, minutely punctate and covered by large foveae. Legs punctate.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body, sparse and suberect on the funicular joints; (2) longer than type (1), erect on the whole body, slightly shorter on the scapes; (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. Ferrugineous brown.

Measurements in mm and Indices: TL 3.60; HL 0.84-0.85; HW 0.76-0.78; EL absent; SL 0.61; WL 1.03-1.04; PeL 0.33; PeW 0.32-0.33; HFeL 0.68; NTiL 0.55-0.56; HBaL 0.43; LS4 0.19-0.20; LT4 0.90-0.91; CI 90.5-91.8; ST 71.8-72.6; IGR 0.21-0.22.

Queen
Differing from the worker in the following details: eyes large, their maximum diameter 1/5 of the head length and composed of many facets with interommatidial pilosity. Ocelli well developed.

Mesosoma robust and convex in profile. Parapsidal furrows weakly marked. Scutellum with the sides converging posteriorly and with the posterior border subtruncate. Metanotum with a lamellaceous tooth.

Measurements in mm and Indices: TL 4.1 1; NL 0.87; HW 0.81; EL 0.17; SL 0.65; WL 1.24; PeL 0.37; PeW 0.36; HFeL 0.77; HTiL 0.60; HBaL 0.48; LS4 0.20; LT4 1.06; CI 93.1 ; SI 74.7; IGR 0.19.

Type Material
Holotype worker from Sabah labelled: "SABAH, Gn. Silam, 810 m, 1983, R. Leakey"; in ; paratypes: 2 workers and 1 gyne, same data and collection as the holotype.

Etymology
"Microsculptum" is a barbarism alluding to the fine integumental structure of this species.