Proceratium papuanum

Identification
A member of the silaceum clade, resembling Proceratium snellingi, but differing from it, in the worker and in the gyne, by the broader frontal carinae, by the more superficial body sculpture and by the smaller value of CI (≤ 95 instead of ≥ 100).

Distribution
Borneo, Indonesia (Sumatra), Malaysia, Papua New Guinea, Philippines, and Solomon Islands.

This taxon was described from New Guinea.

Nomenclature

 *  papuanum. Proceratium papuanum Emery, 1897c: 592, pl. 15, fig. 38 (q.) NEW GUINEA. Senior synonym of caeca: Brown, 1958g: 248; of carinifrons: Baroni Urbani & De Andrade, 2003b: 334.
 * carinifrons. Proceratium carinifrons Menozzi, 1939b: 175, fig. 1 (w.q.) INDONESIA (Sumatra). Junior synonym of papuanum: Baroni Urbani & De Andrade, 2003b: 334.
 * caeca. Ponera caeca Donisthorpe, 1949b: 491 (w.) NEW GUINEA. [Unresolved junior primary homonym of Ponera coeca Santschi, 1914d: 322 (now in Hypoponera).] Junior synonym of papuanum: Brown, 1958g: 248.

Worker
Baroni Urbani and de Andrade (2003) - Head slightly longer than broad and with gently convex sides. Vertex in full face view weakly convex. Clypeus reduced and as long as the antennal sockets. Anterior border of the clypeus truncate. Frontal carinae far from each other, not covering the antennal insertions. Lateral expansions of the frontal carinae very broad, little raised, diverging on the two anterior Fourths, converging on the third fourth, diverging and carinate only on the last fourth. Frontal area gently concave on the three anterior fourths and with a central, thick, longitudinal carina starting in the last fourth and prolonging posteriorly; the carina beginning more anteriorly in some specimes. Head anterolaterally with a short, thin, longitudinal carina. Genal carinae marked, each carina corresponding to the external border of a deep sulcus. Eyes visible as a minute, 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. Masticatory margin of the mandibles with 6-7 denticles before the pointed apical tooth. Palp formula 2,2.

Mesosoma convex and shorter than maximum head length (mandibles included) in profile. Pronotal and propodeal sutures absent. Basal face of the propodeum declivous posteriorly. Declivous face of the propodeum gently sloping posteriorly. Area between basal and declivous faces of the propodeum gently concave medially, dorsally superficially carinate and denticulate on each side. Sides of the declivous face superficially carinate. Propodeal spiracle round and above mid height in lateral view.

Petiole subrectangular and narrow. Anterior border of the petiole straight and anterolaterally carinate. Ventral process of the petiole thicker anteriorly, narrowing and slightly pointed posteriorly. Postpetiole in dorsal view with posteriorly diverging sides. Postpetiolar sternite anteromedially with a marked subtriangular projection, gently convex posteriorly in side view. Constriction between postpetiole and gaster impressed. Gastral tergite I about 1/3 longer than the postpetiole and convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs short. Fore tibiae incrassate. Mid and hind tibiae slightly incrassate. All tibiae with a pectinate spur. Spurs of fore legs without basal spine. Fore basitarsi longer than the mid ones. Wind basitarsi about 1/4 shorter than hind tibiae. Second tarsomere of hind legs shorter than pretarsus. Pretarsal claws simple. Arolia absent.

Sculpture. Head, mesosoma, petiole, postpetiole and gaster punctate, the punctures more marked and raised to form small granulation on the mesosoma and on the postpetiole, absent on the center of the posterior half of the first gastral tergite. Mead sides with additional longitudinal rugosities. Anterior part of the pronotum and centre of the basal face of the propodeum sometimes with short, transversal rugosities. Legs minutely punctate.

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

Measurements in mm and Indices: TL 2.37-2.57; HL 0.55-0.60; HW 0.52-0.56; EL 0.02-0.03; SL 0.36-0.40; WL 0.66-0.70; PeL 0.16-0.19; PeW 0.25-0.27; HFeL 0.39-0.41; HTiL 0.31-0.33; HBaL 0.20-0.24; LS4 0.24-0.27; LT4 0.49-0.55; CI 92.8-94.7; SI 64.3-66.7; IGR 0.48-0.51.

Queen
Baroni Urbani and de Andrade (2003) - Differing from the worlter in the following details: eyes large, about 1/3 of the head length, composed by many facets and with ocular pilosity. Ocelli well developed.

Mesosoma longer than the head length (mandibles included), robust, convex in side view. Parapsidal furrows marked. Scutellum posteriorly with gently converging sides and with the posterior border subround. Dorsum of the scutellum with a thick longitudinal ruga prolonging to the posterior half of the mesonoturn. Metanotuin with a small denticle. Basal face of the propodeum medially concave. Area between basal and declivous faces of the propodeum carinate and denticulate on each side.

Colour. Light ferrugineous with the posterior half of the head dorsum, center of mesosoma, postpetiole and gaster darker. Legs lighter.

Measurements in mm and Indices: TL 2.92-3.12; HL 0.60-0.64; HW 0.56-0.65; EL 0.19-0.21; SL 0.40-0.42; WL 0.88-0.95; PeL 0.19-0.21; PeW 0.28-0.32; HFeL 0.46-0.50; HTiE 0.36-0.40; HBaL 0.27-0.29; LS4 0.32-0.35; LT4 0.63-0.70; CI 93.3-95.0; SI 64.5-66.7; IGR 0.50-0.51.

Type Material
Baroni Urbani and de Andrade (2003):

Type locality New Guinea. Type material: holotype gyne labeled: "N Gulnea, Biro 96, det. Emery, papuanum, Holotypus, Proceratium papuanum Emery,1897, Papp 1974", in, examined.

Proceratium carinifrons Type locality: Fort de Kock, Sumatra. Type material: a worker (syntype) labeled "Fort de Kock, (Sumatra) 920 M. 1926, leg. E. Jacobson", in, examined.

Ponera caeca Type locality: New Guinea. Type material: holotype worker labelled: "Maffin Bay, Dutch N. Guinea, VIII-20.44, E. S. Ross Coll, Type, Ponera caeca Donis, H. Donisthorpe det, 7.VIII.1946, 64, Proceratium papuanum Emery, det. WL Brown, California Academy of Sciences, Type no. 6965"; in, examined.