Proceratium bhutanense

Identification
A member of the itoi clade. Differing from its sister species, Proceratium malesianum, by the absence of erect hairs in the worker. (Baroni Urbani and de Andrade 2003)

Distribution
South Bhutan and North India.

Distribution based on Regional Taxon Lists
Oriental Region: Bhutan, India.

Nomenclature

 *  bhutanense. Proceratium bhutanense De Andrade, in Baroni Urbani & De Andrade, 2003b: 278, figs. 116-117 (w.) BHUTAN.

Worker
Head slightly longer than broad, its sides subparallel anteriorly and gently converging posteriorly. Vertex in full face view straight. Clypeus medially reduced, triangular or subround, between and slightly longer than the antennal sockets. Clypeal dorsum with longitudinal carina. Antenna1 socket with broad torulus. Frontal carinae separate from each other, partially covering the antennal insertions. Frontal area behind the frontal carinae convex. Lateral expansions of the frontal carinae relatively narrow, raised, diverging. Genal carinae marked. Eyes small, appearing as a dark dot below the integument and placed on the midline of the head. First funicular joint subequal in length and width. Funicular joints 2-10 much broader than long. Last funicular joint about as long as the sum of joints 6-10. Scapes much 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 3,2.

Mesosoma slightly longer than the maximum head length (mandibles included). Promesopleural and meso-metapleural sutures impressed ventrally only. Basal face of the propodeum weakly declivous. Declivous face of the propodeum gently concave anteriorly. Basal and declivous faces of the propodeum laterally separate by a carinate denticle or tooth. Sides of the declivous face of the propodeum with a lamella broader posteriorly. Propodeal spiracle round and above the mid height in lateral view.

Petiole convex in profile, with the sides diverging and convex posteriorly in dorsal view; petiolar node relatively flat. Anterior border of the petiole deeply concave and carinate, the carina strongly denticulate on each side.

Ventral process of the petiole triangular or spiniform. Postpetiole broader than the petiole anteriorly; its sides diverging and gently convex posteriorly. Postpetiolar sternite anteromedially with a superficially marked subtriangular projection and straight in side view. Constriction between postpetiole and first gastral segment impressed. Gastral tergite I strongly convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs slender but 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 1/3 shorter than hind tibiae. Second tarsomere of hind legs slightly shorter than the fourth. Pretarsal claws simple. Arolia present.

Sculpture. Head, mesosoma, petiole and postpetiole granulate. First gastral tergite smooth and covered by sparse piligerous punctures; the punctures denser and more marlced on the posterior border and on the sides. Legs granulate, the granulation less marked than on the other body parts.

Body covered by hairs of two main types: (1) short, dense, subdecumbent on the whole body; (2) shorter than hair type (I), dense and subdecumbent on the funicular joints. In addition the funicular joints bear whitish, thick, appressed, sparse hairs.

Colour. Brown or dark brown.

Measurements in mm and Indices: TL 2.92-3.39; HL 0.65-0.76; HW 0.60-0.68; EL 0.03-0.04; SL 0.41-0.48; WL 0.80-0.92; PeL 0.25-0.30; Pew 0.25-0.32; HFeL 0.52-0.56; WTiL 0.43-0.47; HBaL 0.28-0.32; LS4 0.21-0.26; LT4 0.63-0.83; CI 89.3-93.0; ,5161.1-63.1 ; IGR 0.3 1-0.34.

Type Material
Holotype worker from Phuntsholing, Bhutan labelled "Phuntsholing, 2/400 m, 15 4, Nat. - Hist. Museum Basel - Bhutan Expedltlon 1972" in, 1 paratype worker same data and collection as the holotype, 1 paratype worker In MRSN.

Etymology
"bhutanense" is a neologism indicating the provenance of the species from Bhutan.