Proceratium melitense

Identification
A member of the pergandei clade. Proceratium melitense, as was to be expected, exhibits the greatest similarity with its geographically closest species, Proceratium algiricum. Phylogenetically it appears nonetheless close also to two nearctic species, Proceratium chickasaw and Proceratium pergandei for sharing synapomorphically with them (and with other species as well) the rectangular clypeus. The absence of propodeal lamellae, a character shared with all the basic species of the clade differentiates it from algiricum and from the remaining species. Differing from its outgroup species, Proceratium californicum, in the worker by the propodeal suture absent instead of marked; by the antennae and legs with erect-suberect hairs superimposed to the appressed ones instead of appressed hairs superimposed to rare, subdecumbent hairs on the antennae only. (Baroni Urbani and de Andrade 2003)

Distribution
Malta and Sicily.

Distribution based on Regional Taxon Lists
Palaearctic Region: Malta.

Nomenclature

 *  melitense. Proceratium melitanse De Andrade, in Baroni Urbani & De Andrade, 2003b: 239, fig. 100 (w.) MALTA.

Worker
Head longer than broad, with sides weakly convex in the middle and gently converging posteriorly. Vertex in full face view gently convex. Anteromedian part of the clypeus rectangular and strongly protruding anteriorly, dorsally with a very superficially marked bifurcated carina. Frontal carinae gently diverging posteriorly. Lateral expansions of the frontal carinae broad and raised. Head anterolaterally with a short, superficially marked longitudinal carina. Genal carina absent. Gular area not impressed. Eyes absent, recognizable as few minute dots at the mid line of the head. First funicular joint 1/3 longer than broad. Funicular joints 2-10 about as broad as long. Last funicular joint as long as the sum of the joints 8-10. Antennal torulus behind the lateral border of the clypeus. Scapes slightly short of the vertexal margin and thickening apically. Masticatory margin of the mandibles with 4-5 denticles before a pointed apical tooth. Palp formula 4,3.

Mesosoma slightly longer than the head (mandibles included). Pronotum and mesonotum convex in profile. Propodeal suture absent. Basal face of the propodeum slightly declivous posteriorly. Area between basal and declivous faces of the propodeuin weakly concave. Propodeal concavity dorsally superficially marginate and subangulate on the sides. Declivous face of the propodeum marginate. Propodeal lobes round and lamellaceous. Petiole convex in profile. Its sides diverging on the anterior fourth and convex posteriorly in dorsal view. Anterior border of the petiole weakly concave and laterally carinate. Ventral process of the petiole lamelliform and triangular. Postpetiole slightly longer than 1/2 of the gastral tergite I; its anterior face high and broader than the petiole; its sides convex. Postpetiolar sternite anteromedially with a marked subtriangular projection. Constriction between postpetiole and first gastral segment impressed. Gastral tergite I convex on the curvature. Remaining gastral tergites and sternites originating just after the curvature.

Legs slender. All tibiae with a pectinate spur. Spurs of fore legs with basal spine. Fore basitarsi as long as the mid ones. Hind basitarsi about 1/7 shorter than hind tibiae. Second tarsomere of hind legs longer than the pretarsus. Pretarsal claws simple. Arolia present but small.

Sculpture. Head, mesosoma and petiole punctate, the punctures more superficial and sparser on the antero-dorsal part of the mesosoma. Propodeal dorsum and petiole with additional, few, small granulations. Postpetiole and gaster with minute piligerous punctures, smaller on the gaster. Legs finely 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). sparse, erect and suberect on the whole body, 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, short, sparse hairs, and the scapes with sparse hairs similar to type (2) but shorter.

Colour light brown.

Measurements in mm and Indices: TL 4.23-4.40; HL 0.97; HW 0.82-0.85; SL 0.71; WL 1.18-1.24; PeL 0.36-0.37; PeW 0.35-0.37; HFeL 0.84-0.85; HTiL 0.70; HBaL 0.59-0.60; LS4 0.34-0.39; LT4 0.99-1.10; CI 84.5-87.6; SI 72.2-73.2; IGR 0.34-0.35.

Type Material
Holotype worker from Buskett, Malta, labeled: "Malta, Buskett, 11.I.1996, leg. D. Mifsud, In soil, Quercus ilex soil", in MMCR, paratypes 2 workers labeled: "Il Ballut (limits of Wardija), San Pawl il-Bahar, 1.IV.2002, D. Mifsud, shifting leaf litter under Quercus ilex", in DMCM.

Etymology
From the Latin melitensis (Lucretius) = Maltese. This name, however, proved inaccurate when, at a later stage of our work, we received a Sicilian specimen of this species.