Proceratium vinaka

The single known worker of P. vinaka was collected at Mt. Tomanivi on Viti Levu. The type locality is a relatively pristine mid-elevation rainforest. Nevertheless, several tentatively associated males from malaise traps suggest that P. vinaka has a much broader distribution and is also found on Taveuni and Vanua Levu. As in the cases of P. oceanicum and P. relictum, there is no information on the biology of the new species. (Hita Garcia et al. 2015)

Identification
A member of the silaceum clade.

Hita Garcia et al. (2015) - Proceratium vinaka differs from the other members of the P. silaceum clade by the following combination of characters: relatively smaller species (HW 0.52; WL 0.66); in full-face view head weakly longer than wide (CI 93); lateral expansions of frontal carinae conspicuously triangular and acute; petiolar node moderately squamiform (DPeI 263) and only weakly narrowing from base to apex; subpetiolar process rounded, not dentiform nor spiniform.

Despite the morphological similarity of most species of the Proceratium silaceum clade, P. vinaka possesses an interesting character combination that renders it easily identifiable within the Proceratium fauna of Oceania. It cannot be confused with the other two Proceratium species found on Fiji. Both, Proceratium oceanicum and Proceratium relictum, have extremely squamiform petiolar nodes that strongly narrow from base to apex, whereas P. vinaka has a moderately squamiform node that narrows only very weakly from base to apex. This node shape is characteristic for the P. silaceum clade and found in all species except P. oceanicum and P. relictum. In addition, the latter two species have either a dentiform or spiniform ventral petiolar process, which contrasts with the very much reduced and convex process of P. vinaka. Interestingly, this highly reduced ventral process seen in P. vinaka is quite unique and not found in any other member of the P. silaceum clade in Oceania. All other species have either a well-developed lamelliform and approximately rectangular process, or the process is dentiform or spiniform. Another character that distinguishes P. vinaka from P. oceanicum and P. relictum is the development of the lateral expansions of the frontal carinae, which are weakly triangular and moderately rounded in the latter two species, whereas they are conspicuously triangular and acute in P. vinaka. This also separates it from other morphologically similar species found in Oceania, such as Proceratium caledonicum, Proceratium papuanum, or Proceratium politum since they all have rounded or subtriangular extensions that are never as acute as in P. vinaka.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Fiji.

Castes
Known only from the worker caste.

Nomenclature

 *  vinaka. Proceratium vinaka Hita Garcia, Sarnat & Economo, 2015: 107, figs. 1A, D, 5, 6 (w.) FIJI IS.

Description
(N=2). TL 3.38–3.41; EL 0.03; SL 0.55–0.58; HL 0.81–0.83; HLM 1.00–1.02; HW 0.76–0.78; WL 0.99–1.00; HFeL 0.63; HTiL 0.48– 0.50; HBaL 0.38–0.40; PeL 0.63; PeW 0.43; DPeI 680–693; LT3 0.54–0.56; LS4 0.35–0.40; LT4 0.71–0.78; OI 4; CI 93; SI 68–70; IGR 0.49–0.52; ASI 133–139.

In full-face view head longer than broad (CI 93), sides weakly convex, gently broadening posteriorly, vertex shallowly concave. Clypeus conspicuously reduced, relatively narrow, and anteriorly truncate. Frontal carinae relatively short, moderately separated, and not covering antennal insertions, approximately parallel on anterior third and strongly diverging posteriorly, lateral expansions of frontal carinae very broad, raised, and conspicuously triangular and acute; frontal area weakly concave; cephalic dorsum medially with weak carina. Eyes reduced, very small (OI 6), consisting of single ommatidium and located on midline of head. Antennae 12-segmented, scapes short (SI 66), not reaching posterior head margin and noticeably thickening apically. Mandibles elongate-triangular; masticatory margin of mandibles with eight teeth/denticles in total, apical tooth long and acute, second tooth from apex smaller and less acute, remaining six denticles significantly smaller and blunt. Mesosoma in profile moderately convex and clearly shorter than maximum head length including mandibles. Lower mesopleurae with well demarcated sutures, no other sutures developed on lateral or dorsal mesosoma; mesopleurae not inflated posteriorly; propodeum in profile unarmed and rounded, propodeal lobes weakly developed, lamellate and blunt; declivitous face of propodeum gently sloping posteriorly; in posterodorsal view sides of propodeum separated from declivitous face by weak margins; in profile propodeal spiracle rounded and above mid height. Legs moderately long; all tibiae with pectinate spur; calcar of strigil without basal spine; pretarsal claws simple; arolia absent. Petiolar node in profile moderately squamiform, high, and subrectangular, anterior face of petiole relatively straight, node weakly narrowing from base to apex, dorsum of node weakly convex; petiole in dorsal view much broader than long and transverse, around 2.6 times broader than long (DPeI 263); ventral process of petiole relatively reduced, inconspicuous, convex, and without any rectangular, dentiform, or spiniform projections. In dorsal view abdominal segment III anteriorly much broader than petiole; its sides diverging posteriorly; abdominal sternite III anteromedially with a marked subtriangular projection appearing convex in profile. Constriction between abdominal segment III and IV conspicuously impressed. Abdominal segment IV moderately recurved (IGR 0.54), conspicuously rounded on its curvature, especially posteriorly; abdominal tergum IV around 1.4 times longer than abdominal segment III (ASI 138); remaining abdominal tergites and sternites relatively inconspicuous and curved ventrally. All dorsal surfaces of body (including antennal scapes and legs) covered with dense mat of relatively short, decumbent to erect hairs combined with fewer, but significantly longer, erect hairs.

Mandibles conspicuously striate at the base and mostly smooth and shining towards apex; sides of head and anterior cephalic dorsum irregularly foveolate and/or punctate and irregularly rugulose, sculpture on posterior of cephalic dorsum very weak and shining; sculpture on mesosoma, petiole, abdominal tergites III and IV weakly to moderately irregularly foveolate and/or punctate, generally appearing quite smooth and shiny, abdominal sternites III and IV irregularly foveolate and/or punctate and irregularly rugulose, rough in appearance. Body colour uniformly yellowish to light orange brown.

Type Material
Holotype, pinned worker, FIJI, Viti Levu, Savatu Dist., Mt. Tomanivi 2.4 km E Navai Vlg., -17.61806°, 178.0055°, 950 m, mid-elevation rainforest, soil, leaf litter, decaying wood, collection code EMS#2153-4, 25.VI.2005 (E.M. Sarnat) (: CASENT0187587).

Etymology
The name of new species is Fijian and means ‘thank you’ or ‘hello’. With this we want to dedicate the new species to the people of Fiji for their hospitality and kindness shown to EMS and EPE during their years of fieldwork on the archipelago. The species epithet is a nominative noun in apposition, and thus invariant.

Determination Clarifications
Proceratium vinaka was treated as Proceratium sp. FJ01 in Sarnat and Economo (2012).

References based on Global Ant Biodiversity Informatics

 * Hita Garcia F., E. M. Sarnat, and E. P. Economo. 2015. Revision of the ant genus ProceratiumRoger (Hymenoptera, Proceratiinae) in Fiji. ZooKeys 475: 97112.
 * Liu C., G. Fischer, and E. P. Economo. 2015. A rare ant on Samoa: first record of the cryptic subfamily Proceratiinae (Hymenoptera, Formicidae) and description of a new Proceratium Roger species. Journal of Hymenoptera Research 46: 35-44.