Proceratium oceanicum De Andrade, 2003

Garcia, Francisco Hita, Sarnat, Eli M. & Economo, Evan P., 2015, Revision of the ant genus Proceratium Roger (Hymenoptera, Proceratiinae) in Fiji, ZooKeys 475, pp. 97-112 : 102

Taxon classification Animalia Hymenoptera Formicidae

Proceratium oceanicum De Andrade, 2003 Figs 1B, E, 2A, 3, 6

Proceratium oceanicum De Andrade, 2003: 310. [see also: Sarnat and Economo 2012: 166]

Type material.

Holotype, pinned worker, FIJI, Viti Levu, Nadarivatu, -17.5667°, 177.967°, rainforest, on soil, under grass, 16.II.1962, (R.W. Taylor) (ANIC: ANIC32-017668) [not examined].

Non-type material examined.

FIJI: Taveuni, Mt. Devo, 3.9 km SE Tavuki Village, -16.83278°, -179.97343°, 775 m, ex soil, leaf litter, decaying wood, 16.VI.2005 (E.M. Sarnat); Viti Levu, Koroyanitu Eco Park 5.0 km NE Abaca Village, -17.66667°, 177.5525°, 700 m, disturbed forest, sifted litter, 19.IV.-14.V.2003 (M. Tokotaa); Viti Levu, Naqaranibuluti Nature Reserve, near summit, 0.75 km SE Nadarivatu, -17.57278°, 177.9725°, 1000 m, primary rainforest, 26.VIII.2006 (E.M. Sarnat); Viti Levu, Nausori Highlands, 12.I.1972 (W.L. Brown).

Diagnosis.

The following character combination distinguishes Proceratium oceanicum from the remainder of the Proceratium silaceum clade: relatively larger species (HW 0.76-0.78; WL 0.99-1.00); in full-face view head weakly longer than wide (CI 93); lateral expansions of frontal carinae weakly triangular and moderately rounded; petiolar node extremely squamiform (DPeI 680-693) and strongly narrowing from base to apex; subpetiolar process thinly dentiform.

Worker measurements

(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.

Distribution and biology.

Workers of Proceratium oceanicum , even though rarely encountered, were sampled from Viti Levu and Taveuni, but tentatively associated males also suggest its presence on Vanua Levu. All collections are from primary or disturbed rainforest. Unfortunately, there is no available data on the biology of Proceratium oceanicum .

Taxonomic notes.

As already outlined above, Proceratium oceanicum and Proceratium relictum are highly distinctive species that can be easily distinguished from all other congeners by the extremely squamiform petiolar node. This character, among others, also separates both clearly from the new species Proceratium vinaka . Despite its sympatric occurrence, Proceratium oceanicum and Proceratium relictum are not likely to be confused. The latter is significantly larger in size (HW> 1.00; WL> 1.30), has a noticeably broader head (CI 101), and the subpetiolar process is thickly spiniform, whereas Proceratium oceanicum is conspicuously smaller (HW <0.80; WL <1.10), possesses a narrower head (CI 93), and its subpetiolar process thinly dentiform. Additionally, in profile the propodeum of Proceratium oceanicum is rounded while it is weakly, but clearly marginate in Proceratium relictum .