Diacamma carbonarium

Diacamma carbonarium is widespread on Luzon, but restricted to forested areas. It was commonly found in a lowland forest in the Quezon National Park in the central part of Luzon, Philippines. We have studied a few individuals from other parts of the island including its northern and southern regions.

Identification
Laciny et al. (2015) - Rather large species (TL 11.9–14.2 mm). Trunk black, without metallic shimmer. Mandibles dark brown to black. Antennae and legs black. Standing setae abundant, on petiole and gaster distinctly longer than on mesosoma; fine pilosity strongly developed. Trunk strongly striate from genae to gaster tergite 1. Head relatively short, sides posteriorly of eye strongly convex. Posterior of head longitudinally striate until narrowly truncated hind margin; occipital margin ventrally terminating in short, blunt teeth. Eyes small. Clypeus entirely punctured, apex rounded. Mandible with fine striation. Pronotum with transverse-elliptical rugae. Striation on propodeum horizontal. Petiole very stout, its teeth relatively short; subpetiolar process shallowly concave between short anterior and posterior corners. Gaster tergite 1 with coarse semi-circular striation.

Diacamma carbonarium is a large, entirely black species of the Diacamma rugosum group. Compared to similar congeners from the Philippines it never has any metallic shimmer. Its clypeus is entirely punctured and broadly rounded at middle of foremargin. The subpetiolar process is shallowly concave and has a stout posterior tooth. Rare individuals of sympatric Diacamma generali with weak metallic shimmer may be confused with D. carbonarium, but differ by a more angular apex of the clypeus. Additionally, morphometric analysis revealed differences in SpLI (24–31 in carbonarium, 19–27 in Diacamma generali).

Distribution
Records are from the provinces Nueva Viscaya, Laguna, Quezon, Camarines Norte, and Camarines Sur.

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

Nomenclature

 *  carbonarium. Diacamma carbonarium Laciny, Pal & Zettel, 2015: 131, figs. 57, 64-67 (w.) PHILIPPINES (Luzon I.).

Worker
Holotype: TL 13.83; HW 2.43; HL 3.10; EL 0.54; SL 3.52; PH 2.00; PL 1.30; PW 1.46; SpD 0.68; SpL 0.40; WL 4.76; MTL 2.77. Indices: CI 78; SI 145; PI 65; SpDI 47; SpLI 28; EI 22. Measurements of paratypes (n = 14): TL 11.93–14.22; HW 2.15–2.48; HL 2.74–3.13; EL 0.51–0.63; SL 3.10–3.55; PH 1.63–2.04; PL 1.17–1.37; PW 1.23–1.50; SpD 0.59–0.77; SpL 0.29–0.41; WL 4.11–4.76; MTL 2.48–2.80. Indices: CI 78–81; SI 137–145; PI 64–73; SpDI 44–54; SpLI 24–31; EI 22–25.

Structures: Head moderately elongate; sides strongly convex behind small eyes. Very coarse rugae present from genae to gaster tergite 1. Posterior of eyes, longitudinal rugae reaching narrow occipital margin. On ventral side of head occipital margin ending in a small, blunt tooth. Clypeus entirely, often densely punctured, but in some specimens from southern localities the puncturation less dense; especially in large specimens some longitudinal rugae may occur; apex of clypeus rounded, at most with a very obtuse angle. Mandibles always with fine striation. Pronotum with transverse-elliptical rugae. Rugae on mesosoma sides almost horizontal. Posterior face of propodeum separated from sides by carinae. Petiole stout, with coarse rugae and short spines; subpetiolar process shallowly concave between short anterior and posterior corners; shape of posterior tooth rather variable, rarely acute; ventral outline of tooth with short, oblique pilosity. Gaster tergite 1 with thick, concentric, semi-circular rugae; along posterior margin finely punctured. Gaster tergite 2 with very fine, but dense puncturation, almost matt.

Pilosity: Trunk with numerous and long standing setae; Setae on petiole and gaster distinctly longer than on mesosoma. Short appressed pilosity dense and almost completely covering body, only at sides of propodeum reduced. Standing setae on scape very short, those on legs long.

Colour: Trunk entirely black, without any metallic shimmer; at most the apex of gaster weakly reddish brown. Mandibles, antennae, and legs black or very dark brown.

Type Material
Holotype (worker,, CASENT0915966), Philippines, Luzon, Quezon Province, Quezon N. P., Old Zigzag Road, 27–28.I.2002, leg. H. Zettel (#300). Paratypes: all from Luzon Island: 3 workers, same locality data; 6 workers (CZW), same locality, 12–13. II.1996, leg. H. Zettel (#79a); 5 workers (CZW), same locality, 24–30.III.1998, leg. H. Zettel (#165); 1 worker (CZW), same locality, 16.III.1999, leg. S. S. Vichozo & H. Zettel (#202); 1 worker (CZW), same locality, 9.IV.2000, leg. H. Zettel (#253); 5 workers (NHMW), same locality, 14.III.1999, leg. F. Seyfert (#27); 1 worker (CZW), Laguna, San Pablo, Mt. Banahaw, 15.XI.1992, leg. H. Zettel (#6); 1 worker (CZW), Nueva Viscaya, Santa Fe, Imugan, 1200 m a.s.l., 10.XI.2002, leg. H. Zettel; 1 worker (CZW), Laguna, Cavinti, Tibatib, 26.VI.2010, leg. C. V. Pangantihon (#P358); 1 worker (CZW), Camarines Sur, 20 km E Naga, 5 km E Carolina, Mt. Isarog, nr. Malabsay Falls, 4.III.1999, leg. Zettel (#192); 2 workers (CZW), Camarines Norte, SW Daet, San Vicente, Fabrica, Mananap, 6.II.2001, leg. H. Zettel, E. & L. Vichozo (#264); 3 workers (CZW), Camarines Norte, Labo, Tulay na Lupa, Mt. Labo – Mt. Bayabas area, 17–18.III.2004, leg. H. Zettel & C. V. Pangantihon (#382).

Etymology
Named after the deep black colour of the body.