Polyrhachis aporema

The type colony consisted of a silk nest between leaves on a low tree in rainforest (Kohout 2006).

Identification
Polyrhachis aporema is very similar to Polyrhachis kyawthani with which it shares a similar mesosomal profile with a widely rounded propodeum and very steep declivity. However, Polyrhachis aporema differs from Polyrhachis kyawthani in the distinctly convex eyes that clearly break the lateral cephalic outline in full face view. The eyes in Polyrhachis kyawthani are rather flat and situated well inside the cephalic outline. Although similar, the propodeal declivity in Polyrhachis aporema is distinctly lower and weakly concave at the base, while in Polyrhachis kyawthani the declivity is higher and virtually vertical. The petiole in Polyrhachis aporema features a straight anterior face and convex posterior face, while the petiole in Polyrhachis kyawthani is lower and distinctly biconvex. (Kohout 2006)

Distribution
New Britain Island.

This taxon was described from New Guinea.

Castes
Males (undescribed) and immature stages (eggs, larvae and pupae) present in spirit collection. (Kohout 2006)

Worker
Dimensions (holotype cited first): TL c. 6.60, 6.35-7.15; HL 1.62, 1.56-1.68; HW 1.56, 1.45-1.59; CI 96, 93-98; SL 2.25, 2.12-2.25; SI 144, 138-146; PW 1.28, 1.18-1.33; MTL 2.71, 2.56-2.74 (11 measured).

Clypeus in profile weakly convex, posteriorly rounding into weakly impressed basal margin. Frontal triangle indistinct. Frontal carinae sinuate with weakly raised margins; central area weakly convex with frontal furrow distinct for most of its length. Sides of head in front of eyes weakly convex, converging towards mandibular bases; behind eyes sides rounding into broadly convex occipital margin. Eyes convex, in full face view clearly breaking lateral cephalic outline. Ocelli lacking, relative positions indicated by shallow punctures in cephalic sculpture. Pronotum in dorsal view with sides widely rounded, humeri indicated by weak angles in some specimens. Mesosoma in lateral view with pronotum very weakly convex, almost flat; promesonotal suture distinct, rather flat in outline; mesonotal dorsum weakly convex; metanotal groove indicated by very shallow impression; propodeal dorsum widely rounding into rather low, vertical declivity, weakly concave at base. Petiole in profile with anterior face straight, posterior face convex; dorsum armed with four, acute, subequal teeth, tips of dorsal pair distinctly bent backwards. Subpetiolar process acute anteriorly, widely rounded posteriorly. Anterior face of first gastral segment marginally lower than apices of dorsal petiolar spines.

Mandibles finely rugose with sculpture reducing in intensity towards bases; numerous piliferous pits in loose longitudinal rows. Head, mesosoma and gaster finely shagreened dorsally, intensity of sculpturation increasing laterally, becoming reticulate; meso- and metapleurae reticulate-rugose. Petiole finely reticulate dorsally; distinctly reticulate-rugose at base. Shallow punctures and piliferous pits scattered in various densities over most body surfaces, rather diluted along summit of mesosomal dorsum.

Mandibles with medium length, curved hairs fringing masticatory borders. Anterior clypeal margin with usually one or two long, anteriorly directed setae medially and several shorter setae laterally. Paired, medium length, erect or semierect hairs near anterior and basal clypeal margins and fringing frontal carinae; single pair of hairs on vertex; single pair of long hairs on summit of mesonotum. Pair of relatively long, erect hairs on anterior face of front coxae and several shorter, erect hairs ventrally on trochanters and femora. Gaster with numerous, erect, relatively long hairs lining posterior margins of segments with hairs on ventral surfaces more abundant.

Colour. Black, mandibular teeth, condylae, distal ends of antennal scapes, tip of apical funicular segments and legs medium reddish-brown. Funiculi, proximal ends of tibiae and tarsi dark brown.

Queen
Dimensions: TL c. 7.41; HL 1.68; HW 1.53; CI 91; SL 2.21; SI 144; PW 1.62; MTL 2.74 (1 measured). Apart from sexual characters, very similar to worker except: pronotal humeri widely rounded; mesoscutum wider than long with lateral margins converging anteriorly, forming widely rounded anterior margin; median line bifurcate posteriorly; parapsides rather flat, slightly raised posteriorly; mesoscutum in profile widely rounded anteriorly, dorsum very weakly convex. Mesoscutellum convex, marginally elevated above plane of mesosoma; metanotal groove distinct. Propodeal dorsum rather flat before descending into very steep, almost vertical declivity; pair of distinct, subacute, propodeal tuberculae. Other characters, including sporadic pilosity and fine sculpturation, as in worker.

Male
Undescribed

Type Material
Holotype, 5 paratype workers, paratype queen and paratype males in ANIC; 2 paratype workers each in, , and.

Type Locality Information
HOLOTYPE: PAPUA NEW GUINEA, East New Britain Prov., Gazelle Pen., Baining Mts, 3km N of Malasait, 04°26’S, 151°53’E, c. 600m, 11.vii.1984, R.J. Kohout acc. 84.23 (worker). PARATYPES: data (and nest) as for holotype (19 workers, alate queen, 3 males).