Polyrhachis (Aulacomyrma) annulata, Kohout, R. J., 2007

Kohout, R. J., 2007, Revision of the subgenus Aulacomyrma Emery of the genus Polyrhachis F. Smith, with descriptions of new species., Advances in ant systematics (Hymenoptera: Formicidae): Homage to E. O. Wilson - 50 years of contributions. (Memoirs of the American Entomological Institute 80), pp. 186-253 : 216-217

Polyrhachis (Aulacomyrma) annulata , new species

Figures 48, 51, 54

TYPE MATERIAL

HOLOTYPE: PAPUA NEW GUINEA, Mt Tafa , 8 km SE of Mondo , 08 º 38 ’ S, 147 º 07 ’ E, 8500 ft, ii. 1934, L. E. Cheesman ( B. M. 1934 - 321 ) (worker). Type distribution: unique holotype in BMNH .

WORKER

Dimensions of holotype: TL 5.54; HL 1.47; HW 1.47; CI 100; SL 1.43; SI 97; PW 1.12; MTL 1.40.

Anterior clypeal margin arcuate, emarginate medially. In profile clypeus moderately convex with basal margin weakly impressed, indicated by hairline break in cephalic sculpture. Frontal carinae sinuate with moderately raised laminate lobes. Sides of head in front of eyes converging anteriorly; rounding behind eyes into relatively shallow preoccipital margin. Eyes moderately convex, just reaching lateral cephalic outline in full face view. Mesosoma only partially marginate, somewhat antero-posteriorly compressed; pronotal humeri armed with broad-based acute spines with lateral margins continued posteriorly for a short distance before merging with outermost dorsal striae and curving onto sides. Promesonotal suture distinct; metanotal groove lacking. Mesonotal dorsum with distinct lateral margins formed by outermost lateral striae. Propodeum immarginate laterally; propodeal dorsum separated from relatively high, shallowly concave declivity by posterior-most stria that forms a weakly defined posterior margin. Petiole strongly transverse, dorsal margin acute, medially emarginate, strongly sinuate in dorsal view; lateral spines rather short, weakly bent backwards. First gastral segment concave with the anterodorsal margin of concavity rather blunt.

Mandibles finely longitudinally striate-rugose. Head mostly regularly striate, striae V-shaped on clypeus, longitudinal along sides of head and somewhat converging anteriorly from vertex towards frontal carinae. Mesosomal dorsum striate; pronotal striae longitudinal, anteriorly converging on pronotum, oblique on sides; mesonotal-propodeal dorsum with striae strongly bowed, more-or-less semicircular, oblique on sides. Petiole shagreened, becoming more transversely reticulate towards base. Gaster uniformly, finely reticulate.

Mandibles with a few, anteriorly curved hairs along outer and masticatory borders. Antennal scape with a few erect hairs along leading edge and at apex. A few scattered, rather short, variously directed hairs breaking outline of head and mesosoma. Gaster with some longer erect hairs, bordering segments. Appressed pubescence virtually absent from dorsum of head and mesosoma; pale golden pubescence on gastral dorsum, almost obscuring underlying sculpture.

Black. Antennae, femora and first tarsal segments very dark brown, rest of legs medium to light reddish brown; mandibles with anterior half reddish brown; apex of last funicular segment distinctly yellow.

Sexuals and immature stages unknown.

ETYMOLOGY

Name derived from the Latin word annulatus, meaning ringed or circular, with reference to the form of the sculpture of the mesonotal-propodeal dorsum.

REMARKS

With the antero-posteriorly compressed mesosoma, dorsal petiolar margin medially emarginate and striae of the mesonotal-propodeal dorsum more-or-less semicircular, annulata is somewhat similar to breviata. However, both species are easily separated by their size (HL 1.47 in annulata versus 1.15 in breviata) and shape of the petiole which, in annulata , is strongly transverse, while in breviata the petiole is almost as high as wide. The sculpture of the pronotal dorsum in annulata consists of longitudinal, anteriorly converging striae, while in breviata the striae are tranverse and strongly anteriorly bowed medially.