Polyrhachis (Aulacomyrma) excellens Viehmeyer, 1912

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 : 221-222

Polyrhachis (Aulacomyrma) excellens Viehmeyer, 1912

Figures 64, 67, 70

Polyrhachis excellens Viehmeyer, 1912: 14 , fig. 19, 19 a, 19 b. Holotype worker. Type locality: NEW GUINEA ( Kais. Wilhelmsland on data label), Torricelli Mts (Schlaginhaufen), SNSD (examined) .

Polyrhachis (Aulacomyrma) excellens Viehmeyer ; Emery, 1921: 17. Combination in P. (Aulacomyrma) .

Worker

Dimensions of holotype: TL c. 5.19; HL 1.31; HW 1.15; CI 88; SL 1.47; SI 128; PW 0.87; MTL 1.40.

Anterior clypeal margin arcuate with shallow notch medially; basal margin indicated by hairline break in cephalic sculpture. Frontal triangle indistinct. Frontal carinae strongly raised and sinuate with laminate lobes; central area relatively wide with median stria forming short, longitudinal carina. Sides of head in front of eyes weakly converging anteriorly. Eyes strongly convex, in full face view clearly extending beyond lateral cephalic outline. Pronotal dorsum immarginate, rather flat in profile with greatest width at about midlength. Pronotal humeri armed with very prominent, acute spines. Promesonotal suture distinct, well impressed. Mesonotal and propodeal dorsa fused, with ill-defined lateral margins formed by outermost dorsal striae, terminating posteriorly in short, dorsally flattened, blunt teeth. Propodeal dorsum descending into declivity in even, uninterrupted curve. Petiole with dorsal margin sharp, entire; lateral spines relatively short, curved backwards. First gastral segment concave anteriorly; dorsal margin of concavity produced dorso-medially into an extremely high, lip-like prominence that appears very thin in lateral view and almost reaches height of apex of petiolar margin.

Mandibles finely longitudinally striate at bases, more reticulate-punctate at masticatory borders. Sculpture of head and mesosoma very prominent, consisting of strongly raised, regularly-spaced striae that are longitudinal on sides of head and mesonotal-propodeal dorsum; anteriorly converging on clypeus, vertex and pronotal dorsum; oblique on sides of mesosoma. Dorsal surface of pronotal spines and both faces of petiole smooth, microscopically shagreened. First gastral segment very finely striate, striae converging anteriorly and terminating before anterodorsal process that is finely microscopically shagreened.

Semi-erect to erect, short, off-white hairs fringing outer mandibular margins and antennal scapes, only a few hairs arising from clypeus, sides of head near mandibular bases, frontal carinae, vertex and pronotal dorsum. Hairs completely absent from mesonotal-propodeal dorsum. Gaster with a few hairs dorsally and numerous, medium length, golden hairs along posterior margins of apical gastral segments and at apex. Appressed pubescence virtually absent from body, except small diffused patch bordering propodeal declivity.

Body black with striae smooth and shiny. Antennal scapes and femora dark to very dark reddish-brown. Rest of legs medium to light yellowish-brown, except proximal and distal ends of segments bordered dark reddish-brown. Funiculi missing.

REMARKS

The holotype is the only known specimen of this spectacular species. The very strongly produced anterodorsal margin of the first gastral segment in P. excellens represents the most extreme development of this remarkable character.