Polyrhachis (Aulacomyrma) geometrica Fr. Smith, 1859

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 : 222-223

Polyrhachis (Aulacomyrma) geometrica Fr. Smith, 1859

Figures 65, 68, 71

Polyrhachis geometricus Fr. Smith, 1859: 141. Holotype worker. Type locality: INDONESIA, Aru I. (A. R. Wallace), OXUM (examined) .

Polyrhachis (Aulacomyrma) geometrica Fr. Smith : Donisthorpe, 1932: 453. Combination in ( Aulacomyrma ).

WORKER

Dimensions: TL c. 4.89 - 5.14 (4.89); HL 1.25 - 1.34 (1.25); HW 1.09 - 1.18 (1.09); CI 87 - 88 (87); SL 1.31 - 1.37 (1.31); SI 116 - 122 (120); PW 0.90 - 0.94 (0.94); MTL 1.25 - 1.28 (1.25) (3 measured).

Anterior clypeal margin arcuate, only very shallowly truncate medially; clypeus virtually straight in profile. Frontal carinae strongly sinuate, with raised margins; central area relatively wide with distinct, longitudinal carina running towards anterior clypeal margin. Frontal triangle indistinct. Eyes convex, clearly breaking lateral cephalic outline in full face view. Sides of head in front of eyes only weakly converging anteriorly. Pronotum immarginate, widest just below humeri that are armed with small, acute, dorso-ventrally flattened, triangular teeth. Promesonotal suture distinct; metanotal grove lacking, position indicated by slight change in direction of dorsal sculpture and slight depression in lateral outline. Propodeum unarmed. Petiole with dorsal margin emarginate between distinct intercalary teeth; lateral spines relatively long, curved backwards. Anterior face of first gastral segment very shallowly concave medially at base.

Head in front of eyes and on sides more-or-less regularly, longitudinally striate; preoccipital margin with median striae transversely bowed and lateral striae converging anteriorly towards central area between frontal carinae. Sculpture of pronotal dorsum consisting of inverse, wide U- and V-shaped striae, that are laterally uninterrupted and continuous along sides. Mesonotal dorsum with more regular, semicircular striae, outermost forming an ill-defined lateral margin; propodeal dorsum with striae continued obliquely along sides. First gastral segment distinctly, and more densely, longitudinally striate; striae converging anteriorly towards base.

Holotype with pilosity almost completely absent from dorsum of mesosoma and gaster, a few erect to semierect, short hairs on dorsum and sides of head, vertex, along antennal scapes and on tibia of middle and hind legs. Rather sparse, Appressed, silvery pubescence scattered over dorsum of head and mesosoma; more abundant along dorso-posterior borders of gastral segments.

Black, including antennal scapes, coxae, trochanters (except narrow light band at distal ends) and femora of middle and hind legs. Femora of front legs, tibiae and tarsi distinctly light yellowish or reddish brown, except proximal and distal ends of segments very dark brown or black. Basal funicular segments very dark brown with paler, reddish brown bands at their apices; lighter bands becoming progressively wider in distal funicular segments, that are mostly pale, reddish-brown.

ADDITIONAL MATERIAL EXAMINED

PAPUA NEW GUINEA: Huon Pen., lower Busu R., 12. v. 1955, lowl. rf., E. O. Wilson # 1018 (w). Milne Bay Prov., Opanabru, 12 mi W of Raba Raba, 2600 ft, 1. viii. 1969, rf, R. Pullen (worker).

REMARKS

P. geometrica is similar to the other species of the complex, notably to annulata , breviata and monticola , and in addition to the characteristic “ geometrical ” sculpture they share the medially emarginate dorsal margin of the petiole and rather shallowly concave base of the first gastral segment. However, geometrica is easily recognizable by the color of the front femora which are very light, yellowish brown in contrast to the entirely black femora of the middle and hind legs. In the other allied species the femora of all legs are more-or-less uniform in color.