Known only from the holotype worker. Nothing is known about the biology of Polyrhachis gressitti.
Kohout (2007) - Another remarkable species very similar to P. decora, but with a distinctly longer and exceptionally high propodeum with its outline forming an almost perfect semicircle in dorsal view.
Keys including this Species
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
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The subgenus this species is a member of, Aulacomyrma, is poorly colected. Kohout (2007) summarized what is known about their biology in a revision of the species in the subgenus. This offers an explanation as to why most Aulacomyrma are known from few collections and specimens. There are only two records of nests being found. A small colony of Polyrhachis dohrni was collected by Kohout from a dry hollow twig on a living tree at the edge of lowland rainforest. The internal walls of the twig cavity were lined with a little silk. Ward collected a nest of Polyrhachis wardi from a dry twig of a rainforest tree. The colonies of both species were rather small, with only a few workers (5 and 11 respectively, including 2 and 3 alate queens and a single male). If such a nesting pattern is the norm for other species of the subgenus, that might explain the general scarcity of Aulacomyrma material even in the best collections. Many Aulacomyrma species are described and only known from a holotype.
Known only from the worker caste.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- gressitti. Polyrhachis (Aulacomyrma) gressitti Kohout, 2007a: 223, figs. 66, 69, 72 (w.) NEW GUINEA.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Holotype: TL c. 4.23; HL 1.15; HW 0.90; CI 78; SL 1.25; SI 139; PW 0.78; MTL 1.25.
Anterior clypeal margin with minute notch medially; clypeus in profile virtually straight with weakly impressed basal margin. Frontal triangle indistinct. Frontal carinae sinuate, with rather short, laminate, anteriorly truncate lobes. Sides of head in front of eyes converging anteriorly; rounding behind eyes into convex preoccipital margin. Eyes strongly convex, protuberant, in full face view clearly breaking lateral cephalic outline. Mesosoma laterally and posteriorly immarginate, distinctly antero-posteriorly compressed, notably when viewed from side. Pronotal humeri armed with rather strong, horizontal, anteriorly directed spines; pronotal dorsum evenly curved in profile. Promesonotal suture strongly impressed; metanotal groove lacking. Mesonotal-propodeal dorsum distinctly wider than long; propodeal declivity exceptionally high. Petiole with dorsal margin acute, sinuate in dorsal view, lateral spines relatively short, curved backwards. Anterior face of first gastral segment convex.
Mandibles finely longitudinally striate. Sculpture of head and mesosoma consisting of regularly spaced, smooth and glossy striae; mostly longitudinal and somewhat anteriorly converging on head, transverse and anteriorly bowed on pronotum; striae on mesonotal-propodeal dorsum forming imperfect semicircular pattern with outmost striae continuing obliquely onto sides and posteriorly extending into propodeal declivity. Petiole with both faces transversely striate, striae less distinct dorsally, becoming wrinkles just below dorsal margin. First gastral segment distinctly longitudinally striate, dorsum with striae finer and distinctly converging towards base.
Mostly medium length, erect or curved, golden hairs on dorsum of head, mesosoma and gaster; distinctly shorter hairs along leading edge of antennal scapes, dorsal margin of petiole and legs. Appressed pubescence virtually absent from most body surfaces, except dorsum of first gastral segment, where it is rather diluted and reddish.
Black; mandibular masticatory border, antennal scapes, most of femora, basal segment of tarsi and apical segments of gaster reddish brown to dark rusty red. Funiculi, trochanters, proximal ends of femora and apical tarsal segments, light to very light reddish brown.
HOLOTYPE: PAPUA NEW GUINEA: Adelbert Mts, Wanuma, 04º36’S, 145º06’E, 800-1000m, 25.x.1958, J. L. Gressitt (worker). Type deposition: unique holotype in Museum of Comparative Zoology.
Named in honor of the collector, the late J. L. Gressit, Bernice P. Bishop Museum, Honolulu, Hawai’i.
- Kohout, R.J. 2007a. Revision of the subgenus Aulacomyrma Emery of the genus Polyrhachis F. Smith, with descriptions of new species (pp. 186-253). In Snelling, R.R., Fisher, B.L. and Ward, P.S. (eds). Advances in ant systematics: homage to E.O. Wilson – 50 years of contributions. Memoirs of the American Entomological Institute. 80:690 pp. PDF