Polyrhachis excellens

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Polyrhachis excellens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Aulacomyrma
Species: P. excellens
Binomial name
Polyrhachis excellens
Viehmeyer, 1912

Polyrhachis excellens P.jpg

Polyrhachis excellens D.jpg

Known only from the worker holotype.

Identification

Kohout (2007) - The very strongly produced anterodorsal margin of the first gastral segment in P. excellens represents the most extreme development of this remarkable character.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: New Guinea (type locality).

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Polyrhachis excellens for further details

Biology

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.

Castes

Known only from the worker caste.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • excellens. Polyrhachis excellens Viehmeyer, 1912: 14, fig. 19 (w.) NEW GUINEA. Combination in P. (Aulacomyrma): Emery, 1921e: 17. See also: Kohout, 2007a: 221.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Kohout (2007) - 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.

Type Material

Kohout (2007) - Holotype worker. Type locality: NEW GUINEA (Kais. Wilhelmsland on data label), Torricelli Mts (Schlaginhaufen), Museum für Tierkunde (examined).

References