Polyrhachis planata

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Polyrhachis planata
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Aulacomyrma
Species: P. planata
Binomial name
Polyrhachis planata
Kohout, 2007

Polyrhachis planata P.jpg

Polyrhachis planata D.jpg

Known only from the holotype.

Identification

Kohout (2007) - In general appearance and color, P. planata is similar to Polyrhachis pallipes. However, it differs from that and other Aulacomyrma species by its virtually flat pronotal dorsum and distinctly transverse petiolar node with its lateral spines strongly bent backwards.

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 planata 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.

  • planata. Polyrhachis (Aulacomyrma) planata Kohout, 2007a: 205, figs. 21, 24, 27 (w.) NEW GUINEA.

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

Description

Worker

Holotype: TL c. 4.59; HL 1.25; HW 1.08; CI 86; SL 1.31; SI 121; PW 1.00; MTL 1.18.

Clypeus with anterior margin arcuate, entire. Sides of head weakly convex and gently converging in front of eyes towards bases of mandibles. Eyes convex, clearly breaking cephalic outline in full face view. Mesosomal dorsum distinctly marginate along entire length, pronotal and mesonotal margins converging posteriorly. Pronotal dorsum rather flat; humeri armed with broad-based, blunt teeth. Propodeal margins divergent, terminating posteriorly in blunt processes, that appear as minute teeth in profile and form short, transverse, medially unconnected ridges, so that propodeal dorsum descends into concave declivity in medially uninterrupted curve. Petiole strongly transverse, dorsal margin entire; lateral spines very distinct, strongly curved backwards and upwards. Anterior face of first gastral segment concave medially; anterodorsal border of concavity sharply margined, but not distinctly raised above dorsal surface of segment.

Mandibles very finely longitudinally striate. Head and dorsum of mesosoma more-or-less regularly striate; striae mostly longitudinal on head and dorsum of mesosoma, anteriorly converging on clypeus and oblique on sides of mesosoma. First gastral segment shagreened dorsally, longitudinally striate laterally, striae much finer than those on rest of body.

Relatively short, mostly erect, off-white or yellowish hairs, scattered over all dorsal body surfaces; hairs longer on apical segments and venter of gaster, some almost as long as greatest diameter of eye. Rather sparse, appressed, silvery pubescence scattered over dorsum of head and mesosoma dense on pronotal humeri, propodeal dorsum, along lateral and posterior borders of gastral segments and especially on metapleuron and propodeal declivity; midline of declivity glabrous.

Black. Mandibular masticatory border widely, inner mandibular border narrowly, light yellowish brown. Antennal scapes dark reddish brown; funiculi brown, segments becoming progressively lighter towards apex, apical segments yellowish brown. Legs very light, yellowish white (unique holotype may not be fully pigmented individual), only basal portion of trochanters, distal ends of femora, proximal ends of tibiae and basal tarsal segments dark, reddish-brown. Sexuals and immature stages unknown.

Type Material

HOLOTYPE: PAPUA NEW GUINEA, East Sepik Prov., 8km SSW of Dagua, 03º29’S, 143º16’E, 800m, lowland rf., 12-14.vii.1980, P.S. Ward #4747-10 (worker). Type distribution: unique holotype in Australian National Insect Collection.

Etymology

Name derived from the Latin word planus, meaning flat, alluding to its virtually flat pronotal dorsum.

References