Polyrhachis minima

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

Kohout 2007a-58 Polyrhachis minima hal.jpg

Kohout 2007a-58 Polyrhachis minima had.jpg

Nothing is known about the biology of Polyrhachis minima.

Identification

Kohout (2007) - P. minima is one of the smallest members of the subgenus. It is somewhat similar to Polyrhachis wardi but, besides its smaller size (HL 1.09 in minima versus HL 1.15-1.34 in wardi), it differs in having a more convex mesosoma, posteriorly weakened pronotal margins, propodeal margins that are not produced into laterally directed teeth and a higher and more concave propodeal declivity.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

Check distribution from AntMaps.

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Polyrhachis minima 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.

  • minima. Polyrhachis (Aulacomyrma) minima Kohout, 2007a: 202, figs. 12, 15, 18 (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. 3.98; HL 1.06; HW 0.98; CI 92; SL 1.15; SI 117; PW 0.81; MTL 1.06.

Anterior clypeal margin arcuate, with very shallow notch medially; clypeus in profile virtually straight anteriorly, with basal margin shallowly impressed. Frontal carinae strongly sinuate with laminate lobes. Sides of head in front of eyes only weakly converging anteriorly. Eyes convex, in full face view clearly breaking lateral cephalic outline. Mesosoma marginate, margins of pronotal dorsum rather weak, but reaching promesonotal suture. Pronotal dorsum virtually parallel sided; humeri armed with acute, laterally directed, broad-based teeth. Promesonotal suture distinct; metanotal groove indicated by distinct incisions in lateral margins. Propodeum with lateral margins weakly widened posteriorly, terminating in rounded prominences and continued inwards, forming medially discontinued ridges that partly separate propodeal dorsum from relatively high and concave declivity. Petiole transverse, dorsal margin acute and weakly notched medially, strongly sinuate in dorsal view; lateral spines backwardly curved. Anterior face of first gastral segment concave; anterodorsal margin of concavity acute but only very weakly elevated above dorsal face of segment.

Mandibles finely striate. Head mostly longitudinally, somewhat irregularly, striate; striae on sides of head more regular and weakly curved inwards. Sculpture of mesosomal dorsum consisting of longitudinal striae, somewhat anteriorly converging on pronotal dorsum, posteriorly converging on mesonotal-propodeal dorsum; oblique on sides. Propodeal declivity finely shagreened; somewhat tranversely wrinkled medially, very smooth and glossy ventrally. Petiole and dorsum of gaster shagreened, sides of first gastral segment longitudinally striate.

Relatively short, yellowish or off-white, erect or curved hairs on head and mesosoma, most dense and longest on mandibles and clypeus, only a few short, variously curved hairs breaking the outline of vertex and mesosoma. Dorsum of first gastral segment with only a few short hairs, more abundant, longer and more golden towards apex. Somewhat untidy, relatively long, appressed or decumbent, greyish or silvery pubescence present in various density on all body surfaces, densest along preoccipital margin, pronotal humeri, propodeal dorsum, meso- and metapleura and coxae; fairly dense on gastral dorsum, ranging from silvery to golden.

Black. Mandibles, antennae and legs light to medium yellow, only basal portion of scapes, distal ends of femora and first tarsal segments a shade darker.

Type Material

HOLOTYPE: PAPUA NEW GUINEA, Morobe Prov., Huon Pen, lower Busu R., 5.v.1955, lowland rf., E. O. Wilson #954 (worker). Type distribution: unique holotype in Museum of Comparative Zoology.

Etymology

Name derived from the Greek word minys, meaning little or small, referring to its small size.

References