Polyrhachis variegata

AntWiki - Where Ant Biologists Share Their Knowledge
Jump to: navigation, search
Polyrhachis variegata
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Aulacomyrma
Species: P. variegata
Binomial name
Polyrhachis variegata
Kohout, 2007

Polyrhachis variegata P.png

Polyrhachis variegata D.png

Known only from the holotype.

Identification

Kohout (2007) - A rather distinct species easily separated from most others by the posteriorly wide head and distinctly flat eyes, that are situtated well away from the lateral margins of the head. The rather flat and fine sculpture, untidy silvery pubescence and notably the obliquely descending propodeal declivity are also quite distinctive.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

Distribution based on specimens

Loading map...

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

  • variegata. Polyrhachis (Aulacomyrma) variegata Kohout, 2007a: 212, figs. 39, 42, 45 (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. 5.54; HL 1.43; HW 1.37; CI 96; SL 1.47; SI 107; PW 1.06; MTL 1.40.

Anterior clypeal margin distinctly medially emarginate; in profile clypeus very weakly convex, almost straight with rather flat but distinct basal margin. Frontal carinae sinuate, rather short, only moderately raised; frontal triangle indistinct. Sides of head convex, distinctly converging anteriorly towards mandibular bases. Eyes distinctly flat, not reaching cephalic outline in full face view. Mesosoma marginate with propodeal margins somewhat weakly defined. Pronotal humeri armed with laterally directed, broad-based teeth, margins raised and laterally continuous with pronotal margins. Promesonotal suture distinct; metanotal groove lacking. Propodeum terminating in small but distinct tuberculae. Propodeal dorsum descending into oblique declivity in uninterrupted curve. Petiole with acute, finely jagged dorsal margin and short, weakly backwards and upwards curved lateral spines; in dorsal view, dorsal petiolar margin weakly anteriorly bowed. Anterior face of first gastral segment very weakly concave with anterodorsal margin blunt, not raised above dorsum of segment.

Mandibles finely longitudinally striate at bases, becoming more reticulate with several shallow pits towards masticatory borders. Clypeus with very fine, weakly V-shaped striae at base, merging into irregular rugae anteriorly. Vertex and sides of head with fine, rather flat, mostly longitudinal striae. Pronotal dorsum with striae diverging, more-or-less parallel with lateral pronotal margins; striae posteriorly convering on mesonotal-propodeal dorsum, mostly oblique on sides of mesosoma, propodeal declivity only finely shagreened. Petiole with both faces finely shagreened. Gaster with sides longitudinally striate, striae distinctly finer dorsally, first gastral tergite finely reticulate anteromedially.

A few, rather short, erect hairs along outer mandibular edges, anterior clypeal margin, leading edge of antennal scapes, frontal carinae and outer surfaces of hind tibiae; a solitary hair arising from vertex. Hairs completely absent from dorsum of mesosoma, petiole and first gastral segment; only a few hairs, shorter than greatest diameter of eye, concentrated on apex and venter of gaster. Silvery, appressed and semierect, somewhat untidy pubescence in various densities on vertex, pronotal humeri, propodeal dorsum, metapleura, coxae and anterior face of petiole; pubescence virtually absent from front of head; gaster with pubescence more abundant dorsally but not obscuring underlying sculpture.

Black, mandibular masticatory border dark red. Funiculi apically and legs generally dark to medium reddish-brown, tibiae and apical tarsal segments a shade lighter.

Type Material

HOLOTYPE: INDONESIA, IRIAN JAYA, Guega, W of Swart Valley, 03º36’S, 138º25’E, 1200m, 15.xi.1958, J. L. Gressitt (worker). Type distribution: unique holotype in Museum of Comparative Zoology.

Etymology

Named for its somewhat different appearance from that of other members of the subgenus (Latin varius , variegatus = different, different sort).

References