Polyrhachis annulata

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

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Specimen labels

Nothing is known about the biology of Polyrhachis annulata.

Identification

Kohout (2007) - With the antero-posteriorly compressed mesosoma, dorsal petiolar margin medially emarginate and striae of the mesonotal-propodeal dorsum more-or-less semicircular, annulata is somewhat similar to Polyrhachis breviata. However, both species are easily separated by their size (HL 1.47 in annulata versus 1.15 in breviata) and shape of the petiole which, in annulata, is strongly transverse, while in breviata the petiole is almost as high as wide. The sculpture of the pronotal dorsum in annulata consists of longitudinal, anteriorly converging striae, while in breviata the striae are tranverse and strongly anteriorly bowed medially.

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 annulata 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.

  • annulata. Polyrhachis (Aulacomyrma) annulata Kohout, 2007a: 216, figs. 48, 51, 54 (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 5.54; HL 1.47; HW 1.47; CI 100; SL 1.43; SI 97; PW 1.12; MTL 1.40.

Anterior clypeal margin arcuate, emarginate medially. In profile clypeus moderately convex with basal margin weakly impressed, indicated by hairline break in cephalic sculpture. Frontal carinae sinuate with moderately raised laminate lobes. Sides of head in front of eyes converging anteriorly; rounding behind eyes into relatively shallow preoccipital margin. Eyes moderately convex, just reaching lateral cephalic outline in full face view. Mesosoma only partially marginate, somewhat antero-posteriorly compressed; pronotal humeri armed with broad-based acute spines with lateral margins continued posteriorly for a short distance before merging with outermost dorsal striae and curving onto sides. Promesonotal suture distinct; metanotal groove lacking. Mesonotal dorsum with distinct lateral margins formed by outermost lateral striae. Propodeum immarginate laterally; propodeal dorsum separated from relatively high, shallowly concave declivity by posterior-most stria that forms a weakly defined posterior margin. Petiole strongly transverse, dorsal margin acute, medially emarginate, strongly sinuate in dorsal view; lateral spines rather short, weakly bent backwards. First gastral segment concave with the anterodorsal margin of concavity rather blunt.

Mandibles finely longitudinally striate-rugose. Head mostly regularly striate, striae V-shaped on clypeus, longitudinal along sides of head and somewhat converging anteriorly from vertex towards frontal carinae. Mesosomal dorsum striate; pronotal striae longitudinal, anteriorly converging on pronotum, oblique on sides; mesonotal-propodeal dorsum with striae strongly bowed, more-or-less semicircular, oblique on sides. Petiole shagreened, becoming more transversely reticulate towards base. Gaster uniformly, finely reticulate.

Mandibles with a few, anteriorly curved hairs along outer and masticatory borders. Antennal scape with a few erect hairs along leading edge and at apex. A few scattered, rather short, variously directed hairs breaking outline of head and mesosoma. Gaster with some longer erect hairs, bordering segments. Appressed pubescence virtually absent from dorsum of head and mesosoma; pale golden pubescence on gastral dorsum, almost obscuring underlying sculpture.

Black. Antennae, femora and first tarsal segments very dark brown, rest of legs medium to light reddish brown; mandibles with anterior half reddish brown; apex of last funicular segment distinctly yellow.

Type Material

HOLOTYPE: PAPUA NEW GUINEA, Mt Tafa, 8km SE of Mondo, 08º38’S, 147º07’E, 8500ft, ii.1934, L. E. Cheesman (B.M.1934-321) (worker). Type distribution: unique holotype in The Natural History Museum.

Etymology

Name derived from the Latin word annulatus, meaning ringed or circular, with reference to the form of the sculpture of the mesonotal-propodeal dorsum.

References