Polyrhachis decora

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

Polyrhachis decora casent0009238 p 1 high.jpg

Polyrhachis decora casent0009238 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Polyrhachis decora.

Identification

Kohout (2007) - P. decora is rather similar to Polyrhachis gressitti, Polyrhachis kokoda and Polyrhachis mamba which all have virtually identical sculpture of the mesosoma and a rather convex base of the first gastral segment. It differs from all of them in having a highly convex vertex, a feature notably distinct in lateral view. Additionally, decora differs from gressitti in having the mesosomal dorsum distinctly longer, from kokoda by the longitudinally striate first gastral segment and from mamba by the strongly convex, protuberant eyes.

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 decora 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.

  • decora. Polyrhachis (Aulacomyrma) decora Kohout, 2007a: 220, figs. 57, 60, 63 (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

TL c. 5.19-5.74 (5.19); HL 1.31-1.37 (1.31); HW 1.09-1.15 (1.09); CI 81-84 (83); SL 1.37-1.47 (1.43); SI 126-131 (131); PW 0.90-0.94 (0.90); MTL 1.43-1.47 (1.43) (7 measured).

Clypeus with anterior margin arcuate, shallowly medially emarginate; in profile clypeus weakly convex with distinct notch anteriorly formed by furrow between clypeal striae; basal margin very weakly impressed. Frontal triangle indistinct. Frontal carinae very short, strongly raised with laminate lobes. Eyes very convex, protuberant, somewhat protracted posteriorly. Sides of head in front of eyes weakly converging anteriorly; strongly converging behind into laterally and posteriorly immarginate posterolateral corners; in lateral view relatively high vertex descends abruptly into narrow margin. Mesosomal dorsum laterally and posteriorly immaginate. Pronotal humeri armed with very strong, laterally and anteriorly directed spines with raised margins, dorsum of spines shallowly concave. Promesonotal suture distinct; metanotal groove lacking. Combined length of mesosomal and propodeal dorsa distinctly longer than pronotum. Propodeal dorsum descending uninterrupted into rather short propodeal declivity. Petiole scale-like with sharp dorsal margin terminating laterally in short, acute teeth. Base of first gastral segment anteriorly convex.

Mandibles finely longitudinally striate. Sculpture of head, mesosoma and petiole consisting of strongly raised, regularly spaced striae with deep interspaces resulting in a “ploughed” appearance; striae anteriorly converging on clypeus, U-shaped on apex of vertex, strongly curved medially from posterolateral corners towards central area between frontal carinae. Pronotal dorsum with inverse, open V-shaped striae, descending obliquely and uninterrupted onto sides. Mesonotal and propodeal dorsa with regular, U-shaped striae that are continued along sides and interrupted medially by smooth surface of declivity. Petiole with dorsally bowed striae on both faces. Gaster with distinctly finer striae, longitudinal on sides, less distinct and anteriorly converging on dorsum. Off-white, erect, medium length hairs on dorsum of head and mesosoma, a few distinctly shorter hairs along dorsal margin of petiole. Hairs on gaster golden, somewhat longer, curved posteriorly on dorsum. Silvery, appressed pubescence virtually absent from head and mesosoma; small, thin patches on propodeal lobes, along declivity, coxae and subpetiolar process. Gaster with fairly dense, reddish-golden pubescence mostly restricted to dorsum of first segment. Black with very smooth and glossy striae on head, mesosoma and petiole. Antennal scapes very dark, funiculi dark reddish brown with only apical funicular segment distinctly lighter. Legs dark reddish brown, except trochanters and femora, blending from light yellow over proximal halves to very dark brown at distal ends.

Type Material

HOLOTYPE: INDONESIA, IRIAN JAYA (New Guinea: Neth. on data label), Vogelkop, Fak Fak, S. coast of Bomberai Pen., 02º55’S, 132º18’E, 10-100m, 3.vi.1959, T.C. Maa (worker). PARATYPES: data as for holotype (3 workers); Vogelkop, Bomberi, Bomberai Pen., 02º 48’S, 132º50’E, 700-900m, 6.vi.1959, T. C. Maa (2 workers); ditto, 10.vi.1959, J. L. Gressitt (worker). Type distribution: holotype and 2 paratypes in Museum of Comparative Zoology; 1 paratype each in Australian National Insect Collection, The Natural History Museum, California Academy of Sciences and Queensland Museum.

Etymology

Named for its highly decorative sculpture pattern.

References