Polyrhachis simulans

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

Polyrhachis simulans P.png

Polyrhachis simulans D.png

Known only from the holotype.

Identification

Kohout (2007) - P. simulans closely resembles Polyrhachis roberti and they share similar sculpture of the head and mesosoma, including the absence of striae on their mandibles and clypeus. However, they differ in a number of characters, of which the most distinct is the anterior clypeal margin which is entire in simulans, while in roberti the median portion of the margin projects as a narrow, medially emarginate lobe. In full face view the eyes do not reach the cephalic outline in simulans, while they clearly exceed it in roberti. In simulans the lateral margins of the propodeal dorsum terminate in blunt rounded angles, that do not project posteriorly. In contrast, the margins in roberti terminate in a pair of strong, broad-based, triangular, dorsally curved teeth, that project well beyond the posterior border of the propodeum. The petiole in simulans is about as wide as high, while in roberti it is clearly transverse, distinctly wider than high. Most of the body surfaces in simulans have abundant, erect hairs, while only a few hairs break the outline of the head and mesosoma in roberti.

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 simulans 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.

  • simulans. Polyrhachis (Aulacomyrma) simulans Kohout, 2007a: 209, figs. 30, 33, 36 (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. 5.74; HL 1.43; HW 1.31; CI 92; SL 1.47; SI 112; PW 1.15; MTL 1.37.

Anterior clypeal margin arcuate, entire; in profile clypeus weakly convex with rather flat basal margin. Frontal triangle indicated by change in cephalic sculpture. Frontal carinae sinuate, with raised laminate lobes. Sides of head gently convex in front of eyes. Eyes only moderately convex, not reaching lateral cephalic outline in full face view. Mesosoma laterally marginate along entire length. Pronotal humeri armed with acute teeth, their margins raised and continuous with pronotal margins. Promesonotal suture distinct; metanotal groove indicated by shallow incisions in lateral margins. Propodeal dorsum with lateral margins terminating posteriorly in narowly rounded angles with weakly raised margins, appearing as small teeth in lateral view; medially propodeal dorsum rounding into declivity in an uninterrupted curve. Dorsal petiolar margin acute, with medial emargination flanked by pair of intercalary teeth; lateral margin somewhat jagged and terminates in outwards and weakly backwards directed, slender spines. Anterior face of first gastral segment concave, dorso-medial margin of concavity rather blunt.

Mandibles, clypeus and frontal triangle rather smooth, very finely, superficially shagreened with scattered minute punctures, strongly contrasting with rest of head, that is longitudinally striate with striae weakly curved on sides; striae less regular on vertex and somewhat curved along midline. Striation on pronotal dorsum distinctly converging anteriorly and medially; striae on mesonotal- propodeal dorsum converging towards propodeal declivity and oblique on sides. Petiole with both faces finely shagreened. First gastral segment longitudinally striate, striae on dorsum distinctly finer and converging medially towards anterior margin.

Head, body and appendages with numerous erect to semi-erect, whitish or silvery hairs; no hairs on mandibles and clypeus, except a few along anterior margin, and sides of head between eyes and mandibular bases. Gaster with numerous, short, backward-curved hairs, those closer to apex distinctly longer. Mostly appressed, greyish or silvery pubescence on all body surfaces, most diluted on head and pronotum, with denser patches on meso- and metapleura, lateral borders of propodeal declivity and propodeal dorsum, where it curves towards midline. Pubescence relatively abundant on gastral dorsum, but not hiding underlying sculpture.

Black or very dark brown, with funiculi and tibiae of hind legs a shade lighter. Mandibular masticatory borders, tibiae, except their basal margin and apical tarsal segments light, almost yellow with reddish tint.

Type Material

HOLOTYPE: PAPUA NEW GUINEA, Morobe Prov., Huon Penins., lower Busu Riv., 5.v.1955, lowland rf. (E. O. Wilson #950) (worker). Type distribution: unique holotype in Museum of Comparative Zoology.

Etymology

Name derived from the Latin word simulo, meaning imitate or copy, in reference to its similarity to Polyrhachis roberti.

References