Polyrhachis gentilis

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

Kohout 2007a-58Polyrhachis-gentilis hal1.jpg

Kohout 2007a-58Polyrhachis-gentilis hal.jpg

Nothing is known about the biology of Polyrhachis gentilis.

Identification

Kohout (2007) - With its small size and parallel sided mesosoma, P. gentilis superficially resembles Polyrhachis wamuki. However in wamuki the pronotal margins are lacking and the lateral margins of the pronotal spines curve directly onto the sides of the segment without continuing towards the promesonotal suture. The sculpture of the pronotal dorsum also differs with the striae in gentilis only weakly converging, while they are strongly inversely V-shaped and merge along the midline in wamuki.

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 gentilis 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.

  • gentilis. Polyrhachis (Aulacomyrma) gentilis Kohout, 2007a: 200, figs. 10, 13, 16 (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. 4.84; HL 1.28; HW 1.09; CI 85; SL 1.31; SI 120; PW 0.87; MTL 1.22.

Anterior clypeal margin with shallow notch medially. In profile clypeus almost straight anteriorly, weakly convex posteriorly with shallow basal margin. Frontal carinae sinuate with raised laminate lobes; frontal triangle indistinct. Sides of head almost straight in front of eyes, converging anteriorly towards bases of mandibles; gently rounding behind eyes into preoccipital margin. Eyes moderately convex, in full face view breaking lateral cephalic outline. Mesosoma laterally marginate, virtually parallel-sided. Pronotal humeri armed with broad-based teeth that are laterally continuous with pronotal margins; margins weakened posteriorly before reaching distinct promesonotal suture. Metanotal groove absent. Propodeal dorsum terminating in rather distinct, rounded prominences, their posterior margins continued medially but failing to meet, leaving a very narrow gap through which propodeal dorsum descends into declivity; viewed from behind, posterior margin forming an open inverted ‘V’; propodeal declivity concave in lateral view. Petiole with dorsal margin acute, entire; lateral spines relatively short, curved backwards, sinuate in dorsal view. Anterior face of first gastral segment concave, anterodorsal margin of concavity rather acute, but not raised above dorsal face of segment.

Mandibles with rather distinct striae radiating from bases towards masticatory borders. Head mostly longitudinally striate, striae on sides curving inwards from posterolateral corners and continuing anteriorly towards mandibular bases. Striae on vertex mostly longitudinal, a few irregular, mostly transversely bowed striae, medially along preoccipital margin. Pronotal dorsum with striae converging anteriorly towards pronotal collar; striae on mesonotal-propodeal dorsum longitudinal for most of their length, curving strongly inwards before reaching posterior margin. Petiole with both faces and first gastral segment laterally and dorsally shagreened.

Head with numerous, erect and semi-erect, relatively short, hairs that do not exceed the greatest diameter of the eyes in length; hairs distinctly less abundant on mesosomal dorsum and first gastral segment, where they are posteriorly curved. Posterior and ventral gaster with more abundant hairs, some as long as greatest diameter of eyes. Mostly medium length, pale yellow to golden, diluted appressed pubescence on all body surfaces, most abundant and golden on gastral dorsum, almost hiding underlying sculpture; pale yellow or silvery on metapleuron, propodeal declivity and posterior margins of gastral segments.

Black, with legs dark to medium reddish brown. Tibiae, except proximal ends, apical segments of tarsi and funiculi distinctly light yellowish brown.

Type Material

HOLOTYPE: PAPUA NEW GUINEA, Morobe Prov., Huon Pen., Mongi Watershed, Zingzingu, 1200m, 9-10.iv.1955, E. O. Wilson #761 (worker). Type distribution: unique holotype in Museum of Comparative Zoology.

Etymology

Name derived from the Latin word gentilis, meaning gentle.

References