Polyrhachis kokoda

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

Polyrhachis kokoda casent0009241 p 1 high.jpg

Polyrhachis kokoda casent0009241 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Polyrhachis kokoda.

Identification

Kohout (2007) - P. kokoda is superficially similar to Polyrhachis mamba described below, with both species evidently sympatric. The paratype of kokoda was collected together with a mamba queen at the same locality at Oivi Ridge and they were subsequently mounted on the same pin. Both species share the somewhat elliptical striation of the mesosomal dorsum but there the similarity ends. They differ in numerous characters, including the shape of the eyes, which in kokoda are strongly convex and clearly project beyond the lateral outline of the head. In contrast the eyes in mamba are virtually flat and sunk into a shallow concavity in the cephalic sculpture and they do not break the cephalic outline in full face view. In lateral view the outline of the mesosoma in kokoda features a strongly convex pronotal dorsum and the propodeal dorsum descends into the declivity in an uninterrupted curve. In mamba the pronotum is flatter and the propodeal dorsum descends abruptly into a rather short, vertical declivity. The dorsum of the petiole has an acute margin in kokoda, while it is bluntly rounded in mamba. The first gastral segment of kokoda is finely shagreened in contrast to mamba, where its sides are distinctly, longitudinally striate. The pubescence on the head and body is golden in kokoda, with a distinct reddish tint on the gastral dorsum, while in mamba the pubescence is uniformly greyish or white.

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 kokoda 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.

  • kokoda. Polyrhachis (Aulacomyrma) kokoda Kohout, 2007a: 226, figs. 74, 77, 80 (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. 4.64-5.09 (4.79); HL 1.22-1.31 (1.31); HW 1.00-1.06 (1.03); CI 79-82 (79); SL 1.36-1.43 (1.43); SI 135-139 (139); PW 0.97-1.03 (1.00); MTL 1.31-1.40 (1.37) (3 measured).

Clypeus with anterior margin medially truncate or very shallowly emarginate; median longitudinal carina weakly elevated posteriorly before descending towards shallowly impressed basal margin. Frontal carinae sinuate, with rather short, laminate, anteriorly truncate lobes. Sides of head in front of eyes convex; narrowed behind into convex preoccipital margin. Eyes strongly convex, clearly breaking cephalic outline in full face view. Mesosoma immarginate, dorsum sloping onto sides and propodeal declivity in unbroken curve. Pronotal dorsum very strongly raised anteriorly, convex in profile. Pronotal humeri armed with acute, rather long, downward curved spines; bases broad, margins raised. Promesonotal suture distinct; metanotal groove lacking. Petiole with both faces convex and dorsal margin somewhat angular; lateral spines short, curved backwards. Anterior face of first gastral segment convex.

Mandibles distinctly, longitudinally striate. Sculpture of head, mesosoma and petiole consisting of regularly spaced, rather smooth and glossy striae. Head with longitudinal, mostly anteriorly converging striae; clypeal striae terminating just short of anterior margin. Striae on mesosomal dorsum forming an imperfect elliptical pattern, divided in half by promesonotal suture; outermost striae continued obliquely onto sides and posteriorly extending onto propodeal declivity. Petiole with tranverse, dorsally arched striae on anterior face; inversely V-shaped on posterior face and converging upwards towards dorsal margin. Gaster finely, microscopically, shagreened.

Abundant, long, mostly erect or curved, golden hairs on most of body and appendages, hairs reaching greatest diameter of eyes in length, distinctly shorter on antennal scapes and along dorsal margin of petiole. Propodeal declivity with patch of very short, somewhat dorsally curved, off-white hairs. Appressed, golden pubescence very sparse on dorsum of head and mesosoma; more distinct on pronotal dorsum, forming V-shaped patch running from pronotal spines across the segment, and posteriorly towards propodeal declivity. Thin covering of mostly white or silvery pubescence on sides of mesosoma, coxae, appendages and posterior margins of gastral segments; pubescence most abundant and distinctly reddish on gastral dorsum, somewhat obscuring underlying sculpture.

Black, masticatory margins of mandibles, antennal scapes and most of legs medium to dark reddish-brown. Trochanters and basal femora distinctly yellow.

Type Material

HOLOTYPE: PAPUA NEW GUINEA, Northern Prov., Kokoda, 9.iii.1972, P.M. Room #250 (worker). PARATYPES: data as for holotype (1 worker); Oivi Ridge, Kokoda Rd, 1200ft, rf., 18.i.1971, B. B. Lowery (1 worker). Type distribution: holotype in Australian National Insect Collection; 1 paratype each in Museum of Comparative Zoology and Queensland Museum.

Etymology

Named after the type locality, Kokoda village, situated on the northern rim of the Owen Stanley Ranges in the Northern Province of Papua New Guinea.

References