Hirtomyrma

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Hirtomyrma
Polyrhachis bamaga
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Hirtomyrma
Kohout, 2010
Type species
Polyrhachis hirta
Diversity
10 species

Polyrhachis bamaga side AntWiki.jpg

Polyrhachis bamaga top AntWiki.jpg

Specimen labels

This is currently a subgenus of Polyrhachis. Please see Polyrhachis for further information.

The subgenus Hirtomyrma as conceived here effectively replaces the Polyrhachis viehmeyeri-group that was originally established by Emery (1925), within the subgenus Myrmhopla , for two, rather unusual species from New Guinea (Polyrhachis hirta and Polyrhachis viehmeyeri). A third species (Polyrhachis davydovi) from the Aru Is, Indonesia, was described by Karavaiev in 1927. The former group was reviewed by Kohout (1990) who described four new species from northern Australia (Polyrhachis bamaga, Polyrhachis eremita, Polyrhachis loweryi and Polyrhachis rustica) and two extralimital species (Polyrhachis greensladei from the Solomons and Polyrhachis stigmatifera from Seram I., Indonesia). An additional species from South East Asia (Polyrhachis lama) was described by Kohout in 1994, thus raising the number of known species of the group to ten.

Distribution

The main distribution of the subgenus Hirtomyrma ranges from the Moluccas, New Guinea and Bismarck Archipelago to the Solomons and extends south to northern Australia. However, the range of one species (Polyrhachis lama) extends from Java and Hong Kong to the Tibetan Plateau in the Himalayas.

Biology

All known species of this group are apparently social parasites of other ants, notably Ectatomminae and Ponerinae. The association of Polyrhachis loweryi with the genus Rhytidoponera and the extralimital Polyrhachis lama, with the genus Diacamma, were studied by Prof. U. Maschwitz (formerly of Johan Wolfgang Goethe-Universität in Frankfurt am Main, Germany) and his team (Maschwitz et al. 2000, 2003).

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • HIRTOMYRMA [subgenus of Polyrhachis]
    • Hirtomyrma Kohout, 2010: 199 [as subgenus of Polyrhachis]. Type-species: Polyrhachis hirta, by original designation.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Medium sized-ants (HL 1.75-2.20) with general characteristics of the genus. Mandibles with 4 or 5 teeth, very finely longitudinally striate. Anterior clypeal margin truncate medially; posterior margin usually deeply impressed. Frontal carinae rather flat, widely separated. Eyes with numerous, short, erect hairs, strongly convex, almost hemispherical, clearly exceeding lateral cephalic outline in full face view. Median ocellus distinct (as in P. eremita and P. loweryi), vestigial (as in P. rustica) or lacking (as in P. bamaga). Pronotal and propodeal dorsa laterally marginate, virtually flat; mesonotal dorsum transversely convex with less distinct, rather blunt, lateral margins. Pronotum armed with somewhat dorsally flattened, acute spines (except in extralimital P. lama); their length, direction and degree of elevation usually highly variable, even asymmetrical, within a single species (as in P. rustica). Propodeal spines acute, usually longer than pronotal pair, variously elevated. Dorsum of petiole with poorly defined, more-or-less posteriorly sloping platform, bearing a pair of widely separated, diverging spines, without intercalary spines or teeth. Head, mesosoma and petiole with characteristic vermiculate-rugose sculpturation and bristle-like hairs, distinctly shorter than maximum eye diameter. Gaster shagreened, or with base of first tergite finely micro-reticulate and more-or-less shiny (as in most Australian species). Body mostly light to dark reddish-brown, with mandibles, clypeus, frontal carinae, spines and posterior margins of gastral tergites usually narrowly bordered very dark brown.

Queen

Differing from worker in usual characters identifying full sexuality, including three ocelli, complete thoracic structure and wings. Spines shorter and more stubby than in worker. Sculpturation, pilosity and colour essentially as in worker.

References

  • Kohout, R.J. 2010. A review of the Australian Polyrhachis ants of the subgenera Myrmhopla Forel and Hirtomyrma subgen. nov. (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum 55, 167-204.