Polyrhachis nomo

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Polyrhachis nomo
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Cyrtomyrma
Species: P. nomo
Binomial name
Polyrhachis nomo
Donisthorpe, 1941

Polyrhachis nomo casent0903416 p 1 high.jpg

Polyrhachis nomo casent0903416 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Polyrhachis nomo.


Polyrhachis nomo is distinct from Polyrhachis rastellata in having all surfaces of the body covered with short, appressed and decumbent hairs. The pronotal shoulders are widely rounded and the lateral petiolar margins strongly diverging, terminating in slender, acute spines that are distinctly longer than the dorsal pair. In contrast, the pilosity in Polyrhachis rastellata consists of a few scattered hairs on the head, apical portion of the gaster and a tuft of hairs on the summit of the mesosoma. The pronotal dorsum in Polyrhachis rastellata is widest across or just below the narrowly rounded or bluntly angular shoulders. The lateral margins of the petiole are only weakly diverging with the lateral petiolar spines broad-based and rather short. Polyrhachis nomo closely resembles Polyrhachis decumbens from Queensland. Both have a characteristic pile of short, decumbent hairs covering most of the body. Characters distinguishing these two species are described in detail under Polyrhachis decumbens. (Kohout 2006)

Keys including this Species


Distribution based on Regional Taxon Lists

Indo-Australian Region: New Guinea (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb



Known only from (type) workers.


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

  • nomo. Polyrhachis (Cyrtomyrma) rastellata var. nomo Donisthorpe, 1941c: 142 (w.) NEW GUINEA. Raised to species: Kohout, 2006b: 131.

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



Black shining, insertions of the antennae, base of trochanters and of femora narrowly, spurs and claws reddish yellow, legs dark brown to black. The reticulation and small punctures are not as distinct as in rastellata; olothed with very fine, short, not close decumbent yellowish hairs.

Head broad, massive, broader than thorax, cheeks somewhat more rounded than in rastellata, posterior angles not distinct, posterior border not quite as deeply emarginate as in rastellata. Thorax broad, massive, convex; meso-epinotal suture not indicated; scale with four pointed teeth, the outer pair being longer and sharper than in rastellata and the inner pair less close and sharper.

Long. 5-5.5 mm.

Type Material

NEW GUINEA, Mt Nomo, S of Mt. Bougainville, 600-1500 ft, ii-1936, col. L.E. Cheesman. Syntype workers The Natural History Museum, Museum of Comparative Zoology – as reported by Kohout (2006).

The following is in reference to Mount Nomo and Mount Bougainville, as detailed in this account of Cheesman's 1936 expedition (Cheesman 1938):

Before encamping on the Cyclops Mountains I made one trip inland outside the range, through the swamp country behind Mount Bougainville as far as Mount Nomo, south of the Yjapo Mountains on the boundary. I accompanied Herr Stuber, a German planter in the Dutch Government service who was making a reconnaissance with a view to opening up a road leading to gold-bearing country farther inland. As he is a collector of orchids and butterflies Herr Stuber is friendly with the Papuans of that district.

It is interesting country, though not very agreeable for traveling. For two days we were walking through sago swamps with occasional belts of forest on a bush road used by members of the Boundary Commission in 1910. The river Tami and its tributaries drain this low plain, the Tami being a muddy, crocodile-infested river which we had to cross by prau. It carries the overflow of Lake Sentani which lies at the foot of the mountains and is supplied by mountain torrents. The previous week had been rather dry and the water had shrunk more than 7 feet. This exposed very deep mud in the bed on either side of the central channel, and the carriers had considerable difficulty in getting the prau near enough to the banks. We had to wade ashore up to the waist in mud.

On the third day we reached Njau (a new village several miles south of the old one marked on maps), and made a camp between two mountains - one of them Mount Nomo - half a day's journey beyond the village and collected in that neighborhood as long as provisions lasted.


  • Cheesman, L.E. The Cyclops Mountains of Dutch New Guinea. The Geographical Journal, London, 91, 1938, p. 21-30.
  • Donisthorpe, H. 1941. Descriptions of new ants (Hym., Formicidae) from various localities. Annals and Magazine of Natural History (11)8: 199-210.
  • Kohout, R. J. 2006. Review of Polyrhachis (Cyrtomyrma) Forel (Hymenoptera: Formicidae: Formicinae) of Australia, Borneo, New Guinea and the Solomon Islands with descriptions of new species. Memoirs of the Queensland Museum. 52:87-146.