Polyrhachis nomo

Nothing is known about the biology of Polyrhachis nomo.

Identification
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)

Distribution
This taxon was described from New Guinea.

Castes
Known only from (type) workers.

Nomenclature

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

Worker
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
Syntype workers, – as reported by Kohout (2006).

Type Locality Information
NEW GUINEA, Mt Nomo, S of Mt. Bougainville, 600-1500 ft, ii-1936, col. L.E. Cheesman.

This reference is 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 travelling. 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 neighbourhood as long as provisions lasted.