Anochetus armstrongi

[25] Anochetus armstrongi

Samples of A.' armstrongi from eastern Australia usually have the striate sculpture of metanotum and propodeum very restricted, and the integument here mostly smooth and shining; the petiolar node tends to be thick at the apex, and in front view, the apical margin is only just barely emarginate, and the corners are broadly rounded.

The largest specimens (HW up to 1.50 mm) are from the mallee country of northwestern Victoria (Duddo Wells, north of Murrayville,

C. Barrett; Ultima, J. C. Goudie); the smallest eastern ones (HW 1.30-1.40 mm) are from Queensland (Roma, F. H. Taylor; 80-100 miles south of Sarina, P. F. and P. J. Darlington). The type series (ANIC-Canberra, MCZ, BMNH-London) is from Nyngan, central New South Wales (fig. 32).

Western Australian samples tend to be smaller (HW down to 1.20 mm, or even slightly less), the striation is more extensive on the sides of the posterior trunk, and the petiolar node is thinner and more distinctly emarginate, thus raising the question as to whether the western populations may not represent a species separate from armstrongi. The samples vary so widely one to the next that I feel such a separation would be premature. This is a question that needs much more material. Present western series available: Toodyay, A. Douglas; Northam, P. McMillan; Mullewa, W. M. Wheeler. AH of the localities appear to lie in zones now agriculturally modified, but originally in dry sclerophyll woodland or mallee.

The samples of A. rectangularis available (MCZ) are from New South Wales: Warrah, W. W. Froggatt. Queensland: Townsville, separate collections by F. P. Dodd and W. M. Wheeler; north of Mareeba, P. F. and P. J. Darlington; Lynd, 500 m, E. S. Ross and D. Q. Cavagnaro; 40 miles SW of Mt. Garnet, 750 m, Ross and Cavagnaro. The samples vary in color from light brownish-yellow to dark brown with blackish gaster. The head is often lighter and more yellowish than is the trunk.

The variety diabolus as described by Forel corresponds to those samples with the petiolar emargination distinct, rendering the upper corners more marked; this condition is found in several series, and seems to be part of the infraspecific variation.

Of A. turneri, I have studied only the types, from Mackay, Queensland (MHN-Geneva, MCZ), b,ut the variety latunei described by Forel seems to be only a slightly smaller, more lightly sculptured variant, not likely to be a distinct species. R. W. Taylor (in litt.) tells me that he has found A. rectangularis and A. turned to be "widespread in northern Australia", but relatively uncommonly collected. He has independently confirmed the synonymy of their two varieties.

Taylor sends additional records of collections of this group in ANIC-Canberra: A. rectangularis (fig. 36); Queensland: near Dimbulah, 10 miles W of Charters Towers, 14 miles S of Maryborough, Homestead, Brisbane. Northern Territory: 5 km S of Cahills Crossing (12.23S, 132.51E), slopes above Baroalba Spring (12.47S, 132.51E). New South Wales: Bombala. Torres Strait: Prince of Wales Island.

A. turneri (Fig. 33): Queensland: Hinchinbrook Island. Torres Strait: Prince of Wales Island. A. armstrongi: Victoria: Patho, Marysville, Bogan River. New South Wales: Euston, Riverina, Broken Hill, Finlay, 14 miles NW of Leeton, Callubri Station, Talbita, 14 miles N of Quambone. Queensland: St. George, Toobeah, Nindigully, Fletcher, 4 miles WNW of Yelarbon, Helenslee. Western Australia: Mt. Jackson, Weira. South Australia: Mt. Lofty, 25 miles WSW of Mulga Park Head Station.

Taylor also writes of another possibly.undescribed species from northwestern Australia, previously placed in the AN1C collection with armstrongi. He says this form is "rather like paripungens " in structure and sculpture of trunk, "but is as big as armstrongi, with large eyes. It has longer scapes and more generally dispersed and abundant pilosity than do southwestern Australian armstrongi ". This form has been taken at localities in the Hamersley Range, the Kimberleys, and in the Northern Territory: Johnston’s Lagoon, 23 miles SE of Newcastle Waters, Darwin). Taylor proposes and then rejects the hypothesis that these samples could be character-displaced armstrongi under the influence of partly sympatric populations of paripungens in the Darwin area, and perhaps elsewhere in the northwest. A. armstrongi in Western Australia as here defined is a southwestern species, not yet known to occur north of the Geraldton-Mullewa area. We must await samples from the vast reach of arid land between Mullewa and the Hamersleys in order to find out how armstrongi and the possibly undescribed species are related to each other and to paripungens.