Zasphinctus caledonicus

Brown (1975) - An S. caledonicus colony fragment observed over several weeks in an artificial (plaster-bottomed) nest was placed in contact with a colony fragment of Acanthomyops claviger, a North American formicine that Sphinctomyrmex would of course never normally meet in nature. (The Acanthomyops defends itself with formic acid spray and terpenoids such as citrinellal.) The Sphinctomyrmex raided the adjacent Acanthomyops colony, were duly sprayed and smeared with the noxious allomones, but nevertheless returned to their chambers with Acanthomyops adults and brood as prey. The Sphinctomyrmex workers spent an inordinate amount of time grooming themselves and their nestmates, especially just after raids - evidently a behavior pattern aimed at removing the toxic substances they receive from prey species. The Sphinctomyrmex workers and ergatoids also spend a great deal of time in the nest with their long, flexible bodies wrapped around their own brood, thus forming round, dense clusters that may fill large chambers.

Identification
Closely resembling Sphinctomyrmex steinheili of eastern Australia, from which it can be distinguished by the following two characters. (1) Sculpturing, which is dominated by puncturation, is overall denser in caledonicus. In steinheili, the interspace distances over the genal surface are mainly as great as the adjacent puncture diameters or greater, while in caledonicus the genal punctures are contiguous and their borders form an even rugoreticulum. In steinheili, the lateral surfaces of the alitrunk are in large part feebly shining, while in caledonicus these surfaces are entirely opaque. (2) In side view, the dorsal posterior corners of the propodeum form a distinct angle of about 110° in steinheili, but are evenly rounded in caledonicus.

Distribution based on Regional Taxon Lists
Australasian Region: New Caledonia.

Biology
The two type colonies were found in a small, isolated patch of broadleaf evergreen forest on the farm of Mr. D. Fere, about half a kilometer northwest of the Ciu Falls. This little woodlot did not exceed two acres in extent, and its floor had been badly disturbed by cattle. Most of the ants present were found underneath rocks embedded in the soil.

Colonies were quite large, one containing over 500 workers and the other over a thousand. That the colonies may have been in migration is suggested by the fact that they occupied poorly defined galleries in the soil which bore no sign of lengthy occupation. The brood of colony no. 195, collected on December 21, consisted of large numbers of mature larvae; two days later, about three-quarters of a sample of these larvae kept alive in a bottle had spun cocoons. The brood of colony no. 229, collected on December 31, consisted of large numbers of cocoons, all of which contained prepupae of indeterminate caste. These data suggest a high degree of synchronization of brood development, a condition usually associated in ants with a nomadic way of life.

Brown (1975) - An S. caledonicus colony fragment observed over several weeks in an artificial (plaster-bottomed) nest was placed in contact with a colony fragment of Acanthomyops claviger, a North American formicine that Sphinctomyrmex would of course never normally meet in nature. (The Acanthomyops defends itself with formic acid spray and terpenoids such as citrinellal.) The Sphinctomyrmex raided the adjacent Acanthomyops colony, were duly sprayed and smeared with the noxious allomones, but nevertheless returned to their chambers with Acanthomyops adults and brood as prey. The Sphinctomyrmex workers spent an inordinate amount of time grooming themselves and their nestmates, especially just after raids - evidently a behavior pattern aimed at removing the toxic substances they receive from prey species.

The Sphinctomyrmex workers and ergatoids also spend a great deal of time in the nest with their long, flexible bodies wrapped around their own brood, thus forming round, dense clusters that may fill large chambers.

Nomenclature

 *  caledonicus. Sphinctomyrmex caledonicus Wilson, 1957a: 8 (w.q.) NEW CALEDONIA. See also: Wilson, 1958c: 136.

Description
Holotype worker. Head width 0.56 mm, head length 0.71 mm, scape length 0.41 mm, cephalic index 79, scape index 73, exposed length of mandibles 0.06 mm, pronotal width 0.42 mm, petiole width 0.35 mm, petiole length (including peduncles) 0.38 mm, postpetiole width 0.47 mIll, width of next gastric segment 0.60 mm, length of gaster posterior to postpetiole (measured in a straight line) 1.35 mm. Worker variation. Maximum head width range (internidal) 0.50-0.57 IllIll; (intranidal; acc. no. 195) 0.50-0.56 mm. In size as well as other external characters the worker type series is remarkably uniform. Ergatogyne. Head width 0.62 mm, head length 0.76 mm, scape length 0.42 mm, cephalic index 82, scape index 68, exposed length of mandibles 0.09 mm, pronotal width 0.44 mm, petiole width 0.42 mm, petiole length 0.41 mm, postpetiole width 0.60 mm, length of gaster posterior to postpetiole 1.96 mm. This specimen is very worker-like, and can be distinguished only by its slightly larger size, proportionately shorter head and scapes, broader petiole, and larger postpetiole and gaster. In addition the postpetiolar-gastric constriction is somewhat weaker than in the worker.· Compound eyes and ocelli are completely lacking; as in the worker, and the structure of the alitrunk is essentially the same.

Type Material
Described from a long series of workers and a single ergatogyne from Ciu, 300 meters, New Caledonia. The following two accessions, representing separate nest series, are included:no. 195, no. 225. The holotype was chosen from no. 225.