Lioponera dumbletoni

Identification
Distinguished from all other species of the genus by the following combination of characters: moderately large size (head width of type series 1.16-1.25 mm), antennal scapes unusually long, side of alitrunk non-marginate, body surface smooth and shining to shagreened and subopaque, body color deep blackish brown to jet black.

The only other Indo-Australian Cerapachys (Phyracaces) lacking marginations along the sides of the alitrunk are Cerapachys aberrans Clark and Cerapachys longitarsus (pygmaeus synonym) Clark of northern Queensland and Cerapachys hewitti Wheeler of Borneo. These species are easily distinguished from dumbletoni by their much shorter scapes, which reach only to about the posterior margins of the compound eyes when thehead is viewed in full face - in dumbletoni the scapes extend beyond the eyes by about their own maximum width. Of the three species, dumbletoni most resembles aberrans Clark, being very close in size and sculpturing.

Distribution
This taxon was described from New Caledonia.

Biology
Ecological notes. P. dumbletoni was collected at Chapeau Gendarme and Mt. Mou in dry, semi-deciduous "valley-pocket" forest .and at Ciu in moist broadleaf evergreen forest. In all three localities it was limited primarily to the least disturbed portions of the forest, and was never encountered in the adjacent open Melaleuca woodland. At Chapeau Gendarme a large colony (no. 65) was found nesting in several spacious galleries and chambers in the upper layers of a large, moist, fern-covered log. It contained at least 200 workers, a single ergatogyne (later lost), over 100 cocoons and larger larvae, and an undetermined number of eggs. Among the brood were found the hollowed-out propodeum of a worker of an undescribed species of Lordomyrma and the mangled remains of the larva of an undetermined ant genus. These insects appeared to be the prey of the Phyracaces, but of course this cannot be proven. When first disturbed, many of the Phyracaces workers sallied out with a display of aggressiveness unusual for cerapachyines, and one succeeded in stinging me on the forearm. I think it is worth mentioning that this is the only time I have ever been stung by a cerapachyine ant, despite the fact that I have excavated many nests of Phyracaces and other genera without making any effort to protect myself from the workers. The sting caused a prominent welt about six millimeters wide surrounded by an erythema about twenty-five millimeters wide. There was a persistent, dull, throbbing pain of the sort commonly resulting from the stings of ponerine ants.

Description
Holotype worker. Head width 1.17 mm, head length 1.30 mm, scape length 1.08 mm, cephalic index 90, scape index 92, exposed length of mandibles 0.29 mm, eye length 0.33 mm, pronotal width 1.03 mm, petiole width 0.95 mm, petiole length 0.76 mm, postpetiole width 1.09 mm, width of next gastric segment 1.26 mm. Occipital border in full-face view very feebly convex. Alitrunk viewed from above only feebly constricted medially, its dorsolateral area evenly rounded and lacking any trace of margination. Petiolar node seen from directly above with moderately concave anterior border and evenly convex lateral borders, its greatest width 10(,lated in the anterior half. Puncturation as described for P. cohici, except that anterior to the postpetiole the punctures are more scattered, the majority being 0.09 to 0.12 mm apart. On the postpetiole and anterior to this segment the interspaces are for the most part "shagreened, " the shagreening in this' case in reality consisting of regular, minute, contiguous foveolae each about 0.01 mm in diameter. The foveolae are deepest on the dorsal surface of the head and alitrunk, and render most of the cuticular surface there suhopaque. They are absent posterior to the postpetiole. Color as described for P. cohici.

Worker variation. Maximum head width range, Chapeau Gendarme and Mt. Mou series: 1.16-1.25 mm (all shown by acc. no. 65, the holotype nest series). Maximum head width range, Ciu series: 1.11-1.20 mm (all shown by ace. no. 245). The Ciu workers differ significantly from the Chapeau Gendarme and Mt. Mou workers in the intensity of the foveolar" shagreening. " The latter approach the condition described in the holotype, with little deviation. The Ciu specimens have the same basic form of sculpturing, but on the head and alitruncal dorsum the foveolae are much shallower, so that the surface is strongly shining under ordinary reflected light.

Ergatogyne. Head width 1.14 mm, head length 1.26 nnn, scape length 0.76 mm, cephalic index 90, scape index 67, exposed length of mandibles 0.22 mm, eye length 0.30 mm, pronotal width 1.00 mm, petiole width 0.95 mm, petiole length 0.62 mm, postpetiole width 1.32 mm, width of next gastric segment 1.55 mm. Ocelli lacking. More similar to the worker caste than to the queen caste of other Phyracaces species, differing primarily in the following external features. (1) The alitrunk is very worker-like, apparently differing only in the somewhat stronger pleural suturation. The posterior meta pleural suture, which is absent in the dumbletoni worker, is present although feebly developed in the ergatogyne. (2) The petiole is relatively shorter in the ergatogyne. (3) The postpetiole and gaster are much more massive and more poorly demarcated from each other than are the same structures in the worker. Types. Described from a long series of workers from Chapeau Gendarme (Yahoue), Mt. Mou, and Ciu, and a single ergatogyne from Ciu. The following accessions are included, each representing a separate nest series: Chapeau Gendarme, no. 65 (holotype nest series); Mt. Mou, single worker; Ciu, no. 245 and "observation colony."

Etymology
This species is named after Mr. L. Jock Dumbleton, formerly economic entomologist for the South Pacific Commission, and an expert student of the New Caledonian insect fauna.

Additional References
[[Media:Wilson 1957a.pdf|Wilson, E. O. 1957a. The discovery of cerapachyine ants on New Caledonia, with the description of new species of Phyracaces and Sphinctomyrmex. Breviora 74: 1-9]]

Wilson, E.O. 1958c. Observations on the behavior of the cerapachyine ants. Insectes Sociaux 5: 129-140. [(30).vi.1958.]