Tapinoma krakatauae

Type material of this taxon could not be located Heterick and Shattuck (2011). Wheeler’s (1924) detailed description does not match any of the Iridomyrmex species known from the area where it was collected. Based on the original description, it seems unlikely that this taxon belongs to Iridomyrmex. Specifically, Wheeler (1924) notes the following: (1) The ant “lacks” a petiole (presumably he means petiolar node as a gaster is present). (2) The gaster is described as “somewhat deflective”, suggesting it is positioned ventrally. This is not a common position for Iridomyrmex but it is a common orientation in Tapinoma and Technomyrmex. (3) There is no mention of a medial clypeal prominence or anything corresponding to it. Instead, the anterior border of the clypeus is described as “almost straight”. In most of the northern Iridomyrmex that occur outside of Australia (for example Iridomyrmex anceps and Iridomyrmex coeruleus) this anatomical feature is distinct. (4) The ant is very small (1.5 mm). Of the Iridomyrmex occurring in this region, only Iridomyrmex mjobergi would be similar sized; however, I. mjobergi has a distinct petiolar node. (5) The propodeum is not protuberant, a condition found in Iridomyrmex species from this area. (6) The antennal scapes do not reach the posterior margin of the head, a very unusual condition for Iridomyrmex where they normally extend at least slightly beyond the posterior margin of head. (7) The propodeum is sloping and hardly raised, a condition found in Doleromyrma and Tapinoma but not Iridomyrmex. (8) The ant is completely glabrous while northern I. mjobergi always has a few hairs. (9) The posterior margins of the eyes only meet the imaginary horizontal line intersecting the middle of the head capsule. This is much further anterior than found in Iridomyrmex. Taken together, these characters suggest that this taxon belongs in Tapinoma or possibly Technomyrmex rather than Iridomyrmex. Based on the small size we are here transferring it to Tapinoma. Determining the species-level identification of this taxon will require the examination of Tapinoma material from throughout the Krakatau region, an undertaking beyond the scope of this study.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia.

Nomenclature

 *  krakatauae. Iridomyrmex krakatauae Wheeler, W.M. 1924b: 252 (w.) INDONESIA (Krakatau I.). Combination in Tapinoma: Heterick & Shattuck, 2011: 166. See also: Shattuck, 1992a: 15.

Worker
(see the notes above by Heterick and Shattuck [2011] regarding this ants generic identity) Length nearly 1.5 mm. Head distinctly longer than broad, slightly broader behind than in front, with very feebly convex sides, rounded posterior corners and nearly straight posterior border. Mandibles small and narrow, their apical borders with numerous small. crowded denticles. Clypeus convex behind in the middle, depressed anteriorly and laterally, the anterior border nearly straight, not emarginate. Frontal area and groove lacking, frontal carinae parallel, somewhat further apart than their distance from the lateral borders of the head. Eyes moderately large, flat, their posterior orbits at the median transverse diameter of the head. Antennae slender, scapes reaching nearly to the posterior corners of the head; second funicular joint as long as broad, joints 4 and 5 longer than broad, remaining joints lacking. Thorax rather long, in profile with feeble mesoepinotal impression. Pronotum from above one and two-thirds times as broad as long; mesonotum horizontal. slightly longer than broad and slightly broader in front than behind. Epinotum sloping, with indistinct subequal base and declivity, the former scarcely convex, rising very little above the feeble mesoepinotal depression. Petiole lacking and gaster somewhat deflective.

Mandibles and clypeus very smooth and shining, the former with minute scattered punctures. Remainder of body somewhat shining, very finely, densely and superficially punctate.

Without pilosity, except for a row of hairs on the clypeus. Whole body pruinose with fine adherent whitish pubescence, which is longest on the gaster but nowhere completely concealing the surface.

Black, the head and thorax with faint metallic green reflections. Mandibles brown, basal three-fifths of antennal scapes, tarsi and tips of tibiae pale yellow or whitish.

References based on Global Ant Biodiversity Informatics

 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Heterick B. E., and S. Shattuck. 2011. Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae). Zootaxa 2845: 1-174.
 * Shattuck S. O. 1994. Taxonomic catalog of the ant subfamilies Aneuretinae and Dolichoderinae (Hymenoptera: Formicidae). University of California Publications in Entomology 112: i-xix, 1-241.
 * Wheeler, William Morton. 1924. Ants of Krakatau and Other Islands in the Sunda Strait. Treubia. 5(1-3):1-20.
 * Yamane S. 2013. A Review of the ant fauna of the Krakatau Islands, Indonesia. Bull. Kitakyushu Mus. Nat. Hist. Hum. Hist. Ser: A, 11: 1-66