Ponera incerta

Ponera incerta is a rainforest species and is generally limited to ground leaf litter or moss on trees.

Identification
Taylor (1967) - Easily recognized by moderately small size (head width 0.36-0.40 mm in the worker, 0.43-0.44 mm in the queen), additional to the characters of the japonica species group (distinctly to indistinctly 5-segmented antennal club, and clearly incised dorsal mesometanotal suture in the workers). In the japonica group head width range is diagnostic. Ponera japonica is larger than incerta (worker (HW 0.42-0.50 mm) and Ponera swezeyi is smaller (worker HW 0.29-0.33 mm). P. incerta is sympatric with japonica on Java, and with swezeyi on Samoa; in other parts of its range the species group characters are diagnostic.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: Indonesia, Micronesia (Federated States of), New Guinea, Palau, Samoa, Solomon Islands, Tonga.

Biology
Taylor (1967) - New Britain specimens are from a rain forest berlesate, and the New Hebrides specimens were foraging diurnally in leaf litter in primary coastal rain forest (Wilson 1957). In my experience incerta is common in rain forest on all 3 main Samoan Islands, and was present at all elevations which were worked. At Afiamalu, it was extremely common in an area of disturbed rain forest where it had apparently undergone local irruption. This area consisted of about 20 acres of previously rich forest which had been partially cleared to allow access to cattle. About two-thirds of the canopy trees and most of the lower story elements had been felled, apparently some 18 to 20 months previously. Much of the smaller timber had decayed or been removed, but the larger logs remained, generally in sound condition, and rotting branch fragments of up to 10 cm diameter were abundant on the ground. This forest was very wet, moss being plentiful on the ground and especially on the upper surfaces of the fallen logs, where thick cushions were developed. The standing trees were festooned with mosses and epiphytes which appeared more abundant than in the adjacent undisturbed forest.

Nomenclature

 *  incerta. Pseudocryptopone incerta Wheeler, W.M. 1933g: 18, fig. 7 (w.q.) INDONESIA (Java). Taylor, 1967a: 82 (m.l.). Combination in Ponera: Wilson, 1957b: 367. Senior synonym of ratardorum: Taylor, 1967a: 80.
 * ratardorum. Ponera ratardorum Wilson, 1957b: 369, figs. 1, 2 (w.) NEW BRITAIN. Junior synonym of incerta: Taylor, 1967a: 80.

Worker
Length, 1.5 mm.

Head suboblong, one-fourth longer than broad, with nearly straight, subparallel sides and distinctly concave posterior border. Eyes present, minute, at about the anterior sixth of its sides. Mandibles with three small apical teeth; basal portion of masticatory border finely and indistinctly crenulate. Clypeus subcarinate, its anterior border produced in the middle, sinuate on the sides. Frontal carinae small, closely approximated, ciliated; frontal groove distinct as far back as the middle of the head. Antennal scapes reaching to its posterior sixth; clubs of funiculi thick, indistinctly 5-jointed, basal joints, except the first, short and transverse. Thorax in profile with nearly straight horizontal outline; promesonotal suture distinct, arcuate; mesoepinotal suture absent; base of epinotum parallel-sided, longer than the declivity which is straight and marginate laterally. Petiole decidedly higher than long, node somewhat narrowed above in profile, with straight anterior and posterior slopes, the superior border straight and horizontal; seen from above the petiole is broader than long and broader behind than in front, the node semicircular, its anterior surface regularly curved from side to side, its posterior surface fiat. Postpetiole nearly as broad as long, its anterior surface strongly truncated and inclined downward and backward. First gastric segment nearly as long as and slightly broader than the postpetiole; remaining segments very small. Sting well-developed. Legs rather slender.

Shining; dorsal surface of head opaque; mandibles smooth, coarsely and very sparsely punctate; head very densely, thorax and abdomen somewhat more sparsely covered with coarse, sharp punctures.

Pilosity yellowish; pubescence very short, rather abundant and dense on the head, antennae and legs, much more dilute on the thorax, petiole and postpetiole; hairs rather long, confined to the clypeus and gaster, rather abundant on the latter, subappressed on its first segment.

Reddish brown or castaneous; gaster darker; antennae paler; mandibles, legs and tip of gaster brownish yellow.

Taylor (1967) - Characters include:

1. Scapes failing to attain median occipital border by about 2/3 to 1/4 their maximum thickness in Indonesian and E. Melanesian material. Most Samoan specimens have slightly longer scapes, which may almost reach the occipital border.

2. Apical 5 funicular segments forming a club, which varies in distinctiveness but is always easily discernible.

3. Mesometanotal suture (contrary to Wheeler's description) finely and distinctly incised on mesosomal dorsum of holotype and the additional Javanese specimen. The sutural impression is here less intense than in the Melanesian examples, where it is usually very distinct. The range of variation is covered in the Samoan material; so this character cannot be accorded taxonomic significance.

4. Posterior face of the petiolar node, viewed from above, shows all intermediate conditions from shallowly concave to weakly convex. The additional Javanese specimen differs from the holotype in this character ; where the latter has a feebly concave face, that of the former is very weakly but distinctly convex. A similar range is shown by the Samoan material.

5. Palpal formula: Maxillary 2: Labial 2 (6 Samoan specimens dissected).

Queen
Length, 2 mm.

Head broader and more rectangular than in the worker, with straight, parallel sides and nearly straight posterior border. Eyes small, circular, fiat, hairy, situated a distance equal to their diameter from the anterior corners of the clypeus. Ocelli rather large, widely separated. Thorax nearly as broad as the head, somewhat depressed dorsally; epinotum short, subcuboidal, nearly twice as broad as long, its base shorter than the abrupt declivity. Petiole broader than in the worker, with the node more compressed anteroposteriorly and its summit rounded. Postpetiole and gaster more voluminous.

Sculpture, pilosity, and color much as in the worker, but the thorax more opaque, with both the dorsum and pleurae more densely and sharply punctate. Dorsal surface of body somewhat darker brown; first gastric segment nearly black.

Taylor (1967) - Easily assigned to the japonica species group on the basis of the 5-segmented antennal club, relatively small size and brown coloration. Within the group size also allows identification of queens, and there are wing venational differences.

P. incerta is superficially similar to the sympatric Ponera tenuis on Samoa; the latter species is distinguished by its 4-segmented club, lack of a mesometanotal suture in the worker, and the absence of pupal cocoons in all castes.

Known only from Samoa. The following notes are based on 6 alate and dealate specimens, no more than I from a single sample, collected on all 3 major islands. HL 0.51-0.53 mm; HW 0.43-0.44 mm; SL 0.36-0.38 mm; CI 83-84; SI 84-86; PW 0.36-0.37 mm; petiolar node length 0.15-0.16 mm; petiole height 0.34-0.35 mm; dorsal petiole width 0.26-0.28 mm; PNI 72-76; maximum diameter of compound eye 0.14-0.15 mm; ocular index 32-34; palpal formula: Maxillary 2: Labial 2 (2 specimens dissected). Differing from the workers in the usual characters and complying with basic plan of structure for the genus. Wing venation of “coarctata type.”

Male
Taylor (1967) - Known only from 3 specimens collected by Ettershank (his accessions 69 and 71) and associated with workers in Berlesates from Tiapapata, Upolu. Dimensions: HL 0.42-0.44 mm; HW (across eyes) 0.41 -0.44 mm; CI 97-100; Weber's length of mesosoma 0.71-0.77 mm; petiolar node length 0.14-0.16 mm; petiole height 0.23-0.26 mm; dorsal petiole with 0.16-0.19 mm; maximum diameter of compound eye 0.20-0.21 mm; ocular index 48-49; palpal formula: Maxillary 4: Labial 2 (1 specimen dissected, others inspected). General features, and details of terminal abdominal sclerites and genitalia typical for Ponera. Wing venation as in queen.

Immature Forms
Larvae with 3 pairs of glutinous abdominal tubercles. Pupae of all castes enclosed in cocoons.

References based on Global Ant Biodiversity Informatics

 * CSIRO Collection
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 * Clouse R. M. 2007. The ants of Micronesia (Hymenoptera: Formicidae). Micronesica. 39: 171-295.
 * Clouse, R.M. 2007. The ants of Micronesia (Hymenoptera: Formicidae), Micronesica 39(2): 171-295.
 * Dlussky G.M. 1994. Zoogeography of southwestern Oceania. Zhivotnoe naselenie ostrovov Iugo-Zapadnoi Okeanii ekologo-geograficheskie issledovanii 48-93.
 * Field Museum Collection, Chicago, Illinois (C. Moreau)
 * Janda M., G. D. Alpert, M. L. Borowiec, E. P. Economo, P. Klimes, E. Sarnat, and S. O. Shattuck. 2011. Cheklist of ants described and recorded from New Guinea and associated islands. Available on http://www.newguineants.org/. Accessed on 24th Feb. 2011.
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 * Kami KS & Miller SE. 1998. Samoan insects and related arthropods: checklist and bibliography. Bishop Museum Technical Report No. 13.
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 * Wetterer, James K. 2002. Ants of Tonga. Pacific Science. 56.2: 125-135.
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 * Wheeler W. M. 1933. Three obscure genera of ponerine ants. American Museum Novitates 672: 1-23.
 * Wilson E. O. 1957. The tenuis and selenophora groups of the ant genus Ponera (Hymenoptera: Formicidae). Bulletin of the Museum of Comparative Zoology 116: 355-386.
 * Wilson E. O. 1958. Studies on the ant fauna of Melanesia III. Rhytidoponera in western Melanesia and the Moluccas. IV. The tribe Ponerini. Bulletin of the Museum of Comparative Zoology 119: 303-371.
 * Wilson E. O.; Taylor, R. W. 1967. The ants of Polynesia (Hymenoptera: Formicidae). Pacific Insects Monograph 14:1-109.
 * Wilson E.O. 1959. Adaptive shift and dispersal in a tropical ant fauna. Evolution 13(1): 122-144.
 * Wilson EO, Hunt GL. 1967. Ant fauna of Futuna and Wallis Islands, stepping stones to Polynesia. Pacific Insects 9.4: 563-584.
 * Wilson EO, Taylor RW. 1967. The ants of Polynesia. Pacific Insects Monograph 14:1-109.
 * Wilson Edward O. 1959. Adaptive Shift and Dispersal in a Tropical Ant Fauna. Evolution 13(1): 122-144
 * Wilson, Edward O. and George L. Hunt. 1967. Ant Fauna of Futuna and Wallis Islands, Stepping Stones To Polynesia. Pacific Insects. 9(4):563-584.
 * Wilson, Edward O. and Hunt, George L. Jr. 1967. Ant Fauna of Futuna and Wallis Islands, Stepping Stones to Polynesia. Pacific Insects. 9(4):563-584