Ponera coarctata

An inconspicuous slow moving ant, mainly carnivorous, living in small nests with two or three queens and typically less than 60 workers.

Identification
Light to dark brown with sparse pubescence but numerous body hairs especially on the gaster. Head more closely punctured than alitrunk; mandibles with four strong teeth towards apex and smaller indistinct denticulae posteriorly. Eyes are minute and often indistinct. Ocelli absent. Length: 3.0-3.5 mm (Collingwood 1979).

The diagnostic features separating coarctata and Ponera pennsylvanica involve sculpturation in the worker and queen castes, the form of the petiolar node in queens, and differences in the male pygidial structure (Taylor 1967).

Distribution
P. coarctata appears to have its center of distribution in the northern Mediterranean part of Europe. The records from North Africa and the Middle East are too sparse to allow a conclusion as to the abundance of the species there, or as to whether it is distributed clear across North Africa. The records from Britain, Germany, and the U. S. S. R., indicate a probable distributional limit at a latitude of about 52°N (note that the northern English records are dubious). P. coarctata has not been recorded from Scandinavia, although several active myrmecologists have resided there. The lack of records from some other areas (e. g., Turkey) is no doubt due to deficient collections (Taylor 1967).

Throughout Central and South Europe from Portugal to the Caucasus and from North Africa to the Netherlands (Collingwood 1979).

This taxon was described from Luxembourg.

It is also found in Kazakhstan, Gabon, South Africa, United Kingdom of Great Britain and Northern Ireland.



Taylor stated, in reference to this map in his 1967 revision: "Material studied here is represented by closed circles on the map and unverified published records by open ones.

Biology
Taylor (1967) - Little detailed published information is available concerning this subject apart from Gosswald's (1932) review of his collections from the vicinity of Wiirzburg, Germany. He gives records for 20 nests, one of which was taken in sand, in the foundations of a house; with 19 in limestone (Haupmuschelkalk) soils. More colonies (15) were taken on upper Haupmuschelkalk soils than on those of the middle (3) or upper (1) parts of the formation; no possible explanation for this apparent correlation was suggested. Gosswald noted preference by coarctata for dry stony soils, but observed no clear correlation between vegetation type and distribution of the ant. Specimens were collected in woods, woods margins, a domestic garden and in dry grassy wasteland; the species was found most commonly in the latter habitat. Eighteen nests were located under stones, and two were in the soil without a covering object; no general structural regularity of the nests was noted, but it was suggested that the galleries must penetrate deeply into the soil. The largest colony contained 30 workers.

Gosswald gave September as the flight season in Germany, and noted that pupal cocoons containing alate females were found in nests during August. In Britain, Donisthorpe (1927) gives records of free flying alates taken from late August (28th) to late September. I have seen a single male from Charing, Kent, collected on 24.VIII.1904; otherwise all alate specimens agree with Donisthorpe's data. Four Italian and Yugoslavian males in the Finzi collection (MCZ) bear the month only - August in all cases.

Reproductive Female Size Variation
Liebig et al. (1997) - Queens of Ponera coarctata show a pronounced variation in size as measured by ommatidia number and Weber’s alitrunk length. Isometric size variation and the normal distribution of size categories indicate that, despite these differences, only one queen morph exists. Queen size varies less within colonies than between colonies, and thus appears to be colony specific. Ovary length apparently varies with queen size. Similar size variations as in queens also occured in males, but not in workers.

Fennoscandia, Denmark and the British Isles
This is an inconspicuous species of slow movement, mainly carnivorous, living in small nests with two or three queens and 12 to 35 workers. Nests are found under stones or moss in broken stony ground, banks or crumbling cliffs and among flints in open woodland. Alates occur during August and September and have been caught by sweeping hedgerows in late summer (Collingwood 1979).

Germany
Colonies of Ponera coarctata were collected in July and August 1992, and between April and September 1993 in the vicinity of Wtirzburg, Bavaria, Germany. Colonies rarely exceeded 60 workers. The largest was collected at the end of July 1992, and contained two queens, 135 workers, 238 cocoons, and 23 larvae. Colonies collected in the fall contained alate queens and males or pupae of sexuals. (Liebig et al. 1997)

Nomenclature

 *  coarctata. Formica coarctata Latreille, 1802b: 65, pl. 3, fig. 1 (w.q.) LUXEMBOURG. Foerster, 1850a: 46 (m.). Combination in Ponera: Latreille, 1804: 178. Senior synonym of contracta: Roger, 1863b: 16. Senior synonym of atlantis, lucida and material of the unavailable names colchica, taurica referred here: Taylor, 1967a: 21. See also: Emery, 1909c: 368; Donisthorpe, 1915d: 67; Stitz, 1939: 58, Csösz & Seifert, 2003: 207.
 * contracta. Formica contracta Latreille, 1802c: 195, pl. 7, fig. 40 (w.q.) LUXEMBOURG. [Unnecessary replacement name for coarctata Latreille, 1802b: 65.] Junior synonym of coarctata: Roger, 1863b: 16.
 * lucida. Ponera coarctata var. lucida Emery, 1898c: 130 (w.) KAZAKHSTAN. [Misspelled as lucidula by Emery, 1909c: 370.] Junior synonym of coarctata: Taylor, 1967a: 21.
 * atlantis. Ponera coarctata var. atlantis Santschi, 1921e: 166, fig. 2 (w.) TUNISIA. Junior synonym of coarctata: Taylor, 1967a: 21.

Taylor (1967) - There is little appreciable geographic variation in P. coarctata workers, except that those from the Mediterranean parts of its range tend to average slightly smaller than those from more northern locales, and to have somewhat lighter coloration. The smaller size specimens in each sample show various allometric differences from larger samples. Similar intranidal variation is seen in Ponera pennsylvanica, discussed below. Head length and scape length are negatively allometric relative to head width (k = ca 1.4-1.45), petiolar node width is positively allometric (k = ca 0.7), while pronotum width and petiole height are approximately isometric. Thus small specimens tend to yield higher values for scape index and petiolar node index, and lower values for cephalic index than do large ones. In addition petiolar node length is negatively allometric relative to petiole height, so that small workers tend to have bulkier petiolar nodes than large ones; these appear thicker in side view and the dorsal faces more closely approximate a half-circle in extent than do those of large specimens. Smaller specimens tend to be slightly lighter in color, and less hirsute than large ones, and to have the sculpturation a little less intense. There is sufficient variation in color within single samples to suggest that the callow period may be prolonged in this species.

The apparent tendency for color to be less intense in Mediterranean samples, may be correlated with the generally drier conditions there than in the north. The Australian Ponera leae Forel is known to produce small, relatively light colored, eco-types in the drier habitats in which it is found around Sydney. This could well be the case in coarctata, for certain of the Mediterranean samples are of normal dark coloration, and may be from more moist habitats than those usually occupied in this area.

Worker
Taylor (1967) - The following notes are based on several hundred specimens from most parts of the species range (see "Figure 21" map in the distribution section).

No significant geographical variation is detectable in the standard dimensions and indices which are HL 0.67-0.77 mm; HW 0.50-0.60 mm; SL 0.47-0.57 mm; CI 77-82 ; SI 87-98; PW 0.39-0.46 mm; PNL 0.22-0.25 mm; PH 0.38-0.48 mm; DPW 0.29-0.36 mm; PNI 67-82. General form as shown in figs. 15-17. Mandibles triangular, with 3 large teeth occupying apical 1/3 of masticatory border, followed by a regular series of 9-14 minute denticles. Clypeus slightly produced anteriorly, with a rather distinct raised longitudinal carina - probably a vestige of the median tooth, seen in some Indo-Australian species. Scapes usually with their apices approximately contiguous with median occipital border, but they may fail to attain it by up to 1/3 their maximum thickness. Funiculus lacking a segmentally differentiated club, antennomeres increasing regularly in length and breadth towards apex which is moderately incrassate; apical segment a little longer than 2 preceding together. Palpal formula (several specimens dissected); Maxillary 2 : Labial 2. Eyes small, with 1 - 5 very indistinct minute facets, situated about 0.85 X the distance from lateral occipital border to midpoint of anterior genal border. Mesometanotal suture clearly incised on mesosomal dorsum, lateral mesonotal suture less distinct. A small lobate projection present on posterodorsal corner of the mesepisternum, usually separated from it by a fine suture-like trace. Posterolateral propodeal angles not raised, forming blunt angles of about 90" when viewed from above. Node in profile as in fig. 16, subpetiolar fenestra small, circular, posterodorsal teeth small but distinct. Dorsal surface of node, viewed from above, forming distinctly less to slightly more than a half-circle.

Mandibles smooth and shining, with a few scattered punctures, about 0.005 mm in diameter, separated by intervals equal to about 1 /2 their average diameter. Scapes moderately shining, with a cover of fine punctures, spaced at about their average diameter. Pronotum moderately shining, with a scattering of fine point-punctures, spaced at 2-3 X their average diameter. Mesonotum, dorsum of propodeum and sides of mesosoma less densely punctate, and quite strongly shining. Virtually no trace of longitudinal striation on lower mesepisternum and metepisternal area. Declivitous face of propodeum smooth and shining. Node and gaster feebly punctate, moderately shining.

Short erect to sub-erect pilosity and fine pubescence everywhere abundant - the pilosity of the clypeus, frontal lobes, dorsa of propodeum and node, and apex of gaster relatively long. Color ranging from light golden brown to a dark reddish mahogany hue. Mandibles, clypeus, antennae, coxae, and tip of gaster lighter - dull yellowish brown; remaining parts of legs yellowish.

Queen
Taylor (1967) - (fig 4) 11 queens from Italy, France and England, have the following measurements: HL 0.34-0.38 mm; HW 0.28-0.32 mm; SL 0.23-0.29 mm; CI 85-88; SI 84-86; PW 0.23-0.27 mm; PNL 0.11-0.13 mm; PH 0.21-0.24 mm; DPW 0.16-0.20 mm; PNI 63-66; maximum diameter of compound eye 0.07-0.10 mm; ocular index 24-28. Palpal formula (3 specimens dissected): Maxillary 2: Labial 2, as in the worker. General characters much as in P. pennsylvanica, but smaller in size, as indicated in above dimensions. Note that there is no overlap in the ranges of the 2 species for PW, PH, DPW, WL, and PNI. Females of P. coarctata are readily distinguished from those of Ponera pennsylvanica on the basis of these characters, and in addition the sculpturation is much less intense. Mandibles, clypeus, scapes, and front of head as in worker, the latter with punctures slightly larger. Mesosomal dorsum moderately shining, with a scattering of small punctures about 0.005 mm in diameter, separated by distances equivalent to 1-2 X their maximum diameter. These punctures more distinct on scutellum than elsewhere. Sides of mesosoma slightly less heavily punctured than dorsum, and more strongly shining; effaced traces of longitudinal striation present on metepisternal areas. Node and gaster smooth and strongly shining, virtually lacking sculpturation apart from the scattered minute pilosity-bearing punctures. Color generally as in workers, eyes black, wing veins yellowish.

Male
Taylor (1967) - 6 specimens, from various Italian, French, and English localities, are identical in general structure. They have the following dimensions; HL 0.54-0.58 mm; HW (across eyes) 0.61-0.64 mm; CI 112-116; WL 1.06-1.18 mm; PNL 0.19-0.22 mm; PH 0.34-0.39 mm; DPW 0.25-0.28 mm; maximum diameter of eye 0.27-0.31 mm; ocular index 44-47. Palpal formula (4 specimens dissected); Maxillary 5: Labial 3. Wing venation as in queen. General structure very similar to P. pennsylvanica (figs. 9-14). The few points of difference apart from the smaller size include the following: Genitalia in general similar, but the pygidial spine distinctly weaker; sculpturation lighter, pennsylvanica has a shallow, and somewhat obscure puncturation on most parts of the head and mesosoma, which dulls the reflections of these parts, while coarctata has the same surfaces smooth and highly polished. The color tends to be a little darker than in pennsyivanica.

Immature Forms
Taylor (1967) - I have seen no larvae of P. coarctata, but it may be dependably assumed that they have 4 pairs of glutinous "doorknob" tubercles. These have been referred to in the literature on a number of occasions (e. g., Donisthorpe [1915], Escherich [1917, p. 96-97]) and a figure was published by Karawajew (1934). The pupae of all castes are enclosed in cocoons.

Type Material
Taylor (1967) - Ponera coarctata var. atlantis Santschi, 1 92 1, Boll. Soc. Espan. Hist. Nat. 21 : 1 66, fig. 2, worker. Original localities : Algeria and Tunisia. (Syntypes examined-Santschi coll.)

Additional References

 * Collingwood, C. A. 1979. The Formicidae (Hymenoptera) of Fennoscandia and Denmark. Fauna Entomol. Scand. 8:1-174.


 * [[Media:Leibig Heinze Holldobler 1997.pdf|Liebig, J.; Heinze, J.; Hölldobler, B. 1997 ("1995"). Queen size variation in the ponerine ant Ponera coarctata (Hymenoptera: Formicidae). Psyche (Cambridge) 102:1-11. [1997-01-10] PDF]]