Polyergus rufescens

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Polyergus rufescens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Formicini
Genus: Polyergus
Species group: rufescens-breviceps
Species: P. rufescens
Binomial name
Polyergus rufescens
(Latreille, 1798)

Polyergus rufescens casent0010688 profile 1.jpg

Polyergus rufescens casent0010688 dorsal 1.jpg

Specimen labels

Synonyms

The lone European Polyergus species, Polyergus rufescens has a wide range that extends to western Asia.

At a Glance • Slave-maker  
 

Identification

Trager (2013): This is the unique Polyergus species of Europe and western temperate Asia, and appears morphologically to be closely related to the breviceps group, particularly the essentially Mexican species Polyergus topoffi. Future genetic study should deepen our understanding of the relationships of this apparent outlier of what is otherwise a western North American group, distinguished from all other red Polyergus by its Eurasian distribution. It is most similar to Polyergus topoffi among the American species, differing by its slightly (average) narrower head and petiole, and denser, more regular array of bent or strongly flexuous, decumbent pilosity on the first tergite. Specimens from western and especially southwestern Europe are darker in color than those from Asia. Populations of central western Europe have a more pilose vertex than those from the Iberian Peninsula, northern and eastern Europe, and central Asia (½ VeM usually 2–12, compared to ½ VeM 0–2). Lighter color and reduced pilosity were noted as characteristic of the subspecies tianschianicus in Kuznetsov-Ugamsky’s (1927) description, but in fact, color variation seems to be a west to east clinal feature, and the reduced pilosity is a characteristic of peripheral populations, as it is also found in samples from the far west of the range. Thus, the two traits do not covary. In any case, the subspecies are indistinguishable by any other ecological, metric or obvious morphological characters; hence, Trager's (2013) synonymy of this subspecies.

Keys including this Species

Distribution

Trager (2013): Found from Atlantic western Europe east to mountains of western China and “Central Asia”. Extending to 57°N and 88°E, then south to the Caspian, Black, and Mediterranean Coasts.

Distribution based on Regional Taxon Lists

Palaearctic Region: Albania, Armenia, Austria, Belarus, Belgium, Bulgaria, China, Croatia, Czech Republic (type locality), France (type locality), Georgia, Germany, Greece, Hungary, Iberian Peninsula, Italy, Kazakhstan (type locality), Kyrgyzstan, Luxembourg, Netherlands, Norway, Poland, Portugal, Republic of Macedonia, Republic of Moldova, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Trager (2013): The “classical” summaries of the behavior of this ant are from Huber (1810) and Wheeler (1910). In the last decade or so, a number of papers, especially those by le Moli’s Laboratory in Italy, have refined our knowledge of this species, particularly regarding the role of secondary compounds in regulating their behavior (Castracani et al. 2003, 2005, 2008; Grasso et al. 2003, 2004, 2005; Le Moli et al. 2001; Romani et al. 2006; Visicchio et al. 2001, 2003, 2007). The following natural history is paraphrased from a summary kindly provided by Bernhard Seifert (pers. comm., 2009) “P. rufescens is characteristic of dry, semi-dry and sparse grasslands of any sort that supports sufficiently dense host populations. Hosts vary geographically and include a variety of species: Formica cunicularia (16 observations), Formica fusca (12), Formica rufibarbis (10), Formica clara (3), Formica gagates (3) and Formica cinerea (1). Local host species preferences are obvious, and considering the whole distributional range, host species selection appears to be a trade-off between host species abundance and mortality risk—strong and aggressive colonies of F. clara and F. cinerea are only attacked in the absence of less resistant alternatives. In many regions of Central Asia, F. clara is a main host, as it is a dominant species there and has smaller workers than in Central Europe.” And from Roland Schultz (pers. comm., 2012) “The host of P. rufescens in cases from Kyrgyzstan, Kazakhstan and western China is F. clara. Formica clara is the most common “Serviformica” in the high steppes of the Tianshan Mountains of China and Kyrgyzstan, at the altitudes in which also Polyergus appears, below 2500 m. In one case, Seifert found 5 workers of F. exsecta, including one freshly eclosed from the pupa, among a lot of F. clara and P. rufescens.” In a sample from the Tarbagatai Mountains Kazakhstan, Schulz confirmed a mix of F. clara and F. rufibarbis as hosts. In addition, I have series from the Pyrenees with Formica gerardi, where this is the most abundant potential host. Seifert’s abundance/trade-off hypothesis seems plausible and testable; there is much opportunity for careful study of host selection in this species (as also in the quite polylectic North American Polyergus mexicanus).

Hosts

Castes

Worker

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • rufescens. Formica rufescens Latreille, 1798: 44 (w.q.) FRANCE. Schenck, 1852: 70 (m.); Forel, 1874: 137 (gynandromorph); André, 1882b: 163 (w.q.m.); Wheeler, G.C. & Wheeler, J. 1968: 214 (l). Combination in Polyergus: Latreille, 1804: 179. Senior synonym of testacea: Smith, F. 1858b: 57; tianschanicus: Trager, 2013: 510. Current subspecies: nominal plus laeviceps, mexicanus. See also: Stitz, 1939: 369; Hölldobler, 1985: 225; Trager, 2013: 510.
  • testacea. Formica testacea Fabricius, 1804: 400 (q.) CZECHOSLOVAKIA. [Unresolved junior primary homonym of Formica testacea Gmelin, in Linnaeus, 1790: 2804.] Junior synonym of rufescens: Smith, F. 1858b: 57.
  • tianschanicus. Polyergus rufescens subsp. tianschanicus Kuznetsov-Ugamsky, 1927c: 41, figs. 1-6 (w.q.m.) KAZAKHSTAN. Junior synonym of rufescens: Trager, 2013: 510.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Type Material

Description

Worker

Trager (2013) - (N=41) HL 1.23–1.72 (1.59), HW 1.20–1.66 (1.51), SL 0.99–1.31 (1.22), ½ VeM 0–11 (2.41), ½ PnM 3–13 (6.8), WL 1.96–2.60 (2.37), GL 1.44–2.18 (2.13), HFL 1.36–1.92 (1.78), CI 90–99 (95), SI 77–88 (81), HFI 110–130 (1.18), FSI 136–155 (146), LI 3.23–4.32 (3.96), TL 4.67–6.98 (6.14).

Head subrectangular, its length greater than breadth; with conspicuous vertex pilosity (usually 6–12 setae) on most specimens from more western locations and no vertex pilosity (0–1 seta) on specimens from farther east; scape apex reaching about 1/4 the distance between eye and vertex corner, weakly clavate in the apical third, or gradually thickening apically; pronotum with (6)10–20 (25) erect setae; mesonotum with profile flat or very weakly convex for most of its length; propodeum evenly rounded; petiole high, its profile about equal in height to propodeum, petiole straight-sided, petiolar dorsum convex, not emarginate or weakly emarginate; first tergite densely pubescent, with numerous, bent or strongly flexuous, decumbent pilosity concentrated in anterior half of sclerite.

Head matte; mesonotum matte; gaster matte.

Color deep red (especially west) to orangey red (especially east) with weak to notable infuscation (deep, often purplish tinted, brown) of pleura, gaster and appendages in darker individuals.

Etymology

Trager (2013) - Latreille coined this name from the Latin verbal form “rufescens”, meaning reddish or fading to red.

References

  • André, E. 1882c. Les fourmis. [part]. Pp. 153-232 in: André, Edm. 1881-1886. Species des Hyménoptères d'Europe et d'Algérie. Tome Deuxième. Beaune: Edmond André, 919 + 48 pp. (page 163, worker, queen, male described)
  • Forel, A. 1874. Les fourmis de la Suisse. Systématique, notices anatomiques et physiologiques, architecture, distribution géographique, nouvelles expériences et observations de moeurs. Neue Denkschr. Allg. Schweiz. Ges. Gesammten Naturwiss. 26: 1-452 (page 137, gynandromorph described)
  • Hölldobler, B. 1985 [1984]. A new exocrine gland in the slave raiding ant genus Polyergus. Psyche (Camb.) 91: 225-235 (page 225, see also)
  • Latreille, P. A. 1798. Essai sur l'histoire des fourmis de la France. Brive: F. Bourdeaux, 50 pp. (page 44, worker, queen described)
  • Latreille, P. A. 1804. Tableau méthodique des insectes. Pp. 129-200 in: Société de Naturalistes et d'Agriculteurs. Nouveau dictionnaire d'histoire naturelle. Tome 24. Paris: Déterville, 84 + 85 + 238 + 18 + 34 pp. (page 179, Combination in Polyergus)
  • Romani, R., Grasso, D.A., Mori, A., Isidoro, N., Le Moli, F. 2006. Antennal glands of the slave-making ant Polyergus rufescens and its slave-species Formica cunicularia (Hymenoptera, Formicidae). Canadian Journal of Zoology, 84(3):490-494 (DOI: 10.1139/z05-187).
  • Schenck, C. F. 1852. Beschreibung nassauischer Ameisenarten. Jahrb. Ver. Naturkd. Herzogthum Nassau Wiesb. 8: 1-149 (page 70, male described)
  • Smith, F. 1858a. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp. (page 57, Senior synonym of testacea)
  • Stitz, H. 1939. Die Tierwelt Deutschlands und der angrenzenden Meersteile nach ihren Merkmalen und nach ihrer Lebensweise. 37. Theil. Hautflüger oder Hymenoptera. I: Ameisen oder Formicidae. Jena: G. Fischer, 428 pp. (page 369, see also)
  • Trager, J.C. 2013. Global revision of the dulotic ant genus Polyergus (Hymenoptera: Formicidae, Formicinae, Formicini). Zootaxa 3722, 501–548.
  • Wheeler, G. C.; Wheeler, J. 1968a. The ant larvae of the subfamily Formicinae (Hymenoptera: Formicidae): supplement. Ann. Entomol. Soc. Am. 61: 205-222 (page 214, larva described)