Polyergus samurai

Polyergus samurai
Conservation status
Vulnerable (IUCN 2.3)
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Formicinae
Tribe:	Formicini
Genus:	Polyergus
Species group:	samurai
Species:	P. samurai
Binomial name
Polyergus samurai Yano, 1911 Specimen labels
Synonyms
Polyergus samurai mandarin Wheeler, W.M., 1927

Common Name
Samurai-ari
Language:	Japanese

Polyergus samurai is dulotic with Formica japonica as its main host along with Formica hayashi occasionally. A colony with both Formica fukaii and F. japonica as slaves has been observed on Mt. Zao, Miyagi Prefecture (Sonobe, unpublished); this seems to be a rare occurrence. P. samurai nests in the soil and is seldom seen on the ground except when slave-raiding. Raids are carried out at around 3 to 4 pm during summer, when cocoons of slave species are to be found. Hasegawa & Yamaguchi (1995) reported the detailed ecology and raiding behavior of this species. Less common in Shikoku and Kyushu than elsewhere. Nuptial flights occur around July. Chromosome number n = 27 (Crozier, 1970) (Japanese Ant Image Database). Within its range it is the lone Polyergus species. Polyergus samurai is better known from studies of Japanese populations and is relatively poorly studied where it occurs in mainland Asia.

At a Glance

• Dulotic  • Ergatoid queen

Photo Gallery

• 

  Polyergus samurai worker returning from a raid with prey pupa. Photo by Taku Shimada.
• 

  Polyergus samurai queen leaving her nest for her nuptial flight. Japan. Photo by Taku Shimada.

Identification

There was only minor variation among individuals detected among the specimens studied. Wheeler (1927) noted that the Chinese population he described as the subspecies mandarin was possibly blacker than the Japanese population. However, a small sample of workers from Beijing I obtained during this study had coloring indistinguishable from Japanese samples, and photographs sent to me of worker and male specimens from Hebei look typical, including the starkly white appendages of the male.

Polyergus samurai is probably not sympatric with any other species. It is easily distinguished from most other Polyergus species by its dark brown color, appearing nearly black in the field. It is closest to Polyergus nigerrimus, a smaller, darker, shinier species that lives in arid regions to the west of the range of samurai. Polyergus samurai males are notable for their striking white wings (even the veins are very pale yellow), and whitish appendages, including the mouthparts. Gynes also have white wings, with pale brown veins, and partially light brown appendages. This is in contrast to the dark brown appendages, brownish veins and infuscation of the wings of both sexes of nigerrimus.

Keys including this Species

• Key to Polyergus Species

Distribution

This species occurs in humid temperate Asia: Japan, Korea, China and southeastern Russia (teste Kupyanskaya 1990).

Latitudinal Distribution Pattern

Latitudinal Range: 38.283333° to 30.359°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Palaearctic Region: China (type locality), Democratic Peoples Republic of Korea, Japan (type locality), Republic of Korea, Russian Federation.

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

The hosts of samurai in Japan are Formica japonica and rarely, Formica hayashi and even Formica fukaii (of the F. exsecta group), while the types of “subspecies mandarin” were collected with the F. rufibarbis-group species Formica glabridorsis. Polyergus samurai is relatively well studied by several Japanese myrmecologists, but is only poorly known in its mainland Asian range. Terayama, et al. (1993) described four ergatoids found in two colonies of samurai, reporting they had “a well developed spermatheca”, and surmised that they can produce female offspring (though they did not confirm insemination). Hasegawa and Yamaguchi (1994, 1995) reported for this species (and typically for the genus) that raids mostly occurred on warm, sunny days, and mating flights only occurred on sunny days. According to these authors, time of initiation of raids and walking speed of raiders are related to simple environmental variables, especially temperature. Tsuneoka (2008) reported that colonies had a single gyne, housed colony populations of the host Formica japonica much larger than normal host colonies, and that the larger colony size in the parasite colony resulted in typical nest structure, but larger nest dimensions than those of unparasitized F. japonica.

List of Known Hosts

This species is known to enslave the following species:

• Formica fukaii (Trager, 2013; de la Mora et al., 2021; rare)
• Formica glabridorsis (Trager, 2013; de la Mora et al., 2021)
• Formica hayashi (Trager, 2013; de la Mora et al., 2021; uncommon)
• Formica japonica (Tsuneoka, 2008; Tsuneoka & Akino, 2009; Tsuneoka & Akino, 2012; Trager, 2013; de la Mora et al., 2021; common host)

Castes

Terayama et al. (1993) described dimorphic queens: winged and ergatoid

Queen

Images from AntWeb

Queen (alate/dealate). Specimen code casent0173326. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by CAS, San Francisco, CA, USA.

Male

Images from AntWeb

Queen (alate/dealate). Specimen code casent0173325. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by CAS, San Francisco, CA, USA.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• samurai. Polyergus rufescens subsp. samurai Yano, 1911: 110, fig. 1 (w.q.) JAPAN. Terayama, Yamaguchi & Hasegawa, 1993: 511 (ergatoid q.); Imai, 1966: 119 (k.). Raised to species: Emery, 1925b: 269; Wheeler, W.M. 1927e: 3. Senior synonym of mandarin: Trager, 2013: 522. See also: Kupyanskaya, 1990: 209.
• mandarin. Polyergus samurai subsp. mandarin Wheeler, W.M. 1927e: 4 (w.) CHINA. Junior synonym of samurai: Trager, 2013: 522.

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

Type Material

• Polyergus rufescens samurai: Syntype, worker, queen, Tokyo, Japan, 35°41′0″N 139°41′0″E, MCZC Type #21739, Museum of Comparative Zoology; (examined by Trager (2013) but not measured due to dermestid damage).
• Polyergus samurai mandarin: Syntype, workers, Tsinghua nr. Peking (= Pinyin: Qinghua nr. Beijing), China, 40°00′0″N 116°20′0″E, MCZ Type #21740, Museum of Comparative Zoology.

Description

Worker

Trager (2013) - (N=24) HL 1.40–1.76 (1.56), HW 1.29–1.64 (1.47), SL 1.12–1.32 (1.22), ½ VeM 2–5 (2.92), ½ PnM 3–8 (5.67), WL 2.12–2.62 (2.41), GL 1.84–2.40 (2.15), HFL 1.68–2.04 (1.85), CI 92–97 (94), SI 76–93 (83), HFI 121–140 (126), FSI 143–159 (1.53), LI 3.52–4.38 (3.97), TL 5.40–6.72 (6.13).

Head narrowly hexagonal (truncate-ovate), length greater than breadth; with moderate vertex pilosity; scapes about reaching vertex corners, gradually thickening apically in distal half; pronotum with 5–16 erect macrosetae; mesonotum with profile flat for most of its length, with short posterior declivity; propodeal profile subquadrate, with concave posterior declivity; petiole more or less straight-sided above spiracles or convergent dorsad, petiolar dorsum flat or convex, shallowly or not at all emarginate; first tergite densely pubescent; tergite pilosity relatively scant compared to other Polyergus, concentrated in anterior-lateral portions, weakly flexuous, relatively widely separated.

Head matte; mesonotum matte; gaster matte, sometimes weakly shining on the sides.

Color uniform dusky reddish brown or with a slightly darker gaster; with dusky yellow-brown appendages; pilosity yellowish brown.

Karyotype

• See additional details at the Ant Chromosome Database.

 Explore: Show all Karyotype data or Search these data. See also a list of all data tables or learn how data is managed.

• n = 27, 2n = 54 (Japan) (Imai & Yosida, 1964; Imai, 1966; Imai, 1969).

Etymology

Trager (2013) - This ant was named for the traditional Japanese warrior class, the “Samurai,” presumably by analogy to calling these ants “Amazons” in European languages.

References

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• Casacci, L.P., Barbero, F., Slipinski, P., Witek, M. 2021. The inquiline ant Myrmica karavajevi uses both chemical and vibroacoustic deception mechanisms to integrate into its host colonies. Biology 10, 654 (doi:10.3390/ biology10070654)..
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References based on Global Ant Biodiversity Informatics

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