Polyergus samurai

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.

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.

Distribution based on Regional Taxon Lists
Palaearctic Region: China, Democratic Peoples Republic of Korea, Japan , Republic of Korea, Russian Federation.

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



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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.

Nomenclature

 *  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.

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.

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.