Polyergus samurai

Trager, James C., 2013, Global revision of the dulotic ant genus Polyergus (Hymenoptera: Formicidae, Formicinae, Formicini), Zootaxa 3722 (4), pp. 501-548 : 522

Polyergus samurai

Figures 21, 22, 23

Polyergus rufescens samurai Yano 1911: 110 . Syntype worker, gyne: JAPAN, Tokyo. [MCZ, red syntype label 21739] (examined, but not measured due to dermestid damage).

Polyergus samurai: Emery, 1925: 269 ; Wheeler, 1927: 3; Imai, 1966: 125 (karyotype); Terayama et al. 1993: 511 (ergatoid queen); Kupyanskaya, 1990: 209 (in eastern Siberia).

Polyergus samurai mandarin Wheeler 1927: 4 . Syntype workers: CHINA, Tsinghua nr. Peking (= Pinyin: Qinghua nr. Beijing) [MCZ, red syntype label 21740] (examined). New Synonymy.

Measurements (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).

Worker description. 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.

Discussion. 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 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 .

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

Natural history. This species occurs in humid temperate Asia: Japan, Korea, China and southeastern Russia (teste Kupyanskaya 1990). The hosts of samurai in Japan are F. japonica and rarely, F. hayashi and even F. fukaii (of the F. exsecta group), while the types of “subspecies mandarin ” were collected with the F. rufibarbis -group species F. 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 F. 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 .

Distribution of studied specimens. CHINA Beijing 3-VII-1987 Changlu Wang (JCTC); JAPAN: HYOGO Pref. Nakano, Yamaguchi-mura, Arima-gun, 14-VIII-1948. M. Azuma (JCTC); JAPAN KANAGAWA Pref. Odawara July 1977 M. Kubota #201 (JCTC); JAPAN KANAGAWA Pref. Odawara 8 Aug.1968 M. Kubota (JCTC); JAPAN KANAGAWA Pref. Kawasaki 17-VI-1978 S. Kubota (JCTC); JAPAN TOKYO Pref. Koganei City 18-VIII-1977 S. Kubota; JAPAN SAITAMA Osato 26-VII-2006, 36°06’N, 139°13'E Toshiaki Nanbu leg. w/ Formica japonica (teste M. Yoshimura); JAPAN Okitsu (Hondo) 8-25-25 Silvestri. Reported from KOREA, but no specimens examined.

Figures

FIGURES 21 – 23. Lateral, full face, and dorsal views of Polyergus samurai worker CASENT 0281083. Photographs by Shannon Hartman from www. AntWeb. org.