Mature basidiomata of Amanita rubromarginata on ground in a Castanopsis-Quercus forest, 11 Aug. 2010, Ishigaki Island. Photo by Takahashi, H.

スダジイ-オキナワウラジロガシ林内地上に発生したフチドリタマゴタケの成熟した子実体, 2010年8月11日, 石垣島

Immature basidioma of Amanita rubromarginata (KPM-NC0010087), Jun. 8, 2002, Ishigaki Island. Photo by Takahashi, H.

フチドリタマゴタケの幼菌, 2002年6月8日, 石垣島

Basidiomata of Amanita rubromarginata (KPM-NC0023873) on ground in a Castanopsis-Quercus forest, 25 May 2011, Ishigaki Island. Photo by Takahashi, H.

スダジイ-オキナワウラジロガシ林内地上に発生したフチドリタマゴタケの子実体, 2011年5月25日, 石垣島

Mature basidiomata of Amanita rubromarginata (KPM-NC0023873) on ground in a Castanopsis-Quercus forest, 25 May 2011, Ishigaki Island. Photo by Takahashi, H.

老成すると傘中央部が暗色を帯びて灰黄色～黒色になり、周縁部に向かって橙黄色～オリーブ黄色を呈する.

主な形態的特徴

ア) 傘表面は最初帯褐橙色のち帯赤黄色.

イ) 柄表面は黄色地に橙色の段だら模様を表し，上部に薄い膜質で帯赤橙色～帯褐橙色のツバを形成し，根元に厚い袋状のツボがある.

ウ) ヒダは帯赤橙色に縁取られる.

肉眼的特徴: 傘は径 40–80 mm, 最初釣り鐘形, のちほぼ平に開き, 中央部がやや突出し, 周縁部から中心に向かって放射状の長い溝線を表す; 表面は平滑, 湿時やや粘性があり, 初め全体に橙褐色を呈するが, のち周縁部から黄色を帯び, 老成すると傘中央部が暗色を呈し、灰黄色～ほぼ黒色になる. 肉は軟質で, 傘中央部の厚さは3–7 mm, 淡黄色～類白色, 表皮直下は黄色, 味および臭いは温和. 柄は60–120 × 5–16 mm, 類円柱形または頂部に向かってやや細くなり, 中心生, 中空; 表面は粘性を欠き, 絹状～繊維状, 淡黄色, 通常橙赤色～帯褐橙色の圧着した薄い膜質の鱗片がだんだら模様を形成する; ツバは幅10–15 mm, 薄い膜質, 柄の上部に垂れ下がるように付着し, 橙赤色～帯褐橙色, 条線を表す; ツボは20–40 × 10–25 mm, 大形, 厚い膜質, 袋状, 裂け目を生じ, 白色, 時にくすんだ帯褐色の斑点を表す. ヒダは離生, 密 (柄に到達するヒダは 55–70), 1–3の小ヒダを伴い, 幅10 mm以下, 淡黄色; 縁部は長縁毛状, 橙赤色～帯褐橙色に縁取られる.

顕微鏡的特徴: 担子胞子は8–9 × 5.5–7 µm　(n = 20 spores per two specimens, Q = 1.28–1.45), 広卵形～短楕円形, 平坦, 無色, 非アミロイド, 薄壁. 担子器は 25–30 × 8–10 μm, こん棒形, ４胞子性; 偽担子器はこん棒形. ヒダの縁部を構成する細胞 (ツバの残存組織) は30–60 × 8–15 μm, 群生～散生, 亜こん棒形～洋梨形, 無色または暗橙色～橙色の色素が細胞内に存在し, 薄壁. 子実下層は厚さ20–40 μm, 1–3の類球形～楕円形の細胞 (5–20 × 5–14 μm) からなる. 子実層托実質は狭く, 両側型; 菌糸は円柱形, こん棒形～類紡錘形. 傘表皮組織は円柱形の菌糸 (幅 4–8 μm) からなる平行菌糸被を成し, 橙色の色素が細胞内に存在し, 時にクランプを持ち, 薄壁. 傘実質の菌糸は幅5–14 μm, 傘表皮の細胞と平行に配列し, 円柱形, 無色, 薄壁. 柄表皮組織は平行菌糸被を成し, 菌糸は幅4–14 μm, 円柱形, 黄色の色素が液胞内に存在し, 薄壁. 柄の実質は縦に沿って配列した円柱形の菌糸 (幅 8–38 μm) からなり, 無色, 薄壁. ツボの組織は幅4–8 μmの円柱形の菌糸からなり, 広こん棒形または楕円形～類円柱形の細胞 (35–75 × 12–40 μm) が混在し, 時にクランプを持ち, 薄壁.

生態および発生時期: スダジイ, オキナワウラジロガシを主体とする照葉樹林内地上に孤生または散生, 5月～9月.

分布: 沖縄 (石垣島).

供試標本: KPM-NC0011979 (正基準標本), 常緑広葉樹林内地上, 沖縄県石垣市バンナ公園, 2003年9月15日, 高橋春樹採集; KPM-NC0010087, 同上, 2002年6月8日, 高橋春樹採集; KPM-NC0023873, 同上, 2011年5月25日, 高橋春樹採集.

コメント: スリランカから最初報告されたAmanita hemibapha (Berk. & Broome) Sacc. var. hemibapha (Berkeley and Broome 1871; Saccardo 1887; Hongo 1987), 旧ソビエトの沿海州から新種記載されたAmanita caesareoides Lj. N. Vassiljeva (Vassiljeva 1950; Endo et al. 2013), ジャワ島から新種記載されたAmanita javanica (Corner & Bas) T. Oda, C. Tanaka & Tsuda (Boedijn 1951; Oda et al. 1999) はフチドリタマゴタケに最も近縁と思われるが, 傘の色が異なり, ツバは黄色で, ヒダにフチドリを欠く. また最近中国南西部から報告されたAmanita hemibapha var. ochracea Z.L.Yang (Yang 1997) もフチドリタマゴタケに似るが, 傘は黄土色で, 黄色に縁取られた白色のヒダを持つ点で異なる.

Amanita rubromarginata Har. Takah., Mycoscience 45 (6): 372 (2004).

Etymology: The specific epithet means “red marginate”, referring to the reddish orange marginate lamellae.

English name: “Red-Skirted Slender Caesar” (named by Dr. Rodham E. Tulloss).

Macromorphological characteristics: Pileus 40–80 mm in diameter, at first cylindrical-campanulate, then expanding to nearly plane to slightly concave and subumbonate, long sulcate-striate from the margin toward the center; surface glabrous, subviscid when wet, at first orange (6B7–8) to brownish orange (6C7–8 to 7C7–8) overall, then reddish yellow (4B7–8) toward the margin, in age greyish yellow (4C7) to almost black at the center. Flesh soft, 3–7 mm thick in the center of the pileus, yellowish white, deeper yellow below the surface, odor and taste mild. Stipe 60–120 × 5–16 mm, subcylindrical or slightly tapering upward, central, terete, hollow; surface dry, silky fibrillose, pale yellow, usually covered with reddish orange (7B7–8), appressed, indefinite squamules forming irregular transverse zones; annulus 10–15 mm wide, thin, membranous, attached toward the stipe apex, pendant, reddish orange (7B7–8), striate; volva 20–40 × 10–25 mm, large, saccate, thick, membranous, bilobate, white, sometimes stained dingy brownish. Lamellae free, very close (55–70 reaching the stipe), with 1–3 series of lamellulae, up to 10 mm broad, pale yellow; edges fimbriate, reddish orange (7B7–8).

Micromorphological characteristics: Basidiospores 8–9 × 5.5–7 µm　(n = 20 spores per two specimens, Q = 1.28–1.45), broadly ovoid to short ellipsoid, smooth, colorless, inamyloid, thin-walled, with a large refractive guttule. Basidia 25–30 × 8–10 µm, clavate, 4-spored; basidioles clavate. Marginal cells of lamellae (remnants of the annulus) 30–60 × 8–15 µm, gregarious to scattered, narrowly clavate to pyriform, colorless or with dark orange (5A8) to orange (5A6) intracellular pigment, thin-walled. Subhymenium ramose-inflated, 20–40 µm thick, with 1-3 layers of subglobose to ellipsoid cells, 5–20 × 5–14 µm. Hymenophoral trama narrow, bilateral; element hyphae cylindrical, clavate to subfusiform. Pileipellis a cutis of narrow cylindrical cells 4–8 µm wide, with orange (5A6) to deep orange (5A8) intracellular pigment, occasionally with clamped septa, thin-walled. Hyphae of pileitrama 5–14 µm wide, parallel to the pileipellis elements, cylindrical, colorless, thin-walled. Stipitipellis a cutis of parallel, repent hyphae 4–14 µm wide, cylindrical, with reddish yellow (4A7) to deep yellow (4A8) vacuolar pigment, thin-walled. Stipe trama composed of longitudinally running, cylindrical hyphae 8–38 µm wide, colorless, thin-walled. Volval tissue composed of 4–8 µm wide, cylindrical hyphae and scattered, oblong, broadly clavate, ellipsoidal to subglobose cells 35–75 × 12–40 µm, occasionally with clamped septa, thin-walled.

Habitat and phenology: Solitary or scattered on ground in evergreen broad-leaved forests (dominated by Quercus miyagii Koidz. and Castanopsis sieboldii (Makino) Hatus. ex T. Yamaz. et Mashiba), May to September.

Known distribution: Okinawa (Ishigaki Island).

Specimens examined: KPM-NC0011979 (holotype), on ground in a Castanopsis-Quercus forest, Banna Park, Ishigaki-shi, Okinawa Pref., 15 Sep., 2003, coll. Takahashi, H.; KPM-NC0010087, same location, 8 Jun., 2002, coll. Takahashi, H.; KPM-NC0023873, same location, 25 May 2011, coll. Takahashi, H.

Japanese name: Fuchidori-tamagotake.

Comments: Distinctive features of this species are found in the orange to brownish orange then reddish yellow pileus; the pale yellow, squamulose stipe with a thin, membranous, reddish-orange annulus and a thick, saccate volva; the reddish orange marginate lamellae; and the habitat of subtropical evergreen broad-leaved forests.

The long sulcate-striate pileus, the presence of a membranous annulus and a thick, saccate volva, and the inamyloid basidiospores suggest that this species is a member of the section Caesareae Singer ex Singer in the genus Amanita, subgenus Amanita as defined by Singer (Singer 1986). Within the section, this species seems to be closely allied with Amanita hemibapha (Berk. & Broome) Sacc. var. hemibapha, originally described from Sri Lanka (Berkeley and Broome 1871; Saccardo 1887; Hongo 1987), Amanita caesareoides Lj. N. Vassiljeva from the Russian maritime region (Vassiljeva 1950; Endo et al. 2013), and Amanita javanica (Corner & Bas) T. Oda, C. Tanaka & Tsuda, originally described from Java (Boedijn 1951; Oda et al. 1999). These species are distinct in producing a different-colored pileus, a yellow annulus, and not marginate lamellae. Moreover, A. javanica forms wholly orange-yellow to ochre-yellow basidiomata. Amanita hemibapha var. ochracea Z.L.Yang from southwestern China (Yang 1997) also resembles A. rubromarginata to some degree, though it has an ochraceous pileus and yellow marginate, white lamellae.

References文献

Berkeley MJ, Broome CE. 1871. On some species of Agaricus from Ceylon. Trans Linn Soc London 27: 149–152.

Boedijn KB. 1951. Notes on Indonesian fungi. The genus Amanita. Sydowia 5: 317–327.

Corner EJH, Bas C. 1962. The genus Amanita in Singapore and Malaya. Persoonia 2: 241–304.

Endo N, Gisusi S, Fukuda M, Yamada A. 2013. In vitro mycorrhization and acclimatization of Amanita caesareoides and its relatives on Pinus densiflora. Mycorrhiza 23 (4): 303–15.

Hongo T. 1987. Amanitaceae. In: Imazeki R, Hongo T (eds) Colored Illustrations of Mushrooms of Japan I (in Japanese). Hoikusha, Osaka, pp 115–136.

Oda T, Tanaka C, Tsuda M. 1999. Molecular phylogeny of Japanese Amanita species based on nucleotide sequences of the internal transcribed spacer region of nuclear ribosomal DNA. Mycoscience 40 (1): 57–64.

Saccardo PA. 1887. Sylloge Hymenomycetum, Vol. I. Agaricineae. Sylloge Fungorum 5: 1–1146.

Singer R. 1986. Agaricales in modern taxonomy, 4th edn. Koeltz, Koenigstein.

Takahashi H. 2004. Two new species of Agaricales from southwestern islands of Japan. Mycoscience 45 (6): 372–376.

Thongbai B et al. 2016. A new species and four new records of Amanita (Amanitaceae; Basidiomycota) from Northern Thailand. Phytotaxa 286(4):211-231.

Vassiljeva LN. 1950. Species novae fungorum. Notulae Systematicae e Sectione Cryptogamica Instituti Botanici Nomeine V.L. Komarovii Academiae Scientificae USSR 6: 188–200.

Yang ZL. 1997. Die Amanita-arten von Südwestchina. Bibl Mycol 170: 1–240.