ナンヨウシロタマゴタケ
Amanita cf. chepangiana Tulloss & Bhandary, Mycotaxon 43: 25 (1992) sensu Takahito Kobayashi in The fungal flora in southwestern Japan, Agarics and boletes 1: 3 (2016)
ナンヨウシロタマゴタケ(Amanita cf. chepangiana)は、小林孝人さんによって西表島産のサンプルに基づき日本新産種として正式に発表されました。
傘中央部はしばしば淡灰色～淡黄褐色を帯びる性質があります。
温帯産ハマクサギタマゴタケは、ナンヨウシロタマゴタケと形態的にほぼ一致していますが、分子解析による比較はまだ行われておらず、菌根形成に関する詳細も不明です。臭いに関して村上先生にお聞きしたことがありますが、かなり個体差が大きく、ほとんど感じられない場合もあるとのことです。
Basidiomata of Amanita chepangiana (TNS-F-61368) on ground in an evergreen broad-leaved forest, 26 Nov. 2013, Uehara, Iriomote Island. Photo by Dr. Kobayashi, T.
亜熱帯性常緑広葉樹林内地上に発生したナンヨウシロタマゴタケの子実体 (TNS-F-61368), 2011年5月25日, 西表島上原. 写真: 小林孝人氏.
Micromorphological features of Amanita chepangiana (TNS-F-61368): A. Basidiospores. B. Marginal cells of the lamellae. Illustrations by Kobayashi, T.
ナンヨウシロタマゴタケの顕鏡図 (TNS-F-61368): A. 担子胞子. B. ヒダ縁部の細胞. C. ツボを構成する菌糸と末端細胞. 図: 小林孝人氏.
肉眼的特徴 : 傘は径125 mmまで, まんじゅう型～ほぼ平ら, 周縁部に放射状の長い溝線を表す; 表面は平滑, 粘性を欠き, 中央部は淡灰色～淡黄褐色, 周縁部に向かって純白色を呈する. 肉は軟質, 相対的に厚く, 純白色; 特別な味や臭いはない. ヒダは離生, 密, 白色; 縁部は長縁毛状, 同色. 柄は140–170 × 17–19 mm, ほぼ上下同大, 上部に向かいわずかに細くなり, 中心性, 最初中実まもなく上部が中空になる; 表面は粘性を欠き, 繊維状小鱗片で密に被われ, ささくれ状～多少段だら模様を形成し, 純白色; ツバは薄い膜質, 柄の上部に垂れ下がるように付着し, 白色でわずかに黄色の色彩を帯びる; ツボは77 × 46 mmまで, 大形, 袋状, 厚い膜質, 裂け目を生じ, 白色, 時にくすんだ帯褐色の斑点を表す.
顕微鏡的特徴 : 担子胞子は9.3–11.8 × 8.8–11.0 µm (N = 40, 平均10.7–11.0 × 9.6–10.0 µm, Q = 1.0–1.3, mean Q = 1.10–1.12), 亜球形～広卵形, 非アミロイド, 無色, 平滑, 薄壁. 担子器は20–39 × –14.5 µm, 4胞子性, 狭棍棒状, 薄壁. ヒダの縁部の細胞 (ツバの残存組織) は23–50 × 12.5–16.3 µm, 狭円柱状, 棍棒状～短い小柄のある楕円形, ほぼ無色, 薄壁. かすがい状突起を有する.
生態および発生時期: スダジイを主体とする広葉樹林内地上に孤生または散生, 5月～11月.
分布: 沖縄 (西表島), ネパール, タイ北部, 中国南西部, 朝鮮半島.
供試標本: TNS-F-61368, 常緑広葉樹林内地上, 沖縄県八重山郡西表島上原, 2013年11月26日, 小林孝人採集; KPM-NC0023866, 常緑広葉樹林内地上, 沖縄県八重山郡西表島大見謝ロードパーク, 2014年5月24日, Hoang ND Pham採集.
コメント: 本種は柄の基部が球根状膨大部の代わりに袋状のツボを形成し, 発達したツバを有し, 傘周縁部に明瞭な長い溝状条線を表し, 担子胞子が非アミロイドの特徴に基づき, テングタケ属 Amanita, テングタケ亜属 subgenus Amanita, タマゴタケ節 section Caesareae Singer ex Singer (Singer 1986) に分類される.
最初ネパールから記載された A. chepangiana (Tulloss and Bhandary 1992; Yang 1997, 2000, 2005; Sanmee, et al. 2008) は、欧州産 Amanita caesarea var. alba Gillet (Gillet 1878; Neville and Poumarat 2004)に外観が類似するが, 傘周縁部の条線はより短く, 柄が短形で, 担子胞子の幅がより狭い点で有意差が認められる.
Macromorphological characteristics: Pileus up to 125 mm in diameter, convex to nearly plane, with a long sulcate-striate margin; surface glabrous, dry, pale greyish to light yellowish brown at the center, almost pure white toward the margin. Context soft, relatively thick, white; odor and taste indistinct. Lamellae free, crowded, white; edges fimbriate, concolorous. Stipe 140–170 × 17–19 mm, almost equal, slightly tapering upward, central, terete, at first stuffed then becoming hollow above; surface dry, fibrous-scaly to lacerate-scaly, pure white; annulus thin, membranous, attached toward the stipe apex, pendant, white with slightly yellowish tinge ; volva up to 77 × 46 mm, large, saccate, thick, membranous, lobed, white, sometimes stained dingy brownish.
Micromorphological characteristics: Basidiospores 9.3–11.8 × 8.8–11.0 µm (N = 40, averaging 10.7–11.0 × 9.6–10.0 µm, Q = 1.0–1.3, mean Q = 1.10–1.12), subglobose to broadly ovoid, inamyloid, colorless, smooth, thin-walled. Basidia 20–39 × up to 14.5 µm, 4-spored, narrowly clavate, thin-walled. Marginal cells of lamellae (remnants of the annulus) 23–50 × 12.5–16.3 µm, narrowly cylindrical, clavate to ellipsoid with a short pedicellate base, colorless, thin-walled. Clamp connections present.
Habitat and phenology: Solitary or scattered on ground in evergreen broad-leaved forests (dominated by Castanopsis sieboldii (Makino) Hatus. ex T. Yamaz. et Mashiba), May to November.
Known distribution: Okinawa (Iriomote Island), Nepal, northern Thailand, southwestern China, and Korean Peninsula.
Specimens examined: TNS-F-61368, on ground in an evergreen broad-leaved forest, Uehara, Iriomote Island, Yaeyama-gun, Okinawa Pref., 26 Nov. 2013, leg. Takah. Kobayashi; KPM-NC0023866, Oomiya road Park, on ground in an evergreen broad-leaved forest, Iriomote Island, Yaeyama-gun, Okinawa Pref., 24 May 2014, leg. Hoang ND Pham.
Japanese name: Nayou-shiro-tamagotake (named by T. Kobayashi).
Comments: This species belongs to the genus Amanita, subgenus Amanita, section Caesareae Singer ex Singer (Singer 1986) because of the inamyloid basidiospores, the well-developed annulus, the distinctly long sulcate-striate margin of the pileus, and the stipe having a saccate volva instead of a basal bulb.
The macro- and micromorphological characteristics of the present collection correspond well with A. chepangiana originally described from Nepal (Tulloss and Bhandary 1992; Yang 1997, 2000, 2005; Sanmee, et al. 2008).
Amanita caesarea var. alba Gillet (≡ A. caesarea f. alba (Gillet) E.-J. Gilbert) from Europe (Gillet 1878; Neville and Poumarat 2004) is somewhat similar to A. chepangiana in appearance, but it forms shorter marginal striations on the pileus, a much shorter stipe, and short ellipsoid, significantly narrower basidiospores: 10–12 × 7–8.5 µm (Neville and Poumarat 2004).
References 文献
Gillet CC. 1878. Les Hyménomycètes ou Description de tous les Champignons qui Croissent en France 1: 1–176.
Neville P, Poumarat S. 2004. Amaniteae. Amanita, Limacella & Torrendia. Fungi Europaei 9: 1–1120. Candusso, Alassio.
Sanmee R, Tulloss RE, Lumyong P, Dell B, Lumyong S. 2008. Studies on Amanita (Basidiomycetes: Amanitaceae) in Northern Thailand. Fung Diver 32: 97–123.
Singer R. 1986. The Agaricales in modern taxonomy, 4th edn. Koeltz, Koenigstein.
Tulloss RE, Bhandary HR. 1992. Amanita chepangiana - a new species from Nepal. Mycotaxon 43: 25–31.
Yang ZL. 1997. Die Amanita-Arten von Sudwestchina. Bibl Mycol 170: 1–240.
Yang ZL. 2000. Revision of the Chinese Amanita collections deposited in BPI and CUP. Mycotaxon 75: 117–130.
Yang ZL. 2005. Amanitaceae (in Chinese). Flora Fungorum Sinicorum 27: 1–258, Beijing.
Yoshie Terashima (supervisor), Haruki Takahashi (editor), Yuichi Taneyama (editor). 2016. The fungal flora in southwestern Japan: Agarics and boletes. Tokai University Press. 349p.