ヤシモリノカレバタケ

Gymnopus cf. oncospermatis (Corner) Har. Takah., Mycoscience 43 (5): 397 (2002).

≡ Marasmius oncospermatis Corner, Beih Nova Hedwigia 111: 81 (1996) [MB#442746].

ヤシ類に基質特異性がある熱帯性のモリノカレバタケ属の仲間で、菌糸束と菌糸体マットを合体させた様な脈状隆起を形成する菌糸体が基質を取り囲み、ヒダが著しく密になる特徴があります。

黒木秀一氏により宮崎県においてビロウから発生するヤシモリノカレバタケの類似菌が確認されています。

主な形態的特徴

子実体はモリノカレバタケ型で, 淡褐色～類白色の傘と淡褐色～赤褐色の柄を持ち、ヒダは著しく密で、縁シスチジア、傘シスチジア、柄シスチジアは亜円柱形～不規則な形状を成し、短指状分岐物を持ち、根元の白色菌糸体につながる淡黄褐色～淡褐色の脈状隆起を持つ発達した類白色の菌糸体マットが基質全体 (ヤエヤマヤシの枯れた根もしくは枯れ葉の根もと付近) を被う。

本種はCorner (Corner 1996) によってホウライタケ属(Marasmius)の所属種としてシンガポールから最初に報告され、基準産地ではコブダネヤシ属(Oncosperma)の枯れ葉の根元に発生すると言われており、熱帯～亜熱帯のヤシ林におそらく広く分布するものと思われます。

2020年黒木秀一氏が宮崎県青島(ビロウの葉柄上)でヤシモリノカレバタケ類似菌を採集しています。

肉眼的特徴: 傘は径8–30 mm, 最初縁部は内側に巻き, 饅頭形, のちほぼ平らに開き, 老成すると中央部が凹み, 縁部が反り返り, 平坦で条線や溝線を欠く; 表面は乾性, 光沢を欠き, 最初全体に白色の微細な軟毛に被われ, 後粉状, 老成するとしばしばほぼ平滑になり, 幼時全体に淡褐色～赤褐色を帯びるがのち周縁から次第に退色し, 成熟すると淡褐色の中央部を除きほぼ類白色を呈する. 肉は非常に薄く (1.5 mm以下), 類白色, 弾力性があり, 強靱, 臭いおよび味は温和. 柄は20–70 × 1.5–6 mm, 類円柱形, 中心生またはやや偏在生, しばしば偏圧し, 時に縦皺を表す; 表面は最初全体に白色の微細な軟毛に被われ, 後粉状, 老成するとしばしばほぼ平滑になり, 頂部 (類白色) 以外は淡褐色～赤褐色を帯び, 根元は暗色になる; 根本及び基質 (ヤシの根と落ち葉) は淡黄褐色～淡褐色を帯びた脈状隆起を持つ類白色の綿毛状菌糸体に被われる. ヒダは直生～僅かに垂生, 極めて密 (柄に到達するヒダは55–70), 1–2の小ヒダを伴い, 幅 1 mm以下, 白色; 縁部は平坦で同色. 胞子紋は白色.

顕微鏡的特徴: 担子胞子は8–10 × 3.5–4.5 μm (n = 20 spores per two specimens, Q = 2.2–2.3), 楕円形, 平坦, 無色, 非アミロイド, 薄壁. 担子器 は24–30 × 6.5–8 μm, こん棒形, ４胞子性; 偽担子器はこん棒形. 縁シスチジアは 20–55 × 4–7 μm, 不稔帯を形成し, 亜円柱形～不規則な形状をなし, しばしば複数の短指状突起を有し, 無色, 非アミロイド, 薄壁. 側シスチジアはない. 子実層托実質の菌糸は不規則に配列し, 傘実質の菌糸に類似する. 傘表皮の菌糸は平行菌糸被を形成し, 幅4–8 μm, 円柱形, 淡褐色の色素がうすく凝着し, 非アミロイド, 薄壁; 末端細胞は30–60 × 4–8 μm, 類円柱形, しばしば複数の短指状突起を持ち, 無色, 薄壁. 傘実質の菌糸は幅5–12 μm, 並列し, 円柱形, 一菌糸型, 平滑, 無色, 非アミロイド, 薄壁. 柄表皮組織は平行菌糸被を成し, 菌糸は幅4–7 μm, 匍匐性, 円柱形, 淡褐色の色素が細胞内に存在し, 非アミロイド, 薄壁; 柄シスチジアは20–50 × 4–7 μm, 類円柱形～不規則な形状をなし, しばしば複数の短指状突起を有し, 無色, 非アミロイド, 薄壁. 柄実質の菌糸は幅5–13 μm, 縦に沿って配列し, 円柱形, 一菌糸型, 平滑, 無色, 非アミロイド, 薄壁. 全ての組織はクランプを持つ.

生態および発生時期: ヤエヤマヤシの枯れ葉 (特に葉の根もと付近) または枯れた根上に孤生または散生し, しばしば群生, 4月～11月.

分布: 沖縄県 (石垣島), 宮崎県(?), シンガポール (Corner 1996).

供試標本: KPM-NC0013150, ヤエヤマヤシの枯れた根もしくは枯れ葉上, 沖縄県石垣島米原, 2004年5月22日, 高橋春樹採集; KPM-NC0008777, 同上, 2001年10月18日, 高橋春樹採集; TNS-F-48219，同上, 2012年6月10日; TNS-F-48221，同上, 2012年6月10日; TNS-F-61377，同上, 2013年6月3日; KPM-NC0023870, 同上, 2014年6月10日, 高橋春樹採集.

コメント: 子実体の根元および基質を被う発達した綿毛状菌糸体, 不規則に分岐する短指状またはこぶ状の分岐物を持つ平行菌糸被型の傘表皮組織, そして分化した縁シスチジアの存在は本種がモリノカレバタケ属Gymnopus, アマタケ節section Vestipedes Antonin, Halling & Noordel., アマタケ亜節subsection Vestipedes (Antonin and Noordeloos 1997; Mata et al. 2004; Noordeloos and Antonín 2008; Antonín and Noordeloos 2010) に属することを示唆している.

Gymnopus cf. oncospermatis (Corner) Har. Takah.

Mycoscience 43 (5): 397 (2002) [MB#488792].

≡ Marasmius oncospermatis Corner, Beih Nova Hedwigia 111: 81 (1996) [MB#442746].

Etymology: The specific epithet derives from the palm genus Oncosperma on which the basidiomata grow.

Macromorphological characteristics: Pileus 8–30 mm in diameter, at first convex with incurved margin, then expanding to nearly plane, finally with depressed center and upturned margin, smooth; surface dry, dull, when young covered overall with white, fine pubescence, then pruinose, at times almost glabrescent in age, at first light brown (7D4–5) to reddish brown (8D4–5) overall, then paler toward the margin, finally whitish except the pale brownish center. Flesh very thin (up to 1 mm), whitish, pliant, tough, odor and taste mild. Stipe 20–70 × 1.5–6 mm, subcylindrical, central or somewhat eccentric, terete or compressed, at times longitudinally rugulose, at first entirely white villous then pruinose, at times glabrescent in age, whitish at the apex, light brown (7D4–5) to reddish brown (8D4–5) elsewhere, darkening from the base upwards; base covered with whitish mycelial tomentum attached to a whitish extensive mycelial mat with pale yellowish to pale brownish mycelial veins on the dead leaf bases and root of the palm. Lamellae adnate to subdecurrent, very close (55–70 reach the stipe), with 1–2 series of lamellulae, up to 1.5 mm broad, white; edges even, concolorous. Spore print pure white.

Micromorphological characteristics: Basidiospores 8–10 × 3.5–4.5 μm (n = 20 spores per two specimens, Q = 2.2–2.3), ellipsoid, smooth, colorless, inamyloid, thin-walled. Basidia 24–30 × 6.5–8 μm, clavate, four-spored; basidioles clavate. Cheilocystidia 20–55 × 4–7 μm, forming a compact sterile edge, subcylindrical to irregularly shaped, with or without one or several digitate projections, colorless, inamyloid, thin-walled. Pleurocystidia none. Hymenophoral trama irregular; element hyphae similar to those of the pileitrama. Pileipellis a cutis of cylindrical cells 4–8 μm wide, thinly encrusted with light brown pigment, inamyloid, thin-walled; pilocystidia 30–60 × 4–8 μm, subcylindrical or irregularly shaped, with or without one or several digitate projections, colorless, thin-walled. Hyphae of pileitrama 5–12 μm wide, parallel to the pileipellis elements, cylindrical, smooth, monomitic, colorless, inamyloid, thin-walled. Stipitipellis a cutis of parallel, repent hyphae 4–7 μm wide, cylindrical, with light brown intercellular pigment, inamyloid, thin-walled; caulocystidia 20–50 × 4–7 μm, subcylindrical to irregularly shaped, with or without one or several digitate projections, colorless, inamyloid, thin-walled. Stipe trama composed of longitudinally running, cylindrical hyphae 5–13 μm wide, monomitic, smooth, colorless, inamyloid, thin-walled. All tissues with clamp connections.

Habitat and phenology: Solitary to scattered, often gregarious, on dead leaf bases and roots of the palm Satakentia liukiuensis H.E.Moore, April to November.

Known distribution: Okinawa (Ishigaki Island), Singapore (Corner 1996).

Specimens examined: KPM-NC0013150, on a dead leaf base and root of the palm S. liukiuensis, Yonehara, Ishigaki-shi, Okinawa Pref., 22 May 2004, coll. Takahashi, H.; KPM-NC0008777, same location, 18 Oct. 2001, coll. Takahashi, H.; TNS-F-48219，same location, 10 Jun. 2012, coll. Takahashi, H.; TNS-F-48221，same location, 10 Jun. 2012, coll. Takahashi, H.; TNS-F-61377，same location, 3 Jun. 2013, coll. Takahashi, H.; KPM-NC0023870, same location, 10 Jun. 2014, coll. Takahashi, H.

Japanese name: Yashi-morino-karebatake.

Comments: Distinctive features of this species are found in the collybioid basidiomata producing a pale brownish to whitish pileus and a light brown to reddish brown stipe; the very close lamellae; the subcylindrical to irregularly shaped cheilocystidia, pilocystidia and caulocystidia with one or several digitate projections; and the whitish basal tomentum attached to the distinct, whitish extensive mycelial mat with pale yellowish to pale brownish mycelial veins on the dead leaf bases and roots of S. liukiuensis.

Its distinct basal tomentum, the cutis with more or less diverticulate terminal elements in the pileipellis, and the presence of well-differentiated cheilocystidia suggest that this species is a member of the subsection Vestipedes in the section Vestipedes Antonin, Halling & Noordel. of the genus Gymnopus (Antonin and Noordeloos 1997; Mata et al. 2004; Noordeloos and Antonín 2008; Antonín and Noordeloos 2010). This species was first described by Corner (Corner 1996) from Singapore as Marasmius oncospermatis Corner. It is said to grow on the dead leaf bases of the palm Oncosperma in the type locality, and seems to be widely distributed in tropical and subtropical palm forests.

References 文献

Antonín V. 2007. Monograph of Marasmius, Gloiocephala, Palaeocephala and Setulipes in Tropical Africa, Fungus Flora of Tropical Africa Vol. 1. National Botanic Garden of Belgium.

Antonín V. Noordeloos ME. 2010. A monograph of marasmioid and collybioid fungi in Europe. IHW-Verlag.

Corner EJH. 1996. The agaric genera Marasmius, Chaetocalathus, Crinipellis, Heimiomyces, Resupinatus, Xerula and Xerulina in Malesia. Beih Nova Hedwigia 111: 1–175.

Mata JL, Hughes KW, Petersen RH. 2004. Phylogenetic placement of Marasmiellus juniperinus. Mycoscience 45 (3): 214–221.

Noordeloos ME, Antonín V. 2008. Contribution to a monograph of marasmioid and collybioid fungi in Europe. Czech Mycology 60 (1): 21–27.

Takahashi H. 2002. Two new species and one new combination of Agaricales from Japan. Mycoscience 43 (5): 397–403.

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