ユキホウライタケ

Marasmius nivicola Har. Takah., Mycoscience 41: 539-543, 2000

シバフタケ節の仲間で、傘は最初淡褐色のち類白色～ほぼ白色を呈し、柄の表面は小鱗片に被われ、ヒダは連絡脈を表します。種小名(nivicola) は雪の住人を意味し、雪が積もったように落ち葉の間に厚い白色菌糸マットを形成します。ヒダの連絡脈の有無と柄の色を除けば、欧州と北アフリカに分布する Marasmius wynneaeに類似しています。 

韓国 (Antonin et al. 2010)において本種の分布が確認されています。

文献

Antonin V., Ryoo R., Shin H.-D. 2010. Marasmioid and gymnopoid fungi of the Republic of Korea. 2. Marasmius sect. Globulares. Persoonia 24: 49-59

  肉眼的特徴: 傘は径 10-35 mm, 最初半球形で縁部は内側に巻き, のち饅頭形になり, 中央部が凹み, 老成すると周縁にやや溝線を表し, 吸水性, 平滑, 幼時全体に淡黄土色を帯びるがまもなく白色になり, 時に中央部のみ黄褐色を帯びる. 肉は厚さ 1.5 mm以下, 白色または淡黄褐色, 特別な味や臭いはない. 柄は 20-50×1.5-3 mm, ほぼ上下同大または根本僅かに太くなり, 中心生, やせ型, 中空, 全体に白色, 時に根本が黄土色を帯び, 全面にわたって細鱗片状～粉状, 表面は全体に粉状～細軟毛に被われ, 頂部白色, 下方に向かって暗褐色を呈し, 基部は黒色, 根本は発達した綿毛状の白色菌糸体に被われ, 落ち葉の堆積に厚い菌糸マットを形成する. ヒダは上生, やや疎 (柄に到達するヒダは 18-22), 幅 2.5 mm以下, 白色, 明瞭な連絡脈を形成する; 縁部は平坦, 縁取りを欠く.

  顕微鏡的特徴: 担子胞子は 6-8×3-4 μm, 楕円形, 無色, 平坦, 非アミロイド, 薄壁. 担子器は 23-35×4-5 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 9-20×5-8 μm, 群生し, こん棒形, 平坦, しばしば瘤状に分岐するかまたは裂け目を生じ, 無色, 非アミロイド, 薄壁. 側シスチジアはない. 傘の表皮は子実層状被をなし, 広こん棒形～洋梨形の細胞(15-40×6-17 μm)からなり (Globularis-type), 無色, 非アミロイド, 薄壁. 柄シスチジアは多生し, 25-65×8-15 μm, こん棒形～紡錘形, 平坦, 無色, 偽アミロイド, 薄壁. 実質の菌糸は偽アミロイド. 全ての組織の菌糸はクランプを持つ.

  分布: 日本 (神奈川、東京), 韓国 (Antonin et al. 2010).

  供試標本: KPM-NC0006038 (基準標本), on leaf litter in broad-leaved forest, Yamato-shi, Kanagawa-ken, 20 Jun. 1996; CBM-FB-24595, on leaf litter in broad-leaved forest, Yamato-shi, Kanagawa-ken, 8 Oct. 1998; KPM-NC0006037, on leaf litter in broad-leaved forest, Mt.Takao, Hachiouji-shi, Tokyo, 7 Jul. 1999.

  コメント: シバフタケ節 (sect.Globulares) に所属し, 傘は最初淡褐色のち類白色～ほぼ白色で, 柄の表面は小鱗片状, ヒダは著しい連絡脈を表し, 基質の間に厚い菌糸マットを形成する. 東京都及び神奈川県の落ち葉堆積上に発生. 標本は神奈川県立生命の星・地球博物館(KPM) 及び千葉県立中央博物館 (CBM) の標本庫に登録, 収蔵されている.

Marasmius nivicola Har. Takah., Mycoscience 41: 539-543, 2000

  Pileus 10-35 mm in diam, at first hemispherical with an incurved margin, then convex with a depressed center, not umbonate, center smooth, in age somewhat sulcate-striate toward the margin, hygrophanous, glabrous, evenly pale ochraceous when young, then becoming pure white overall, sometimes pale ochraceous at the disk. Flesh up to 1.5 mm thick, white or pale ochraceous, odor mild, taste none; consistency tough. Stipe 20-50×1.5-3 mm, almost equal or slightly enlarged at the base, central, slender, terete, hollow, entirely pure white or sometimes pale ochraceous only at the base, furfuraceous to pruinose over the entire length; base covered with white, mycelial tomentum attached to an extensive mycelial mat in the substratum. Lamellae adnexed, subdistant (18-22 reach the stipe), up to 2.5 mm broad, concolorous with the pileus, distinctly intervenose; edges even, concolorous.

  Basidiospores 6-8×3-4 μm, ellipsoid, colorless, smooth, inamyloid, thin-walled. Basidia 23-35×4-5 μm, clavate, four-spored; basidioles clavate. Cheilocystidia 9-20×5-8 μm, forming a compact sterile edge, clavate, smooth, often nodose or shortly lobed, colorless, inamyloid, thin-walled. Pleurocystidia none. Hymenophoral trama regular, colorless, dextrinoid, with cylindric hyphae 4-15 μm wide. Pileipellis hymeniform, consisting of broadly clavate to pyriform (Globularis-type) cells 15-40×6-17 μm, colorless, inamyloid, thin-walled. Hyphae of pileitrama 4-17 μm wide, subparallel, loosely interwoven, subcylindric, smooth, colorless, dextrinoid. Stipitipellis a cutis of parallel, repent hyphae 3-6 μm wide, cylindric, smooth, colorless or pale melleous, dextrinoid, thin-walled; caulocystidia numerous, 25-65×8-15 μm, clavate to fusoid, smooth, colorless, dextrinoid, thin-walled. Stipe trama composed of longitudinally running, cylindric hyphae 4-15 μm wide, smooth, colorless or pale melleous, dextrinoid, thin-walled. All tissues with clamp connections.

  Known distribution: Japan (Kanagawa, Tokyo), Republic of Korea (Antonin et al. 2010: Persoonia 24, 2010: 49-59).

  Habitat: Scattered to caespitose on leaf litter of broad-leaved forest dominated by Quercus serrata Thunb. and Aphananthe aspera (Thunb.) Planch., from June to November, common.

  Specimens examined: KPM-NC0006038 (holotype), on leaf litter in broad-leaved forest, Yamato-shi, Kanagawa-ken, 20 Jun. 1996; CBM-FB-24595, on leaf litter in broad-leaved forest, Yamato-shi, Kanagawa-ken, 8 Oct. 1998; KPM-NC0006037, on leaf litter in broad-leaved forest, Mt.Takao, Hachiouji-shi, Tokyo, 7 Jul. 1999.

  Japanese name: Yuki-houraitake (first collected and named by Mr. Minoru Aoki).

  Notes: The diagnostic features of this species are its entirely white, collybioid basidiomata with a furfuraceous to pruinose stipe and distinctly intervenose lamellae, the white, extensive mycelial mat attached to base of the stipe, and the inconspicuous, occasionally nodose, clavate cheilocystidia.

  The collybioid habit, the dextrinoid tramal hyphae, and the hymeniform pileipellis composed of Globularis-type cells suggest the placement of this taxon in the genus Marasmius section Globulares Kuhner in Singer's classification (Singer, 1986). Within the section, Marasmius nivicola has some features in common with neotropical Marasmius cohortalis Berk. in Vidensk. (Pegler, 1983; Singer, 1958, 1965, 1976), such as a white pileus, white or cream, intervenose and anastomosing lamellae, white, tomentose basal mycelium, and inconspicuous, small to medium-sized cheilocystidia. According to Singer's descriptions (Singer, 1958, 1965, 1976), M. cohortalis has a chestnut brown stipe and frequently nodulose or hook-bearing pileipellis elements. Marasmius nivicola is also similar to Marasmius pellicidus Berk. & Broome from New Caledonia (Desjardin and Horak, 1997) and Sri Lanka (Berkeley and Broome, 1875), and Marasmius papyraceus Massee from Singapore (Corner, 1996). These species, however, differ in having non-intervenose lamellae and a brown to reddish brown stipe.