肉眼的特徴: 傘は径20-50 mm, 最初から漏斗型をなし, 縁部ははじめ内側に巻く, 平坦, 吸水性, 湿時半透明の条線を表し, 平滑, 白色, 老成時淡黄色. 肉は薄く (1.8 mm以下), 白色; 強い粉臭があり, 無味. 柄は 20-30×2-15 mm, ほぼ上下同大または基部に向かって細まり, 中心生, もろく, 中空, 白色, 平坦, 平滑, 根本は白色の綿毛状菌糸体に被われる. ヒダは弧状に垂生し, やや疎 (柄に到達するヒダは18-25), 狭幅 (1-5 mm) で薄く, 時に小ヒダとともに叉状分岐し, 浅い連絡脈が発達し, 白色.
顕微鏡的特徴: 担子胞子は 5-6.5×3-4 μm, 卵形～楕円形, 平坦, 無色, 非アミロイド, 薄壁. 担子器は21-29×5-6.5 μm, こん棒形, ４胞子性. ヒダの縁部は稔性. 側シスチジア及び縁シスチジアを欠く. 傘の表皮は匍匐性の糸状菌糸からなる平行菌糸被, しばしば末端部に顕著な無色の粒状内容物を持つ厚壁な袋状または広こん棒形の細胞 (17-60×10-17 μm)が見られる. 傘の実質は並列または錯綜した円柱形の菌糸からなり, しばしば表皮と同様の厚壁な袋状の末端細胞が見られる. 実質は一菌糸型. 全ての組織の菌糸はクランプを有する.
供試標本: CBM-FB-24119 (基準標本), on leaf litter in Quercus-Pasania forests, Yamato -shi, Kanagawa-ken, 15 Jul. 1998; KPM-NC0005003, on leaf litter in deciduous oak forest, Machida-shi, Tokyo, 19 Jul. 1992; KPM-NC0005004, on leaf litter in deciduous oak forest, Machida-shi, Tokyo, 23 Sept. 1993; CBM-FB-24118, on leaf litter in Quercus-Pasania forests, Yamato-shi, Kanagawa-ken, 22 Sept. 1997;CBM-FB-16056, on leaf litter in deciduous oak forest, Sakura-shi, Chiba-ken, 4 Oct. 1997.
コメント: ユキラッパタケはスリランカ産 Clitocybe trogioides の変種として記載された種類であるが, ヒダの幅がしばしば 5 mm以上に達し, 球形細胞が実質に存在する性質から, 独立種として扱うのが妥当と思われる. ユキラッパタケはシロサカズキタケに似るが, 傘の中央部が柄の根元まで貫通し, 球形細胞が菌糸の末端に位置する点で異なる. 南関東に広く分布し, 広葉樹林内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.
Clitocybe trogioides Corner, Beihefte Nova Hedwigia 109: 126. 1994.
var.odorifera Har.Takah., Mycoscience 41: 15-23, 2000 Figs. 1-3
≡ (?) Singerocybe alboinfundibuliformis (S.J. Seok et al.) Zhu L. Yang, J. Qin & Har. Takah.
A typo differt cellulis pileipellis sphaerocystis terminalibus intus granulis coagulatis praeditis.
Holotypus: In folia dejecta in silva, Yamato-shi, Kanagawa-ken, Japonia, 15 Jul. 1998, H. Takahashi (CBM-FB-24119).
Etymology: from Latin, odorifera = emitting a smell.
Pileus 20-50 mm in diam, infundibuliform from the first, margin incurved at first, smooth, hygrophanous, translucent-striate when wet, glabrous, white, pale yellowish in age. Flesh thin (up to 1.8 mm thick), white; odor strongly farinaceous, taste not distinctive. Stipe 20-30×2-15 mm, subequal or tapering toward the base, central, terete, brittle, hollow, white, smooth, glabrous, with white basal tomentum. Lamellae arcuate-decurrent, subdistant (18-25 reach the stipe), narrow (1-5 mm broad) and thin, occasionally branching dichotomously with lamellulae, shallowly intervenose, white; edges even, concolorous.
Basidiospores 5-6.5×3-4 μm, ovoid-ellipsoid, smooth, colorless, inamyloid, thin-walled. Basidia 21-29×5-6.5 μm, clavate, four-spored. lamella-edge fertile. Pleurocystidia and
cheilocystidia absent. Elements of hymenophoral trama 30-70×4-9.5 μm, cylindric, subparallel, smooth, colorless, walls up to 1 um thick. Pileipellis a cutis of subparallel or
irregularly interwoven, repent hyphae with tubular element cells 15-60×2-6 μm, terminal cells 17-60×10-17 μm, vesiculose or broadly clavate, with remarkable hyaline tubercular-coagulate contents, walls up to 1 μm thick, hyaline, smooth. Pileitrama of cylindric, subparallel or loosely interwoven hyphae, with smooth, hyaline walls up to 1 μm thick; element cells 20-70×2.5-6 μm. Stipitipellis composed of interwoven, repent hyphae with element cells 30-110×4-8 μm, cylindric, occasionally intermixed with vesiculose terminal elements as in the pileipellis, smooth, colorless, walls up to 1 μm thick. Elements of stipe trama 50-120×4-10 μm, cylindric, more or less longitudinally oriented, smooth, colorless, walls up to 1 μm thick. Hyphae with clamps.
Known distribution: Japan (Chiba, Kanagawa, Tokyo).
Habitat: Solitary to caespitose, on leaf litter in lowland forests dominated by Quercus serrata Thunb., Pasania edulis Makino and Ligustrum japonicum Thunb., from July to
October, common.
Holotype: CBM-FB-24119, on leaf litter in Quercus-Pasania forests, Yamato-shi, Kanagawa-ken, 15 Jul. 1998.
Other specimens examined: KPM-NC 0005003, on leaf litter in deciduous oak forest, Machida-shi, Tokyo, 19 Jul. 1992; KPM-NC0005004, on leaf litter in deciduous oak forest, Machida-shi, Tokyo, 23 Sept. 1993; CBM-FB-24118, on leaf litter in Quercus-Pasania forests, Yamato-shi, Kanagawa-ken, 22 Sept. 1997; CBM-FB-16056, on leaf litter in deciduous oak forest, Sakura-shi, Chiba-ken, 4 Oct. 1997.
Japanese name: Yuki-rappatake.
Notes: The type variety of Clitocybe trogioides, recently described from Sri Lanka by Corner (1994), is easily recognized by the white, infundibuliform basidiomata, the veined
lamellae, and the vesiculose terminal elements of the pileipellis. The Japanese variety odorifera, described herein, differs from it in having a strongly farinaceous smell, larger basidiospores (4-4.3 x 2.8-3 μm in var.trogioides: Corner, 1994), and remarkable hyaline tubercular-coagulate contents in the vesiculose terminal cells of the pileipellis hyphae. The irregularly arranged pileipellis hyphae in the expanded pilei of C. trogioides (including var. odorifera) form a cutis-like structure. This structure suggests that Clitocybe trogioides belongs to section Bulluliferae in the subgenus Cystoclitus. However, if greater taxonomic emphasis is placed on the presence of vesiculose cells that are terminally disposed in the pileipellis hyphae, it would be better placed in section Cystoclitus of the same subgenus than in section Bulluliferae; members of the latter section also have vesiculose cells in the pileipellis hyphae, but the cells are disposed not terminally but interposally.
Literature cited
Corner, E.J.H. 1994. Agarics in Malesia, I. Tricholomatoid. Beihefte Nova Hedwig. 109: 1-138.
