オチバサカズキタケ

Clitocybe minutella Har. Takah., Mycoscience (2003) 44:103-107　

子実体は小型 (通常傘の径は１cm前後)で、オウギタケ型の独特な形状になる点で他の白色カヤタケ属類似菌と容易に識別できます。毛状被からなる傘表皮組織の構造はカヤタケ属の仲間として異質です。

肉眼的特徴: 傘は径 5-16 mm, 最初饅頭形で縁部は内側に巻き, のち漏斗型になり, 時に鈍頭の中丘を具える; 表面は平坦, 密綿毛状, 全体に白色または中央部のみ淡褐色を帯びる. 肉は厚さ 1 mm 以下, 白色, 特別な味や臭いはない. 柄は 11-25×1.5-3.5 mm, ほぼ上下同大, しばしば根本に向かってやや太くなり, 中心生, やせ型, 中空; 表面は密綿毛状～繊維状, 全体に白色, 根本は発達した剛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. ヒダは深く垂生し, やや疎 (柄に到達するヒダは 18-24), 幅 1 mm 以下, 白色, 縁部は同色.

顕微鏡的特徴: 胞子は 6-7.5×3.5-4μm, 楕円形, 平坦, 無色, 非アミロイド, 薄壁. 担子器は 35-53×7-10μm, こん棒形, 1-2胞子性. 縁シスチジア及び側シスチジアを欠く. 子実層托実質の菌糸は並列し, 傘実質の菌糸に似るが, 鮮黄色の色素塊が細胞間に見られる. 傘表皮の菌糸は毛状被を形成し, 幅 4-7μm, 円柱形, 平坦, 無色または淡褐色, 薄壁, 時に隔壁にクランプが見られる. 実質の菌糸はしばしば隔壁にクランプを持ち, 骨格菌糸を欠き, 菌糸構成は一菌糸型.

供試標本: KPM- NC0008692 (正基準標本), Izumino-mori, Yamato-shi, Kanagawa-ken, Oct. 26, 2000, coll. H.Takahashi; KPM- NC0008693 same place, Nov.1, 2000, coll. H.Takahashi.

コメント: オチバサカズキタケ節 (SectionVernae) に属し, 子実体は小型で (通常傘の径は１cm前後),類白色～淡褐色, 非吸水性の傘を形成し, 傘の表皮は毛状被からなる. 本種はシロヒメカヤタケClitocybe candicans (Pers.: Fr.) P.Kumm. に似るが, 子実体はより小型で, 非吸水性の傘を有し, 表皮は毛状被からなり, 1-２胞子性の担子器を持つ点で異なる. 晩秋の頃，神奈川県大和市の広葉樹の落ち葉堆積上に発生し, 基質に厚い菌糸マットを形成する. 標本は神奈川県立生命の星・地球博物館の標本庫(KPM)に登録, 収蔵されている.

Clitocybe minutella Har. Takah., Mycoscience (2003) 44:103-107　　

Pileus 5-16 mm in diameter, at first convex with an incurved margin, then plano-convex, soon depressed at the center, sometimes with a obtuse umbo; surface smooth, tomentose to velvety, white overall or pale brownish at the center. Flesh up to 1 mm, white; odor and taste not distinctive. Stipe 11-25×1.5-3.5 mm, almost equal or somewhat thickened toward the base, central, slender, terete, hollow; surface tomentose to fibrillose, entirely white; base covered with white, strigose mycelial tomentum attached to an extensive mycelial mat in the leaf litter. Lamellae deeply decurrent, subdistant (18-24 reach the stipe), with 0-2 series of lamellulae, up to 1 mm broad, white; edges.

Basidiospores 6-7.5×3.5-4μm [Q = length/breadth: 1.7-1.9, n = 20 spores per two specimens], ellipsoid, smooth, colorless, inamyloid, thin-walled. Basidia 35-53×7-10 μm,

clavate, one or two-spored. Cheilocystidia and pleurocystidia absent. Hymenophoral trama irregular; hyphae similar to those of the pileitrama. Pileipellis a trichodermium of vertically arranged, cylindrical cells 4-7 μm wide, smooth, colorless or with pale brown intracellular pigment, thin-walled, occasionally with clamped septa. Hyphae of pileitrama 4-8 μm wide, horizontally arranged, parallel each other, monomitic, colorless, inamyloid, thin-walled, occasionally with clamped septa. Stipitipellis a cutis of parallel, repent hyphae 2.5-4 μm wide, cylindrical, sometimes with finger-like projections, colorless, inamyloid, thin-walled, occasionally with clamped septa. Hyphae of stipe trama 3.5-7 μm wide, longitudinally running, monomitic, unbranched, cylindrical, smooth, colorless, inamyloid, thin-walled, occasionally with clamped septa.

Known distribution: Japan (Kanagawa). Habitat: Solitary to scattered, on leaf litter in

deciduous oak forests, from October to November.

Specimens examined: KPM- NC0008692 (holotype), Izumino-mori, Yamato-shi, Kanagawa-ken, Oct. 26, 2000, coll. H.Takahashi; KPM- NC0008693 same place, Nov.1, 2000, coll. H.Takahashi.

Japanese name: Ochiba-sakazuki- take.

Notes: This species is characterized by its white,

very small, clitocyboid basidiomata with a non hygrophanous pileus and a white strigose mycelial tomentum at the base of stipe, the relatively small basidiospores, the lack of

cystidioid cells in the hymenium and cortical layer, the trichodermial elements in the pileipellis, and its habitat on leaf litter in deciduous oak forests. Its small clitocyboid habit,

the non hygrophanous pileus, and the slender stipe with white rhizoids from the base place this species in the genus Clitocybe section Vernae Singer (Singer 1986).

Within the section, C. minutella seems to be closely related to Clitocybe prunosa (Lasch in Fries) P.Kumm. (Bigelow 1982; Harmaja 1969) which differs in having much larger

basidiomata, greyish brown to brown pileus, two to four-spored basidia, and horizontally arranged pileipellis elements. North American Clitocybe fusipes Peck (Bigelow 1982), which belongs in the section Candcantes (Quel.) Konrad & Maubl., bears some resemblance to C. minutella because of its small, whitish basidiomata. This North American species, however, differs in having a hygrophanous pileus, four-spored basidia, farinaceous odor, and habitat under conifers. European Clitocybe colina (Velen.) Klan (Klan 1979) is also similar to C. minutella, but the former has a whitish grey to greyish brown pileus, light cream colored lamellae, and four-spored basidia.

References

Bigelow HE (1982) North American species of Clitocybe, part l. Cramer, Vaduz

Harmaja H (1969) The genus Clitocybe (Agaricales) in Fennoscandia. Karstenia 10:5–168

Klán J (1979) Clitocybe collina (Velen.) Klán, a characteristic species of dry non-sylvan communities. Ceská Mykol 33:36–39

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

Takahashi, H. 2003. New species of Clitocybe and Crepidotus (Agaricales) from eastern Honshu, Japan. Mycoscience. 44(2):103-107