ササノホウライタケ

Marasmius sasicola Har.Takah., Mycoscience (2002) 43:343-350. 　

ヒメホウライタケ節の仲間で、枯れた笹の葉上から発生します。淡褐色～類白色の小型の子実体(傘径 5-10 mm)を形成し, 傘は扇のヒダ状の溝線を表し, ヒダは疎で襟帯を形成し, ヒダの縁部と傘の表皮は箒状細胞からなります。梅雨時、普通に見られますが、微小で目立たないせいかあまり報告例がありません。

肉眼的特徴: 傘は径 5-10 mm, 饅頭形で平開せず, 明瞭な扇のヒダ状の溝線を表し, 乾性,

表面は全体に微細な粒状小鱗片を表すが次第に平滑になり, 最初全体に淡褐色を帯び, のち

周縁から徐々に退色し, 成熟時はほぼ類白色. 肉は非常に薄く (厚さ 0.4 mm以下), 類白色, 弾

力性があり, 強靱, 特別な味や臭いはない. 柄は 2-3×0.3-0.4 mm, 糸状, 中心生, 全体に暗褐

色～黒色, 平滑; 根本に発達した菌糸体は見られない. ヒダは上生～直性, 疎 (柄に到達する

ヒダは 6-8), 時に襟帯を形成し, 幅 2 mm以下, 白色; 縁部は全縁で, 縁取りを欠く.

顕微鏡的特徴: 担子胞子は 8-10×4-5μm, 楕円形, 平坦, 無色, 非アミロイド, 薄壁. 担子

器は不明; 偽担子器は 18-26×6-10 μm, こん棒形. 縁シスチジアは群生し, 縁部に不稔帯を

成し, 傘の上表皮細胞に似るが無色. 側シスチジアはない. 子実層托実質は不規則に配列す

る; 菌糸は傘実質に似る. 傘の上表皮はハリガネオチバタケ型 (Siccus-type) の細胞からなる

子実層状被を形成する; ハリガネオチバタケ型の細胞 (付属糸を除く) は 17-27×7-10μm,

類こん棒形～こん棒形, 頂部に複数の指状付属糸 (2-8×0.5-2μm) を持ち, 細胞壁は赤褐色

で厚さ 1μm以下, 偽アミロイド. 傘実質の菌糸は幅 5-14μm, 一菌糸型, 不規則に配列し, 円

柱形, 偽アミロイド, 隔壁にクランプを持つ, 薄壁. 柄の表皮は円柱形の菌糸 (幅 3-6μm) が平

行菌糸被を成し, 褐色の色素を有し, 非アミロイド, 厚壁 (1μm), クランプを持つ; 柄シスチジア

はない. 柄の実質の菌糸は偽アミロイドでクランプを持つ.

供試標本: KPM- NC0007424, Ikuta-ryokuchi, Kawasaki- shi, Kanagawa-ken, 18 Jun.

2000; KPM-NC0007425, same place, June 19, 2000; KPM-NC0008686 (基準標本), same

place, June 24, 2001; KPM-NC0008687, same place, June 28, 2001; KPM- NC0008688,

same place, July 3, 2001.

コメント: ヒメホウライタケ節　(Section Marasmius) に属し, 淡褐色～類白色の小型の子実

体を形成し, 傘は扇のヒダ状の溝線を表し, ヒダは疎で襟帯を形成し, ヒダの縁部と傘の表皮

は箒状細胞からなる. スリランカ及びインドネシアから知られている Marasmius subconiatus　

Petch は本種に最も近縁と思われるが, 柄の基部が有毛であること, ヒダに襟帯を形成しない

こと, そして淡黄色の縁シスチジアを有するなどの点で異なる. 神奈川県川崎市の枯れた笹の

葉上から発生. 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.

Marasmius sasicola Har.Takah., Mycoscience (2002) 43:343-350. 　　 　

Pileus 5-10 mm in diameter, convex, not expanding to plano-convex, plicate-striate, dry,

dull, minutely granulose overall, glabrescent in age, at first light brown overall, then paler

toward the margin, almost whitish at maturity. Flesh very thin (up to 0.4 mm), whitish, pliant,

tough, odor and taste none. Stipe 2-3×0.3-0.4 mm, wiry, filiform, central, terete, dark brown

to black overall, glabrous; base insititious, without rhizomorphs. Lamellae adnexed to adnate,

distant with no lamellulae (6-8 reach the stipe), sometimes collariate, up to 2 mm broad,

white; edges terete, concolorous.

Basidiospores 8-10×4-5μm [Q = length/breadth: 2, n = 20 spores per two specimens],

ellipsoid, smooth, colorless, inamyloid, thin-walled. Basidia not observed; basidioles 18-26×6-

10 μm, clavate. Cheilocystidia forming a compact sterile edge, similar to the pileipellis

elements but colorless. Pleurocystidia none. Hymenophoral trama irregular; element hyphae

similar to those of the pileitrama. Pileipellis a hymeniform layer of Siccus-type cells, with

smooth, reddish-brown walls up to 1 μm thick, dextrinoid; main cell bodies 17-27×7-10μ

m, clavate to subclavate; setulae 2-8×0.5-2 μm, cylindrical with obtuse apex, rarely

forked. Hyphae of pileitrama 5-14 μm wide, monomitic, irregularly arranged, cylindrical,

dextrinoid, thin-walled, with clamped septa. Stipitipellis a cutis of parallel, repent hyphae 3-6

μm wide, cylindrical, inamyloid, with smooth, brown walls up to 1 μm thick, with clamped

septa; caulocystidia none. Stipe trama composed of longitudinally running, cylindrical hyphae

4-11 μm wide, monomitic, with smooth, colorless walls up to 0.5 μm thick, dextrinoid, with

clamped septa.

Distribution: Japan (Kanagawa).

Habitat: Gregarious on dead fallen leaves of grass bamboo (Sasa sp.) in lowland forests,

June.

Specimens examined: KPM- NC0007424, Ikuta-ryokuchi, Kawasaki- shi, Kanagawa-ken,

18 Jun. 2000; KPM-NC0007425, same place, June 19, 2000; KPM-NC0008686 (holotype),

same place, June 24, 2001; KPM-NC0008687, same place, June 28, 2001; KPM-

NC0008688, same place, July 3, 2001.

Japanese name: Sasa-no-houraitake.

Notes: This species is characterized by its small, pale colored, plicate-sulcate pileus, the

filiform, wiry, blackish stipe, the collariate, distant lamellae, the Siccus-type cheilocystidia

and pileipellis elements, and its habitat on fallen dead leaves of grass bamboo. Its central,

insititious stipe, the collariate lamellae, and its Siccus-type pileipellis elements suggest that

this species belongs in the section Marasmius, subsection Penicillati Singer, as defined by

Singer (1986).

Marasmius subconiatus Petch, originally described from Sri Lanka (Pegler 1986; Petch

1948) and recently reported from Indonesia (Desjardin et al. 2000), is phenetically similar to

M. sasicola. The former species, however, differs in forming a noninsititious stipe and

moderately distant, non-collariate, orange-marginate lamellae bearing pale yellow

cheilocystidia.