タイシャアシナガタケ(代赭足長茸)

Mycena fuscoaurantiaca Har. Takah.,Mycoscience (2007) 48: 342-357.

傘と柄は代赭色(くすんだ黄赤)を呈します。晩秋(11月)、落枝上から発生。

肉眼的特徴: 傘は径 8-11 mm, 最初釣り鐘形, のちやや饅頭形に平開し, 放射状の溝線を

表し, やや吸水性, 湿時半透明の条線を表し, 乾性, 初め白色粉状, のち平滑になり, 中央部

は暗褐色, 周縁部に向かって褐色～帯褐橙色 (代赭色, くすんだ黄赤, RGB値＝ #B4532A) を

呈する.　肉は傘の中央部において厚さ 0.5 mm 以下, 白色, 特別な味や臭いはない. 柄は 30-

60×0.5-0.8 mm, 円柱形, 中心生, やせ型, 中空, 乾性, 最初白色粉状, のち平滑になり, 全体

に橙色～帯褐橙色を帯び, 根本は白色の剛毛に被われる. ヒダは上生し, 疎 (柄に到達するヒ

ダは 16-18), 幅 1.8 mm以下, 淡褐色, 縁部は粉状, 縁取りを欠く.

顕微鏡的特徴: 担子胞子は 9-10.5×6-7 μm, 短楕円形, 表面は平坦, 無色, 弱アミロイド,

薄壁. 担子器は 19-30×7-9 μm, こん棒形, 2胞子性. 縁シスチジアは 25-47×3-20 μm, 群

生し, 片脹れ状紡錘形, 平坦, 無色～淡紫色, 薄壁. 側シスチジアは 27-75×5-20 μm, 散生

し, 色と形状は縁シスチジアと同様. 子実層托実質の菌糸は偽アミロイド. 傘の上表皮層の菌

糸は匍匐性で, 幅 2-7μm, 平行に配列し, 円柱形, 疣状～短指状突起に被われ, 淡褐色～褐

色, 薄壁. 上表皮下層の菌糸は無色, 実質の大部分は偽柔組織状 [pseudoparenchymatous:

著しく肥大し, 複数の隔壁を持った短形の菌糸細胞] で, 菌糸は平列 し，偽アミロイド. 柄表皮

の菌糸は平坦, 淡褐色～褐色. 菌糸はクランプを欠く.

供試標本: KPM-NC0008698 (holotype), Ikuta-ryokuchi, Kawasaki-shi, Kanagawa pref., 30

Nov. 2000, coll. H.Takahashi; same place, 13 Nov. 1999, coll. H.Takahashi; same place, 23 Nov.

2000, coll. H.Takahashi.

コメント: 傘と柄は代赭色(くすんだ黄赤)を呈し, 担子胞子は弱アミロイド, 縁シスチジアと側シ

スチジアは片脹れ状紡錘形で平坦, 傘の表皮組織は多分枝菌糸が存在するが柄表皮の菌糸

は平坦で, 菌糸はクランプを欠く. 晩秋の頃 (11月), 神奈川県川崎市生田緑地の広葉樹林内

の落枝上に発生. 標本は神奈川県立生命の星・地球博物館 (KPM) の標本庫に登録, 収蔵さ

れている.

本種は Maasの分類概念 (Maas 1980, 1988a) による アクニオイタケ節 (section

Fragilipedes) に属し, 北米産 Mycena subfusca A.H. Sm. (Maas 1988c; Smith 1947)に近縁と思

われるが, 北米産種は紡錘形～こん棒形の縁シスチジア及びこん棒形～不規則な形状の柄シ

スチジアを有し, 側シスチジアを欠く.

Mycena fuscoaurantiaca Har. Takah., Mycoscience (2007) 48: 342-357.

　 Etymology: From Latin, fusco - (dark-) ＋ aurantiaca (orange yellow), referring to the

color of basidiomata.

Pileus 8-11 mm in diam, conico-convex to campanulate, then plano-convex in age,

radially sulcate-striate almost to the disc, subhygrophanous, dry, minutely white pruinose at

first, soon glabrescent, evenly colored brown (6D7-8 to 6E7-8) to brownish orange (6C7-8)

when young, with a somewhat darker (6F6-8) disk, fading to paler toward the margin with

age. Flesh up to 0.5 mm, white; odor and taste not distinctive.　Stipe 30-60×0.5-0.8 mm,

cylindrical, central, slender, terete, hollow, dry, orange (6B7-8) to brownish orange (6C7-8)

over the entire length, at first entirely white pruinose, glabrescent in age; base white strigose.

　Lamellae adnexed, distant (16-18 reach the stipe), up to 1.8 mm broad, thin, pale brownish;

edges pruinose, concolorous.

　Basidiospores (n = 88 spores of 5 basidiocarps) 9-10.5×6-7 μm, Q (length/breadth) =

1.5, short ellipsoid, smooth, colorless, weakly amyloid, thin-walled.　Basidia 19-30×7-9 μm,

clavate, two-spored. Basidioles clavate.　Cheilocystidia 25-47×3-20 μm, abundant,

forming a sterile lamella edge, fusoid-ventricose with prolonged obtuse apex, smooth,

colorless or pale vinaceous, thin-walled. Pleurocystidia 27-75×5-20 μm, scattered, similar

in shape and color to the cheilocystidia.　Hymenophoral trama regular; element hyphae 10-

22 μm wide, cylindrical, often somewhat inflated, walls thin, smooth, colorless, dextrinoid.　

Pileipellis a cutis of parallel, repent hyphae 2-7 μm wide, cylindrical, smooth or covered

with scattered, warty or finger-like diverticulae, thin-walled, brownish; underlying hyphae

parallel, hyaline, dextrinoid, with short and inflated cells up to 34 μm wide.　Stipitipellis a

cutis of parallel, repent hyphae 2-4 μm wide, cylindrical, smooth, brownish, thin-walled.　

Stipe trama composed of longitudinally running, cylindrical hyphae 8-20 μm wide, smooth,

colorless, dextrinoid.　The strigose hairs at the base of stipe 2-6 μm wide, arising directly

from the stipitipellis, repent or erect, cylindrical, with rounded apex, sometimes flexuous,,

smooth, colorless, thin-walled. Clamp connections absent in all tissues.

Known distribution: Japan (Kanagawa).

　 Habitat: Solitary to scattered on dead fallen twigs in lowland forests dominated by

Carpinus tschonoskii Maxim. and Quercus myrsinaefolia Blume, November.

　 Specimens examined: KPM-NC0008698 (holotype), Ikuta-ryokuchi, Kawasaki-shi,

Kanagawa pref., 30 Nov. 2000, coll. H.Takahashi; same place, 13 Nov. 1999, coll. H.Takahashi;

same place, 23 Nov. 2000, coll. H.Takahashi.

Japanese name: Taisha-ashinagatake.

Notes: This species is characterized by its glabrescent, brownish orange pileus and

stipe, the weakly amyloid basidiospores, the smooth, fusoid-ventricose cheilocystidia and

pleurocystidia with prolonged obtuse apex, the diverticulate pileipellis elements, and the

absence of clamp connections. These features suggest that this species belongs in the

section Fragilipedes (Fr.) Quel., as defined by Maas Geesteranus (Maas Geesteranus 1980,

1988a). Within the section, North American M. subfusca A.H. Sm. (Smith 1947; Maas

Geesteranus 1988c) seems to be closely related with M. fuscoaurantiaca. The former

species, however, differs in having fusiform to broadly clavate cheilocystidia without a

narrow neck, clavate to irregularly shaped caulocystidia, and lacking pleurocystidia.