オリーブサカズキタケ

Gerronema nemorale Har. Takah., Mycoscience 41 (1): 16 (2000)

典型的なオリーブサカズキタケは傘が小さく、柄が長いのが特徴で、培養条件下で基質上に白色綿毛状菌糸体が発達することはありますが、菌糸束を形成しません。傘は一般に幼時オリーブ緑色を帯び、後黄色になります。 日本の温帯地域では普通に見られますが、亜熱帯の沖縄ではまだ見たことがありません。温帯に偏った分布域の特性や子実体の類型などから判断すると、北米産 Gerronema strombodesに近縁と思われます。

肉眼的特徴: 傘は径6-15 mm, 最初半球形, のちヒダサカズキ型, 初め平坦であるが間もなく放射状に溝線を表し, 幼時粉状, 埋生繊維状, 幼時オリーブ褐色, のち灰緑色, 老成時鈍黄色, 縁部は時に鋸歯状.　肉は非常に薄く (0.5 mm以下), 淡黄色; 特別な味や匂いはない. 柄は20-40×1-2.5 mm, ほぼ上下同大であるが基部は肥大する, 中心生またはやや偏在性, やせ型, 強靱, 中空, 淡黄色, 全体に小鱗片状; 根本は白色の剛毛状～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 25-35), 幅狭く (0.8-1.2 mm), 薄く, 淡黄色.

胞子紋は白色.　

微鏡的特徴: 担子胞子は8.5-10×5-6 μm, 楕円形～広楕円形, 平坦, 無色, 非アミロイド, 薄壁. 担子器は26-35×5-7 μm, こん棒形, ４胞子性. 縁シスチジアは30-50×4-7μm, 多生し, 不規則な円柱形, 平坦, 無色または淡黄色の内容物を持ち, 薄壁. 側シスチジアはない. 傘の表皮は錯綜した円柱形の菌糸が平行菌糸被をなし, 菌糸細胞は無色または淡黄色の内容物を有し, 薄壁; 傘シスチジアは 15-37×2-8μm, 広こん棒形～頂部頭状形, 傾伏性 (decumbent). 傘実質の菌糸細胞は 70-150×5-10 μm, 並列し, 円柱形, 時に分岐し, 少数の瘤状突起を持ち, 薄壁, 平坦, 無色, 非アミロイド, 厚壁で (1.5 μm) 長い円柱形の細胞 (幅7-11 μm) がしばしば混在する. 柄シスチジアは 25-60×3.5-8 μm, 不規則な円柱形～広こん棒形, しばしば頂部頭状形になり, 上向性. 柄の実質を構成する菌糸は幅 5-13 μm, 円柱形, 無分岐, 平坦, 厚壁(厚さ 1.5 μm), 無色, 非アミロイド. 凝着色素を欠く. 全ての組織にクランプが見られる.

供試標本: CBM-FB-24129 (基準標本), on dead fallen twig in Quercus-Pasania forests, Yamato-shi, Kanagawa-ken, 27 Jun. 1996; CBM-FB-24128, on dead fallen twig in Quercus-Pasania forests, Yamato-shi, Kanagawa-ken,12 May 1994; CBM-FB-24130, on dead fallen twig in deciduous oak forest, Mt.Takao, Hachiouji-shi, Tokyo,10 Aug.1998.

コメント: 全体に鈍黄色～オリーブ灰色を帯びた小型のヒダサカズキ型の子実体を形成する. 南関東において普通に見られ, 広葉樹林内の落枝上から発生.

本種は Gerronema 属 (Sect. Xanthophylla)と Hydropus 属 (Sect. Mycenoides Subsect. Anthidepades) の中間に位置する種類と思われる. 本種の実質にはやや厚壁な菌糸が見られるが, Hydropus 属に一般に見られる様な著しく肥大した (幅 10-30μm) 紡錘形の骨格菌糸 (sarcoskeletals) と異なる点 (本種の実質の菌糸は円柱形で幅 5-13μm) を重視し, 本種をGerronema 属に置いた.

オリ－ブサカズキタケの東南アジア産類似菌の検索表

１. 縁シスチジアを欠く. 　→　２

１. 縁シスチジアを持つ. 　→　４

２. 傘表皮は直立した類こん棒形～類紡錘形の傘シスチジアを持つ. 傘は硫黄色で中央部 は灰褐色. 柄は中心生. 胞子は長楕円形. 5-7.5×3-4μm. ２胞子性. 中米産.

　　　　Gerronema citrinum (Corner) Pegler

２. 傘表皮はシスチジアを持たない. ４胞子性. 　→　３

３. 柄はしばしば偏在生～側生. 胞子は広卵形, 6.5-8×5-7.2μm．傘は硫黄色～芥子色. 中米産.

Gerronema icterinum (Sing.) Sing.

３. 柄は中心生. 胞子は類球形～卵形 6-7×4-5μm. 傘は淡黄色～レモン色 (citrine yellow). 中米産.

Gerronema tenue Dennis

(Gerronema Sect. Romagnesia Subsect. Porpophora Sing.)

４. 傘表皮はシスチジアを持たない. 傘は径10 mm以下, 柄は短形 (3-7 mm). 傘の表面は

淡黄灰色で, 中央部は暗色の繊維紋を表す. 縁シスチジアは不規則な紡錘形で頂部に

糸状の付属糸を持つ. 日本産.

ウスキサカズキタケ Hydropus kansaiensis Clemencon & Hongo

　　　　　　　　　　(Hydropus Sect. Floccipedes Subsect. Floccipedes ニセアシナガタケ亜節)

４. 傘表皮はシスチジアを持つ. 　→　５

５．実質の菌糸細胞は円柱形で通常径 5-13μm. 傘の表面は最初暗灰褐色～オリ－ブ色, のちオリ－ブ灰色～鈍黄色. 傘及び柄の表面は暗色の粉状物を欠く. 柄の根元は白色の長軟毛に被われる. 縁シスチジアは不規則な円柱形. 日本産.

オリ－ブサカズキタケ Gerronema nemorale Har.Takahashi

５. 実質は紡錘形の骨格菌糸(sarcoskeletals)からなり, 骨格菌糸の幅は10-30 μmに達する．

傘の表面は最初暗灰色, のち淡黄色～明るい蜜色. 傘の中央部と柄の表面は暗色の粉状

を呈する. 柄の根元は無毛（？). 縁シスチジアは類紡錘形～こん棒形で, しばしば頂部は糸状に細まる.

(Hydropus Sect. Mycenoides Subsect. Anthidepades) 　→　６

６．傘は径 10-60 mm, ヒダは幅 2-6 mm. マレーシア産.

Hydropus anthidepas (Berk.& Br.) Sing.

(= Trogia anthidepas (Berk.& Br.) Corner; Omphalia anthidepas Berk.& Br.)

６．傘は径 4-23 mm, ヒダは幅 0.5-2 mm. マレーシア産.

Trogia mellea Corner

Gerronema nemorale Har. Takah., Mycoscience 41: 15-23, 2000　　　　　　　　

Etymology: from Latin, nemorale = pertaining to woods; referring to the habitat growing in woodlands.

Pileus 6-15 mm in diam, at first hemispherical, then convex with depressed center, eventually concave or umbilicate, at first smooth but soon radially striate to sulcate, pruinose when young, innately fibrillose- striped, olive brown (4F4-4F6, 4E5-4E7) when young, then greyish green (29E5, 30E5), finally dull yellow (3B4), margin sometimes undulate. Flesh very thin (up to 0.5 mm), pale yellow; odor and taste not distinctive. Stipe 20-40×1-2.5 mm, almost equal but swollen at the base, central or somewhat eccentric, slender, terete, tough, hollow, pale yellow (3A3), furfuraceous overall; base covered with conspicuous white mycelioid bristles. Lamellae arcuate-decurrent, subdistant (25-35 reach the stipe), narrow (0.8-1.2 mm broad), thin, pale yellow; edges fimbriate, concolorous.

Spore print pure white. Basidiospores 8.5-10×5-6 μm, ellipsoid to broadly ellipsoid, smooth, colorless, inamyloid, thin-walled. Basidia 26-35×5-7 μm, clavate, four-spored. Cheilocystidia 30-50×4-7μm, abundant, irregularly cylindric to strangulated, smooth, colorless or with pale yellow contents, thin-walled. Pleurocystidia absent. Hymenophoral trama subregular; element cells 30-150×3-8 μm, cylindric, occasionally branching, with a few knob-like processes, walls thin, smooth, colorless, inamyloid, sometimes intermixed with elongate, cylindric, thick-walled (up to 1.5 μm thick) cells 7-11 μm diam. Pileipellis a cutis of interwoven, repent hyphae with element cells 35-90×2-4.5 μm, cylindric, smooth, colorless or with pale olive-brown to pale yellow contents, thin-walled; terminal cells (pileocystidia) 15-37×2-8μm, broadly clavate to capitulate, decumbent. Elements of pileitrama 70-150×5-10 μm, subparallel, cylindric, occasionally branching, with a few knob-like processes, walls thin, smooth, colorless, inamyloid, sometimes intermixed with elongate, cylindric, thick-walled (up to 1.5 μm thick) cells 7-11 μm diam. Stipitipellis a cutis of parallel, repent hyphae 3-5 μm wide, cylindric, smooth, colorless or with pale yellow contents, thin-walled; terminal cells (caulocystidia) 25-60×3.5-8 μm, irregularly cylindric to broadly clavate, often with capitate apex, ascendant. Stipe trama composed of longitudinally running, thick-walled (up to 1.5 μm thick) cells 5-13 μm wide, cylindric, unbranched, smooth, colorless, inamyloid. Pigment incrustations absent. Clamps present in all tissues.

Known distribution: Japan (Kanagawa, Tokyo).

Habitat: Solitary to caespitose, on dead fallen twigs in lowland forests dominated by Pasania edulis Makino, Quercus myrsinaefolia Blume and Ligustrum japonicum Thunb., from May to October, common.

Holotype: CBM-FB-24129, on dead fallen twig in Quercus-Pasania forests, Yamato-shi, Kanagawa-ken, 27 Jun. 1996.

Other specimens examined: CBM-FB- 24128, on dead fallen twig in Quercus-Pasania forests, Yamato-shi, Kanagawa-ken,12 May 1994; CBM-FB- 24130, on dead fallen twig in deciduous oak forest, Mt.Takao, Hachiouji-shi, Tokyo,10 Aug.1998.

Japanese name: Oriibu-sakazukitake.

Notes: The important combination of features delimiting this species is the relatively small, olivaceous, omphalioid basidiomata with an innately fibrillose pileus, the irregularly

cylindric cheilocystidia, the broadly clavate pileocystidia and caulocystidia with yellow intracellular pigments, and the lignicolous habitat. These characteristics place this species in the genus Gerronema section Xanthophylla Singer (Singer, 1986), where it seems to be allied with several neotropical taxa, viz. Gerronema icterinum (Singer) Singer (Singer, 1948; Pegler, 1983), Gerronema tenue Dennis (Dennis, 1961; Pegler, 1983), and Gerronema citrinum (Corner) Pegler (Corner, 1966; Pegler, 1983). The latter three taxa differ primarily in forming fertile lamella edges without cheilocystidia. Moreover, G. icterinum has veined and forked lamellae, while G. tenue has a citrine yellow pileus and an insititious stipe. Gerronema citrinum also differs in having a relatively larger pileus (20-30 mm in diam.: Corner, 1966) colored greyish brown toward the center and in having much smaller basidiospores (6-7.5×3.5-4 μm: Corner, 1966) associated with two-spored basidia. Gerronema nemorale is also comparable with two Malaysian taxa in having cheilocystidia, viz. “Trogia” anthidepas (Berk. et Broome) Corner (Corner, 1966) and “Trogia” mellea Corner (Corner, 1966). The latter two taxa are distinct in having no olivaceous tones in the pileus surface, fuscous pruinose pileus center and stipe, subclavate or subventricose cheilocystidia, and in lacking mycelial bristles at the base of stipe. Furthermore, T. anthidepas has much larger pileus (10-60 mm in diam: Corner, 1966), and T. mellea forms conspicuous mycelial strands on the substratum.

Literature

Corner, E.J.H. 1966. A monograph of cantharelloid fungi. Ann. Bot. Memoir 2: 1-255.

Corner, E. J. H. 1994. Agarics in Malesia, I. Tricholomatoid. Beih. Nova Hedwig. 109: 1-138.

Dennis, R.W.G. 1961. Fungi Venezuelani: IV Agaricales. Kew Bull. 15: 67-156.

Pegler, D.N. 1983. Agaric flora of the Lesser Antilles. Kew Bulletin Add. Ser. IX. Her Majesty's Stationery Office, London.

Singer, R. 1948. Diagnoses fungorum novorum agaricalium. Sydowia 2: 26-42.

Singer, R. 1986. Agaricales in modern taxonomy, 4th. ed. Koeltz Scientific books, Koenigstein.

Takahashi, H. 2000. Two new species and one new variety of Agaricales from central Honshu, Japan. Mycoscience. 41(1):15-23