ムラサキヤマンバ

 Marasmiellus crassitunicatus  Har.Takah. et Degawa, Mycoscience (2006) 47(5): 257-262　 

ダラリと長く垂れた貞子の髪の毛を彷彿とさせる毛髪状菌糸束を伴う謎の妖怪きのこです～((m(|||_゜)m。

菌糸束は落ち葉や材などの基質という栄養物の上に形成された紐状の構造で、栄養素や水分の輸送、吸水、菌糸体の移動および繁殖、基質上のコロニー形成の機能があると考えられています。ムラサキヤマンバの毛髪状菌糸束は菌糸束の中でも極めてユニークな形状を成しており、このような特殊な構造の生態における役割については、まだよく分かっていません。

  肉眼的特徴: 傘は径 2.5-7 mm, ほぼ円形～腎臓形, 最初饅頭形のち平開し, 縁部は最初内側に巻くが成熟すると反り返り, 平坦; 表面は微細な繊維状～密綿毛状, 表面全体が一様に暗赤褐色; 縁部は全縁, 時に波状. 肉は厚さ 0.5 mm以下, 類白色または淡褐色, 強靱, 吸水復元性がある; 特別な味や臭いはない. 柄は 2-5×0.4-0.8 mm, 相対的に短形, ほぼ上下同大または下方に向かってやや細くなり, 偏在生, やせ型, 中空, 強靱; 表面は小鱗片状または繊維状～密綿毛状, 全体に傘より濃い暗赤褐色～暗褐色; 根元に発達した菌糸体は見られない. ヒダは上生～やや垂生, 疎 (柄に到達するヒダは 6-11), 幅 0.9 mm以下, 0-3 の小ヒダを伴い, 時に二股に分岐し, 傘と同色; 縁部は平坦, 同色. 胞子紋は白色.

   顕微鏡的特徴: 担子胞子は 8-11×2.5-3.5 μm (Q = length/breadth: 2, n = 20 spores per two specimens), 類円柱形, 無色, 平坦, 非アミロイド, 薄壁. 担子器は 16-25×5-7 μm, こん棒形, ４胞子性; 偽担子器は紡錘形またはこん棒形. 縁シスチジアは 15-27×5-10 μm, 群生し, 縁部に不稔帯を成し, 類円柱形～類こん棒形, 上部は不規則な分岐物に被われ, 無色, 時に帯褐色, 非アミロイド, 薄壁. 側シスチジアはない. 子実層托実質は平列型; 菌糸は幅 4-8 μm, 円柱形, 暗褐色の顆粒状色素 (アンモニア不溶性)に被覆され, 非アミロイド, 薄壁. 傘の表皮は発達の悪い不連続なラメアレス構造を形成する; 菌糸は緩く錯綜し, 糸状, 幅 3-6 μm,所々瘤状に分岐し, 暗褐色の顆粒状色素 (アンモニア不溶性)に被覆され, 非アミロイド, 薄壁. 傘実質の菌糸は幅 4-7 μm, 円柱形, 平坦, 並列するかまたは不規則に錯綜し, 非アミロイド,無色で色素の凝着は見られない. 柄の表皮は糸状の菌糸 (幅 3-5 μm)が平行菌糸被を成し, 時に瘤状に分岐し, 暗褐色の顆粒状色素 (アンモニア不溶性)に厚く被われ, 非アミロイド, 薄壁; 柄シスチジアはない. 柄の実質は縦に沿って配列した円柱形または紡錘形の菌糸細胞 (40-130×3-15 μm)からなり, 平坦, 無色, 非アミロイド, 細胞壁は著しく厚い (5 μmに達する). 全ての組織において菌糸はクランプを有する.

    分布: 東京都高尾山, 神奈川県, 山口県, 長野県, 茨城県筑波山(？).

  供試標本: KPM-NC0005064, Mt.Takao, Tokyo-Metropolis, on living bark of Abies firma, July 15, 1999, coll. W. Ikeda & H.Takahashi; KPM-NC0005077, same place, August 13,1999, coll. W. Ikeda & H.Takahashi; KPM-NC0006041, same place, July 15, 1999, coll. W. Ikeda & H.Takahashi; KPM-NC0006724, same place, June 15, 2000, coll. H.Takahashi; KPM-NC-0007933, same place, Sept. 18, 2000, coll. H.Takahashi; KPM-NC0008691, same lace, June 24, 2001, coll. H.Takahashi; KPM-NC0012147, same place (but other habitat; on bark of Chamaecyparis, Oct. 26, 2003, coll. H. Hagiwara, S. Ono, H. Murano & Y. Degawa; KPM-NC0012845, Jakuchikyo, Yamaguchi pref., on living bark of Abies firma, Jul. 22, 2000, coll. M. Izawa; KPM-NC0012846, Matsubarako, Koumicho, Nagano pref., on living bark of Carpinus, Aug. 1, 2004, coll. M. Kobayashi; on living bark of Pinus thunbergii Parl., dawara-shi, Kanagawa-ken, June 11, 2005, coll. Y. Degawa.

  コメント: 子実体は全体に暗赤褐色～暗褐色を帯び, 特に柄は濃色. 傘表皮, ヒダ実質, そして柄表皮の菌糸は暗褐色の顆粒状色素に被覆される. 柄の実質は主に隔壁以外の部分が肥大した (紡錘形の) 短い (長さ40-130μｍ) 厚壁菌糸からなる.

  毛髪状菌糸束は子実体と同色で、通常子実体と同時に発生し、不稔性、 15-25×0.025-0.11 mm, 糸状, 柔軟, 柄とほぼ同色, 空中に向かって伸長し, 子実体から独立して基質上に束状の集団を形成し, 外観は変形菌のオオムラサキホコリStemonitis splendens Rostafinski の子実体に似るが, 菌糸束は糸状で変形菌のように子嚢と柄に分化しないため肉眼的に識別は容易である. 不稔性の毛髪状菌糸束の顕微鏡的外層構造は柄の表皮と共通し, 内層を構成する菌糸細胞は 50-200×4-15 μm, 互いに平行に走り, 円柱形または紡錘形, 時に分岐し, 平坦, 無色, 非アミロイド, 薄壁または厚壁 (厚さ 1-5 μm), 菌糸は多数のクランプを有する.

  子実体及び不稔性の毛髪状菌糸束はモミ, ヒノキ, シデ, クロマツなどの生木樹皮に束生する. 東京都高尾山, 神奈川県, 山口県, 長野県で子実体と毛髪状菌糸束の同一基質上における同時発生が確認されている. 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.

  不稔性の毛髪状菌糸束は Stemonitis 属の子実体に類似しているため, 変形菌の分野では 正体不明の菌として以前から問題にされてきた. 毛髪状菌糸束はクランプを有することから, アナモルフ (無性世代)ではないと考えられる.

  不稔性の毛髪状菌糸束については、色素及び解剖学的性質、そしてムラサキヤマンバの子実体と同時発生する生態から判断して、子実体と何らかの関係を持つものと推測されるが、 この不稔性菌糸束の生態における機能と役割及び子実体との同一性については、今のところ不明である.

Marasmiellus crassitunicatus  Har.Takah. et Degawa, Mycoscience (2006) 47(5): 57-262

    Etymology: from Latin, crassi- (thick) + tunicatus (walled), referring to the thick-walled elements of the stipe trama.

  Pileus 2.5-7 mm in diam, orbicular to reniform, convex then applanate with involute then reflexed margin, smooth; surface minutely fibrillose to felty-tomentose, evenly colored dark reddish-brown (8E7-8E8 to 9E7-9E8); margin entire or sometimes undulating. Flesh up to 0.5 mm thick, whitish or pale brownish, tough, reviving; odor and taste not distinctive. Stipe 2-5×0.4-0.8 mm, relatively short, recurved, subequal or somewhat tapering toward the base, strongly excentric, slender, terete, solid, tough; surface furfuraceous to fibrillose-tomentose, dark reddish-brown (9F7-9F8) to dark violet-brown (10F7-10F8); basal mycelium none. Lamellae adnate to adnate-subdecurrent, distant (6-11 reach the stipe), up to 0.9 mm broad, with 0-3 series of lamellulae, sometimes forked, concolorous with the pileus; edges even, concolorous.

  　Spore print white. Basidiospores 8-11×2.5-3.5 μm (Q = length/breadth: 2, n = 20 spores per two specimens), subcylindrical, colorless, smooth, inamyloid, thin-walled. Basidia 16-25×5-7 μm, clavate, four-spored; basidiole fusoid to clavate. Cheilocystidia 15-27×5-10 μm, forming a compact sterile edge, subcylindrical to subclavate, with irregularly branched, apical diverticulae, colorless or sometimes pale brownish, inamyloid, thin-walled. Pleurocystidia none. Hymenophoral trama subregular; element hyphae 4-8 μm wide, cylindrical, encrusted with granules of dark brown pigment which are insoluble in ammonium hydroxide, inamyloid, thin-walled.　Pileipellis a poorly developed and discontinuous Rameales-structure of loosely interwoven, filiform hyphae 3-6 μm wide, with scattered, rod-like or knob-like diverticulae, incrusted with granules of dark brown pigment which are insoluble in ammonium hydroxide, inamyloid, thin-walled. Hyphae of pileitrama 4-7 μm wide, cylindrical, subparallel to interwoven, smooth, colorless, not incrusting, inamyloid, thin-walled. Stipitipellis a cutis of parallel, repent, filiform hyphae 3-5 μm wide, occasionally with scattered, rod-like or knob-like diverticulae, heavily encrusted with granules of dark brown pigment which are insoluble in ammonium hydroxide, inamyloid, thin-walled; caulocystidia none. Stipe trama composed of longitudinally running, cylindrical or fusoid hyphae with cells 40-130×3-15 μm, smooth, colorless, inamyloid, sometimes with a secondary septum (without clamps), with highly thickened walls up to 5 μm. Clamps present in all tissues.

　　Known distribution: Japan (Kanagawa, Nagano, Tokyo, Yamaguchi).

　　Habitat: Densely gregarious or caespitose on the bark of living Abies firma Sieb.et Zucc., Carpinus sp.,Chamaecyparis obtusa Endl., or Pinus thunbergii Parl., in summer season (June to October).

  　Specimens examined: KPM-NC0005064, Mt.Takao, Tokyo-Metropolis, on bark of living Abies firma, July 15, 1999, coll. W. Ikeda & H.Takahashi; KPM-NC0005077, same place, August 13, 1999, coll. W. Ikeda & H.Takahashi; KPM-NC0006041, same place, July 15, 1999, coll. W. Ikeda & H.Takahashi; KPM-NC0006724, same place, June 15, 2000, coll. H.Takahashi; KPM-NC-0007933, same place, Sept. 18, 2000, coll. H.Takahashi; KPM-NC0008691, same place,June 24, 2001, coll. H.Takahashi; KPM-NC0012147, same place (but other habitat; on bark of Chamaecyparis, Oct. 26, 2003, coll. H. Hagiwara, S. Ono, H. Murano & Y. Degawa); KPM-NC0012845, Jakuchikyo, Yamaguchi pref., on living bark of Abies firma, Jul. 22, 2000, coll. M. Izawa; KPM-NC0012846, Matsubarako, Koumicho, Nagano pref., on bark of living Carpinus, Aug. 1, 2004, coll. M. Kobayashi; Aug. 1, 2004, coll. M. Kobayashi; on bark of living Pinus thunbergii Parl., Odawara-shi,Kanagawa-ken, June 11, 2005, coll. Y. Degawa.

　　Notes: The distinctive features of the present species are its dark reddish-brown to violet-brown, orbicular to reniform basidiomata; microscopically the very thick, dark brown incrustation in the cortical layer, and the highly thick-walled, inflating, fusiform hyphal cells of the stipe trama.

  　Its small, dark reddish-brown basidiomata with a strongly eccentric stipe, and its pileipellis consisting of a poorly developed and discontinuous Rameales-structure suggest placement of this species in the subsection Inodermini Singer of the section Marasmiellus in Singer's classification (Singer, 1973, 1986). Within the subsection, M. crassitunicatus  is comparable with two tropical taxa in having purplish brown pileus and lamellae, viz, Marasmiellus goossensiae (Beeli) Pegler (Pegler, 1977, 1986) from East Africa and Sri Lanka, and neotropical Marasmiellus purpureus (Berk.& Curt.) Murrill (Pegler,1983; Singer,1973). The latter two taxa, however, differ in forming a plicate-sulcate pileus, a whitish stipe, and slightly broader basidiospores.

  The species is also well characterized by its habitat; on the bark of living Abies or Carpinus trees. It should be noted that in all cases as far as we examined, the basidiomata were constantly accompanied by tufts of short filiform rhizomorphs of a fungus. This sterile structure is independently produced nearby the basidiomata of the species and having the following morphological features:

  Rhizomorphs 15-25×0.025-0.11 mm, filiform, pliant, violet brown, fasciculate in small clusters, reminiscent of tufted sporangia of Stemonitis splendens Rostafinski (Myxomycetes); external elements 3-5 μm wide, parallel, repent, filiform, heavily encrusted with granules of dark brown pigment which are insoluble in ammonium hydroxide, inamyloid, thin-walled; internal elements 50-200×4-15 μm, parallel, cylindrical or fusoid, sometimes branched, smooth, colorless, inamyloid, thin or thick-walled (1-5 μm), numerous clamps present.

  These morphological characters and growing habits strongly suggest that this tuft of rhizomorphs is produced by M. crassitunicatus.  It seems to have a function as a propagule on the surface of bark. Further critical investigations including cultural or molecular studies, should be needed to prove the continuity between this sterile structure and the basidiomata.