キヒダサカズキタケ
Hydropus aurarius Har. Takah., Mycoscience 43 (5): 399 (2002) [MB#489168]
カヤタケ型の子実体を形成する中型種で, 暗褐色の小鱗片に被われた傘と柄からなり, 鮮黄色のヒダを持ちます。 ニセアシナガタケ属(Hydropus)は傘表皮組織がしばしば不連続な子実層状被をなし、実質は紡錘形の骨格菌糸を有する性質があります。 属内では紡錘形の骨格菌糸を持つ点で熱帯産Hydropus anthidepas 近縁種群に近いと思われます。広葉樹の材から単生～散生し, 神奈川, 宮城, 栃木に分布し、地球博物館がある小田原市入生田が基準産地です。
黄色の色素を持つ点で欧州産 Chrysomphalina chrysophylla に外観が似ていますが、キヒダサカズキタケは実質が紡錘形の骨格菌糸と原菌糸からなる (*Sarcodimitic) 点で欧州産種と異なります。
写真のサンプルは培養条件下で発生したため、子実体の類型が自然環境下のものと多少異なります。
Kanagawa pref. 2000
A Basidiospores. B Basidium and basidiole. C Elements of the pileipellis. D Caulocystidia. All figures from the holotype. Bars 10µm.
肉眼的特徴: 傘は径 20-35 mm, 最初半球形のち漏斗型になり, 通常暗褐色を帯びた鈍頭の中丘を持つ; 表面は平坦, 黄色の地に暗褐色の粒状細鱗片に密に被われる. 肉は厚さ 1.5 mm 以下, 淡黄色, 特別な味や臭いはない. 柄は 50-70×4-5.5 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, しばしば縦皺を表す; 表面は黄色の地に暗褐色の粒状細鱗片に密に被われ, 根本に顕著な白色綿毛状菌糸体が存在する. ヒダは垂生し, やや疎 (柄に到達するヒダは 35-38), 幅 2.5 mm 以下, 鮮黄色を呈し, 縁部は同色. 胞子紋は白色.
顕微鏡的特徴: 胞子は 5-6.5×2.7-3.2 μm, 楕円形, 平坦, 無色, 非アミロイド, 薄壁. 担子器は 25-30×5-6 μm, こん棒形, ４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. 傘表皮の菌糸は平行菌糸被を形成し, 幅 3-8 μm, 円柱形, 平坦, 無色または黄褐色, 薄壁, 時にクランプが見られる; 傘シスチジアは 20-40×4-8μm, 類円柱形, 傾伏性, 時に密集し, 黄褐色の液胞を持つ. 柄シスチジアは 30-50×5-7 μm, 類こん棒形, 黄褐色の液胞を持つ. 実質の菌糸はしばしば隔壁にクランプを持ち, 紡錘形の骨格菌糸を有する (*Sarcodimitic).
コメント: 本種の粒状鱗片を形成する上表皮層はシスチジア形の末端細胞が断続的にやや密集した構造を成すため, Sect. Mycenoides Subsect. Anthidepades に置くのが妥当と思われる.
ニセアシナガタケ属 (Hydropus) の特徴は Singer (1986) の分類概念におけるヒナノヒガサ属 (Gerronema)に類似するが, ヒナノヒガサ属は一般に表皮組織に暗色の色素を欠き, 実質の菌糸構成は一菌糸型になる.
* Sarcodimitic: dimitic な菌糸構成における細い円柱形の骨格菌糸が肥大した (径 10-30μｍ) 紡錘形の骨格菌糸 (図E. sarcohyphae: sarco- = flesh) に置き換わった構造.
Hymenogloea, Hemimycena, Mycena, Hydropus 等の軟質菌に広く見られる. 一方 Lentinus の様な dimitic な菌糸構成を 持つ分類群は,骨格菌糸が肥大していないため, 肉の質が硬く, 強靱になる.
Sarcodimiticを構成する菌糸 (Corner 1966)
Hydropus aurarius Har.Takah., Mycoscience (2002) 43:397-403
Pileus 20-35 mm in diameter, at first hemispherical, then convex with depressed center, usually with a dark brownish, obtuse umbo, smooth, covered overall with minute, dark brown, fibrillose-floccose particles which crowd toward the disk, yellowish under dark brown particles. Flesh up to 1.5 mm, pale yellow; odor and taste not distinctive. Stipe 50-70×4-5.5 mm, almost equal or somewhat thickened toward the base, central, slender, terete, hollow, often entirely longitudinally rugulose, dark brown furfuraceous overall on the yellowish background; base covered with conspicuous white mycelioid tomentum. Lamellae arcuate-decurrent, subdistant (35-38 reach the stipe), with 1-3 series of lamellulae, up to 2.5 mm broad, yellow (3A7-8); edges concolorous.
Spore print pure white. Basidiospores 5-6.5×2.7-3.2 μm [Q = length/breadth: 1.8-2.0, n = 20 spores per two specimens], ellipsoid, smooth, colorless, inamyloid, thin-walled. Basidia 25-30×5-6 μm, clavate, four-spored. Cheilocystidia and pleurocystidia absent. Hymenophoral trama regular; hyphae similar to those of the pileitrama but with vivid yellow (3A8), intercellular, coagulate pigments. Pileipellis a cutis of cylindrical cells 3-8 μm wide, smooth, colorless or with yellowish brown (5E6-7 to 5F6-7) contents, thin-walled, occasionally with clamped septa; pileocystidia 20-40×4-8μm, subcylindrical, decumbent, sometimes aggregate, with yellowish brown (5E6-7 to 5F6-7), vacuolar pigments. Hyphae of pileitrama 3-25 μm wide, parallel to the pileipellis elements, sarcodimitic, intermixed with filamentous, short hyphae and very long, strongly inflated, unbranched, subfusiform hyphae, colorless, inamyloid, thin-walled, occasionally with clamped septa. Stipitipellis a cutis of parallel, repent hyphae 3-8 μm wide, cylindrical, colorless or pale yellow, inamyloid, thin-walled, occasionally with clamped septa; caulocystidia 30-50×5-7 μm, subclavate, smooth, with yellowish-brown (5E6-7 to 5F6-7), vacuolar pigments, thin-walled. Hyphae of stipe trama 5-18 μm wide, longitudinally running, sarcodimitic, very long, strongly inflated, unbranched, subfusiform to cylindrical, smooth, colorless or pale yellow, inamyloid, thin- or slightly thick-walled, occasionally with clamped septa.
Known distribution: Japan (Kanagawa, Miyagi, Tochigi).
Habitat: Solitary to scattered, on fallen dead twigs in lowland oak forests.
Specimens examined: KPM-NC0006727 (holotype), Iriuda, Odawara-shi, Kanagawa-ken, July 2, 2000, coll. H.Takahashi; the same place, Aug. 21, 2000, coll. H.Takahashi; the same place, Sept. 5, 2000, coll. H.Takahashi; KPM-NC0008684, Ryuoukyo, Fujiwara-cho, Tochigi-ken, Aug. 25, 2001, coll. Y.Shibata; KPM-NC0008685, Mt.Aoba, Sendai-shi, Miyagi-ken, Aug. 5, 2001, coll. Y.Goto & Y.Ando.
Japanese name: Kihida-sakazukitake.
Notes: The important combination of features delimiting this species is its clitocyboid basidiomata with a dark brown furfuraceous pileus and stipe, the vivid yellow lamellae, the relatively small basidiospores, the sarcodimitic trama, and its habitat on a fallen dead twig.
The presence of sarcodimitic tramal hyphae suggests that this species belongs in the genus “Trogia" as defined by Corner (1966). However, because of the too wide concept, I do not accept the generic circumscription of “Trogia" (sensu Corner). Its clitocyboid habit and vivid yellow lamellae has superficial resemblance to the genus Gerronema (Singer 1986) which differs in having mostly filamentous, monomitic tramal hyphae and usually lacking fuscous pigments in the terminal elements of the pileipellis and stipitipellis.
This species seems to be allied with several neotropical taxa, viz. Hydropus citrinus Singer (Singer 1982), Hydropus xanthosarx Singer & Grinling (Singer and Grinling 1967),
Gerronema icterinum (Singer) Singer (Pegler 1983), and “Trogia” citrina Corner (Corner 1966). Hydropus citrinus and H. xanthosarx differ in forming cheilocystidia and having a
glabrous pileus and stipe. Gerronema icterinum and T. citrina primarily differ in having a glabrescent pileus and stipe colored sulphur yellow to mustard yellow. Moreover, T. citrina has two-spored basidia. Hydropus aurarius is also similar to “Trogia" straminea Corner (1966) from Singapore which differs in having pale ochraceous lamellae, much larger basidiospores, and ventricose- lanceolate pileocystidia that form palisadoderm in the pileipellis.
References
Corner EJH (1966) A monograph of cantharelloid fungi. Ann Bot Mem 2:1–255
Pegler DN (1983) Agaric flora of the Lesser Antilles. Kew Bull Addit
Ser IX. Her Majesty’s Stationery Office, London
Singer R (1982) Hydropus (Basidiomycetes-Tricolomataceae-Myceneae). Flora Neotrop Monogr 32:1–153
Singer R (1986) The Agaricales in modern taxonomy, 4th edn. Koeltz, Koenigstein
Singer R, Grinling K (1967) Some Agaricales from the Congo. Persoonia 4:355–377
Takahashi, H. 2002. Two new species and one new combination of Agaricales from Japan. Mycoscience. 43(5):397-403