クロムラサキニガイグチ

Tylopilus fuligineoviolaceus Har.Takah., Mycoscience 48(2): 97 (2007)

Misapplied name: Tylopilus plumbeoviolaceus ss. Takahashi (1993)

傘は最初暗青紫色を帯びるが, しばしば黒褐色になり, 柄の表面は暗青紫色で頂部に青紫色の繊細な網目を表し (網目を完全に欠くこともある), 肉は苦みがあり, ほとんど変色しないが管孔は空気に触れると徐々に褐色に変わる.

本種はマレーシアと中国(Wu et al. 2016)に分布するTylopilus atripurpureusに外観が類似する。

Tylopilus atripurpureus (Corner) E. Horak, Malayan Forest Records 51: 131 (2011)

Synonymy:

Boletus atripurpureus Corner, Boletus in Malaysia (Singapore): 166 (1972)

肉眼的特徴: 傘は径 40-80 mm, 最初半球形, のち饅頭形～ほぼ平開し, 縁部は最初内側

に巻く; 表面は乾性, やや密綿毛状, 最初全体に濃青紫色, 成熟するとしばしば黒褐色を帯び

る. 肉は厚さ 10 mm, 固くしまり, 白色, 通常空気に触れてもほとんど変色しない; 特別な臭いは

なく, 苦みがある. 柄は 50-80×10-25 mm, ほぼ上下同大または下方に向かってやや太くなり,

中心生, 中実; 表面は乾性, やや密綿毛状～ほぼ平滑, しばしば縦皺を表し, 時に頂部に青紫

色の繊細な網目模様を表し, 暗青紫色を帯び, 根元に向かってやや淡色になり, 頂部は類白

色; 根本は類白色の密綿毛状菌糸体に被われる. 管孔は厚さ 7 mm以下, 直生～やや上生,

幼時白色, のち帯紅色, 空気に触れると徐々に褐色に変わる; 孔口は小型 (2-3 per mm), 類

角形, 縁取りはなく, 傷つけると褐色に変わる.

顕微鏡的特徴: 担子胞子は 7-9×4-4.5 μm [Q = length/breadth: 1.75-2, n = 20 spores

per two specimens], 楕円形～やや紡錘形, 平坦, 帯紅色, 厚壁. 担子器は 10-20×5-7 μm,

こん棒形, ４胞子性. 偽担子器はこん棒形. 縁シスチジアは群生し, 20-35×4-6 μm, 紡錘形～

類紡錘形, 平坦, 無色, 薄壁. 側シスチジアは散生し, 縁シスチジアに似るがやや大型. 傘の上

表皮層は緩く錯綜した菌糸からなる毛状被を形成し, 老成すると不規則に錯綜する; 末端細胞

は円柱形, 幅 3-6 μm, 青紫褐色の色素が液胞内に存在し (vacuolar pigment), 薄壁, 傘シス

チジアはない. 傘実質の菌糸は緩く錯綜し, 円柱形, 幅 4-10 μm, 無色, 薄壁. 柄の実質は縦

に沿って配列した円柱形の菌糸 (幅 4-10 μm)からなり, 無色, 薄壁. 全ての組織において菌

糸はクランプを欠く.

供試標本: KPM-NC0008740 (holotype), Iriuda, Odawara-shi, Kanagawa pref., Sept. 26,

2001, coll.M.Nishimura; same place, July 20, 2000, coll. H.Takahashi; same place, Sept. 10,

1999, coll. H.Takahashi; Yoyogi-kamizono-cho, Shibuya-ku, Tokyo-Metropolis, July 13, 1986,

coll. H.Takahashi; same place, July 19, 1986, coll. H.Takahashi; same place, July 29, 1986, coll.

H.Takahashi; Zushi-shi, Kanagawa pref, July 14, 1985, coll. H.Takahashi.

コメント: 子実体は中型で，苦みがあり，傘は最初暗青紫色を帯びるが, しばしば黒褐色に

なり, 柄の表面は暗青紫色で頂部に青紫色の繊細な網目を表し (網目を完全に欠くこともあ

る), 肉はほとんど変色しないが管孔は空気に触れると徐々に褐色に変わる. 北米産

Tylopilus plumbeoviolaceus (Snell & E.A.Dick) Singer, 沖縄 (西表島)産スミレニガイグチ

Tylopilus obscureviolaceus Har.Takah., 及びブドウニガイグチ Tylopilus vinosobrunneus Hongo

は子実体の色が本種に最も類似しているが，北米産種は管孔が変色せず，担子胞子はより

長形 (10-13×3-4 μm: Bessette et al. 2000)で, 傘の表皮組織において紡錘形の傘シスチジ

アが子実層状被を形成する．スミレニガイグチは, 傘が黒褐色を帯びず, 管孔は変色性を欠

き, 柄は褐色を帯びる. ブドウニガイグチは傘がワイン褐色～赤褐色を帯び, 肉は明らかに赤

変し, 側シスチジアは黄褐色の内容物を有し, 傘の表皮において短い円柱形の細胞が短細胞

被に近い構造を形成する.

東京 (渋谷区代々木神園町), 神奈川県 (小田原市, 逗子市)の照葉樹林内地上に発生.

日本産イグチ科検索表Ⅲ (高橋 1993) においてムラサキニガイグチの和名で T.

plumbeoviolaceus と同定した種類であるが、その後の調査により、別種であることが判明し

た。

Tylopilus fuligineoviolaceus Har.Takah., Mycoscience 48(2): 97 (2007)

Misapplied name: Tylopilus plumbeoviolaceus ss. Takahashi (1993)

Etymology: Latin, fuligineo- (fuligineous-) + -violaceus (violaceous), referring to the color

of basidiomata.

　Pileus 40-80 mm in diameter, at first hemispherical, becoming broadly convex to nearly

plane in age, with inrolled then straight margin; surface dry, subtomentose, at first entirely

deep violet (15E8-16E8) to dark violet (15F8), usually becoming blackish brown overall at

maturity, sometimes almost blackish brown from the outset. Flesh up to 10 mm thick, firm,

white, unchanging or rarely changing to pale brown above the tubes and beneath the pileus

surface when exposed; odor indistinct, taste bitter. Stipe 50-80×10-25 mm, equal or

somewhat enlarged toward the base, central, terete, solid; surface dry, entirely

subtomentose to subglabrous, sometimes longitudinally rugulose, sometimes slightly

reticulated by a thin-veined, purplish reticulum at the apex, deep violet (15E8-16E8) to dark

violet (15F8), often paler toward the base, whitish at the very apex; base covered with

whitish mycelium. Tubes up to 7 mm deep, adnate to slightly adnexed, white when young, dull

pinkish in age, slowly changing to brown when cut; pores small (2-3/mm), subcircular,

concolorous, slowly changing to brown where handled.

　　Basidiospores (n = 122 spores of 5 basidiocarps) 7-9×4-4.5 μm, Q (length/breadth) =

1.75-2.0, ellipsoid to subfusiform, inequilateral with a shallow suprahilar depression in profile,

smooth, pinkish in H2O, thick-walled (up to 1 μm). Basidia 18-20×5-7 μm, clavate, four-

spored. Basidioles clavate. Cheilocystidia gregarious, 20-35×4-6 μm, fusiform to

subfusiform, smooth, hyaline, thin-walled. Pleurocystidia scattered, similar in shape to the

cheilocystidia but lager. Hymenophoral trama divergent, composed of hyphae 4-10 μm

wide, cylindrical, smooth, hyaline, thin-walled. Pileipellis a trichodermium of vertically

arranged, loosely interwoven hyphal elements, with violet brown (in H2O) vacuolar pigment,

thin-walled; terminal cells subcylindrical, 3-6 μm wide, without pilocystidia. Pileitrama

consisting of cylindrical, loosely interwoven hyphae 4-10 μm wide, smooth, colorless, thin-

walled. Stipe trama composed of longitudinally arranged, cylindrical cells 4-10 μm wide,

smooth, colorless, thin-walled. Clamps absent in all tissues.

Known distribution: Kanagawa, Tokyo.

　　Habitat: Solitary to scattered, on ground in broad-leaved forests (dominated by Ardisia

japonica (Thunb.) Blume, C. cuspidata var. sieboldii, Quercus salicina Blume, and Q. acuta

Thunb. ex Murray, July to September.

　Specimens examined: KPM-NC0008740 (holotype), Iriuda, Odawara-shi, Kanagawa pref.,

Sept. 26, 2001, coll.M.Nishimura; same place, July 20, 2000, coll. H.Takahashi; same place,

Sept. 10, 1999, coll. H.Takahashi; Yoyogi-kamizono-cho, Shibuya-ku, Tokyo-Metropolis, July

13, 1986, coll. H.Takahashi; same place, July 19, 1986, coll. H.Takahashi; same place, July 29,

1986, coll. H.Takahashi; Zushi-shi, Kanagawa pref., July 14, 1985, coll. H.Takahashi.

　Japanese name: Kuro-murasaki-nigaiguchi.

　Notes: This species is characterized by its deep violet to blackish brown pileus, the white,

bitter flesh, the brunnescent hymenophore, and the habitat in warm temperate Quercus-

Castanopsis forests.

　　This species is somewhat similar in appearance to T. obscureviolaceus Har.Takah. from

subtropical Japan (Takahashi 2004) and T. vinosobrunneus Hongo from warm temperate

Japan (Hongo 1979). Tylopilus obscureviolaceus forms a persistently dark purple pileus,

unchanging hymenophore, and a brownish stipe. Tylopilus vinosobrunneus is distinct in

forming a light brown to reddish brown pileus, rufescent flesh, pleurocystidia with

ochraceous oily contents, and pileipellis composed of erect chains of short cylindrical

elements.

Tylopilus fuligineoviolaceus might be mistaken also for North American T.

plumbeoviolaceus (Snell & E. A. Dick) Snell & E.A. Dick (Snell 1936; Snell and Dick 1941,

1970; Singer 1947; Smith and Thiers 1971; Grund and Harrison 1976; Wolfe 1986; Bessette

et al. 2000), but can be distinguished, because in the latter the pileus fades to purple brown,

purple grey, brown, dull cinnamon, or tan; the tubes and pores never change in color when

exposed or injured; and according to Wolfe's type study (Wolfe 1986), the pileipellis is a

hymeniform composed of fusoid-ventricose to narrowly fusoid-ventricose pilocystidia.