ヒイロウラベニイロガワリ

Boletus generosus Har. Takah., Trans. mycol. Soc. Japan 29: 15-123, 1988.

肉眼的特徴: 傘は径 6-13 cm, 最初饅頭形のち平開し, 縁部は幼時内巻し且つ管孔側に

やや突出する; 表面は最初乾性のち湿時粘性, 平滑, 最初全体に暗赤色または黄味を帯びた

周縁部に向かってやや退色し, 老成時はより暗色になり, 傷つくと即座に青変し, しばしば傷つ

いた部分が黒変する. 管孔は厚さ 5-15 mm, 柄の周囲において陥入し, 黄色, 空気に触れると

即座に青変するがのち次第に帯褐色になる; 孔口は小型,帯褐赤色-濃赤色, 傷つくと即座に

青変したのちゆっくりと暗褐色または黒褐色に変わる. 柄は 5-9×1-3 cm, 上下同大または根

本に向かってやや太くなり, 中実; 表面は乾性, 全体に帯赤黄色または淡黄色, 触れたり傷つ

いた部分は即座に青変した後褐変し, 通常上部に帯褐赤色の繊細な網目を表し, 網目以外の

部分は帯褐赤色の粉状または小鱗片状; 根本の菌糸体は灰白色. 肉は硬くしまり, 厚く, 帯黄

色, 空気に触れると即座に青変する; 特徴的な味や臭いはない. 胞子紋はオリーブ褐色.

　 顕微鏡的特徴: 担子胞子は 9.5-12×4.5-5.5 μm,下部側面になだらかな凹みがあり (イグ

チ型), 長楕円形, 平坦, 薄壁, 無色または淡い蜜色. 担子器は 25-40×10-15μm，４胞子性.

縁シスチジアは 25-50×9-12 μm，便腹形, 上部は嘴状に長く伸び, 淡赤色の色素を有する.

側シスチジアは縁シスチジアと同形. 子実層托実質はイグチ亜型(Boletus-subtype: 原基は散

開構造. 成熟段階の側層の菌糸は無色 (中層は淡い蜜色～無色) で外側に向かって明瞭に

屈曲し, 著しくゼラチン化するため菌糸は互いに隙間をおいて緩く配列する). 傘の表皮はゼラ

チン化した毛状被からなり, 末端細胞は幅 3-8 μm, 円柱形または狭幅なこん棒形, 細胞壁は

平坦で薄く, 淡赤色の色素を有する. 柄シスチジアは 20-50×7.5-12.5 μm, 紡錘形または便

腹形で上部は嘴状に長く伸び, 帯褐赤色の色素を有する. 柄担子器は 2-4 胞子性. クランプ

を欠く.

　 供試標本: 東京都八王子市高尾山山頂付近のコナラ, クヌギを中心とする広葉樹林内地上

に発生, 31 Aug. 1983, H. Takahashi, TUAT 209; 24 Aug. 1985, H. Matsui & H. Takahashi,

TUAT 505 (holotype); 16 Aug. 1987, H. Takahashi, TUAT 731; 神奈川県津久井郡藤野町陣馬

山のコナラ, クヌギを中心とする広葉樹林内地上に発生, 16 July 1985, H. Takahashi, TUAT

443; 埼玉県秩父郡皆野町美ノ山, 1997年7月27日, 坂本晴雄氏採集, KPM-NC0008734.

コメント: 本種はウラベニイロガワリ節 (sect. Luridi Fr.) に属し, 傘表面および孔口は濃い

暗赤色で, 子実体に傷をつけると即座に青変する性質がある. また傘の表皮は湿ったとき比較

的強い粘性を帯び，柄の表面は黄色地に赤色の細点を密布し，かつ上半分が明瞭な網目に

おおわれる等の性質がある. 本種の発生はややまれで，７月下旬～８月にかけてコナラ─クヌ

ギ林に発生し, 分布は東京都八王子市高尾山, 神奈川県津久井郡陣馬山, 埼玉県秩父郡皆

野町美ノ山, 兵庫県神戸市北区(？). 供試標本は東京農業大学図書館標本部 (TUAT) 及び神

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. 生態写真 (Fig.1.)

は松井英幸氏によって撮影された.

Boletus generosus Har. Takah., Trans. mycol. Soc. Japan 29: 15-123, 1988. Figs.１-3

Pileus 6-13 cm broad, convex, expanding to broadly convex, margin projecting slightly

beyond the tubes and incurved when young; surfaceat first dry then viscid to subglutinous

when wet, glabrous, at first evenly colored deep red (10C8-11C8) to brownish red (10C7)

orsomewhat paler toward the yellowish margin (near 4A6-4A7), when old becoming darker,

and often with blackish stains where injured, immediately changing to blue where bruised.

Veil absent. Tubes 5-15 mm deep, depressed around the stipe, pastel yellow (2A4) to light

yellow (2A5), quickly changing to blue then slowly fading to brownish when cut; pores small, 2

-3 per mm, subcircular, at first brownish red(10C7) to deep red (10C8), reddish yellow (4A6-

4A7) at the pileus margin, becoming almost dark brown when very old, quickly changing

toblue then slowly becoming dark brown or blackish when bruised. Stipe　5-9 cm long, 1-3

cm thick at the apex, subequal or somewhat thickened toward the base (2-4 cm thick),

solid; surface dry, reddish yellow (4A6-4A7) entirely or light yellow (3A5) to deeper yellow

(near 3A6-3A7) toward the apex, becoming brownish red (10C7) from the base when old,

quickly staining blue where handled and there slowlydiscoloring into dark brown or blackish,　

finely reticulated over the upper half or rarely only at the extreme apex by a thin-veined,

brownishred (10C7) reticulum with meshes subequal (above) to longitudinally elongated

(below), pruinose to furfuraceous in addition; basal myceliumsordid gray.　Flesh firm, thick,

yellowish, tinged with brownish red around worm holes, staining blue instantly when cut;

taste mild, odor none.　

Basidiospores olive brown in deposit, 9.5-12×4.5-5.5 μm, inequilateral with a shallow

suprahilar depression in profile, oblong in face view, smooth, thin-walled, hyaline to pale

melleous in KOH; Basidia 25-40×10-15μm，4-spored. Cheilocystidia 25-50×9-12 μm，

ventricose-rostrate with an acute apice, with pale reddish contents turning hyaline to pale

melleous in KOH. Pleurocystidia similar to cheilocystidia. Hymenophoral trama bilateral of

the Boletus-subtype. Pileus cuticle an ixotrichodermium of erect, loosely interwoven,

gelatinous hyphae; terminal cells 3-8 μm broad, cylindrical to narrowly clavate, walls

smooth and thin, with pale reddish contents turning hyaline to pale melleous in KOH;

pileocystidia infrequent, usually occurring over the discal portion of the pileus, 30-50×17-22.

5 μm, sphaeropedunculate to broadly clavate-mucronate, thin-walled, with deep red

contents turning melleous in KOH. Caulocystidia 20-50×7.5-12.5 μm, subclavate，fusoid to

ventricose-rostrate, thin-walled, with brownish red contents turning hyaline to pale melleous

in KOH; caulobasidia 2-4 spored. Clamp connections absent.

Specimens examined: On ground in Quercus serrata-Quercus acutissima forests, Mt.

Takao, Hachiouji, Tokyo, 31 Aug. 1983, H. Takahashi, TUAT 209; 24 Aug. 1985, H. Matsui & H.

Takahashi, TUAT 505 (holotype); 16 Aug. 1987, H. Takahashi, TUAT 731; on ground in

Quercus serrata-Quercus acutissima forests, Mt. Jinba, Tsukui-gun, Kanagawa, 16 July

1985, H. Takahashi, TUAT 443; Yoshino-yama, titibu-gun, Saitama, 27 Jul. 1997, H.

Sakamoto, KPM-NC0008734.

　　Known distribution: Eastern Japan (Tokyo, Kanagawa, Saitama).

Boletus generosus is characterized by the deep red to brownish red color of the pileus

and pores, the viscid pileus cuticle composed of an ixotrichodermium, the reddish yellow,

finely reticulate stipe, the quick change to blue when bruised or injured and the habitat in

deciduousoak forests.

It belongs to the sect. Luridi Fr. and comes very close to Boletus flammans Dick & Snell

(1965; Grund and Harrison, 1976; Snell and Dick,1970; Weber and Smith, 1985), Boletus

rubroflammeus Smith and Thiers (1971) and Boletus frostii Russell apud Frost (1874; Smith

and Thiers, 1971; Weber and Smith, 1985), the three from North America. B. flammans has a

more redder stipe and lacks distinct viscidity in the pileus cuticle (Dr. N. S. Weber, personal

communication). Moreover, the invariably habitat under conifers and the basidiospores　

which　are　significantly　narrower (3.8-4.8µm,　mostly 4.1-4.4µm: Dick and Snell, 1965)

distinguish it from B. generosus.　B. rubroflammeus differs in having a non-viscid pileus and

deep purplish red color in both the pileus and stipe.　B. frostii is distinct in having much

longer basidiosporesand a rather strongly lacunose-reticulate stipe.　B. generosus also

appears to be closely related to Boletus dupainii Boudier (1902; Alessio, 1985; Leclair and

Essette, 1969; Marchand, 1973; Singer, 1967) from Europe and Boletus rubroglutinosus

Corner (1974) from Sarawak because of the red color and the viscid pileus. The latter two

species, however, are typically non-reticulate in the stipe and has intensely redder colors in

the basidiocarps.　Furthermore the basidiospores are larger in B.dupainii and somewhat

narrower in B. rubroglutinosus.

　 Mr. M. Aoki first collected this fungus in Mt.Takao, Tokyo in 1979 and gave a Japanese

name,“Hiiro-urabeni-irogawari".