バライロウラベニイロガワリ

Boletus rhodocarpus Uehara & Har. Takah., Mycoscience 42: 347-353, 2001　　　　

傘表面は圧着した小鱗片に被われ、は最初類白色～ベージュ色、 のち次第に濃赤色～バラ色を帯びます。柄の表面は通常上部～中部にかけて濃赤色の繊細な網目模様を表します。 コメツガ, シラビソなどの寒温帯性樹林内地上に発生。重度の胃腸障害を引き起こす毒キノコです。

肉眼的特徴: 傘は径 60-110 (150) mm, 最初半球形, のち饅頭形に平開し, 縁部は最初内

側に巻く; 表面は乾性, 滑らか, はじめ絹状, 成熟すると全体が黒褐色の圧着した小鱗片に被

われ, 最初類白色～淡灰褐色, のち次第に赤色～濃赤色を帯び, 傷つくと即座に青変する. 肉

は厚さ10 mm以下, 固くしまり, 淡黄色, 空気に触れると即座に青変したのちゆっくりと褐色に変

わる; 特別な味や臭いはない. 柄は 70-120×14-30 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, 地色は淡黄色, 通常上部に濃赤色の繊細な網目

を表すがしばしば不明瞭になり, 下方に向かって濃赤色の粉状～小鱗片状になり, 触れると即

座に青変したのちゆっくりと褐色になる; 根元は類白色の密綿毛状菌糸体に被われる. 管孔は

深さ -7 mm, 柄の周囲において陥入し, 淡黄色, 空気に触れると即座に青変する; 孔口は小型

(2-3 per mm), 類角形, 濃赤色, 傷つくと即座に青変する.

顕微鏡的特徴: 担子胞子は 11.5-13×4-5 μm [Q = length/breadth: 2.60-2.87], 長楕円

形, 平坦, 蜜色, 厚壁. 担子器は 25-35×8.5-12 μm, こん棒形, ４胞子性. 縁シスチジアは群生

し, 25-32×5-7 μm, 紡錘形, 平坦, 赤色の細胞間色素が存在し, 薄壁. 側シスチジアは散生

し, 形状は縁シスチジアに似るが色素を欠く. 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); 菌糸は幅

3.5-8 μm, 円柱形, 平坦, 無色, 薄壁. 傘表皮の外層 (最上層)は匍匐性の圧着した菌糸から

なり, 原基に近い未熟な段階を除き通常毛状被にはならない; 菌糸は幅 4-8μｍ, 平列し, 円

柱形, 時に褐色の細胞間色素が細胞壁に沈着し, 厚壁 (厚さ1 μm以下). 傘表皮の内層は外

層から明瞭に分化し, 緩く錯綜した円柱形の菌糸 (幅 4-8 μm) からなり, 赤色の細胞間色素

が存在し, 厚壁 (厚さ1 μm以下). 傘の実質は円柱形の緩く錯綜した菌糸 (幅 3-10 μm)から

なり, 平坦, 無色, 薄壁. 柄の表皮は子実層状被をなし, 柄シスチジアが密生して柄の表皮全体

を被う; 柄シスチジアは広こん棒形, 平坦, 赤色の細胞間色素が網目または小鱗片の間に散在

するがそれ以外の部分は無色または淡黄色, 厚壁 (厚さ1 μm以下); 柄の表皮下層は平列し

た匍匐性の菌糸 (幅 2.5-5 μm) からなり, 円柱形, 平坦, 無色または淡黄色, 薄壁. 柄の実質

は縦に沿って配列した円柱形の菌糸細胞 (幅 3.5-10 μm)からなり, 無分岐, 平坦, 無色. 全て

の組織において菌糸はクランプを欠く.

供試標本: KPM-NC0007127 (基準標本), 富士山, 標高 1300-1700m 付近, 山梨県, 2

Sept. 2000, 上原貞美 & 高橋春樹; 同上, 6 Sept. 1988, 上原貞美 & 高橋春樹; 同上, 5 Aug.

1995, S.Uehara & H.Takahashi; 同上, 30 Jul.1998, 上原貞美 & 高橋春樹.

コメント: 子実体は大型で, 傘は最初類白色～ベージュ色, のち次第に濃赤色～バラ色を帯

び, 成熟すると黒褐色の細鱗片を表し, 柄の表面は傘と同色で細鱗片状を呈し, 一般に上部に

繊細な網目模様を表すが, 網目模様は不明瞭なこともある. コメツガ, シラビソなどの寒温帯性

樹林内地上に発生. 分布は日本 (本州中部の亜高山帯, 北海道?). 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. 本種の和名は埼玉きのこ研究会

の上原貞美氏によって命名された. 胃腸障害を引き起こす有毒種と言われている.

Boletus rhodocarpus Uehara & Har.Takah., Mycoscience 42: 347-353, 2001

Pileus 60-110 (150) mm in diam, at first hemispherical, expanding to broadly convex, with

inrolled then straight margin; surface dry, smooth, at first dull silky, then covered overall

with blackish brown, small, appressed scales, ground color whitish to pale grayish brown

when young, then red (10B7-8 to 11B7-8) or deep red (10C8 to 11C8) (under brownish

scales), immediately changing to blue when bruised. Flesh up to 10 mm thick, firm, light

yellow, quickly changing to blue then slowly fading to brownish when cut; odor and taste

indistinct. Stipe 70-120×14-30 mm, subequal or somewhat enlarged toward the base,

central, terete, solid; surface dry, finely reticulated on the light yellow background above by

a thin-veined, deep red (10C8 to 11C8) reticulum, deep red (10C8 to 11C8) pruinose to

furfuraceous toward the base, immediately staining blue where handled and there slowly

discoloring into brownish; base covered with whitish mycelial tomentum. Tubes -7 mm deep,

depressed around the stipe, light yellow, staining blue instantly when cut; pores small (2-3

per mm), subcircular, deep red (10C8 to 11C8), quickly staining blue where handled.

Basidiospores 11.5-13×4-5 μm [Q = length/breadth: 2.60-2.87], inequilateral with a

shallow suprahilar depression in profile, oblong ellipsoid in face view, smooth, melleous, thick-

walled. Basidia 25-35×8.5-12 μm, clavate, four- spored. Basidioles clavate. Cheilocystidia

gregarious, 25-32×5-7 μm, fusiform, smooth, with intercellular high red (9A8 to 10A8)

pigment, thin-walled. Pleurocystidia scattered, similar in shape to cheilocystidia but

colorless. Hymenophoral trama bilateral-divergent of the Boletus subtype; elements 3.5-8 μ

m wide, cylindric, smooth, colorless, thin-walled. Outermost layer of pileipellis consisting of

repent, appressed elements, not trichodermial; constituent hyphae 4-8 um wide, parallel,

cylindric, with intercellular brownish pigment, occasionally incrusting, with brownish walls up

to 1 μm thick. Innermost layer of pileipellis well differentiated from the upper stratum,

made up of loosely interwoven, cylindric elements 4-8 μm wide, with intercellular high red

(9A8 to 10A8) pigment, with high red (9A8 to 10A8) walls up to 1 μm thick. Pileitrama of

cylindric, loosely interwoven hyphae 3-10 μm wide, smooth, colorless, thin-walled.

Stipitipellis hymeniform, consisting of caulocystidia which envelop the entire stipe surface;

caulocystidia broadly clavate, smooth, with intercellular high red (9A8 to 10A8) pigment in

the meshes and squamules, hyaline elsewhere, with walls up to 1 μm thick; underlying

stratum composed of parallel, repent hyphae 2.5-5 μm wide, cylindric, smooth, colorless,

thin-walled. Stipe trama composed of longitudinally running, cylindric cells 3.5-10 μm wide,

unbranched, smooth, colorless. Clamps absent.

Known distribution: Japan (Shizuoka, Yamanashi).

Habitat: Solitary to scattered, on ground in highland (subalpine) forests dominated by

Tsuga diversifolia and Abies veitchii, July to September, common.

Specimens examined: KPM-NC0007127 (holotype), Mt.Fuji, at alt. 1300-1700 m,

Yamanashi-ken, 2 Sept. 2000, coll. S.Uehara & H.Takahashi; the same place, 6 Sept. 1988,

coll. S.Uehara & H.Takahashi; the same place, 5 Aug.1995, coll. S.Uehara & H.Takahashi; the

same place, 30 Jul.1998, coll. S.Uehara & H.Takahashi.

Japanese name: Barairo-urabeni- irogawari (named by Mr. Sadayoshi Uehara).

Notes: This species is characterized by its large, deep red basidiomata, the pileus

covered with small, blackish brown, appressed scales which form a cutis-like structure in the

outermost layer of the mature pileipellis, the finely reticulate stipe, the quick coloration blue

when bruised, and the habitat in subalpine coniferous forests. Its Boletus-habit of

basidiomata with discolorous, minute pores suggests that this species belongs in the section

Luridi Fr. as defined in Singer (Singer, 1986).

Within this section, the beige (only when young) to red, dry pileus and the finely

reticulated, red stipe of B. rhodocarpus are also features of such European taxa as Boletus

rhodopurpureus Smotl. (Alessio, 1985; Breitenbach and Kranzlin, 1991), Boletus

rhodoxanthus (Krombh.) Kallenb. (Alessio, 1985; Breitenbach and Kranzlin, 1991; Singer,

1967), Boletus satanoides Smotl. (Singer, 1967), and Boletus splendidus C. Martin (Alessio,

1985; Breitenbach and Kranzlin,1991). These species differ from B. rhodocarpus mainly in

having a pileus without brownish scales and habitat in hardwood forests. Boletus

rhodocarpus is also similar to two North American taxa: Boletus flammans E.A.Dick & Snell

(Bessette et al., 2000; Dick and Snell, 1965; Grund and Harrison, 1976; Snell and Dick, 1970)

and Boletus rubroflammeus A.H.Sm. & Thiers (Bessette et al., 2000; Smith and Thiers, 1971).

Boletus flammans differs in having a dark red to brick red or reddish brown pileus without

brownish scales and a yellow stipe base. Boletus rubroflammeus differs in having a deep

purplish red pileus without brownish scales and habitat in broadleaved forests.