ホテイイロガワリ
Boletus ventricosus Taneyama & Har. Takah., Mycoscience Volume 54:458-468, 2013
(Available online 25 April 2013: http://www.sciencedirect.com/science/article/pii/
MycoBank no.: MB564207
Etymology: from Latin, ventricosus referring to the ventricose stipe.
Mature basidioma (TNS-F-44612). Bar 20 mm. 種山裕一氏撮影
Vertical section of the mature basidioma (TNS-F-44612). Bar 20 mm. 種山裕一氏撮影
Figs. 13-21 Micromorphological features of B. ventricosus (Holotype): 13 Elements of the
pileipellis. 14 Cheilocystidia. 15 Pleurocystidia. 16 Basidia. 17 Basidiospores. 18 Caulobasidia.
19 Caulocystidia from the upper portion of stipe. 20 Caulocystidia from the lower portion of
stipe. 21 Underlying stratum of the stipitipellis forming the reticulum. Bars 13-16 and 18-21
20 μm; 17 10 μm. 原図: 種山裕一氏
生態: アカマツ (Pinus densiflora), ミズナラ（Quercus crispula）, コナラ (Q. serrata)が混交した
林内地上に孤生～散生, 7月～9月.
分布: 日本 (長野, 新潟).
主な形態的特徴:
１）柄は上部を中心に繊細な網目模様を表し, 通常下方に向かって膨大化し, しばしば片膨れ
状を成す.
2) 子実層托は極めて短く (3 mm以下), 黄色～灰橙色を帯びる.
3) 肉は空気に触れると即座に濃く青変する.
4) 柄シスチジアはしばしば複数の隔壁を持ち, 広こん棒形～樽形.
5) 柄の網目を形成する組織につながる実質の層は著しく膨大化した紡錘形～樽形の菌糸細
胞からなる.
所属位置並びに近縁種
ヤマドリタケ型の子実体を形成し, 柄の表面に繊細な網目模様を表し, 管孔内部と同色の
微細な孔口を持つ性質は, 本種がSinger (1986) の分類概念によるアミアシイグチ節 (Section
Appendiculati Konr. & Maubl.) に属することを示唆している. アミアシイグチ節の子実体の類型
は多くの点でウラベニイロガワリ節 (Section Luridi Fr. sensu Singer 1986)と共通するが, 柄の
表面に網目模様を表し, 同時に管孔内部と同色の孔口を併せ持つ分類群はウラベニイロガワ
リ節において知られていない.
ホテイイロガワリと共通する極めて短い子実層托 (3 mm以下)を形成する国内産分類群とし
てニセアシベニイグチB. pseudocalopus Hongo (Hongo 1972; Hongo and Nagasawa 1975;
Nagasawa 1989)が知られている. しかしニセアシベニイグチは通常円柱形の柄を持つこと, 網
目は柄の頂部に限られること, 一般に管孔がやや垂生すること, 嘴状突起を持つ頂部頭状形
の縁シスチジアを形成すること, より小型の柄シスチジアを有すること, そして柄の表皮下層に
位置する実質の菌糸細胞が膨大化しない性質によりホテイイロガワリと区別できる. 中国産B.
dimocarpicola M. Zang & Sittigul from China (Zang et al. 1999; Zang 2006)は極めて短い子実
層托および下部が膨大化した柄を有する性質においてホテイイロガワリに類似するが, 前者は
肉に変色性を欠き, 柄の表面に網目を形成せず, 卵状楕円形の担子胞子を持ち, 子実層托実
質においてキヒダタケ亜型の構造を成し, ムクロジ科の樹木リュウガン (Dimocarpus longan)
の林内に発生する点でホテイイロガワリと異なる.
Macromorphological features:
Pileus (Fig. 11) 90-180 mm in diam, at first hemispherical to convex, becoming plano-
convex, with often undulating, deflexed margin that yields a slightly exceeding pileipellis;
surface glabrous, subviscid when wet, reddish brown (8D5-6) or yellowish brown (5D6)
overall when young, then light brown (7D6) to brown (7E6) or brownish orange (6C6) to
reddish brown (8E6) toward the margin, darker in old specimens, instantly changing to
blackish when bruised, orange (6C8) in KOH and NH4OH. Flesh (Fig. 12) 10-35 mm thick at
the center of the pileus, becoming very thin toward the margin, pastel yellow (3A4) to light
yellow (4A5), instantly changing to deep blue when cut, orange (5A5) in KOH, negative in
NH4OH and Fe(OH)SO4; taste and odor mild or vaguely of Japanese incense. Stipe (Fig. 11)
60-175 × 24-50 mm, usually more or less thickened downwards, often ventricose and
somewhat tapering toward the base or at times subbulbous at the base, central, terete,
solid; surface dry, at first entirely orange red (8A7-8), then becoming reddish brown (8E5 to
9E5) from the base upward, greyish orange (6B6) at the apex, finely reticulate overall or at
least over the upper half by a thin-veined, orange (5A7 to 6A7) reticulum with meshes
subequal (above) to longitudinally elongated (below), instantly changing to deep blue where
handled; basal mycelium yellowish white (4A2). Tubes (Fig. 12) up to 3 mm deep extremely
short in comparison with the thickness of the flesh, adnate or slightly depressed around the
stipe, yellow (3B7) when young, greyish orange (5B7) in aged specimens, instantly changing
to deep blue when exposed, reddish brown (8E6) in KOH, brownish (6E6) in NH4OH; pores 2-
3 per mm, subcircular, concolorous with the tubes, instantly changing to deep blue when
bruised. Spore print olive brown (4E5).
Micromorphological features:
Basidiospores (Fig. 17) (9.1-) 9.6-11.0 (-13.2) × (3.7-) 4.0-4.6 (-5.4) μm (n = 147, mean
length = 10.31 ± 0.69 μm, mean width = 4.32 ± 0.28 μm, Q = (2.0-) 2.3-2.5 (-2.7), mean
Q = 2.39 ± 0.13), inequilateral with a shallow suprahilar depression in profile, subfusoid to
oblong-ellipsoid in face view, with a rounded apex, smooth, yellowish grey (3B2) in water, dull
yellow (3B3) in KOH, inamyloid but infrequently weakly dextrinoid, with slightly thickened
walls (up to 0.5 μm). Basidia (Fig. 16) (24.7-) 26.8-33.0 (-38.3) × (8.6-) 9.1-10.2 (-11.2) μ
m, clavate, pale yellow in KOH, 4-spored; sterigmata (3.2-) 4.3-5.8 (-7.0) × (1.6-) 1.9-2.3 (-
2.7) μm. Basidioles clavate. Cheilocystidia (Fig. 14) abundant, (11.5-) 16.2-25.5 (-31.1) × (5.
9-) 6.7-8.7 (-10.6) μm (n = 55, mean length = 20.88 ± 4.67 μm, mean width = 7.72 ± 1.00
μm), subclavate to narrowly fusoid-ventricose, occasionally 2 septate, smooth, colorless in
water, pale yellow (4A3) in KOH, inamyloid or weakly amyloid, thin-walled. Pleurocystidia (Fig.
15) scattered, (34.4-) 41.1-56.0 (-66.5) × (5.8-) 7.2-10.1 (-11.9) μm (n = 31, mean length
= 48.57 ± 7.45 μm, mean width = 8.63 ± 1.43 μm), narrowly fusoid-ventricose to
subcylindrical, smooth, colorless in water, pale yellow (4A3) in KOH, inamyloid or weakly
amyloid, thin-walled. Hymenophoral trama bilateral-divergent of the Boletus-subtype;
elements in lateral strata 6.2-10.7 μm wide, cylindrical, hyaline in KOH, amyloid; elements in
a mediostratum (3.4-) 4.4-5.6 (-6.3) μm wide, cylindrical, pale yellow (4A3) in KOH, amyloid.
Pileipellis (Fig. 13) made up of matted interwoven elements; constituent hyphae 4-8 μm
wide, cylindrical, infrequently partially nodulose, often embedded in a gelatinous matrix, with
brownish orange (6C8) intracellular pigment in water, orange (5B7) in KOH, inamyloid, thin-
walled; terminal cells (27.8-) 41.5-70.8 (-93.0) × (5.4-) 5.9-8.8 (-12.6) μm (n = 33, mean
length = 56.17 ± 14.64 μm, mean width = 7.33 ± 1.47 μm), subclavate to cylindrical.
Pileitrama of cylindrical, loosely interwoven hyphae (4.2-) 5.2-8.5 (-14.8) μm wide, smooth,
colorless in water, hyaline in KOH, weakly dextrinoid, thin-walled. Stipitipellis hymeniform,
consisting of moniliform sterile cells (caulocystidia) and infrequent caulobasidia which
envelope the entire stipe surface; a lateral stratum of the stipe trama in the reticulum (Fig.
21) well differentiated and perpendicularly arranged to long axis of the stipe trama, (52-) 85-
235 (-340) μm thick, made up of a compact layer of highly inflated fusiform to doliform
hyphal cells (5.9-) 7.8-18.2 (-25.1) μm wide (n = 57, mean width = 13.00 ± 5.16 μm), often
2-3 septate; caulocystidia (19.0-) 22.6-33.8 (-45.3) × (7.8-) 8.3-13.2 (-16.0) μm (n = 29,
mean length = 28.22 ± 5.59 μm, mean width = 10.76 ± 2.42 μm) at the apex of stipe (Fig.
19), (20.3-) 25.2-43.1 (-57.9) × (8.6-) 10.7-16.1 (-19.4) μm (n = 37, mean length = 34.14 ±
8.97 μm, mean width = 13.37 ± 2.71 μm) at the middle portion of stipe, (17.5-) 24.8-40.0
(-46.7) × (8.1-) 10.1-15.9 (-20.6) μm (n = 52, mean length = 32.41 ± 7.60 μm, mean
width = 12.99 ± 2.88 μm) at the base of stipe (Fig. 20), clavate to broadly clavate or
doliform, colorless or with pale orange (5A3) to light orange (5A4-5) contents (in water) in
some terminal cells of the stipe base, brownish in KOH, inamyloid, smooth, thin-walled;
caulobasidia (Fig. 18) (18.7-) 22.9-30.8 (-35.0) × (8.2-) 8.4-9.8 (-10.5) μm, 4-spored. Stipe
trama composed of longitudinally running, cylindrical cells (3.6-) 4.5-8.3 (-11.1) μm wide,
unbranched, smooth, colorless, thin-walled. Clamp connections absent.
Habitat: Solitary to scattered, on ground in lowland mixed forests dominated by Pinus
densiflora Sieb. & Zucc., Quercus crispula Blume and Quercus serrata Murray, July to
September.
Known distribution: Japan (Nagano, Niigata).
Specimens examined: TNS-F-44613 (holotype), Jizoukubo, Iizuna-cho, Kamiminochi-
gun, Nagano Pref., on ground in mixed forest dominated by P. densiflora and Q. serrata, 750
m alt., 27 Jul 2011, coll. Taneyama, M.; TNS-F-44605, the same place, 30 Jul 2008, coll.
Taneyama, M.; TNS-F-44607, the same place, 6 Aug 2009, coll. Taneyama, M.; TNS-F-
44608, the same place, 6 Aug 2009, coll. Taneyama, M.; TNS-F-44610, the same place, 15
Sep 2009, coll. Taneyama, M.; TNS-F-44612, the same place, 27 Jul 2011, coll. Taneyama,
M.; TNS-F-44614, the same place, 30 Aug 2011, coll. Taneyama, M.; TNS-F-44615, the
same place, 27 Aug 2006, coll. Taneyama, Y.; TNS-F-44616, the same place, 16 Sep 2006,
coll. Taneyama, Y.; TNS-F-44617, the same place, 30 Jul 2009, coll. Taneyama, M.; KPM-
NC0022677, the same place, 19 Jul 2012, coll. Taneyama, M.; KPM-NC0022684, the same
place, 3 Aug 2012, coll. Taneyama, M.; KPM-NC0022686, KPM-NC0022687, the same place,
17 Aug 2012, coll. Taneyama, M.; TNS-F-44606, Matsushiro, Nagano-shi, Nagano Pref., on
ground in mixed forest dominated by P. densiflora and Q. serrata, 440 m alt., 18 Jul 2009,
coll. Fujisawa, T.; TNS-F-44609, Kinasa, Nagano-shi, Nagano Pref., on ground in mixed forest
dominated by Q. crispula, 1100 m alt., 26 Aug 2009, coll. Fujisawa, T.; TNS-F-44611, Hida-
iseki Park, Myoko-shi, Niigata Pref., on ground in mixed forest dominated by P. densiflora
and Q. serrata, 70 m alt., 8 Jul 2011, coll. Taneyama, M.
Japanese name: Hotei-irogawari.
Comments: The diagnostic features of this species are the finely reticulate, usually
ventricose or subbulbous stipe, the yellow to grayish orange, extremely short hymenophore,
the strongly cyanescent flesh, the often moniliform, broadly clavate to doliform
caulocystidia, the highly inflated fusiform to doliform hyphal cells in the lateral stratum of
stipe trama forming the reticulum, and the habitat in lowland, mixed forests. Giving
consideration to its boletoid basidiomata with a finely reticulate stipe and minute pores
concolorous with the tubes, B. ventricosus seems to be best accommodated in the section
Appendiculati Konr. & Maubl. sensu Singer (1986). It should be noted that, although its habit
of basidiomata suggests the alliance with the section Luridi Fr. sensu Singer (1986), no
species with a combination of a finely reticulate stipe and pores concolorous with the tubes
has not been known in that section.
Boletus ventricosus is similar to Japanese B. pseudocalopus Hongo (Hongo 1972; Hongo
and Nagasawa 1975; Nagasawa 1989) due to its extremely short tubes, which differs in
forming a usually not bulbous stipe inconspicuously reticulated only at the extreme apex,
typically moderately decurrent hymenophore, sphaeropedunculate cheilocystidia with an
occasional mucro, and much smaller caulocystidia measuring 17-33 × 7.5-12.5 μm (Hongo
and Nagasawa 1975) and non-inflated elements (5.2-9.2 μm wide) in the lateral stratum of
stipe trama (KPM-NC0022688, KPM-NC0022689, KPM-NC0022690). Boletus ventricosus
also has characteristics such as extremely short tubes and a bulbous stipe in common with
B. dimocarpicola M. Zang & Sittigul from China (Zang et al. 1999; Zang 2006). The latter
species, however, differs from the present species in having unchanging flesh, a non-
reticulate stipe, ellipsoid-ovoid basidiospores, Phyllopours-subtype structure of the
hymenophoral trama, and a habitat in Dimocarpus longan forests.
References
Hongo T, 1972. Notulae mycologicae (11). Memoirs of the Faculty of Education, Shiga
University. Natural Science 22: 63-68.
Hongo T, Nagasawa E, 1975. Notes on some boleti from Tottori. Reports of the Tottori
Mycological Institute 12: 31-40.
Nagasawa E, 1989. Boletaceae. In: Imazeki R, Hongo T (eds), Colored illustrations of
mushrooms of Japan II. Hoikusha, Osaka, pp 1-44 (in Japanese).
Singer R, 1986. The Agaricales in modern taxonomy, 4th edn. Koeltz, Koenigstein.
Zang M (ed), 2006. Flora fungorum sinicorum. Boletaceae, vol 22. Science Press, Beijing.
Zang M, Chen SM, Sittigul C, 1999. Some new and interesting taxa of Boletales from tropical
Asia. Fungal Science, Taipei 14: 19-25.