Content uploaded by Takahito Kobayashi
Author content
All content in this area was uploaded by Takahito Kobayashi on Jun 12, 2018
Content may be subject to copyright.
Mycoscience (2002) 43:411–415 © The Mycological Society of Japan and Springer-Verlag Tokyo 2002
FULL PAPER
Takahito Kobayashi
Type studies of the new species of
Pluteus
described by Seiya Ito and
Sanshi Imai from Japan
Received: February 20, 2002 / Accepted: August 1, 2002
Abstract Five species of the genus Pluteus described by S.
Ito and S. Imai, and two species of Pluteus described by S.
Imai alone, have been revised. Six type specimens of these
species are preserved in SAPA, and the author has con-
firmed that they belong to the genus Pluteus. Metuloids
were observed from P. daidoi and P. horridilamellus.
Pluteus daidoi, having a cutis type of pileipellis, belongs to
section Pluteus. Pluteus horridilamellus has a hymeniform
pileipellis. A new section, Pluteus sect. Horridus, character-
ized by its metuloids with a thick wall and acute apex, is
established for P. horridilamellus. Also, the type collections
of Pluteus bulbosus, P. machidae, P. okabei, and P.
verruculosus were studied.
Key words Agaricales · Japan · Pluteaceae · Pluteus · Type
study
Introduction
Imai established a large number of new taxa belonging to
the Agaricales (Nagasawa 1982). For the genus Pluteus Fr.,
collaborating with Ito, Imai described five new species from
the Bonin Islands, namely Pluteus horridilamellus, P.
okabei, P. machidae, P. daidoi, and P. verruculosus (Ito
and Imai 1940). From Hokkaido, Pluteus bulbosus and P.
macrosporus were established by Imai (1938). I searched
the holotypes of these species and found five type speci-
mens collected from Bonin Islands and one type specimen
collected from Hokkaido, namely P. bulbosus, kept in
SAPA.
T. Kobayashi (*)
Systematic Botany, Northern Bioresources and Ecology, Graduate
School of Agriculture, Hokkaido University, North 9, West 9, Kita-
ku, Sapporo, Hokkaido 065-8589, Japan
Tel. 81-11-706-3742; Fax 81-11-706-4508
e-mail: tkobayas@museum.hokudai.ac.jp
Materials and methods
All specimens cited in this paper are deposited in the her-
barium of the Hokkaido University Museum (SAPA). For
microscopic observations, dried specimens were rehydrated
in 10% NH4OH. Length measurements excluded the
apiculus for spores. The abbreviation Q is the ratio of spore
length to spore width.
Taxonomy
Pluteus bulbosus S. Imai, J. Fac. Agric. Hokkaido Imp.
Univ. 43:162, 1938. Fig. 1
Spores 6.0–8.5 5.0–7.0µm, on average 6.7 5.9 µm, Q
1.1–1.2, globose to broadly ellipsoid, surface smooth,
slightly yellow to slightly pink, thick-walled. Pleurocystidia
56–94 12.0–28.8µm, narrowly ventricose, ventricose to
fusiform, sometimes with a long neck, thin-walled, almost
hyaline to slightly yellow. Caulocystidia descending to base,
ventricose, with a short neck, thin-walled, almost hyaline to
slightly yellow, sometimes with yellowish-brown content at
upper part, scanty.
Collection examined: Japan, Hokkaido: Province
Ishikari, Nopporo, on rotting wood in woods, autumn, leg.
S. Imai, no. 348 in SAPA: holotype.
Imai (1938) placed P. bulbosus in the section Pruinosi
S. Imai (a synonym of section Celluloderma Fayod) on the
basis of its pruinose pileus surface. I could not confirm its
pileipellis structure, however, because the type specimen
was in poor condition. Pluteus boudieri P.D. Orton is close
to P. bulbosus because of the bulbous base of its stipe, but
the former has a whitish to pinkish pileus margin. Pluteus
plautus (Weinm.) Gillet is similar to P. bulbosus, and the
former is the same as P. boudieri, according to Vellinga
and Schreurs (1985). However, P. plautus differs from P.
bulbosus and P. boudieri by virtue of the translucently stri-
ate surface of its pileus.
412
Pluteus daidoi S. Ito & S. Imai, Trans Sapporo Nat. Hist.
Soc. 16:47, 1940. Fig. 2
Spores 7.0–9.0 6.5–7.5µm, on average 7.9 7.0 µm, Q
1.1–1.2, subglobose to broadly ellipsoid, surface smooth,
pale yellow, thick-walled. Pleurocystidia as metuloids 68–88
14.4–28.8µm, ventricose to fusiform, with four apical
hooks, thick-walled, almost hyaline to slightly yellow.
Caulocystidia not observed. Pileipellis a cutis, duplex,
with the uppermost layer up to 45µm thick, composed of
subregular to regular hyphae, 3.0–6.0µm in diameter,
almost hyaline to grayish-brown, the subtending layer up to
221µm thick, composed of subregular hyphae 5.5–7.5µm in
diameter, almost hyaline to pale yellow, with horizontally
ellipsoid holes. Clamp connections not observed.
Collection examined: Japan, Tokyo: Bonin Islands, Hah-
ashima, Okimura, Kuwanokiyama, on the ground in woods,
Nov. 20, 1936, collected by K. Daido, in SAPA: holotype.
I could not observe basidia and cheilocystidia because
the specimen was in poor condition.
Pluteus daidoi belongs to the section Pluteus ( section
Fibrillosi S. Imai). Pluteus daidoi is related to Pluteus
atricapillus (Batsch) Fayod [ P. cervinus (Schaeff.) P.
Kumm.], but the former has olive-brown fibrils at margin
of its pileus, and it lacks brown fibrils on the surface of its
stipe. Murrill (1911) established Pluteus harrisii Murrill as
“cystidia none.” However, Banerjee and Sundberg (1995)
found thick-walled pleurocystidia with versiform apical pro-
jections in the holotype of P. harrisii. Thus, P. harrisii is
close to P. daidoi. However, P. harrisii is different from the
latter in having irregular hooks on its pleurocystidia and a
trichodermal pileipellis.
Pluteus horridilamellus S. Ito & S. Imai, Trans. Sapporo
Nat. Hist. Soc. 16:46, 1940. Fig. 3
Spores 5.0–6.5 3.8–5.0µm, on average 5.8 4.3 µm, Q
1.1–1.5, subglobose to broadly ellipsoid, surface smooth,
slightly violet to pale violet, thick-walled. Pleurocystidia as
metuloids 77–94 19.9–29.5µm, ventricose to fusiform,
with an acute apex usually, without hooks, thick-walled,
filled with slightly brown pigment, rather scanty. Thin-
Fig. 1. Pluteus bulbosus S. Imai. A Spores. B Pleurocystidia.
C Caulocystidia of lower stipe. Bars A 10 µm; B, C 20 µm
Fig. 2. Pluteus daidoi S. Ito & S. Imai. A Spores. B Pleurocystidia. Bars
A 10 µm; B 20µm
413
walled pleurocystidia also present, 74–84 20.4–25.2 µm,
fusiform to ventricose, slightly yellow or filled with slightly
brown pigment, abundant. Cheilocystidia as metuloids 48–
95 9.6–16.8µm, fusiform to narrowly ventricose, with
an acute apex, sometimes with a pedicellate base, without
hooks, thick-walled, sometimes septate at lower part, filled
with orange-brown pigment. Caulocystidia as metuloids
descending to base, similar to cheilocystidia, without hooks,
thick-walled, rather scanty. Pileipellis a hymeniform, com-
posed of pileocystidia 30–54 6.0–8.4µm, narrowly
fusiform to narrowly cylindrical with an acute apex, thick-
walled, filled with orange-brown pigment. Clamp connec-
tions not observed.
Collection examined: Japan, Tokyo: Bonin Islands,
Hahashima, Okimura, Kuwanokiyama, on rotten wood in
shady woods, Nov. 18, 1936, no. 56 in SAPA: holotype.
Fayod (1889) established a section Hispidoderma
characterized by a hispid cuticle and assigned P. leoninus
(Schaeff.: Fr.) P. Kumm. alone to this section. The
pileipellis of P. leoninus is composed of thin-walled ele-
ments (Vellinga 1990). Thus, P. horridilamellus is excluded
from the section Hispidoderma because it has thick-walled
pileocystidia. Pluteus horridilamellus does not belong to
Micaceae J.E. Lange (no rank indicated), because this
group is characterized by globular cells of cuticle (Lange
1917). The section Pluteus ( section Trichoderma Fayod)
is characterized by numerous metuloids and pilose or
hyphous elements in the pileipellis (Singer 1986). Pluteus
horridilamellus has metuloids, but it has a hymeniform
pileipellis. Pegler (1986) allowed for the section Pluteus
having a trichodermal pileipellis in his key to sections of
the genus Pluteus. However, elements on the pileus of P.
horridilamellus are not trichoderm hyphae but metuloids
characterized by a thick wall and an acute apex. Therefore,
no section for P. horridilamellus could be found in the pre-
vious literature. A new section of Pluteus for this species is
required as defined below.
Pluteus section Horridus Takahito Kobayashi, sect. nov.
Epicutis pilei hymeniformis; pileocystidia crassitunicata;
pleurocystidia crassitunicata; elementa pileipellis
metuloidea, crassitunicata, apice acuta; sporae globosae vel
ellipsoideae.
Pileipellis a hymeniform, composed of metuloids, thick-
walled. Pleurocystidia thick-walled. Spores globose to ellip-
soid, surface smooth, thick-walled, slightly yellow to pale
violet.
Type species: Pluteus horridilamellus S. Ito & S. Imai.
Pluteus magnus McClatchie is similar to P. horridil-
amellus because of the acute apex of pleurocystidia
(metuloids), but the pileipellis of P. magnus is composed
of filamentous hyphae (Banerjee and Sundberg 1995).
Pluteus conizatus (Berk. & Broome) Sacc. is also similar to
P. horridilamellus, but the former has a disrupted
trichodermal pileipellis (Pegler 1986).
Pluteus machidae S. Ito & S. Imai, Trans. Sapporo Nat.
Hist. Soc. 16:47, 1940. Fig. 4
Spores 5.3–7.5 5.0–6.5µm, on average 6.4 5.4 µm, Q
1.0–1.3, globose to subglobose, surface smooth, slightly
yellow to slightly red, thick-walled. Pleurocystidia 38–53
10.8–17.5µm, often with an acute apex, sometimes with a
cylindrical neck, sometimes with a short pedicel at base,
often filled with yellow to gray-yellow pigment, slightly
yellow rarely, thin-walled. Caulocystidia not observed.
Pileipellis a hymeniform, pileocystidia narrowly obovoid to
narrowly ventricose, often with a long neck, often with a
pedicel, filled with orange-brown pigment, thin-walled.
Clamp connections present, scanty.
Collection examined: Japan, Tokyo: Bonin Islands,
Hahashima, Kitamura, Sekimonzan, on a dead trunk in
woods, Nov. 20, 1936, no. 63 in SAPA: holotype.
Fig. 3. Pluteus horridilamellus S. Ito & S. Imai. A Spores. B
Pleurocystidia (metuloids). C Pleurocystidia (thin-walled cystidia). D
Cheilocystidia. E Caulocystidia at base. F Pileipellis. Bars A 10µm; B–
F 20 µm
414
Fig. 4. Pluteus machidae S. Ito & S. Imai. A Spores. B Pleurocystidia.
C Pileipellis. Bars A 10µm; B, C 20µm
I could not observe basidia and cheilocystidia because
the specimen was in poor condition.
This species belongs to the section Celluloderma Fayod.,
although the type specimen of P. machidae rarely has clamp
connections.
Pluteus machidae is close to P. thomsonii (Berk. &
Broome) Dennis due to its hymeniform pileipellis, but P.
machidae has a smooth pileus. Pluteus machidae is similar
to P. pouzarianus Singer var. albus Bonnard in appearance
(Bonnard 1993), but the latter has metuloids. Pluteus
romellii (Britzelm.) Sacc., recorded in Japan recently by
Takahashi (2001), was distinguished from P. machidae by
having a yellow to lemon stipe and broadly ellipsoid to
broadly clavate cells in its pileipellis. Pluteus splendidus A.
Pearson was synonymized with P. romellii by Vellinga
and Schreurs (1985), but Wuilbaut (2001) kept this taxon
as a variety of P. romellii, namely Pluteus romellii var.
splendidus (A. Pearson) Wuilb. It is also different from P.
machidae in having chrome-yellow at the center of its pileus
and stipe surface (Pearson 1952).
Pluteus macrosporus S. Imai, J. Fac. Agric. Hokkaido Imp.
Univ. 43:160, 1938.
No type collection was found at SAPA.
Pluteus okabei S. Ito & S. Imai, Trans. Sapporo Nat. Hist.
Soc. 16:46, 1940. Fig. 5
Spores 6.0–7.0 5.5–6.5µm, on average 6.8 6.1 µm, Q
1.0–1.3, globose to broadly ellipsoid, surface smooth,
slightly yellow, thick-walled. Caulocystidia not observed.
Collection examined: Japan, Tokyo: Bonin Islands,
Chichishima, Mt. Asahiyama, on decayed wood in woods,
Nov. 12, 1936, no. 36 in SAPA: holotype.
The type is in bad condition. I confirmed that Pluteus
okabei is a member of the genus Pluteus by spore character,
but did not observe the pileipellis or metuloids.
Pluteus verruculosus S. Ito & S. Imai, Trans. Sapporo Nat.
Hist. Soc. 16:47, 1940. Fig. 6
Spores 5.8–7.0 5.3–6.5µm, on average 6.3 5.8 µm, Q
1.0–1.1, globose to subglobose, surface smooth, slightly
yellow, thick-walled. Caulocystidia not observed.
Collection examined: Japan, Tokyo: Bonin Islands,
Hahashima, Kitamura, Sekimonzan, on the ground in
woods, Nov. 20, 1936, in SAPA: holotype.
The specimen is badly preserved because the bottle has
dried out. The specimen of P. verruculosus shows smooth
and globose to subglobose spores, and P. verruculosus be-
longs to the genus Pluteus. However, I could not see the
pileipellis or cystidia.
Acknowledgment I am indebted to Professor Hideki Takahashi,
Hokkaido University Museum, for critical reading of this manuscript.
Fig. 5. Spores of Pluteus okabei S. Ito & S. Imai. Bar 10 µm
Fig. 6. Spores of Pluteus verruculosus S. Ito & S. Imai. Bar 10 µm
415
References
Banerjee P, Sundberg WJ (1995) The genus Pluteus section Pluteus
(Pluteaceae, Agaricales) in the midwestern United States.
Mycotaxon 53:189–246
Bonnard J (1993) Clé provisoire des Plutées européens à boucles.
Mycol Helv 6:203–205
Fayod V (1889) Prodrome d’une histoire naturelle des Agaricinés. Ann
Soc Nat Bot VII 9:181–411
Imai S (1938) Studies on the Agaricaceae of Hokkaido. 1. J Fac Agric
Hokkaido Imp Univ 43:1–178, 3 pl
Ito S, Imai S (1940) Fungi of the Bonin Islands. IV. Trans Sapporo Nat
Hist Soc 16:45–56
Lange JE (1917) Studies in the Agarics of Denmark. Part 3. Pluteus.
Collybia. Inocybe. Dansk Bot Ark 2:1–50, 3 pl
Murrill WA (1911) The Agaricaceae of tropical north America. IV.
Mycologia 3:271–282
Nagasawa E (1982) A list of agaric and bolete taxa published by Dr.
Sanshi Imai (1900–1976). Rep Tottori Mycol Inst (Jpn) 20:76–82
Pearson AA (1952) New records and observations. V. Trans Br Mycol
Soc 35:97–122, 1 pl
Pegler DN (1986) Agaric flora of Sri Lanka. Kew Bull Addit Ser 12
Singer R (1986) The Agaricales in modern taxonomy, 4th edn.
Koenigstein, p 981, pl 88
Takahashi H (2001) Pluteus romellii (Agaricales, Basidiomycetes), new
to Japan, found in Odawara. Nat Hist Rep Kanagawa 22:21–23
Vellinga EC (1990) Pluteus Fr. In: Bas C, Kuyper TW, Noordeloos
ME, Vellinga EC (eds) Flora Agaricina Neerlandica, vol 2. Balkema,
Rotterdam, pp 31–55
Vellinga EC, Schreurs J (1985) Notulae ad floram Agaricinam
Neerlandicam. VIII. Pluteus Fr. in West Europe. Persoonia 12:337–
373
Wuilbaut JJ (2001) Le genre Pluteus. Misc Mycol 68:22–39
