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In this study, eight species of Chroogomphus are recognized from Europe: C. britannicus, C. aff. liformis 1, C. fulmineus, C. cf. helveticus, C. mediterraneus, C. cf. purpurascens, C. rutilus, and C. subfulmineus. Different candidates for the application of the name C. rutilus are evaluated and the best fit to the description is selected; lecto- and epitypes are chosen to fix the name. Chroogomphus fulmineus and C. mediterraneus are also epitypified and a new species, C. subfulmineus, is described. The infrageneric classification is revised and a new subgenus Siccigomphus and three new sections, Confusi, Filiformes, and Fulminei are introduced. The former sections Chroogomphus and Floccigomphus are elevated to subgeneric level. Comparison of the ITS regions (nuc rDNA ITS1-5.8S-ITS2) of all species studied shows that there is a minimum interspecific difference of 1.5 %, with the exception of the two species belonging to sect. Fulminei which differ by a minimum of 0.9 %. Ecological specimen data indicate that species of Chroogomphus form basidiomes under members of Pinaceae, with a general preference for species of Pinus. Five European species have been recorded under Picea, while Abies and Larix have also been recorded as tree associates, although the detailed nutritional relationships of the genus, involving other suilloid fungi in particular, have yet to be fully clarified.
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ARTICLE
271
© 2018 International Mycological Association
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VOLUME 9 · NO. 2
INTRODUCTION
Originally a subgenus of Gomphidius (Singer 1948),
Chroogomphus was elevated to generic status by Miller
(1964). More recent molecular analyses have shown the
genus to be monophyletic (Miller & Aime 2001, Miller 2003, Li
et al. 2009). Species of Chroogomphus are characterized by
basidiomata with pale orange to ochraceous lamellae when
young, an ochraceous pileal trama, a moist to viscid pileipellis,
an ephemeral brous veil, and hyphae at the base of the stipe
that have an amyloid reaction in Melzer’s reagent. By contrast,
species of the sister genus Gomphidius are characterised
by basidiomata with pallid to white lamellae when young, a
pallid to white pileal trama, a glutinous pileipellis and veil and
non-amyloid to dextrinoid hyphae at the base of the stipe
(Miller 1964, Miller & Aime 2001, Li et al. 2009). Both genera
have decurrent lamellae and basidiospore deposits that are
grey to black. The genus Chroogomphus has been further
divided into two sections: Chroogomphus, with a pileipellis
of compressed gelatinised hyphae, and Floccigomphus
(originally recognised as a subgenus of Gomphidius), with
non-gelatinised, tomentose to brillose innate hyphae in the
pileipellis (Miller 1964). However, these divisions have since
been shown not to represent monophyletic lineages (Li et al.
2009). Chroogomphus also includes one species, C. albipes,
which is currently unique in the genus due to the secotioid
basidiomata. Because of this and other unusual morphological
characters, this species was originally described as Secotium
albipes (Zeller 1948) and then recombined as Brauniellula
albipes (Smith & Singer 1958); however, molecular studies
have shown that it belongs to Chroogomphus (Miller 2003,
Li et al. 2009). Brauniellula would normally have priority over
Chroogomphus, but the latter name was conserved over it by
Aime & Miller (2006); it is now accepted as the correct name
of the genus.
Six species currently assigned to Chroogomphus have
type localities in Europe: C. britannicus A. Z. M. Khan &
Hora 1978, C. corallinus O.K. Mill. & Watling 1970, C.
fulmineus (R. Heim) Courtec. 1988, C. helveticus (Singer)
M.M. Moser 1967, C. mediterraneus (Finschow) Vila et al.
Diversity of Chroogomphus (Gomphidiaceae, Boletales) in Europe, and
typication of C. rutilus
Ross Scambler1,6, Tuula Niskanen1, Boris Assyov2, A. Martyn Ainsworth1, Jean-Michel Bellanger3, Michael Loizides4 , Pierre-
Arthur Moreau5, Paul M. Kirk1, and Kare Liimatainen1
1Jodrell Laboratory, Royal Botanic Gardens, Kew, Surrey TW9 3AB, UK; corresponding author e-mail: t.niskanen@kew.org
2Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Str., 1113 Soa, Bulgaria
3UMR5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, INSERM, 1919, route de Mende, F-34293 Montpellier
Cedex 5, France
4P.O. box 58499, 3734 Limassol, Cyprus
5Université de Lille, Fac. Pharma. Lille, EA 4483 IMPECS, F – 59000 Lille, France
6 Present address :Department of Applied Sciences, University of the West of England, Frenchay Campus, Coldharbour Lane, Bristol, BS16
1QY, UK
Abstract: In this study, eight species of Chroogomphus are recognized from Europe: C. britannicus, C. aff.
liformis 1, C. fulmineus, C. cf. helveticus, C. mediterraneus, C. cf. purpurascens, C. rutilus, and C. subfulmineus.
Different candidates for the application of the name C. rutilus are evaluated and the best t to the description is
selected; lecto- and epitypes are chosen to x the name. Chroogomphus fulmineus and C. mediterraneus are
also epitypied and a new species, C. subfulmineus, is described. The infrageneric classication is revised and
a new subgenus Siccigomphus and three new sections, Confusi, Filiformes, and Fulminei are introduced. The
former sections Chroogomphus and Floccigomphus are elevated to subgeneric level. Comparison of the ITS
regions (nuc rDNA ITS1-5.8S-ITS2) of all species studied shows that there is a minimum interspecic difference
of 1.5 %, with the exception of the two species belonging to sect. Fulminei which differ by a minimum of 0.9 %.
Ecological specimen data indicate that species of Chroogomphus form basidiomes under members of Pinaceae,
with a general preference for species of Pinus. Five European species have been recorded under Picea, while
Abies and Larix have also been recorded as tree associates, although the detailed nutritional relationships of the
genus, involving other suilloid fungi in particular, have yet to be fully claried.
Article info: Submitted: 27 November 2017; Accepted: 27 August 2018; Published: 5 September 2018.
Key words:
DNA barcode
ITS
molecular systematics
new taxa
taxonomy
doi:10.5598/imafungus.2018.09.02.04 IMA FUNGUS · 9(2): 271–290 (2018)
Scambler et al.
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272 IMA FUNGUS
2006, and C. rutilus (Schaeff.) O.K. Mill. 1964. However, the
application of these names remains open to interpretation as
no type material has been sequenced to date. In addition,
there are differing opinions regarding synonymy, as well
as uncertainties regarding the delimitation of taxa and
identication of specimens due to overlapping morphological
characters. There is, therefore, disagreement over the total
number of species of Chroogomphus thought to occur in
Europe and in individual European countries. C. rutilus was
considered to be the only European species by Miller (1964)
and, more recently, Knudsen & Taylor (2012) regarded this
as the only species occurring in northern Europe. Similarly, it
is the only currently accepted species on the British and Irish
checklist (Legon & Henrici 2005). By contrast, from the latest
molecular study by Martín et al. (2016) it can be inferred that
at least six species occur in Europe.
Members of the genus Chroogomphus occur throughout
the Northern Hemisphere, with only one species, C. papillatus,
reported from the Southern Hemisphere (Raithelhuber 1974).
It is notable that currently there is no molecular evidence of
any of the species having a distribution encompassing both
North America and Eurasia. Moreover, there do not appear to
be many species with an intercontinental distribution across
both Europe and Asia (Miller & Aime 2001, Li et al. 2009,
Martín et al. 2016); C. rutilus occurs in both Europe and Asia;
and C. purpurascens, originally described from the former
Soviet Union, is now known also to occur in Europe (Li et al.
2009).
The most useful morphological characters for distinguish-
ing similar species of Chroogomphus include: thickness of
the cystidial wall, width of hyphae in the pileipellis and spore
size. The gelatinization of hyphae in the pileipellis can also be
a useful character, as can the colour of the mycelium at the
base of the stipe (Miller & Aime 2001, Li et al. 2009, Martín
et al. 2016).
Species of Chroogomphus are found in coniferous
forests dominated by Pinaceae. Miller described the genus
as forming basidiomes under a variety of conifers including
Larix, Picea, Pinus, Pseudotsuga, and Tsuga (Miller 1964),
and some North American species such as C. tomentosus
and the East Asian C. pseudotomentosus are recorded from
under several tree genera (Miller & Aime 2001, Li et al. 2009).
However, recent studies have shown that Chroogomphus
basidiomes are primarily found under species of Pinus,
especially in Europe. Also, some species are found only
forming basidiomes under members of Pinus subgen. Pinus,
whilst others form these only with Pinus subgen. Strobus (Li
et al. 2009). In Europe, subgenus Strobus contains the native
ve-needled species Pinus cembra and P. peuce. All other
native European Pinus species are two-needled and belong
to subgenus Pinus. Unlike Chroogomphus species, those
belonging to the sister genus Gomphidius are not found
with members of Pinoideae but only with the other Pinaceae
subfamilies Piceoideae, Lariceideae, and Abietoideae (Miller
2003, Li et al. 2009), although some exceptions to this have
been recorded: G. nigricans Peck 1897 with Pinus strobus
(Miller 2003), G. roseus (Fr.) Fr. 1838 with Pinus spp.
(Knudsen & Taylor 2012), and G. tyrrhenicus D. Antonini & M.
Antonini 2004 with Arbutus unedo and Quercus ilex (Antonini
& Antonini 2002, Vila et al. 2006).
Previous studies have reported that Chroogomphus is
associated with other suilloid fungi, namely Rhizopogon
and Suillus, but is also able to form ectomycorrhizas with
species of Pinaceae (Agerer 1990). Similarly, when studying
the closely-related genus Gomphidius, Olsson et al.
(2000) concluded that G. roseus was a parasite on Suillus
bovinus, as opposed to, or possibly as well as, being an
ectomycorrhizal partner of conifers. The detailed resource
relationships of Chroogomphus, and of Gomphidiaceae in
general, remain unclear and lie beyond the scope of the
current study.
In this paper we aim to: (1) provide a clearer picture of
the overall species diversity of Chroogomphus in Europe; (2)
typify C. rutilus in order to x the application of this sanctioned
name; and (3) provide an updated infrageneric classication.
MATERIALS AND METHODS
Morphological examination
The following descriptions of macromorphological characters
of the specimens studied were based on notes taken from
fresh collections and associated photographs, with the
exception of C. britannicus whose description is based on the
protologue. The colour nomenclature in the description of C.
britannicus follows Ridgway (1912). A total of 43 specimens
were examined, the majority of these were from RBG Kew’s
collection (K), the Botanical Museum of the University of
Helsinki (H), the herbarium of the Faculty of Pharmacy, Lille
(LIP), the Mycological Collection of the Institute of Biodiversity
and Ecosystem Research, Soa (SOMF), and the private
fungarium of M. Loizides.
Micromorphological characters were observed using light
microscopy. Dried tissue fragments of lamellae, pileipellis,
stipe and basal mycelium were mounted in Melzer’s reagent
or a 10 % potassium hydroxide (KOH). Melzer’s reagent was
used for all measurements and for testing the colour reactions
of tissues. For each specimen, measurements of 20 mature
spores (obtained from natural spore deposits or naturally
discharged spores on the stipe apex) and 10 cystidia were
recorded. For the novel species described in this study, a
minimum of 30 spores and 20 cystidia were measured from
each specimen. Each range of values contains a minimum
of 90 % of the measurements made and values shown in
brackets indicate the extremes of the recorded ranges. Q is
used to indicate the length/breadth ratio of the spores. Mean
values are indicated by “av.”. The pileipellis of specimens was
observed by taking scalp and cross-sectional samples and
mouting them in Melzer’s reagent.
DNA extraction, PCR amplication, sequencing
and data analysis
DNA was extracted from dried material (lamellae) with the
NucleoSpin Plant kit (Macherey-Nagel, Düren, Germany) or the
REDExtract-N-Amptm Plant PCR Kit (Sigma-Aldrich, St Louis,
MO), following the manufacturer’s instructions. Primers ITS 1F,
ITS 4b and ITS 4 (White et al. 1990, Gardes & Bruns 1993) were
used to amplify ITS regions and ITS 1F and ITS 4 were used in
direct sequencing. PCR amplication and sequencing followed
Liimatainen et al. (2014) and Richard et al. (2015).
Chroogomphus in Europe
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VOLUME 9 · NO. 2
Sequences were assembled and edited with Sequencher
4.1 (Gene Codes, Ann Arbor, MI). Our phylogenetic analysis
included the newly-generated sequences together with
selected published sequences of Chroogomphus specimens
downloaded from GenBank and UNITE (Kõljalg et al. 2013).
Identical sequences sourced from the same geographical
region (country, state or province/territory) were excluded.
Several Gomphidius, Rhizopogon and Suillus sequences
were chosen as outgroup species following Li et al. (2009),
although a slightly different range of species was used. The
ITS alignment of 89 sequences was produced with MAFFT
v. 7.0 (Katoh & Standley 2013) under default settings. The
ITS alignment was manually adjusted in Seaview (Galtier
et al. 1996). The alignment obtained is composed of 915
nucleotides (including gaps) and is available at TreeBASE
under accession S22668 (http://www.treebase.org/treebase-
web/home.html). Sequences were subjected to Maximum
Likelihood (ML) analysis as implemented in RAxML version 8
(Stamatakis 2014) with 1000 bootstrap replicates under the
GTRGAMMA model.
Genetic differences within and between species were
calculated for paired sequences by dividing the number of
indels and/or substitutions found in the ITS1+5.8S+ITS2
regions by the length of the shortest sequence in the pair.
RESULTS
Phylogenetic analysis
Analysis of the ITS regions of the specimens resulted in the
phylogenetic tree shown in Fig 1. Eight European species
of Chroogomphus were recovered. However, the European
status of one of these, here referred to as C. aff. liformis
1, is currently based on a single ITS sequence downloaded
from GenBank which was originally obtained from a Pinus
cembra ectomycorrhizal root-tip in Austria. Further sampling
is therefore required to support its formal recognition as
a distinct species. The remaining seven are based on
multiple good quality sequences. The phylogenetic analysis
revealed several clades of species with high bootstrap
support (BS value mainly > 85), which are proposed as new
sections and subgenera herein (see below). The subgenera
Chroogomphus, Floccigomphus, and Siccigomphus received
BS values of 94, 100, and 100 respectively. Within subgenus
Chroogomphus, sect. Chroogomphus has a BS value of 86,
sect. Confusi 100, sect. Filiformes 78, and sect. Fulminei 100.
All European species included in this analysis show
intraspecic variation of less than 1 % and receive bootstrap
support of over 90%, with the exception of those in sect.
Fulminei. All species examined can also be identied based
on their macro- and micromorphological characters (see
below). Interspecic variation is over 1.5 % in all cases
except within sect. Fulminei. The two species in this section
differ by less than 1 % in some cases, yet inspection of
the ITS regions of the two reveals 5 diagnostic nucleotide
differences, conrming the presence of two separate but
closely-related species.
TAXONOMY
In the following list of taxa, formal names are only applied
to specimens based on molecular and morphological
matching type materials. Inclusion of “cf.” within a name (C.
cf. purpurascens and C. cf. helveticus) indicates that types
and type-derived sequences have not been analysed, and
the corresponding descriptions only include elements from
sequenced materials.
Chroogomphus (Singer) O.K. Mill., Mycologia 56: 529
(1964).
Basionym: Gomphidius subgen. Chroogomphus Singer, Pap.
Mich. Acad. Sci. 32: 150 (1948) [“1946”].
Type: Chroogomphus rutilus (Schaeff.Fr.) O.K. Mill. 1964.
Description: Basidiomata small to large, usually expanding
fully but secotioid in one species. Pileus subconical to plane,
surface smooth or brillose, dry to somewhat viscid to viscid;
varying in colour from ochraceous-orange to reddish-brown
through to purplish, vinaceous or leaden-grey. Lamellae
typically decurrent, pale orange to ochraceous-orange when
young, though often coloured grey by black spores; in C.
mediterraneus rarely purple, becoming greyish orange to
wood-brown with age. Trama of the pileus and stipe pale
orange to orange-yellow. Veil on stipe ephemeral, brous,
sometimes forming a thin ring on the upper part of the stipe.
Spore deposit blackish. Stipe basal mycelium composed
of amyloid hyphae. Basidiospores boletoid, smooth, dark,
blackish, weakly to strongly dextrinoid. Cystidia cylindrical to
fusiform, thick- or thin-walled.
Ecology and distribution: Found throughout the Northern
Hemisphere in coniferous forests, primarily under species of
Pinus, but also under other species of Pinaceae.
Currently included subgenera: Chroogomphus, Floccigom-
phus, and Siccigomphus.
Notes: The genus Chroogomphus can be distinguished from
the sister genus Gomphidius by the typically orange-yellow
pileal trama, amyloid mycelium at the base of the stipe, and
pale orange to ochraceous lamellae when young. Species of
Gomphidius have a white to pallid pileal trama, non-amyloid
mycelium at the base of the stipe, and white to pallid lamellae
when young. The genus Chroogomphus receives high boot-
strap support as a monophyletic taxon. The group can be
further divided into three subgenera and ve sections/clades
based on morphological characters which are supported by
the molecular data.
Chroogomphus subgen. Chroogomphus
Type: Chroogomphus rutilus (Schaeff.) O.K. Mill. 1964.
Description: Basidiomata small to large, usually expanding
fully but secotioid in one species. Pileus subconical to plane,
surface smooth or brillose, somewhat viscid to viscid, but
reported to be dry in the C. britannicus protologue; varying
in colour from ochraceous orange to reddish brown through
Scambler et al.
ARTICLE
274 IMA FUNGUS
AF205649 C. rutilus Switzerland
sect. Chroogomphus
subgenus
Chroogomphus
EU706328 C. orientirutilus HT China
EU706327 C. orientirutilus China
EU706325 C. orientirutilus China
100
0.05
HM049561 C. rutilus China
UDB015203 C. rutilus Estonia
K(M)198589 C. rutilus ET Germany
K(M)175891 C. rutilus Greece
SOMF29760 C. rutilus Bulgaria
K(M)167792 C. rutilus Italy
LIP0401324 C. rutilus France
KR673676 C. rutilus Korea
K 82320 C. rutilus UK(M)
K(M)233762 C. cf. purpurascens UK
SOMF29762 C. cf. purpurascens Bulgaria
H6016159 C. cf. purpurascens Finland
FJ481128 C. cf. purpurascens Germany
EU706330 C. cf. purpurascens China
HM545722 C. fulmineus Italy
K(M)190394 C. fulmineus ET Corsica
LIP0401321 C. fulmineus France
LT219435 C. fulmineus Spain sect. Fulminei
LIP0401323C. subfulmineus Cyprus
UDB001529 C. subfulmineus UK
AF205639 C. subfulmineus Finland
LIP0401318 C. subfulmineus HT Cyprus
sect. Confusi
ML411181/1 C. mediterraneus Cyprus
SOMF29763 C. mediterraneus Bulgaria
K 233761 C. mediterraneus Germany(M)
LT219430 C. mediterraneus ET Spain
H6029004 C. mediterraneus Finland
FR2015401 C. mediterraneus Greece
LIP0401328 C. mediterraneus France
K 175418 C. mediterraneus UK(M)
EF423623 C. confusus China
EF423622 C. confusus China
EU697239 C. cf. albipes USA
AF205637 C. cf. albipes USA
EU697240 C. cf. albipes USA
sect. Filiformes
H6045578 C. britannicus Finland
H6001678 C. britannicus Finland
K 233759 C. britannicus Germany(M)
H6025417 C. britannicus Finland
K(M)46653 C. aff. ochraceus Canada
EF619654 C. cf. ochraceus USA
EU706323 C. filiformis HT China
EU706324 C. filiformis China
FJ513327 C. filiformis China
KM504402 C. aff. filiformis 1 Austria
DQ367894 C. aff. filiformis 2 Canada
/Vinicolores
AF205646 C. cf. vinicolor USA
H7031963 C. cf. vinicolor USA
FJ845402 C. cf. vinicolor Canada
AF205660 C. cf. jamaicensis Jamaica
AF205658 C. cf. jamaicensis Dominican Republic
H7019100 C. cf. helveticus Slovakia
FJ652070 C. cf. helveticus CzechR
AF205642 C. cf. helveticus Austria
AF205650 C. cf. helveticus Switzerland
GU187514 C. cf. helveticus Germany
EU706329 C. roseolus China
EF423620 C. roseolus HT China
subgenus
Siccigomphus
subgenus
Floccigomphus
HM240518 C. tomentosus Canada
AF205648 C. tomentosus USA
AF205668 C. tomentosus USA
AF205663 C. pseudotomentosus Unknown
EU706334 C. aff. pseudotomentosus China
AY077472 G. glutinosus USA
AF205647 G. glutinosus USA
UDB000694 G. glutinosus Sweden
DQ099900 G. subroseus Canada
DQ384576 G. subroseus Canada
EF530941 G. smithii Canada
DQ533976 G. oregonensis Unknown
L54114 G. oregonensis USA
UDB000665 G. roseus Sweden
AF205638 G. roseus Japan
UDB011692 G. roseus Estonia
AJ419200 G. roseus Spain
AY077474 G. nigricans USA
AF205659 G. nigricans USA
AY077469 G. borealis Russia
AJ515419 Rhizopogon sp. SH183757 USA
EF619746 Rhizopogon sp. SH183757 USA
JQ991779 Rhizopogon sp. SH183760 China
KC346848 Rhizopogon evadens SH221971 USA
KC346845 Rhizopogon bacillisporus SH221971 USA
L54105 S. cavipes Unknown
AB284451 S. paluster Japan
100
100
86
100
72
100
90
100
96
57
94
100
95
96
78
100
97
100
91
100
100
100
100
100
100
60
99
100
100 100
100
100
98
77
100
100
95
100
93 100
75
97
100
50
95
69
61
Fig. 1. Phylogeny resulting from the RaXML analysis of ITS regions. Bootstrap values greater than 50 % are indicated above branches. The
sequences originating from type specimens are in boldface. HT = holotype; ET = epitype.
Chroogomphus in Europe
ARTICLE
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VOLUME 9 · NO. 2
to purplish, vinaceous or leaden grey. Lamellae typically
decurrent, pale to ochraceous orange when young, in C.
mediterraneus rarely purple, though often coloured grey
by spores. Spore deposit blackish. Basidiospores boletoid,
smooth, dark, blackish, weakly to strongly dextrinoid. Cystidia
cylindrical to subclavate to subfusiform. Lamellar trama
hyphae amyloid or non-amyloid. Pileipellis of somewhat
narrow hyphae in a layer which is gelatinised to some degree.
Ecology and distribution: Throughout the Northern
Hemisphere in coniferous forests, primarily under species of
Pinus, but also under other species of Pinaceae.
Currently included sections: Chroogomphus, Confusi,
Filiformes, Fulminei, and /Vinicolores.
Notes: Species of subgenus Chroogomphus are distinguished
by having a pileipellis composed of gelatinised hyphae which
are typically narrow (1.5–8.0 μm wide), but may be broader
in species of section Confusi (1.5–12.5 μm). The pileipellis
hyphae of species in the Asian/North American subgenus
Floccigomphus and the circumboreal Siccigomphus are non-
gelatinised and usually broader: (5–)7–13(–25) μm (Miller &
Aime 2001) and 4–17 μm respectively (Fig. 2).
Chroogomphus sect. Chroogomphus
Type: Chroogomphus rutilus (Schaeff.) O.K. Mill. 1964.
Description: Basidiomata medium to large. Pileus subconical
to plane, sometimes umbonate, often brillose, somewhat
viscid to viscid; pale reddish pink to reddish brown to
vinaceous brown when mature. Lamellae decurrent to
adnate. Stipe often quite long (>30 mm). Basal mycelium
whitish to salmon to purple-pink. Trama of the pileus and
stipe ochraceous to salmon-ochraceous to orange-yellow,
often brighter at the base of the stipe. Basidiospores boletoid,
smooth, dark, blackish, weakly to moderately dextrinoid,
narrow. Cystidia cylindrical to subfusiform, thick-walled in
some species. Lamellar trama composed of amyloid hyphae.
Pileipellis of narrow, gelatinised hyphae.
Ecology and distribution: Throughout Eurasia, in coniferous
and mixed forests forming associations primarily with species
of Pinus (both subgenera Pinus and Strobus), but also with
other species of Pinaceae.
Currently included species: C. orientirutilus, C. cf. purpurascens,
and C. rutilus.
Notes: Species of sect. Chroogomphus all have a lamellar
trama composed of amyloid hyphae, a character shared
with species of sect. Fulminei, though members of the latter
section have an orange-apricot pileus when young, red to
pinkish patches on the stipe, especially at the base, and a
trama at the base of the stipe coloured either dark grey or
olivaceous green. The species of section Confusi are best
distinguished from this section by their non-amyloid lamellar
tramal hyphae (Fig 3).
The current delimitation of section Chroogomphus differs
from that of Miller (1964), who originally characterized it as
having species with a viscid pileus of somewhat appressed,
gelatinised hyphae and included C. jamaicensis, C. ochra-
ceus, and C. vinicolor, as well as C. rutilus. This concept cor-
responds with subgenus Chroogomphus as described here,
which contains the same species and is dened by similar
morphological characters.
Chroogomphus rutilus (Schaeff.) O.K. Mill., Mycologia
56: 543 (1964).
(Figs 3B, 4A, 5A, 6A)
Basionym: Agaricus rutilus Schaeff., Fung. Bavar. Palat. 4:
24 (1774); nom. sanct. (Fries 1821).
A B
Fig. 2. The two different types of pileipellis found in European species of Chroogomphus. A. Subgenera Siccigomphus and Floccigomphus
are characterized by species with broad pileipellis hyphae that lack a gelatinous layer; non-gelatinised pileipellis hyphae of C. cf. helveticus
(H7019100). B. Species of subgen. Chroogomphus have narrower pileipellis hyphae embedded in a gelatinous layer; these gelatinised pileipellis
hyphae are found in all other European species, in this example, C. britannicus (K(M)77895, holotype). Bar = 50 μm. Photographs: Ross
Scambler.
Scambler et al.
ARTICLE
276 IMA FUNGUS
Synonyms: Agaricus viscidus L., Sp. pl. 2: 1173 (1753); de
Fries (1821).
Agaricus rufescens J.F. Gmel., Syst. Nat., 13th edn 2(2): 1406
(1792); nom. illegit.
Agaricus gomphus Pers., Icon. Desc. Fung. Min. Cognit. 2:
51 (1800).
Agaricus viscidus [ß.] atropunctus Pers., Syn. Meth. Fung. 2:
292 (1801).
Agaricus viscidus [α.] communis Alb. & Schwein., Consp.
Fung.: 158 (1805).
Gomphidius viscidus [*] testaceus Fr., Epicr. Syst. Mycol.:
319 (1838). Types: Sowerby, Col. Fig. Engl. Fungi Mushr.
1: tab. 105, 1805 (as Agaricus rutilus; – lectotypus hic
designatus, MBT379514). – Estonia: Voru Maakond:
antsla vald, in coniferous forest, 27 Aug. 2010, V.
Liiv (TU106902 (TU(M), epitypus hic designatus,
MBT379498).
Gomphidius testaceus (Fr.) Mussat, in Saccardo, Syll. Fung.
15: 152 (1901).
Gomphidius viscidus f. testaceus (Fr.) Kavina, Trav. Mycol.
Tchecoslov. 1(2): 6 (1924).
Gomphidius rutilus f. testaceus (Fr.) Pilát & Dermek, Hrib.
Huby: 163 (1974).
Chroogomphus testaceus (Fr.) Příhoda, in Příhoda et al.,
Kap. Atlas Hub: 237 (1987).
Gomphidius litigiosus Britzelm., Bot. Centralbl. 54: 71 (1893).
? Chroogomphus corallinus O.K. Mill. & Watling, Notes Roy.
Bot. Gard. Edinb. 30: 391 (1970).
Types: Schaeffer, Fung. Bavar. Palat. 1: tab. 55, 1762
(lectotypus hic designatus, MBT379513). – Germany:
Baden-Württemberg: Schwarzwald, Seedorf (ca 2 km SW),
alt. 670–680 m, coniferous forest of Picea abies, on limestone,
27 Aug. 2009, H. Döring & Schwarzwälder Pilzlehrschau
(K(M)198589 – epitypus hic designatus, MBT379497;
GenBank MG457852).
Description (a few measurements based on notes accompanying
one, non-epitype, collection are also included): Pileus 20–90
mm, conical when young, then low convex to almost plane in
age, sometimes umbonate; margin inrolled; surface somewhat
viscid, brillose with some appressed reddish brown scales,
sometimes shiny; pale reddish brown to yellow-brown, often
more distinctly yellow close to the margin, to vinaceous brown,
often turning a deep reddish brown when dried. Lamellae
decurrent to adnate, very crowded to somewhat crowded,
colour not recorded when very young, spores soon colouring
the lamellae pale to medium grey. Stipe 40–130 × 6–30 mm,
cylindrical, often tapering towards the base, upper part pale
reddish to pale yellow, sometimes with a pink hue, becoming
deeper yellow towards the base, with a few lamentous veil
remnants at the stipe apex. Basal mycelium white. Trama of the
pileus and stipe not recorded. Taste and odour not distinctive.
Basidiospores boletoid, smooth, dark, blackish, weakly
to moderately dextrinoid, (14.0–)16.0–21.5(–23.0) × 5.5–
7.0(–7.5) μm, av. = 18.0 × 6.2 μm, av. range = 16.7–20.5
× 5.9–6.4 μm, Q = (2.09–)2.43–3.63–4.03), Q av. = 2.94, Q
av. range = 2.69–3.47. Basidia bisporic or tetrasporic, 38–72
× (9–)10–14 μm, long clavate. Pleuro- and cheilocystidia
101–220 × 11–22 μm, av. = 137.2 × 16.7 μm, av. range =
125.3–158.2 × 13.8–19.0 μm, cylindrical to subfusiform,
often thick-walled (walls to 3.0 μm), hyaline in KOH, hyaline
to yellow in Melzer’s. Lamellar trama composed of amyloid
hyphae. Pileipellis of gelatinised hyphae, 1.5–8.0 μm diam,
av. 3.8 μm, mostly non-amyloid with some scattered amyloid
elements. Hyphae of the basal mycelium cylindrical, 4.0–12.5
µm diam, with a thick amyloid coating of blue granules when
observed in Melzer’s, though hyphae are sometimes smooth;
clamp connections observed, but uncommon.
ITS sequence (GenBank MG457852) distinct from other
members of sect. Chroogomphus. This species is most closely
related to C. orientirutilus (GenBank EU706328, holotype),
from which it differs in the ITS regions by 17 substitutions and
indel positions, a similarity of 97.4 %.
A
B
AB
Fig. 3. Degree of amyloidity of the lamellar trama of European species of Chroogomphus. A. Subgen. Siccigomphus and sect. Confusi in subgen.
Chroogomphus are characterised by species with reduced amyloidity in the lamellar trama; non-amyloid lamellar trama of C. mediterraneus
(H6029004). B. Other sections of subgenus Chroogomphus have distinctly amyloid lamellar trama; amyloid lamellar trama of C. rutilus
(K(M)198589). Bar = 50 μm. Photographs: Ross Scambler.
Chroogomphus in Europe
ARTICLE
277
VOLUME 9 · NO. 2
Ecology and distribution: In coniferous and mixed forests,
but also in more urban environments such as lawns in parks
and cemeteries. Basidiomes primarily found under species of
Pinus subgenus Pinus, though it has also been found under
Picea and Abies. Producing basidiomata in the autumn, from
mid-August to mid-October. Known as a common species
throughout Europe as far north as Estonia, but to date not
from Fennoscandia, it also occurs in parts of Asia as far east
as China and Korea.
Notes: Chroogomphus rutilus usually has quite large
basidiomata, and is the only European member of the
genus to have thick-walled cystidia (Fig 4A). This is the
micromorphological character that sets it apart from other
species most clearly. The few photographs of the species
we have seen suggest that the lamellae could be truly grey
from the beginning. If this is conrmed in future observations,
it would set C. rutilus apart from all the other European
members of the genus. Indeed, the presence of pale orange
to ochraceous lamellae in young basidiomata is currently
regarded as a characteristic of the genus.
The name C. rutilus was rst used by Schaeffer (1774)
in Germany, and has since been applied broadly throughout
Europe. The epitypied concept of C. rutilus is in accordance
with that recognised by Miller & Aime (2001), Li et al. (2009),
and Martín et al. (2016), however it should be noted that the
phylogenies published by these authors also include other
clades of downloaded sequences labelled as C. rutilus or “C.
rutilus” which represent the newly recognized C. subfulmineus
(see below).
The original description of C. rutilus is ambiguous.
Schaeffer describes a species with a pileus at rst subconical
and reddish brown, then atter and striate and nally
depressed at the centre with a pale earthy colour. The lamellae
become reddish brown and the stipe is concolorous, stout
and curved at the attenuated base. The veil is lamentous,
there is no annulus, and the species is found in arid forests. In
the protologue, Schaeffer (1774) refers to his plate 55 which
illustrates a species with a reddish brown brillose pileus
that is conical when young, becoming low convex to plane
with age, with decurrent, brownish-grey lamellae. In deciding
upon an epitype to support the lectotypication of C. rutilus
and stabilise the application of this name, we also considered
specimens we have assigned to C. britannicus and C.
mediterraneus, both of which are known to occur in Germany,
comparing their original descriptions with Schaeffer’s original
concept of C. rutilus. Due to the greyish lamellae illustrated in
the young basidiomata in the lectotype (a character absent in
C. britannicus and C. mediterraneus), we chose to retain the
concept of C. rutilus adopted in the recent molecular studies
of Miller & Aime (2001), Li et al. (2009), and Martín et al.
(2016). Applying the name C. rutilus to this species should
also ensure that further confusion over names is minimised.
The species described in this paper as C. subfulmineus was
not considered for epitypication, even though it has been
named C. rutilus in previous studies (Miller & Aime 2001, Li
et al. 2009 as C. “rutilus”), since it is so far unknown from
Germany.
Comparison of the available ITS sequence data suggests
that the name C. corallinus is a synonym of C. rutilus as
originally proposed by Miller (2003). Although Miller’s
proposal is based on the placement of a single sequence
derived from C. corallinus collected in the UK, he did not
specify whether the holotype (collected in 1969) had been
sequenced. C. corallinus was originally described by Miller
& Watling (1970) and the type locality is a conifer plantation
near Loughborough, England, from where several collections
were made between 1968–1970. One of these collections
is most likely (R. Watling, pers. comm.) the source of the
sequence in Miller (2003) and so it is possible that the
sequenced basidiome was produced by the same mycelium
as the holotype. On the other hand, there are some troubling
differences between the morphological characters in the
original description of C. corallinus and those in our current
concept of C. rutilus. The cystidia of C. corallinus are described
in Miller & Watling (1970) as “thin-walled, rarely thick-walled”,
whereas in C. rutilus the reverse is true. The differing texture
of the pileipellis is also noteworthy. The pileal surface of the
Loughborough collections was described as “matt”, “dry”
“woolly”, “tomentose” and “velvety” (Watling 1969, 1970,
2004, Miller & Watling 1970, Watling & Hills 2005) leading to
an initial misdetermination as C. helveticus (Watling 1969).
The inference is that the dry aspect of the pileus is due to
the non-gelatinised pileipellis hyphae; indeed, this is stated
by Watling & Hills (2005). Nevertheless, following the limited
sequence-based evidence of synonymy in Miller (2003),
Watling & Hills (2005) considered the observed variation
AB
Fig. 4. The two different types of pleuro- and cheilocystidia found
in European species of Chroogomphus. A. Thick-walled cystidia,
only found in C. rutilus (K(M)198589). B. Thin-walled cystidia, found
in all other European species; C. cf. purpurascens (K(M)233762).
Photographs: Ross Scambler.
Scambler et al.
ARTICLE
278 IMA FUNGUS
in pileipellis texture and cystidial wall thickness, which had
previously been used to distinguish C. corallinus and assign
it to section Floccigomphus, as falling within their revised
concept of C. rutilus. However, the degree of morphological
difference is such that a sequencing and microscopic study
of the holotype of C. corallinus is needed to conrm it as a
taxonomic synonym of C. rutilus.
Numerous other names in the literature have been
synonymised with C. rutilus, and many of their descriptions
refer to the Schaeffer plate used to lectotypify that species
here. We also regard Chroogomphus testaceus as a
synonym. The original description refers to Sowerby’s gure
of Agaricus rutilus, plate 105, which is used for lectotypifcation
here. In choosing an epitype for C. testaceus, we selected
the specimen which most closely resembles the lectotype.
Of all the European species studied, the current concept of
C. rutilus seems to provide the best match with that of C.
testaceus.
Additional specimens examined: Bulgaria: Samokov: Govedartsi,
Rila Mountain, near Picea abies, Pinus sylvestris also present in the
forest, 14 Sep. 2014, B. Assyov (SOMF29760, GenBank MG457861).
Channel Islands: Jersey: St Brelade, Red Houses, Parc du Pont
Marquet, parkland under Pinus radiata, 18 Oct 2015, N.W. Legon
(K(M)235485, GenBank MH037156). – France: Nord: Le Touquet-
Paris-Plage, under Pinus sp., 30 Sep. 2014, A. Thorel PAM14093001
(LIP 0401324, GenBank MG457862). Savoie: Bessans, with Pinus
sylvestris, 6 Sep. 2002, P.-A. Moreau PAM02090618 (LIP 0401326);
Jarrier, with Pinus sylvestris, 18 Sep. 2014, M. Durand MDH01 (LIP
0401325). – Greece: Trikala: South Pindos Mountains, Amarantos,
with Abies borisii-regis, 18 Oct. 1999, A. E. Hills (K(M)175891,
GenBank MG457853); Voras, alt. 1800 m, with Pinus sp., Dec.
2014, A. Triantaphyllos PAM14120001 (LIP 0401327). – Italy:
Trento: Peregine Valsugana, Susa, with Pinus sp., 8 Sep. 2002,
A. E. Hills (K(M)167792, GenBank MG457851). – Romania: with
Pinus sylvestris, 2014, M. M. Pop (FR2015502).– United Kingdom:
England: Kent, Tunbridge Wells cemetery, near Pinus sp., 17 Oct.
2005, E. W. Brown (K(M)135802, GenBank MG457848); Somerset,
Crewkerne Grammar School grounds, near Pinus sp., 28 Oct.
1975, J. Keylock (K(M)108451, GenBank MG457850). N. Ireland:
Fermanagh, Inisherk, Crom Estate, with Pinus sylvestris, 15 Oct.
2000, E. E. Emmett (K(M)82320, GenBank MG457849).
Specimen details of downloaded European sequences: Czech
Republic: Ústecký: Roudnice nad Labem, with Pinus subgenus
Pinus sp., 30 Aug. 2008, J. Borovicka (HKAS 55294 (KUN),
FJ652071). – Estonia: Voru Maakond: Noarootsi vald, Aulepa, with
bushes of Juniperus, 08 Sep. 2007, I. Saar (TU101333 (TU(M)),
UNITE UDB019693). Viljandi: Lilli, in temperate broadleaf forest, 20
Sep. 2015, [Collector unknown] (TU116830 (TU(M)), UDB025603). –
Poland: [Ecology unknown], 13 Oct. 2014, [Collector unknown], ID
PAN 592 (GenBank KM085388); : [Ecology unknown], 13 Oct. 2014,
[Collector unknown], ID PAN 762 (GenBank KM085373). – Russia:
Kirov Oblast: Zuyevsky, Kyrov, with Pinus subgenus Pinus sp., 16
Aug. 2006, B. Tolgor HMJAU 4665 (JLAU, GenBank EU791582). –
Switzerland: [Ecology unknown], O. K. Miller (OKM24401, GenBank
AF205649).
Specimen details of downloaded Asian sequences: China:
Yanqing: [Ecology unknown], [Collector unknown] (GenBank
HM049562). Huairou, [Ecology unknown], [Collector unknown]
(GenBank HM049561); [Ecology unknown], [Collector unknown]
(GenBank KM488533). Jilin: Jilin Agriculture University, with Pinus
subgenus Pinus sp., 8 Sep. 2004, J. R. Wang HMJAU 3681 (JLAU,
GenBank EU791580). – South Korea: Ulleung-do: Nari-basin,
[Ecology unknown], 16 Oct. 2012, [Collector unknown] (KA12 1684,
GenBank KR673618); Nasujeon, [Ecology unknown], 23 Sep. 2013,
[Collector unknown] (KA13 2103, GenBank KR673676).
Chroogomphus cf. purpurascens (Lj.N. Vassiljeva)
M.M. Nazarova, in Wasser, Nizsh. Rast. Griby
Mokh. Sovetsk. Dal’nego Vostoka 1: 378 (1990).
(Figs 4B, 5B, 6B)
Description (some macroscopic features based on Li et al.,
2009): Pileus 20–50 mm, conical when young, low convex
in age, with inrolled margin, surface viscid, sometimes
slightly brillose; pink to purplish when young, becoming
pale brown to brownish red to greyish red to dark purple with
age. Lamellae adnate to decurrent, somewhat crowded to
distant, salmon-ochraceous then greyish to pale brown with
age. Stipe 35–55 × 7–10 mm, cylindrical, sometimes tapering
towards the base, pale yellow to pale brown, becoming darker
towards the base, sometimes with a lilac pinkish pruina in
young specimens, with some lamentous veil remnants at the
stipe apex. Basal mycelium salmon to purple pink. Trama of
the pileus and stipe salmon-ochraceous, sometimes greyish
green at the very base. Taste and odour not distinctive.
Basidiospores boletoid, smooth, dark, blackish, moder-
ately dextrinoid, (14.0–)15.0–18.0(–19.0) × 5–6.5 μm, av.
= 16.6 × 5.7 μm, av. range = 16.0–17.2 × 5.2–6.1 μm, Q =
(2.57–)2.63–3.52(–3.72), Q av. = 2.95, Q av. range = 2.83–
3.06. Basidia tetrasporic, rarely bisporic, 37–60 × 9–12.5
μm, long clavate. Pleuro- and cheilocystidia 89–196 × 11–17
μm, av. = 123.5 × 14.2 μm, av. range 114.5–132.5 × 13.5–
15.0 μm, cylindrical to subfusiform, thin-walled (to 1.0 μm),
hyaline to deep brown in KOH, hyaline in Melzer’s. Lamellar
trama composed of amyloid hyphae. Pileipellis of gelatinised
hyphae, 3.0–8.0 μm diam, av. 5.5 μm, mostly non-amyloid
with some scattered amyloid elements. Hyphae of the basal
mycelium cylindrical, 4.0–12.5 µm diam, with a thick amyloid
coating of blue granules when observed in Melzer’s; clamp
connections observed, but uncommon.
ITS sequence (GenBank MG457855) distinct from other
members of section Chroogomphus. This species is most
closely related to C. rutilus, from which it differs in the ITS
regions by 34 substitutions and indel positions, a similarity
of 94.7 %.
Ecology and distribution: In coniferous and mixed forests.
Li et al. (2009) reported that C. cf. purpurascens occurs
with members of Pinus subgen Strobus. Our collection data
indicate that this species has a broader range of associates
including P. sylvestris and P. nigra. One collection has also
been reported as made from a Picea abies dominated forest,
however the presence of Pinus in that forest cannot be ruled
out. Producing basidiomata in the autumn, from mid-August
to mid-November. This species is found across most of
Europe, as far north as Finland, west to the Channel Isles,
and east as far as Russia (Kirov). It is also known from parts
of Asia, including far eastern Russia, from where it was rst
described, and China.
Chroogomphus in Europe
ARTICLE
279
VOLUME 9 · NO. 2
AB
C
E
D
F
G
CD
E
H
Fig. 5. Basidiomata of selected Chroogomphus species. A. C. rutilus (TU106902). B. C. cf. purpurascens (K(M)233762). C. C. mediterraneus
(K(M)237593). D. Atypical C. mediterraneus (K(M)237779). E. C. fulmineus (LIP 0401320). F. C. cf. helveticus (H7019100). G. C. subfulmineus
(LIP 0401318, holotype). H. C. subfulmineus (LIP 0401323, showing colour of the trama). Not to scale; bar applies to F only. Photographs: A,
Vello Liiv; B, and C, Geoffrey Kibby; D, Mel Oxford; E, Pierre-Arthur Moreau; F, Kare Liimatainen; and G and H, Michael Loizides.
Scambler et al.
ARTICLE
280 IMA FUNGUS
Notes: Chroogomphus cf. purpurascens has narrower spores
than other members of the genus (width av. 5.2–6.1 μm), and
it is also distinguishable, at least when young, due to its pink
to purplish pileus. In some instances, young basidiomata also
have a stipe with lilac pinkish pruina.
A study of the type material is currently lacking for C.
purpurascens and specimens sequenced by Li et al. (2009)
from “eastern Russia” were of European Russian origin far
from the type locality. Several characters in the specimens we
have examined match Vassiljeva’s (1950) original description,
such as the colour of the pileus and the size of the spores,
but until a type study and associated sequence analysis
has been carried out the identication cannot be conrmed.
Vassiljeva’s collections, if preserved, are expected to be in
the Institute of Biology and Soil Science, Far Eastern Branch,
Russian Academy of Sciences (Vladivostok, VLA).
Specimens examined: Bulgaria: Burgas Province: Malko Tarnovo,
Strandzha, with Pinus nigra, 18 Oct. 2014, B. Assyov (SOMF29761).
Blagoevgrad Province: West Frontier mts, Ograzhden Mt, with Pinus
nigra, 21 Nov. 2014, B. Assyov (SOMF29762, GenBank MG457863).
Channel Islands: Jersey: St Brelade, Rue du Pont Marquet,
Jersey Lavender Farm, JE3 8DS, in woods under Pinus sylvestris,
28 Oct. 2016, G.G. Kibby (K(M)233762, GenBank MG457854). –
Finland: Varsinais-Suomi: Lohja, Vappula, NNW-shore of the pond
Jusolanlampi, in grass-herb forest of Picea abies, 29 Aug. 1999, U.
Nummela-Salo & P. Salo (H6016159, GenBank MG457855).
Specimen details of downloaded European sequences: Czech
Republic: Ústecký: Roudnice nad Labem, with Pinus subgenus
Strobus sp., 14 Sep. 2008, J. Borovicka (HKAS 55295 (KUN),
GenBank FJ652072). – Germany: Hesse: Marburg, with Pinus
subgenus Strobus sp., [Collector unknown] (HKAS 54925 (KUN),
GenBank FJ481128). – Russia: Kirov Oblast: Nikitintsy, with Pinus
subgenus Strobus sp., 12 Aug. 2006, B. Tolgor HMJAU 4633 (JLAU,
GenBank EU706332); Falyonsky, with Pinus subgenus Strobus sp.,
15 Aug. 2006, B. Tolgor HMJAU 4634 (JLAU, GenBank EU706333).
Specimen details of downloaded Asian sequences: China: Jilin:
Changchun, Jingyuetan National Forest Park, with Pinus subgenus
Strobus sp., 20 Sep. 2004, J. R. Wang HMJAU 3489 (JLAU,
GenBank EU706330); Changchun, Jingyuetan National Forest Park,
with Pinus subgenus Strobus sp., 24 Aug. 2004, J. R. Wang HMJAU
3687 (JLAU, GenBank EU706331).
Chroogomphus sect. Confusi Niskanen, Scambler &
Liimat., sect. nov.
MycoBank MB823592
Etymology: Named after the type species of the section.
Diagnosis: The mostly non-amyloid hyphae of the lamellar
trama distinguish the species of this section from the others
of the subgenus Chroogomphus that have amyloid lamellar
trama hyphae.
Type: Chroogomphus confusus Y.C. Li & Zhu L. Yang 2009.
Description: Basidiomata small to large, one species
secotioid. Pileus subconical to plane, sometimes umbonate,
somewhat viscid to viscid; wood-brown to brownish orange to
cream-orange, rarely purple. Lamellae extremely decurrent
to adnate. Basal mycelium whitish to grey to yellowish ochre.
Trama of the pileus and stipe orange to orange-yellow.
Basidiospores boletoid, smooth, dark, blackish, weakly to
strongly dextrinoid. Cystidia cylindrical to subfusiform, thin-
walled. Lamellar trama composed of mostly non-amyloid
hyphae. Pileipellis of somewhat narrow to narrow, gelatinised
hyphae.
Ecology and distribution: Known from North America and
Eurasia, in coniferous and mixed forests, found primarily
under species of Pinus subgen. Pinus, but also under other
species of Pinaceae.
Currently included species: C. cf. albipes, C. asiaticus, C.
confusus, and C. mediterraneus. The ITS sequences of
C. asiaticus (GenBank AF205664 Nepal, holotype, Pinus
roxburghii, Alnus nepalensis forest; GenBank AF205666
Nepal, Pinus roxburghii forest) were short and thus not
included in our analysis. However, the phylogenetic analysis
of Miller & Aime (2001) shows that these specimens belong
in this section. The holotype sequence of C. confusus
(GenBank EF423621) was also omitted from our analysis
due to its short length, though this is shown to cluster with the
other specimens of C. confusus in Li et al. (2009).
Notes: Some features of the above description do not apply
to the unusual secotioid species, C. albipes (syn. Brauniellula
albipes). All other members of the section form basidiomata
above ground. Species of sect. Confusi have reduced
amyloidity in the lamellar trama. Although the degree of
amyloidity may vary to some extent and some species have
weakly scattered amyloid elements, these should generally
be scarce enough to avoid confusion with species of other
sections of subgenus Chroogomphus. Chroogomphus cf.
albipes has been described as having an amyloid trama in
previous studies (Miller 2003), but the precise location was
not specied. No collections of C. cf. albipes were available
for study, but in Smith & Singer’s (1958) description there is no
indication that the lamellar trama has amyloid elements. This
section received high bootstrap support in our phylogenetic
analysis.
Chroogomphus mediterraneus (Finschow) Vila et
al., Errotari 3: 68 (2006).
(Figs 3A, 5C–D, 6C)
Basionym: Gomphidius mediterraneus Finschow, Veroff.
Uberseemus. Bremen, A 5: 43 (1978).
Types: Spain: Balearic Islands: Eivissa, Sant Josep de sa
Talaia, Puig d’en Serra, alt. 200 m, under Pinus halepensis,
08 Nov 1973, H. Kuhbier [det. G. Finschow] (BREM 2060
– holotype); ibidem, alt. 250–300 m, under Pinus halepensis,
18 Nov 2012, A. Serra (hb. Siquier, JLS 3539 – epitypus hic
designatus, MBT379523; GenBank LT219430).
Description: Pileus 30–70(–90) mm, hemispherical to convex
or more rarely subconical when young, becoming low convex
to applanate or weakly umbilicate with age, rarely also weakly
umbonate, margin usually inrolled, surface innately brillose,
subviscid to dry; colour when young ranging from dark
Chroogomphus in Europe
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VOLUME 9 · NO. 2
charcoal-grey to olivaceous grey, paling in age to olivaceous
brown, vinaceous brown, ochraceous brown or pinkish brown,
often with ochraceous orange, pinkish, or cream-orange
patches, rarely the whole pileus purple, becoming dark
purplish vinaceous to blackish brown when dried. Lamellae
moderately to deeply decurrent and distinctly arcuate, distant,
when young covered with a fugacious, orange cortinoid veil
soon disappearing, ochraceous orange to deep apricot-
orange when young and remaining so for a long time, rarely
purple, gradually mottled from maturing spores and nally
pale brown to olivaceous brown at full maturity; edges more
or less smooth and concolorous or slightly paler. Stipe 30–90
× 5–20(–30) mm, cylindrical to fusiform, often exuous and
rooting, apricot-orange to ochraceous buff, frequently with
dark remnants of cortinoid veil at the apex, covered in orange
or pinkish brils below, occasionally with a pinkish ush.
Basal mycelium tomentose, distinctly ochraceous yellow or
more rarely dull ochraceous cream. Trama of the pileus and
stipe uniformly apricot-orange, sometimes vaguely darkening
towards the base. Taste and odour weak, somewhat sour;
more distinctly acidic in overripe basidiomata.
Basidiospores boletoid; subfusoid to ellipsoid, smooth,
thick-walled, dark, blackish, weakly to strongly dextrinoid,
(14.0–)15.0–18.5(–20.5) × (5.0–)6.0–7.5(–8.0) μm, av. 16.9 ×
6.6 μm, av. range 16.3–18.0 × 5.9–6.8 μm, Q = (1.87–)2.11–
2.96(–3.36), Q av. 2.57, Q av. range 2.43–2.70. Basidia
bisporic or tetrasporic, 40–75 × 9.5–14 μm, long clavate.
Pleuro- and cheilocystidia 91–153 × 11–22 μm, av. 122.3 ×
15.3 μm, av. range 108.0–130.5 × 13.8–18. 3 μm, cylindrical
to subfusiform or subutriform, sometimes subcapitate, thin-
walled (to 1.0 μm), but occasionally also thick-walled (to 2.0
μm), frequently with coarse lateral encrustations; hyaline to
brown in KOH, hyaline in Melzer’s. Lamellar trama composed
of inamyloid hyphae, yellow to pinkish in Melzer’s. Pileipellis
of somewhat gelatinised or gelatinised hyphae, 1.5–12.5
μm diam, av. 5.3 μm, mostly inamyloid, with some scattered
amyloid elements. Hyphae of the basal mycelium cylindrical,
4.0–16.0 µm diam, with a thick amyloid coating of blue
granules when observed in Melzer’s; clamp connections
observed, but uncommon.
ITS sequence (GenBank MG457831) distinct from the
other members of section Confusi. This species is most
closely related to C. confusus, from which it differs in the ITS
regions by 13 substitutions and indel positions, a similarity of
98.0 %.
Ecology and distribution: Forming basidiomes in autumn,
winter and spring in coniferous and mixed forests, particularly
in rich grass-herb forests in the north of its range, more
commonly in thermo- and meso-Mediterranean pine forests
in the south, often with mixed sclerophyllous vegetation in the
understory. It is found under species of Pinus subgen. Pinus,
mainly P. halepensis and P. brutia in the Mediterranean
range, but in other parts of Europe also with P. sylvestris, P.
halepensis, and P. nigra, with a single record under Picea
and another one under Larix. Contrary to the specic epithet,
C. mediterraneus is very widely distributed, reaching as far
north as Scotland and Finland, although it may be endemic
in Europe. Basidiomata have been observed several times in
direct contact with basidiomata of Rhizopogon cf. luteolus, R.
cf. roseolus, and R. cf. vulgaris.
Notes: Chroogomphus mediterraneus is a species of
remarkable plasticity (Siquier et al. 2016), but differs from
ABCD
EH
FG
Fig. 6. Basidiospores of Chroogomphus species: A. C. rutilus (K(M)198589). B. C. cf. purpurascens (K(M)233762). C. C. mediterraneus
(K(M)233761). D. C. britannicus (H6045578). E. C. fulmineus (LIP 0401320). F. C. subfulmineus (LIP 0401318, holotype, with unusually broad
spores). G. C. subfulmineus (UDB001529). H. C. cf. helveticus (H7019100). The degree of spore dextrinoidity does not appear to be a consistent
character within species. Bar = 20 μm. Photographs: Ross Scambler.
Scambler et al.
ARTICLE
282 IMA FUNGUS
all other European members of the genus, with the notable
exception of C. cf. helveticus (subgen. Siccigomphus), in
lacking an amyloid reaction in the lamellar trama. Apart from
the ecology, it can be distinguished from C. cf. helveticus
because the latter has a yellow to orange-apricot, dry pileus
when young and broader pileipellis hyphae (to 17 μm wide)
that are not embedded in a gelatinised layer. As also noted
by Martín et al. (2016), the distinctly ochraceous yellow or
ochraceous cream mycelium at the stipe base is usually
an excellent diagnostic eld character separating this
species from C. rutilus, which has a whitish or cream basal
mycelium. The deep orange lamellae of C. mediterraneus,
which maintain this colour until late in maturity, might be
another useful character for discriminating this species from
C. rutilus. This needs to be more thoroughly evaluated when
further molecularly-conrmed collections become available.
Epitypication of C. mediterraneus with a modern
sequenced specimen (JLS 3539, GenBank LT219430) was
necessary since three previous attempts at sequencing the
holotype of C. mediterraneus in different laboratories were
unsuccessful (Martín et al. 2016). The selected specimen
is from the type locality (topotype) and its morphological
characters match the description of the holotype (Martín
et al. 2016). Collections previously reported as “C. rutilus
in Cyprus (e.g. Loizides et al. 2011) all corresponded to C.
mediterraneus, greatly extending the species’ biogeographical
range towards the eastern Mediterranean.
Additional specimens examined: Bulgaria: Blagoevgrad Province:
West Frontier mts, Logodazh village, with Pinus nigra, 22 Sep.
2014, B. Assyov (SOMF29763, GenBank MG457857). – Cyprus:
Troodos, under P. nigra subsp. pallasiana, 18 Nov. 2014, M.
Loizides ML411181/1, FR2015390 (GenBank MG457867). –
Finland: Uusimaa: Porvoo, Bjurböle, NE side of Meteoriittitie,
E from Mäntymäki, in grass-herb forest dominated by Betula
pendula, 11 Sep. 1997, U. Nummela-Salo &P. Salo (H6016157,
GenBank MG457834). Varsinais-Suomi: Lohja, Virkkala, E part
of Pähkinäniemi, very rich, dry grass-herb forest with calcareous
bottom, 29 Aug. 1999, U. Nummela-Salo & P. Salo (H6016160,
GenBank MG457836). Etelä-Karjala: Lappeenranta, Ihalainen,
Mattila, S from the highway, NE of the Russian military cemetery, on
dry heath forest dominated by Pinus sylvestris, with rich calcareous
bottom, 5 Sep. 2003, U. Nummela-Salo & P. Salo (H6002491,
GenBank MG457839). Etelä-Häme: Padasjoki, Kasiniemi,
Viitaniemi, in herb-rich mesic forest, 5 Sep. 2011, V. Haikonen
(H6029004, GenBank MG457831). – France: Savoie: Chambéry,
les Charmettes, with Pinus sp., 11 Nov. 2014, M. Durand MDH03
(LIP 0401328, GenBank MG457839). – Germany: Thuringia:
Ilmenau, between Oberporlitz and Unterporlitz, with Picea, 28 Sep.
2016, R.A. Fortey (K(M)233760, GenBank MG457835); Ilmenau,
on the road to Unterporlitz, with Pinus sp. (Betula also present),
28 Sep. 2016, P.A. & K. Cavanagh (K(M)233761, GenBank
MG457833). – Greece: [Locality unknown], under Pinus sp., 1
Nov. 2014, E. Papadopoulou FR2015401 (GenBank MG457868). –
United Kingdom: Wales: Monmouthshire, Hardwick Plantation nr.
Highmoor Hill, Larix woodland, 17 Dec 2017, M. Oxford & W. Thomas
(K(M)237779, GenBank MH037154). Scotland: Mid-Perthshire,
Black Wood of Rannoch, with Pinus (Betula also present), 24
Aug. 2015, T. Niskanen TN15-015 (K(M)200317, GenBank
MG457837); TN15-014 (K(M)200316, GenBank MG457838): South
Aberdeenshire, Linn of Dee, with Pinus sylvestris, 27 Aug. 2003,
S. Kelly (K(M)175418, GenBank MG457832).– Spain: Castilla-La
Mancha: Puente de Vadillos, Hoz de Beteta, near Pinus sylvestris,
P. nigra, 1 Nov 2017, G. Kibby (K(M)237593, GenBank MH037155).
Specimen details of downloaded sequences: Spain: Balearic
Islands: Eivissa, Sant Josep de sa Talaia, es Cap Falcó, alt. 0–25
m, under Pinus halepensis, 4 Dec. 2009, J. L. Siquier & J. C. Salom
(JLS 2917, GenBank LT219429); Formentera, Torrent de Cala
Saona, under Pinus halepensis, 7 Dec. 2008, J. L. Siquier & J. C.
Salom (JLS 3006, GenBank LT219431); Mallorca, Pollença, Puig de
Son Vila, alt. 100–200 m, under Pinus halepensis, 21 Nov. 2009, J. L.
Siquier & J. C. Salom (JLS 2887, GenBank LT219432); Menorca, Es
Mercadal, Sa Roca, alt. 180–240 m, under Pinus halepensis, 14 Nov.
2011, J. L. Siquier & J. C. Salom (JLS 3384, GenBank LT219433).
Teruel: Mora de Rubielos, Puerto de San Rafael, alt. 1400 m, under
Pinus nigra and P. sylvestris, 6 Oct. 2009, J. L. Siquier & J. C. Salom
(JLS 2775, GenBank LT219434).
Chroogomphus sect. Filiformes Niskanen, Scambler
& Liimat., sect. nov.
MycoBank MB823593
Etymology: Named after the type of the section.
Diagnosis: The combination of a yellow basal mycelium and
amyloid lamellar tramal hyphae distinguish this section from
others of subgenus Chroogomphus.
Type: Chroogomphus liformis Y.C. Li & Zhu L. Yang 2009.
Description: Basidiomata small to large. Pileus subconical
to plane; greyish orange to orange to ochraceous when
mature; subviscid to viscid. Lamellae decurrent. Basal
mycelium yellowish. Basidiospores boletoid, smooth, dark,
blackish, weakly to strongly dextrinoid. Cystidia cylindrical to
subclavate to subfusiform. Pileipellis of narrow, gelatinised
hyphae.
Ecology and distribution: Known from North America and
Eurasia, in coniferous and mixed forests forming basidiomes
primarily under species of Pinus (subgenera Pinus and
Strobus), but also under other species of Pinaceae.
Currently included species: C. britannicus, C. liformis, C. aff.
liformis 1, C. aff. liformis 2, C. cf. ochraceus, and C. aff.
ochraceus “Canada”.
Notes: Other sections with amyloid lamellar tramal hyphae
do not have a yellow basal mycelium, and although C.
mediterraneus (sect. Confusi) does have yellow mycelium, it
lacks amyloid hyphae in the lamellar trama.
Chroogomphus britannicus A.Z.M. Khan & Hora,
Trans. Brit. Mycol. Soc. 70: 155 (1978).
(Figs 2B, 6D)
Types: United Kingdom: England: Berkshire (vice-county
22), Mortimer, Benyon’s Inclosure, in plantation of Pinus
sylvestris, 22 Nov 1971, A. Z. M. N. A. Khan (K(M)77895
– holotype); ibidem, in plantation of P. sylvestris, 29 May
Chroogomphus in Europe
ARTICLE
283
VOLUME 9 · NO. 2
1972, A. Z. M. N. A. Khan (K(M)206849 – paratype, GenBank
MG457841).
Description (macroscopic features based on the original
description by Khan & Hora 1978): Pileus to 17 mm, convex,
margin inrolled, smooth; yellowish orange near ‘Ochraceous-
Orange’ to ‘Ochraceous-Buff’, dry or slightly viscid when
moist. Lamellae decurrent, thick, ‘Light Vinaceous-Cinnamon’
to ‘Light Pinkish-Cinnamon’ when young, becoming ‘Wood
Brown’ with age. Stipe to 60 × 8 mm, tapering below to 6
mm at the base, concolorous with the pileus or paler. Basal
mycelium yellowish. Trama of the pileus and stipe ‘Pale Yellow
Orange’ to ‘Capucine Buff’. Taste and odour not distinctive.
Basidiospores boletoid, smooth, dark, blackish, weakly
to strongly dextrinoid, (17.0–)18.0–23.5(–26.5) × (6.0–)6.5–
8.0(–9.0) μm, av. 20.3 × 7.1 μm, av. range 18.7–21.1 × 6.7–
7.1 μm, Q = (2.31–)2.51–3.17(–3.46), Q av. 2.87, Q av. range
2.76–2.99. Basidia bisporic or tetrasporic, 36–64 × 9.5–12.5
μm, long clavate. Pleuro- and cheilocystidia 105–200 ×
12–28 μm, av. 152.0 × 16.5 μm, av. range 130.5–169.2 ×
13.8–24.0 μm, cylindrical to subfusiform, rarely capitate, thin-
walled (to 1.0 μm), hyaline to brown in KOH, hyaline to yellow
in Melzer’s. Lamellar trama composed of amyloid hyphae.
Pileipellis of gelatinised hyphae, 1.5–7.0 μm diam, av. 3.9
μm, mostly inamyloid with some scattered amyloid elements.
Hyphae of the basal mycelium cylindrical, 4.5–14.0 µm diam,
with a thick amyloid coating of coarse, blue granules when
observed in Melzer’s; clamp connections not observed.
ITS sequence (GenBank MG457847) distinct from other
members of sect. Filiformes. This species is most closely
related to C. cf. ochraceus (EF619654), from which it differs
in the ITS regions by 18 substitutions and indel positions, a
similarity of 97.3 %.
Ecology and distribution: Mainly in coniferous forests and
acid heath dominated by Pinus sylvestris, though it has
once been recorded under Picea. The type locality is a pine
plantation indicating that it is able to occur (or at least persist
for a few years) in anthropogenic habitats. Basidiomata are
produced in the autumn, from late August to late November.
This species has one of the most northern distributions of the
genus, with two specimens collected from Finland’s northern
boreal regions. Although it is recorded in the UK, from where
it was originally described, it is currently only known there
from the type materials collected in 1971 and 1972.
Notes: Chroogomphus britannicus is notable for having
longer spores than most other members of the genus, with the
exception of C. fulmineus and C. subfulmineus. However, it
can be distinguished from C. fulmineus by the slightly broader
spores and the considerably coarser amyloid granules on
the hyphae of the basal mycelium (Fig. 7A). Chroogomphus
subfulmineus, on the other hand, does have an overlapping
distribution, with collections from Britain and Finland, and
the two species have similarly broad spores, but again C.
britannicus has coarser amyloid granules on the hyphae of
the basal mycelium. The absence of reddish to pink patches
on the stipe, and lack of olivaceous trama at the stipe base
of C. britannicus should also enable positive identication.
In our phylogenetic analysis, C. britannicus clusters close
to C. liformis, from which it can be distinguished due to its
slightly broader and longer spores. Chroogomphus liformis
is currently only known from China.
A morphological examination of the original material of C.
britannicus was carried out during this study. The characters
of both the holotype and paratype were found to conform to
those of the more recent collections, but comparison with
Khan & Hora’s (1978) original description of C. britannicus
highlighted a signicant difference in the description of the
pileipellis. It is originally described as having an “epicutis
of non-agglutinated, interwoven, inamyloid hyphae”, yet we
found it to have a gelatinous (agglutinated) outer layer of
hyphae (Fig. 2B). It may be that the fresh material possessed
an overlying dry layer, accounting for the “lamentous, dry
pileal surface”, which might have subsequently receded into
the gelatinous layer during drying.
Fig. 7. Hyphae of the basal mycelium with a thick amyloid coating of blue granules when observed in Melzer’s reagent: A. Chroogomphus
britannicus (H6045578) with coarse amyloid granules. B. C. subfulmineus (DG56) with ner amyloid granules. Bar = 10 μm. Photographs: Ross
Scambler.
A
B
A
AB
Scambler et al.
ARTICLE
284 IMA FUNGUS
Successful sequencing of the paratype of C. britannicus
conrmed that it does not match any sequences published
in previous studies of Chroogomphus, and yet it clustered
with six other specimens sequenced during this study (not all
included in the phylogeny), as well as two ITS2 sequences
from GenBank. This is possibly due to a lack of sequenced
collections from northern Europe in earlier studies. Only the
ITS2 region of the paratype was successfully recovered and
for this reason it has been omitted from the phylogeny. It
is a species distinct from C. britannicus sensu Martín et al.
(2016; GenBank AF205639) which we describe below as C.
subfulmineus.
Additional specimens examined: Finland: Etelä-Karjala: Parikkala,
Kirkonkylä, Sikoharju, Pinus sylvestris dominated heath, 13 Sep.
2003, V. Haikonen (H6059351, GenBank MG457844). Satakunta:
Honkajoki, Kivimäki, SE of the Siikainen-Honkajoki road, with Pinus
sylvestris in pine-dominated heath on sandy soil, 22 Sep. 2006, E.
Ohenoja (H6045578, GenBank MG457847); Siikainen, east of
Katselmankallio, west of Kaakkurilammet, dry pine-dominated acid
heath, old track, 20 Sep. 2006, E. Ohenoja (H6059327, GenBank
MG457845). Perä-Pohjanmaa: Kemijärvi, lower south slope of the fjell
Pyhätunturi, coniferous forest dominated by Pinus sylvestris, Betula
and Picea abies, 27 Aug. 2008, E. Ohenoja (H6001678, GenBank
MG457842); Rovaniemi, Pisavaara Strict Nature Reserve, acid pine
forest of Pinus sylvestris, 19 Sep. 2009, J. Kinnunen (H6025417,
GenBank MG457846). – Germany: Thuringia: east of Ilmenau, under
Picea, 1 Oct. 2016, A. Henrici (K(M)233759, GenBank MG457843).
Specimen details of downloaded sequences: Sweden: [Ecology
unknown], 6 Dec. 2014 [Collector unknown] (GenBank KM493150,
only ITS2 region). [Locality unknown], [Ecology unknown], 12 Dec.
2016, [Collector unknown] (GenBank KU062814, only ITS2 region).
Chroogomphus aff. liformis 1
Notes: This species is currently known only from a single ITS
sequence from GenBank clustering close to C. liformis. More
specimen data are required to study this species properly.
Specimen details of downloaded sequences: Austria: Haggen, in
subalpine forest of Pinus cembra, ectomycorrhizal root tip, 13 Dec.
2014, [Collector unknown] (GenBank KM504402).
Chroogomphus sect. Fulminei Niskanen, Scambler
& Liimat., sect. nov.
MycoBank MB823594
Etymology: Named after the type of the section.
Diagnosis: The combination of whitish to orange basal
mycelium, reddish patches on the stipe, dark or olivaceous
trama at the base of the stipe, and amyloid lamellar trama
hyphae distinguish this section from others of subgenus
Chroogomphus.
Type: Chroogomphus fulmineus (R. Heim) Courtec. 1988.
Description: Basidiomata medium to large. Pileus low convex,
surface smooth, brillose with age, dry to viscid; ochraceous
orange, reddish orange to apricot-orange when young, dark
brown, purple-red to leaden grey when mature. Lamellae
subdecurrent to decurrent. Stipe with patches of pinkish to
vinaceous red, especially towards the base. Trama of the
base of the stipe dark or olivaceous. Basal mycelium whitish
to orange.
Ecology and distribution: Found in northern and southern Eu-
rope, in coniferous and acidophilous coastal or mountainous
forests under species of Pinus subgen. Pinus. To date, spe-
cies of this clade have not been found with tree species other
than those belonging to subgen. Pinus.
Currently included species: C. fulmineus, and C. subfulmineus.
Notes: As with sect. Chroogomphus, these species have
a lamellar trama composed of amyloid hyphae. However,
species of sect. Chroogomphus typically have a pileus that
is reddish brown or pink to purplish when young, rather
than apricot-orange or reddish (as seen in the centre of the
pileus of C. subfulmineus in Fig 5G). Reddish to pink patches
towards the base of the stipe are mostly absent in sect.
Chroogomphus, and the trama at the base of the stipe is
either salmon-ochraceous or orange-yellow in colour, rather
than dark grey or olivaceous green. Species of sect. Fulminei
should not be confused with C. liformis of sect. Filiformes,
which may also have a pinkish stipe base when dried, but
differs in the other characters mentioned above.
Chroogomphus fulmineus (R. Heim) Courtec.,
Docums Mycol. 18 (72): 50 (1988).
(Figs 5E, 6E)
Basionym: Gomphidius viscidus var. fulmineus R. Heim,
Trab. Mus. Nac. Cienc. Nat., ser. Bot. 15: 68 (1934).
Types: Spain: Catalunya: Dos Rius, 30 Oct. 1932, R.
Heim [Champ. Catalogne n°28, as “Gomphidius viscidus
var. fulgens”] (PC0706649 – lectotypus hic designatus,
MBT379515).France: Corsica: Haute-Corse, Balagne, Forêt
de Bonifatu, in woodland over granite, with Pinus pinaster, 20
Nov 2013, [Collector unknown] (K(M)190394 – epitypus hic
designatus, MBT379522; GenBank MG457856).
Description: Pileus 10–45 mm, subconical to convex when
young, becoming low convex with age, margin inrolled, surface
slightly brillose with age, somewhat viscid to viscid; apricot-
orange when young, sometimes with patches of light pink,
then dark brown to leaden grey with age. Lamellae decurrent,
somewhat crowded, colour not recorded when very young,
spores soon colouring the lamellae pale to medium grey, then
faded brown at maturity. Stipe 30–80 × 4–10 mm, cylindrical,
often tapering towards the base, ochraceous orange to
apricot-orange, then dark brown to leaden grey, with reddish
to pinkish patches which increase in frequency towards the
base, with a few lamentous, white veil remnants at the stipe
apex, covering the lamellae when young. Basal mycelium
whitish. Trama of the pileus and upper part of the stipe pale
ochraceous orange, dark grey to black with olivaceous hints
at the very base. Taste and odour not recorded.
Basidiospores boletoid, smooth, dark, blackish, weakly
to strongly dextrinoid, (18.0–)19.0–24.0(–25.5) × (5.5–)6.0–
Chroogomphus in Europe
ARTICLE
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VOLUME 9 · NO. 2
7.0(–8.0) μm, av. 21.2 × 6.5 μm, av. Range 20.6–22.4 × 6.3–
6.6 μm, Q (–2.78)2.94–3.67(–3.81), Q av. 3.26, Q av. range
3.11–3.39. Basidia bisporic or tetrasporic, 48–63 × 9.5–12.5
μm, long clavate. Pleuro- and cheilocystidia 79–165 × 13–19
μm, av. 125.0 × 14.3 μm, av. range 110.6–133.4 × 13.8–14.8
μm, cylindrical to subfusiform, thin-walled (to 1.0 μm), some
medium to large brown encrustations visible in KOH, hyaline
in Melzer’s. Lamellar trama composed of amyloid hyphae.
Pileipellis of gelatinised hyphae, 3.0–8.0 μm diam, av. 5.4
μm, mostly inamyloid with some scattered amyloid elements.
Hyphae of the basal mycelium cylindrical, 4.5–16.0 μm diam,
with a thick amyloid coating of blue granules when observed
in Melzer’s; clamp connections not observed.
ITS sequence (GenBank MG457856) is distinct from the
other members of sect. Chroogomphus. This species is most
closely related to C. subfulmineus (MG457866), from which
it differs in the ITS regions by ve substitutions and indel
positions, a similarity of 99.1 %.
Ecology and distribution: Known from coniferous and
acidophilous coastal forests, to 700 m elev. in Corsica
at supramediterranean levels, found mainly under Pinus
pinaster, though it has also been recorded forming basidiomes
under P. halepensis and P. pinea. Producing basidiomata in
autumn, from late October to November. This species occurs
throughout the Mediterranean, and as far north as Scotland,
UK. Basidiome formation has been observed close to
Rhizopogon roseolus, Suillus bellinii, and S. collinitus, albeit
without direct basidiomatal contact.
Notes: Chroogomphus fulmineus usually has a smaller pileus
than other members of the genus, and the spores are longer
and have higher Q values on average (Q av. range 3.11–3.39)
than any other Chroogomphus species studied. The sister
species, C. subfulmineus, produces larger basidiomata, to 100
mm across, has somewhat wider spores, with lower average
Q values (Q av. range 2.12–3.12) and broader cystidia.
Across the genus, cystidial size tends to be highly variable,
but between these two species at least, the difference in
width appears to be consistent. Examination of the trama
also reveals differences between the two species. That of C.
fulmineus is pale ochraceous orange at the stipe apex, and
dark grey to black with greenish tints at the base, whereas the
trama of C. subfulmineus is brighter yellow at the stipe apex
and then faintly olivaceous at the stipe base. Morphologically,
C. fulmineus may also be confused with C. britannicus (sect.
Filiformes), however, that species has slightly broader spores,
coarser amyloid granules on the hyphae of the basal mycelium
and predominantly fusoid cystidia.
The original material of Gomphidius viscidus var. fulmineus
(Heim et al. 1934) had never been revised before. It was recently
rediscovered at PC, with other collections from Catalonia cited
in the same paper, collected by Heim during a one-month
foray in autumn 1932. Only one packet labelled “Gomphidius
viscidus var. fulgens”, with one sketch and a single young
specimen (“Dos Rius, 30-X [1932], n°28”), here designated as
lectotype, could be found as original material. There was also
a handwritten description associated with the packet details of
another collection, provisionally named “Gomphidius unicolor”,
used in the original description of G. viscidus var. fulmineus,
with line drawings of fresh specimens coded with the Séguy
colour chart reproduced by Heim et al. (1934: pl. 1, g. 3). By
deduction, this last collection probably came from "Environs
de Girona, échantillons apportés à l’exposition, 5-XI" as cited
in the protologue.
To assess the current application of the name C.
fulmineus, Heim’s original description was compared with
the known European species of Chroogomphus. The
macromorphological characters, in particular the small
basidiomata, apricot-orange colour of the pileus, the
vinaceous red stipe base and black to greenish trama of the
stipe base, are all in accordance with the current species
concept. The single basidiome in the lectotype collection
is very young, but taking that into consideration, the spore
measurements from the type specimen, 18.5–22 × 6–7.5 μm,
av. 19.7 × 6.8 μm, t well with our observations and also other
micromorphological characters accord with our species. An
attempt was made to sequence the holotype of C. fulmineus,
however, due to the specimen’s age this was unsuccessful.
We therefore considered it necessary to designate specimen
K(M)190394 as a modern epitype.
Considering the disjunction between North American and
European species of Chroogomphus, and in expectation of
thorough type revisions of North American taxa, the synonymy
between C. fulmineus and C. ochraceus, proposed by Singer
(1986: 736), and later by Villareal & Heykoop (1996), is
thought to be doubtful and is not retained here.
Additional specimens examined: France: Corse du Sud: Bastelica,
in pine forest with Pinus pinaster, 19 Nov. 2014, P.-A. Moreau
PAM14111904 (LIP 0401321, K(M)237214, GenBank MG457864).
Pas-de-Calais: Le Touquet-Paris-Plage, in acidophilous coastal
forest with Pinus pinaster, 11 Nov. 2014, E. Bastien & P.-A. Moreau
PAM14111104 (LIP 0401320, K(M) 237215). – Spain: Castilla-La
Mancha: Albalate de las Nogueras, near Pinus sylvestris, 3 Nov
2017, [Collector unknown] (K(M)237592). – United Kingdom:
Scotland: Morayshire, Aviemore, with Pinus sp., 20 Aug 2017, M.
Tortelli (K(M)237988).
Specimen details of downloaded sequences: Italy: Liguria:
Imperia, San Remo, with Pinus pinaster, 30 Oct. 2010, [Collector
unknown] (GenBank HM545722). – Spain: Jaén: Arroyo Frio, Sierra
de Cazorla, under Pinus halepensis and P. pinaster, 4 Nov. 2013, J.L.
Siquier (JLS 3264, GenBank LT219435).
Chroogomphus subfulmineus Niskanen, Loizides,
Scambler & Liimat., sp. nov.
MycoBank MB823599
(Figs 5G–H and 6F–G)
Etymology: Named for its similarity to Chroogomphus
fulmineus.
Diagnosis: The sister species, C. fulmineus, produces
considerably smaller, viscid basidiomata <45 mm with more
vivid orange colours, and a pale ochraceous orange trama at
the stipe apex becoming dark grey to black at the stipe base.
Type: Cyprus: Troodos, under Pinus brutia, 18 Nov. 2014,
M. Loizides (LIP 0401318 – holotype, GenBank MG457866;
K(M)237213, hb. M. Loizides ML411181/2 – isotypes).
Scambler et al.
ARTICLE
286 IMA FUNGUS
Description: Pileus (25–)40–80(–100) mm, hemispherical to
subconical when young, expanding to convex or low convex
with age, rarely indistinctly umbonate, margin somewhat
inrolled; pileal surface innately brillose, mostly dry to
somewhat viscid in humid conditions, never glutinous, reddish
orange to copper-orange when young, then reddish brown,
purple-brown or leaden grey in age, sometimes remaining
reddish-orange at the centre. Lamellae subdecurrent to
decurrent, at rst covered with a fugacious, cortinoid, pinkish
yellow to straw-coloured veil soon disappearing, somewhat
crowded, dingy ochraceous to ochraceous brown when
young, subdistant at full maturity (~12 per cm) and coloured
olivaceous grey to sepia-brown from the spores; lamellar
edges smooth and concolorous. Stipe 55–100 × 5–20 mm,
fusiform-rooting and strongly tapering towards the base,
covered in reddish, purple-red or orange-red brils on an
ochraceous yellow to ochraceous buff background, apex often
with a pinkish band. Basal mycelium orange to ochraceous
orange. Trama of the pileus and stipe straw-yellow to yolk-
yellow at the stipe apex, faintly to somewhat olivaceous at the
base when sectioned. Taste and odour sourish, somewhat
citrus-like.
Basidiospores boletoid, subfusoid to ellipsoid, smooth,
thick-walled, dark, blackish, weakly to moderately dextrinoid,
sparsely guttulate in water, (16.0–)17.0–24.0(–26.0) × (6.0–)
7.0–8.0(–8.5) μm, av. 20.6 × 7.0 μm, av. range 17.5–21.6 ×
6.4–7.7 μm, Q = (2.03–)2.18–3.37(–3.71), Q av. 2.81, Q av.
range 2.29–3.12. Basidia bisporic or tetrasporic, 30–75 × (8–
)9.5–14 μm, long clavate. Pleuro- and cheilocystidia 80–185
× 10–27 μm, av. 140.6 × 17.1 μm, av. range 133.4–155 ×
16.2–19.0 μm, subcylindrical, subutriform, or subcapitate,
thin-walled (to 1.0 μm), hyaline to brown in KOH, hyaline in
Melzer’s; encrustations not seen. Lamellar trama composed
of amyloid hyphae. Pileipellis composed of gelatinised,
sparsely septate hyphae 1.5–7.0 μm diam, av. 4.3 μm, mostly
inamyloid, with some scattered amyloid elements. Hyphae of
the basal mycelium cylindrical, 3.0–11.0 µm diam, with a thick
amyloid coating of blue granules when observed in Melzer’s;
clamp connections not observed.
ITS sequence (GenBank MG457866) distinct from the
other members of section Chroogomphus. This species is
most closely related to C. fulmineus (GenBank MG457856),
from which it differs in the ITS regions by 5 substitutions and
indel positions, a similarity of 99.1 %.
Ecology and distribution: In coniferous forests and plantations,
found with species of Pinus subgenus Pinus, mainly P.
sylvestris and P. nigra on acidic substrates, and so far not
recorded forming basidiomes under other coniferous genera.
Producing basidiomata in the autumn, from early August to
early November. Known from northern and southern Europe.
There is currently a lack of collections from central Europe;
however, the presence in Cyprus and the UK suggests it may
also occur in intermediate localities.
Notes: Chroogomphus subfulmineus is a large species with
typically dull reddish colours, a more or less dry or only slightly
viscid pileus, an orangish mycelium, and a deep yolk-yellow
trama at the stipe apex becoming somewhat olivaceous at
the stipe base.
Microscopically, C. fulmineus also has narrower cystidia
on average (av. range 13.8–14.8 μm). The species has longer
spores than most other members of the genus, with the
exception of C. fulmineus and C. britannicus. However, spores
of C. subfulmineus are generally broader than those of C.
fulmineus, and in the case of the holotype (LIP 0401318) they
were especially broad (Fig 6F–G), a character which appears
to be consistent throughout all collections of this species from
Cyprus. The spores of C. britannicus are also broad, and the
two species may be indistinguishable based on this character
alone, but C. britannicus has coarser amyloid granules on
the hyphae of its basal mycelium. It also differs in its lack of
reddish to pink colouration towards the stipe base, as well
as in the colour of its trama. Chroogomphus britannicus is
further described as a very small, ochraceous orange to
ochraceous buff species not exceeding 20 mm across, with
predominantly fusoid cystidia (Khan & Hora 1978), a feature
not seen in our collections of C. subfulmineus.
In previous analyses, the names C. rutilus or “C. rutilus
(Miller & Aime 2001, Li et al. 2009) and, more recently,
the name C. britannicus (Martín et al. 2016), have been
provisionally applied to this species. However, successful
sequencing of the 40-year-old paratype of C. britannicus in
this study, has demonstrated this taxon to be phylogenetically,
as well as morphologically distinct from C. subfulmineus.
Additional specimens examined: Cyprus: Troodos, under Pinus
nigra subsp. pallasiana on serpentine soil, 6 Nov. 2014, M. Loizides
ML41116/1, LIP 0401319; ibidem, ML4193/1 (LIP 0401323, GenBank
MG457865). United Kingdom: Scotland: Moray, Culbin Forest,
plantation of Pinus sylvestris and P. nigra (Betula pubescens also
present), 8 Aug. 2003, D. Genney IA09 (UNITE UDB001530; ibidem,
10 Oct. 2003, D. Genney DG56 (ABDF, UNITE UDB001529).
Specimen details of downloaded sequence: Finland: Inarin Lappi:
Utsjoki, Kevo, ecology unknown, O. K. Miller OKM17238 (GenBank
AF205639).
Vinicolores
Currently included species: C. cf. jamaicensis, and C. cf.
vinicolor.
Ecology and distribution: Known from North America,
basidiomata under species of Pinus.
Notes: This clade receives high bootstrap support in our
analysis, yet we are hesitant to designate it formally as a
section since the specimen data available are not based on
type materials. Here we leave it unranked pending further
study.
Chroogomphus subgen. Floccigomphus (Imai)
Niskanen, Scambler, & Liimat., comb. nov.
MycoBank MB823595
Basionym: Gomphidius sect. Floccigomphus Imai, J. Fac.
Agric., Hokkaido Imp. Univ. 43: 285 (1938).
Type: Chroogomphus tomentosus (Murrill) O.K Mill. 1964
(syn. Gomphidius tomentosus Murrill 1912).
Description (based on Miller & Aime 2001): Basidiomata
small to medium sized. Pileus conical to convex, umbonate,
Chroogomphus in Europe
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287
VOLUME 9 · NO. 2
brillose, dry; pale to dark orange. Lamellae decurrent, light
orange when young, vinaceous with age. Basidiospores
broadly elliptic, dextrinoid. Cystidia fusiform, thick-walled.
Lamellar trama composed of strongly amyloid hyphae.
Pileipellis of somewhat broad to broad, non-viscid hyphae.
Ecology and distribution: Known from North America and
Asia, associated with species of Pinus and other species of
the family Pinaceae.
Currently included species: C. pseudotomentosus, and C.
tomentosus.
Notes: Species of subgen. Floccigomphus can be dened
by their somewhat broad, non-gelatinised pileipellis hyphae
and amyloid lamellar trama. They form a basal clade within
the genus alongside subgen. Siccigomphus, the species of
which also have broad, non-gelatinised pileipellis hyphae but
lack amyloid elements in the lamellar trama and have thin-
walled cystidia.
Chroogomphus subgen. Siccigomphus Niskanen,
Scambler, & Liimat., subgen. nov.
MycoBank MB823597
Etymology: Referring to the dry pileus of its species.
Diagnosis: The combination of broad, non-gelatinised
pileipellis hyphae, inamyloid lamellar trama and narrow
spores with a low Q value (Q av. <2.60) distinguish this
subgenus from others of genus Chroogomphus.
Type: Chroogomphus roseolus Y.C. Li & Zhu L. Yang 2009.
Description: Basidiomata small to medium sized. Pileus
subconical to almost plane, appressed brillose-scaly, surface
dry. Lamellae typically decurrent, pale to ochraceous-orange
when young though later coloured grey by spores. Basidiospores
boletoid, smooth, moderately to strongly dextrinoid. Cystidia
cylindrical to subfusiform, thin-walled. Lamellar trama composed
of inamyloid hyphae. Pileipellis of somewhat broad to broad
hyphae not embedded in a gelatinous layer.
Ecology and distribution: Found in Eurasia and North America,
in coniferous and mixed forests under species of Pinus (both
subgenera Pinus and Strobus), and other species of the
family Pinaceae, e.g. Picea abies.
Currently included species: C. cf. helveticus, C. cf. leptocystis,
C. roseolus, and C. cf. sibiricus. The ITS sequences of C. cf.
leptocystis (GenBank FJ157000, OKM2981, USA, ID) and C.
cf. sibiricus (GenBank AH009856, OKM21628, Korea) were
short and thus not included in our analysis. However, the
phylogenetic analyses of Miller & Aime (2001) and Li et al.
(2009) show that those specimens belong in this subgenus.
Notes: Members of subgen. Siccigomphus can be dened
by their broad, non-gelatinised pileipellis hyphae, inamyloid
lamellar trama and narrow spores with a low Q value (Q
av. <2.60). Species of subgen. Floccigomphus have similar
pileipellis characters to those of this subgenus, but the two
groups can be easily distinguished by the amyloidity of the
lamellar trama: species of Floccigomphus have an amyloid
lamellar trama. In addition, the cystidia are thick-walled.
Chroogomphus cf. helveticus (Singer) M.M. Moser,
in Gams, Kl. Krypt.-Fl., 3rd edn 2b (2): 51 (1967).
(Figs 2A, 5F and 6H)
Basionym: Gomphidius helvetica Singer, Schweiz. Z. Pilzk.
28: 198 (1950).
Description: Pileus 30–50 mm, convex when young, later
low convex, surface dry, felty-scaly-brillose, though scales
not very evident in wet weather or in old basidiomata; yellow
to orange-apricot when young, often with a pinkish or even
violaceous tint, turning ochraceous orange when handled.
Lamellae somewhat decurrent, medium-spaced, yellow to pale
orange when young, later greyish from the spores. Stipe 30–
60 × 10–16 mm, cylindrical, often tapered at the base, yellow
to pale orange, becoming reddish orange when handled,
with a few lamentous veil remnants at the stipe apex. Basal
mycelium pale to ochraceous yellow to pinkish. Trama of the
pileus and stipe yellow to yellowish orange, brown at the very
base of the stipe. Taste and odour not distinctive.
Basidiospores boletoid, smooth, dark, blackish, mod-
erately to strongly dextrinoid, 15.0–19.0(–20.0) × 6.0–7.5
μm, av. 17.2 × 6.7 μm, av. range 16.0–18.0 × 6.4–7.0 μm, Q
(2.38–)2.40–2.75(–2.80), Q av. 2.59, Q av. range 2.58–2.60.
Basidia bisporic or tetrasporic, 35–55 × 8–11(–12.5) μm, long
clavate. Pleuro- and cheilocystidia 73–133 × 12–19 μm, av.
108.8 × 14.8 μm, av. range 104.0–113.0 × 14.5–15.0 μm,
cylindrical to subfusiform, thin-walled (to 1.5 μm), hyaline to
brown in KOH, sometimes with encrustations, hyaline in Mel-
zer’s. Lamellar trama composed of inamyloid hyphae, yellow-
ish to weakly pink in Melzer’s. Pileipellis of non-gelatinised
hyphae, 4.0–17.0 μm diam, av. 9.6 μm, mostly inamyloid
with some scattered amyloid elements. Hyphae of the basal
mycelium cylindrical, 4.5–11.0 µm diam, with a thick amyloid
coating of blue granules when observed in Melzer’s; clamp
connections not observed.
ITS sequence (GenBank MG457859) distinct from other
members of subgen. Siccigomphus. This species is most
closely related to C. roseolus (EU706329), from which
it differs in the ITS regions by 10 substitutions and indel
positions, a similarity of 98.5 %.
Ecology and Distribution: In coniferous and mixed forests,
basidiomes formed at least under Picea abies, one record
also from a mixed forest under Larix decidua. Producing
basidiomata in the autumn, in September. Occuring in the
Alps, Carpathians, and high mountains of the Balkans.
Notes: This is currently the only reported European spe-
cies belonging to subgen. Siccigomphus, and so can be
distinguished from the others by the broad, non-gelatinised
pileipellis hyphae. Chroogomphus roseolus is morphologi-
cally similar, but is only known from China and Pakistan (Li et
al. 2009, Razak et al. 2016).
This species was originally described from basidiomes
under Pinus cembra, a 5-needled pine, in Switzerland (Singer
1950). However, none of the collections examined in this study
Scambler et al.
ARTICLE
288 IMA FUNGUS
have been recorded under this tree species. Li et al. (2009)
state that this species is associated with members of Pinus
subgen. Strobus. However, two of the three specimens they
studied were rst sequenced by Miller & Aime (2001) who did
not mention any such ecological relationships. In the literature,
a subspecies C. helveticus subsp. tatrensis (Pilát) Kuthan &
Singer 1976 is reported with Picea and 2-needled pines and is
distinguished from C. helveticus subsp. helveticus that occurs
with 5-needled pines (Singer & Kuthan 1976, Breitenbach &
Kränzlin 1991). We here refer to our species provisionally as
C. cf. helveticus, based on the name that has been applied to
it in previous studies (Miller & Aime 2001, Li et al. 2009, Martín
et al. 2016), but further study of this taxon is needed since no
type material of C. helveticus has been examined yet.
Specimens examined: Austria: Tyrol: Ötztaler Alpen, Sölden,
in mixed woodland with Larix decidua, 2 Sep. 2002, S. E. Evans
(K(M)105170, GenBank MG457860). – Slovakia: Žilina: Liptovska
Kotlina basin, Važec, in meadows and stands along creeks N of the
village, in woods of Picea abies, 30 Sep. 2003, T. Niskanen & K.
Liimatainen F03-1673 (H7019100, GenBank MG457859).
Specimen details of downloaded sequences: Austria:
Klausoden, ecology unknown, O. K. Miller OKM21376 (GenBank
AF205642). – Czech Republic: Central Bohemian Region:
Neustupov, ecology unknown, [Date and collector unknown] (HKAS
55293 (KUN), GenBank FJ652070). – Germany: Bavaria: under
conifers, 26 Sep. 1996, M. Kronfeldner (GenBank GU187514). –
Switzerland: Alp Claire, ecology unknown, O. K. Miller OKM24410
(GenBank AF205650).
Key to the European species of Chroogomphus
Each of the seven described European Chroogomphus species can be identied using the key below. Some sections and
subgenera are monotypic in Europe, in which case these are included preceding their representative species.
1 Pileus hyphae non-gelatinised . ........................................................................................................................................ 2
Pileus hyphae gelatinised . ....................................................................................................... 3. subgen. Chroogomphus
2 (1) Lamellar trama amyloid; cystidia thick-walled .............................................................................. subgen. Floccigomphus
Lamellar trama non-amyloid; cystidia thin-walled ............................................. subgen. Siccigomphus, C. cf. helveticus
3 (1) Lamellar trama inamyloid or with very few amyloid elements ........................................ sect. Confusi, C. mediterraneus
Lamellar trama distinctly amyloid ..................................................................................................................................... 4
4 (3) Basal mycelium yellowish ................................................................................................ sect. Filiformes, C. britannicus
Basal mycelium whitish to salmon to purple-pink to orange ............................................................................................ 5
5 (4) Reddish patches towards base of stipe ................................................................................................... 6. sect. Fulminei
Yellow-orange to dark brown towards base of stipe ...................................................................... 7. sect. Chroogomphus
6 (5) Q av. usually > 3.1; cystidia narrow (av. <15 μm wide); trama at base of stipe dark grey to black ............... C. fulmineus
Q av. usually < 3.1; cystidia broad (av. >15 μm wide); trama at stipe base faint to somewhat olivaceous
................................................................................................................................................................ C. subfulmineus
7 (5) Cystidia thick-walled (to 3 μm) ............................................................................................................................ C. rutilus
Cystidia thin-walled (to 1 μm) ............................................................................................................ C. cf. purpurascens
DISCUSSION
European species of Chroogomphus
Eight species are currently recognized from Europe. One of
them, C. cf. helveticus, belongs to subgen. Siccigomphus
whereas all other species belong to subgen. Chroogomphus.
Six of the species received high support in our phylogenetic
analysis and had an intraspecic variation of less than 1 %; the
interspecic variation was over 1.5 %. The only exception was
between the species pair C. fulmineus and C. subfulmineus,
where there was an interspecic variation of 0.9 %, and
intraspecic variations of 0.6 % (C. fulmineus) and 0.4 % (C.
subfulmineus). This corresponds to the ndings from other
groups of subclass Agaricomycetinae as well, for example in
Cortinarius and the family Lyophyllaceae, a threshold value
of 99 % was found to be suitable for distinguishing species
in the majority of lineages, although some morphologically
distinguishable species had an even higher threshold value,
likely indicating a recent radiation (Niskanen et al. 2011,
Bellanger et al. 2015, Garnica et al. 2016).
Morphology-based identication
Through careful examination of specimens, we have been
able to delimit the currently known European species of
Chroogomphus on the basis of morphology, using mainly
microscopic characters. These delimitations are supported
by our molecular data, and to some extent also by our
geographical and ecological data. In summary, important
distinguishing characters for species identication are: colour
of pileus when young, colour of trama, spore size (length, width,
and Q value), amyloidity of the lamellar trama, wall thickness
of cystidia, gelatinisation of the pileipellis and diameter of the
pileipellis hyphae. The bruising colour of basidiomata is also a
potentially useful character in identication, but this feature is
Chroogomphus in Europe
ARTICLE
289
VOLUME 9 · NO. 2
not included in our descriptions as macromorphological data
are currently lacking for some species. One character which
does not appear to be useful is spore dextrinoidity, as this was
found to vary considerably within the same species. Another
character which might be of limited value in Chroogomphus
is the presence of clamp connections, as these can be rare
or absent and so their presence can be difcult to determine
with certainty. However, based on preliminary observations,
studying the clamps from the looser mycelial strands from the
mycelial mat could give better results; at least these hyphae
are not heavily incrusted with amyloid granules that can
sometimes obscure clamp connections. Further observations
of this microcharacter in good material are needed.
Though not every species can be dened by single char-
acters, combinations of characters along with geographical
and ecological data should in most cases allow for positive
identication. Infrageneric clades can mostly be distinguished
by an assessment of gelatinisation within the pileipellis and/
or the amyloidity of the lamellar trama.
When distinguishing between Chroogomphus and its
sister genus Gomphidius, it is important to note that lamellae
in young specimens of Chroogomphus are not always the pale
orange to ochraceous, rarely purple, colour that characterizes
the genus, but are often coloured grey by spores long before
maturity. This character should therefore be observed in the
youngest possible specimens to avoid confusion.
Ecology and distribution
Within their infrageneric taxa, species of Chroogomphus do
not appear to be conned to narrow geographic regions.
Subgen. Siccigomphus has representatives across the
Northern Hemisphere, as do sections Confusi and Filiformes.
Members of Floccigomphus are found in North America and
Asia, but not Europe; whilst those of sect. Chroogomphus
are found throughout Eurasia, but not North America. Sect.
Fulminei and /Vinicolores have narrower distributions and are
found in Europe and North America respectively.
Species of Chroogomphus can occur in a broader habitat
range than has been suggested in previous studies (Miller
2003, Li et al. 2009). Five species, C. britannicus, C. helveticus,
C. mediterraneus, C. purpurascens, and C. rutilus, have now
been reported producing basidiomes under Picea and other
coniferous genera besides Pinus. In the light of this evidence,
and considering the observations made by Agerer (1990), their
occurrence is determined by the presence of the mycorrhizal
partner and to unknown extent also by the presence of
Rhizopogon/Suillus species. The exact biological nature, and
degree of specicity of these relationships, is not currently
well understood and should be investigated further. Future
collections of Chroogomphus should include notes on the
presence of any Rhizopogon or Suillus present in the vicinity.
Infrageneric classication
The infrageneric clades recovered in our analysis all receive
high bootstrap support (BS >75) and generally correspond
well to those found in previous studies (Miller 2003, Li et al.
2009, Martín et al. 2016). The subgenera Floccigomphus
and Siccigomphus as dened here are recovered with high
support in all three studies. Furthermore, all the sections of
subgen. Chroogomphus are found in all previous analyses.
The study of Miller (2003) also shows subgen. Chroogomphus
as monophyletic. However, in both Li et al. (2009) and Martín
et al. (2016) some sections of the subgenus are not grouped
with the main clade, but in those cases the topology of the
tree is not well supported.
In our phylogenetic analysis, subgen. Floccigomphus
formed the basal clade in the genus. This position
indicates that subgen. Floccigomphus, along with subgen.
Siccigomphus, which clusters nearby, represent ancestral
clades within the genus. This would suggest that species
of Chroogomphus may have originally lacked a gelatinised
layer in the pileipellis, and that this feature emerged during
subsequent evolution, along with an overall narrowing of the
pileipellis hyphae.
By formally recognising sections and subgenera within
Chroogomphus, we aim to stabilise the groups that have al-
ready been proven to exist by both molecular and morpho-
logical data. Establishing infrageneric taxa is important in con-
solidating the afnities of closely-related species. By dening
these groups morphologically, it becomes easier to observe
the evolution of characters within the genus. It is also conveni-
ent for future studies wherein infrageneric taxa can be referred
to by name, reducing confusion. Although some sections cur-
rently lack unifying morphological features, we aim to have es-
tablished a robust infrageneric framework upon which future
studies of the genus Chroogomphus can be built.
ACKNOWLEDGEMENTS
We would like to thank Roy Watling for advice regarding the taxonomic
placement of C. corallinus. We also thank the curators of K(M), H and
PC fungaria, and are very grateful to Triantafyllos Angelou, Antonis
Athanasiades, Eric Bastien, Pat and Keith Cavanagh, Maurice Durand,
David Genney, Geoffrey Kibby, Vello Liiv, Maria Marinela, Mel Oxford,
Eleni Papadopoulou, Irja Saar, Andy Taylor, and Alexis Thorel, for the
provision of valuable specimens, collection data, and photographs
used during this study. The sequencing of the Finnish specimens was
partly supported by Kone Foundation (FinBOL-project).
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