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Mycologia, 94(6), 2002, pp. 998-1016.
© 2002 by The Mycological Society of America

Proceedings towards a natural classification of the worldwide taxa Phellinus s.l. and Inonotus s.l., and phylogenetic relationships of allied genera


Tobias Wagner 1

     Institut für Botanik, Universität Regensburg, Universitätsstrasse 31, D-93040 Regensburg, Germany

Michael Fischer 2

     Staatliches Weinbauinstitut Freiburg, Merzhauser Strasse 119, D-79100 Freiburg, Germany

    ABSTRACT
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 LITERATURE CITED
 

The classification of Phellinus s.l., Inonotus s.l. and the phylogenetic relationships of allied genera were studied using nuc-lsu rDNA sequence data. The worldwide taxon sampling comprised 107 species, 99 of them belonging to the Hymenochaetales. The phylogenetic trees were discussed in relation to morphological and anatomical features of the fruit bodies. The Hymenochaetales formed no monophyletic group and several non-Hymenochaetales appeared as intermingled with the Hymenochaetales. Trichaptum abietinum and Oxyporus populinus showed no certain affinities within the Hymenochaetales, whereas Basidioradulum radula was closely related to Phellopilus nigrolimitatus, and Hyphodontia quercina and Schizopora paradoxa were related to Coltricia, Coltriciella and Pyrrhoderma adamantinum. Phellinus s.l. and Inonotus s.l. formed no monophyletic groups, and a subdivision in the following genera is accepted: Phellinus s.s., Inonotus s.s., Inocutis, Fomitiporella, Aurificaria, Phylloporia, Fulvifomes, Mensularia, Pseudoinonotus, Fomitiporia, Porodaedalea, Onnia, Fuscoporia, and Inonotopsis. Coltricia and Coltriciella were confirmed as seperate genera. The taxonomic status of Phellinidium and Pyrrhoderma remained uncertain. 16 new combinations are proposed.

Key words: aphyllophoroid fungi, Basidiomycota, Hymenochaetaceae, Hymenochaetales, molecular systematics, taxonomy


    INTRODUCTION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 LITERATURE CITED
 
The two large genera within the Hymenochaetales, Phellinus s.l. and Inonotus s.l., exhibit a worldwide distribution. About 150 and 100 species, respectively, are presently acknowledged for these genera (Larsen and Cobb-Poulle 1990Citation, Ryvarden pers comm). Most likely these numbers of taxa are incomplete; while extensive studies on the occurrence and systematics of Phellinus s.l. and Inonotus s.l. have been carried out for European and North American taxa (Jahn 1963Citation, 1981Citation, Ryvarden 1978Citation, Fiasson and Niemelä 1984Citation, Jülich 1984Citation, Gilbertson and Ryvarden 1986–1987Citation, Ryvarden and Gilbertson 1993–1994Citation), such data are mostly missing for other geographic regions. However, important overviews on the biodiversity of taxa are available for regions such as New Zealand (Cunningham 1965Citation), East Africa (Ryvarden and Johansen 1980Citation), South America (Rajchenberg 1989Citation), and East Asia (Dai 1999Citation, Nunez and Ryvarden 2001Citation).

All species of Phellinus s.l. and Inonotus s.l. live as parasites and/or saprophytes on a wide variety of angiosperms and/or gymnosperms and produce a white rot. Some of the taxa play a prominent role in forest ecosystems, especially in Northern Europe and North America. Species of both genera are characterized by poroid fruit bodies. The shape of the fruit bodies is variable however, and even between closely related species it may range between resupinate, effused-reflexed, pileate, substipitate, and stipitate.

The generic concepts of Phellinus s.l. and Inonotus s.l., which are traditionally based on mitism of the hyphal system and consistency of the fruit bodies (Phellinus s.l.: dimitic and perennial; Inonotus s.l.: monomitic and annual) have repeatedly been demonstrated as artificial (Fiasson and Niemelä 1984Citation, Corner 1991Citation, Dai 1995Citation, 1999Citation, Fischer 1996Citation, Wagner and Fischer 2001Citation) and intermediate forms occur. For instance, in P. discipes, P. erectus, P. gilvus, and I. dryadeus fruit bodies are annual and the hyphal system is dimitic or transitional between monomitic and dimitic. On the other side, species such as P. pachyphloeus, P. poeltii, P. ribis, P. robustus, and P. sulphurascens produce perennial fruit bodies, but have monomitic hyphal systems or show transitions between monomitic and dimitic (Domanski et al 1973Citation, Jahn 1981Citation, Fiasson and Niemelä 1984Citation, Corner 1991Citation, Ryvarden and Gilbertson 1993–1994Citation, Dai 1995Citation, 1999Citation).

Numerous characters from morphology, anatomy, sexuality, nuclear behavior, pigmentation, and ecology suggest that Phellinus s.l. and Inonotus s.l. are heterogeneous (Fiasson 1982Citation, Fiasson and Niemelä 1984Citation, Dai 1995Citation, 1999Citation, Fischer 1996Citation). Smaller, more homogeneous subgroups are evident within both taxa and, based upon an examination of mostly North American and European collections, several attempts were undertaken to split Phellinus and Inonotus into a number of smaller, more natural genera. As a result Phellinus s.l. comprises numerous generic notations, namely Ochroporus, Pyropolyporus, Porodaedalea, Fuscoporia, Fomitiporella, Fomitiporia, Fuscoporella, Fulvifomes, Scalaria, Pseudofomes, Daedaleoides, Phellinidium, Phellopilus, and Phaeoporus, as well as Inonotus s.l., namely Mucronoporus, Onnia, Flaviporellus, Mensularia, Xanthoporia, Inonotopsis, Inocutis, and Pseudoinonotus (Fiasson and Niemelä 1984Citation, Ryvarden 1991Citation, Ryvarden and Gilbertson 1993–1994Citation, Dai 1995Citation, 1999Citation, Niemelä et al 2001Citation, Wagner and Fischer 2001Citation).

Mostly derived from characters of morphology, anatomy, pigmentation, and karyology, Fiasson and Niemelä (1984)Citation revised the taxonomy of the European poroid Hymenochaetales and proposed to split the Hymenochaetales into two families, i.e., the Phellinaceae, comprising Phellinus s.s., Fomitiporia, Fulvifomes, Fuscoporia, Inonotopsis, Ochroporus, Onnia, Phellinidium, and Porodaedalea, and the newly described Inonotaceae, comprising Inonotus s.s., Inocutis, and Phylloporia. Later on, this system was accepted by Jahn and Jahn (1986)Citation, Nuss (1986)Citation, and Hansen and Knudsen (1997)Citation. Fischer (1996)Citation was able to verify the generic status of Fomitiporia by restriction analyses of mitochondrial DNA and ribosomal DNA combined with results from sexuality, DNA content of nuclei, and karyology. However, since the study by Fiasson and Niemelä was based on European material only, neglecting the numerous tropical species, the suggested splitting concept has been mostly rejected subsequently (Gilbertson and Ryvarden 1986–1987Citation, Parmasto 1988Citation, Larsen and Cobb-Poulle 1990Citation, Ryvarden and Gilbertson 1993–1994Citation). Dai (1999)Citation accepts the genera Fomitiporia and Phellinidium, but only grants subgeneric level to Phellinus s.s., Fulvifomes, Fuscoporia, Phellinidiopsis, and Porodaedalea.

Only recently, sequence data from the nuclear encoded large subunit (nuc-lsu) rDNA together with traditional characters were used to re-examine the classification and phylogenetic relationships of the Hymenochaetales (Fischer et al 2001Citation, Niemelä et al 2001Citation, Wagner 2001Citation, Wagner and Fischer 2001Citation, 2002Citation, Wagner and Ryvarden 2002Citation). The study of Wagner and Fischer (2001)Citation was based on 43 taxa of the poroid Hymenochaetales, mostly of European origin. DNA data together with characters from morphology, anatomy, pattern of reproduction, and karyology demonstrated both Phellinus s.l. and Inonotus s.l. as polyphyletic, the former subdivided into the genera Phellinus s.s. (type species: P. igniarius), Porodaedalea (P. pini), Fomitiporia (F. punctata), Fuscoporia (F. ferruginosa), Phellinidium (P. ferrugineofuscum), and Phylloporia (P. parasitica), the latter subdivided into the genera Inonotus s.s. (I. hispidus), Inocutis (I. rheades), Mensularia (M. radiata), Pseudoinonotus (P. dryadeus), and Inonotopsis (I. subiculosa). Phellopilus was proposed for the strongly divergent taxon P. nigrolimitatus (Niemelä et al 2001Citation). All these studies have demonstrated such diverse characters as the pattern of sexuality, the morphology and color reactions of the basidiospores, and the occurrence of tramal and hymenial setae, as diagnostic for delimitating natural entities in the Hymenochaetales.

So far, within Phellinus s.l. and Inonotus s.l. extensive phylogenetic data are mostly missing for non-European taxa, which make up approximately two thirds of the presently achnowledged species. The generic concepts of Phellinus s.l. and Inonotus s.l., still mostly based on European taxa, are evaluated by the inclusion of selected taxa originating from North and South America, Africa, Asia, and Australia.

Both Phellinus s.l. and Inonotus s.l. belong to the Hymenochaetales (Oberwinkler 1977Citation; formerly Hymenochaetaceae sensu Donk 1948Citation) and exhibit the typical characteristics of the order, such as the xanthochroic reaction (darkening of the trama with KOH), the yellow to deep brown trama, the clampless hyphae, the occurrence of setae (not in all species), and the cause of a white rot. The available data on the ultrastructure of the septal pores showed non-perforated parenthesomes to be a common character for the Hymenochaetales (Moore 1980Citation, Keller 1997Citation, Müller et al 2000Citation). Recently, phylogenetic analysis of sequence data of nuclear encoded small subunit (nuc-ssu) and mitochondrial encoded small subunit (mt-ssu) rDNA (Hibbett and Donoghue 1995Citation, Langer 1998Citation, Hibbett and Thorn 2001Citation), as well as nuc-lsu rDNA (Langer 2001Citation) demonstrated several aphyllophoralean taxa such as Hyphodontia, Schizopora, Oxyporus, Basidioradulum, and Trichaptum as closely related to the Hymenochaetales. However, the relationships of these taxa have not been studied yet on the basis of nuc-lsu sequences comprising a worldwide taxon-sampling of the Hymenochaetales.

All in all, our phylogenetic analyses are based on nuc-lsu rDNA sequence data of 104 European (55%) and non-European taxa (45%) of Phellinus s.l., Inonotus s.l. and allied genera of the hymenochaetoid clade sensu Hibbett and Donoghue (1995)Citation and Hibbett and Thorn (2001Citation; see Table I ).


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TABLE I. List of taxa, included in the phylogenetic analysis; sources of fungal material, and GenBank accession numbers

 

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TABLE I. Continued

 

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TABLE I. Continued

 

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TABLE I. Continued

 

    MATERIALS AND METHODS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 LITERATURE CITED
 
Our molecular data set was from 88 taxa of Phellinus s.l. (poroid; approx 41% of described species) and Inonotus s.l. (poroid; approx 28%), and in addition 3 taxa of Coltricia (poroid), 4 taxa of Coltriciella (poroid), Aurificaria luteoumbrina (poroid), Asterodon ferruginosus (hydnoid), Hymenochaete rubiginosa (corticioid), and Pseudochaete tabacina (corticioid). Field data of the collections are given in Table I. Nuc-lsu sequences of Hyphodontia quercina (odontoid), Schizopora paradoxa (odontoid to poroid), Oxyporus populinus (poroid), Basidioradulum radula (odontoid) and Trichaptum abietinum (poroid), all unresolved in their relationships to the Hymenochaetales, were included as well (see Table I). Previous DNA data suggested russuloid taxa were closely related to the hymenochaetoid clade (Hibbett and Donoghue 1995Citation, Hibbett et al 1997Citation, Hibbett and Thorn 2001Citation). Therefore, three species from the russuloid clade, namely Russula violacea (agaricoid), Bondarzewia montana (poroid) and Stereum hirsutum (corticioid), were chosen as outgroups. Fifty-five of these sequences were newly generated for this study, the remaining sequences have been published before (Wagner 2001Citation, Wagner and Fischer 2001Citation, 2002Citation, Wagner and Ryvarden 2002Citation).

DNA was isolated from cultured mycelia or herbarium specimens. Cultures were grown on 2% malt extract agar (2% malt extract, 2% agar, 0.05% yeast extract in distilled water) at 23 C. Total DNA was isolated from cultures and fresh material as described by Lee and Taylor (1990)Citation. However, DNA pellets were air-dried and were redissolved in 100 µL TE buffer (10 mM Tris HCl, 1 mM EDTA, pH 8.0). DNA extractions from herbarium species were performed with the DNeasy Plant Mini Kit (Qiagen) according to the manufacturer's protocol.

DNA-dilutions varied from 1:100 to 1:1000 in distilled water. Approximately 1400 bases (b) of the nuc-lsu rDNA were amplified using Taq polymerase (Eurogentec) and primers LR0R (ACC CGC TGA ACT TAA GC) and LR7 (TAC TAC CAC CAA GAT CT) on a Biometra TRIO-Thermoblock, using the following parameters: 94 C denaturation step (1 min), 47 C annealing step (45 s), and 72 C primer extension (2 min). The cycle was repeated 37 times. A final incubation step at 72 C (7 min) was added after the final cycle. PCR products were purified with the QIAquick PCR Purification Kit (Qiagen). Cycle sequencing reactions were set up with primer LR0R or LR5 (TCC TGA GGG AAA CTT CG; primer sequences used in this study were obtained from http://www.botany.duke.edu/fungi/mycolab/primers.htm) using the ABI PRISM BigDye Terminator Cycle Sequencing Ready Reaction Kit (Applied Biosystems, California). Parameters for the reactions were: 96 C denaturation step (30 s), 48 C (LR0R) and 49 C (LR5) annealing step (15 s), and 72 C primer extension (4 min). The cycle was repeated 35 times. Cycle sequencing products were run on an ABI 377 automated DNA sequencer (Applied Biosystems).

Approximately 900 b of the sequences, starting from primer LR0R, were automatically aligned using ClustalX (Thompson et al 1997Citation). A final alignment was performed by eye. Gaps in the alignment were treated as missing data. All positions were included in the final alignment. The sequences obtained have been deposited in GenBank (see Table I). Sequence alignments have been deposited in TreeBASE as submission no. SN 979.

Maximum parsimony (MP) analysis was performed with PAUP 4.0b2 (Swofford 1999Citation) using heuristic search, with tree-bisection-reconnection (TBR) branch-swapping algorithm, MulTrees option in effect, and zero length branches collapsed. All characters were of unordered type and had equal weight. We performed a two-step analysis: step one used 100 heuristic searches, keeping up to 100 trees per replicate; step two used TBR branch swapping on the shortest trees found in step one. Maxtrees option was set to autoincrease. To estimate branching order, a bootstrap analysis (Felsenstein 1985Citation) was run with 100 heuristic replicates, maxtrees were set to 100.

The distance analysis was calculated with components of the PHYLIP 3.5c packet (Felsenstein 1995Citation) integrated in ClustalX. The distance matrix was generated using Kimura 2-parameter distances, weighting transition:transversion ratio 2:1. Neighbor-joining (NJ, default parameters) was used to calculate the tree. Bootstrap analysis was run with 1000 replicates. Both the NJ tree and the MP tree were rooted with the outgroups.

To rate the results of the parsimony analysis, constrained trees were created in MacClade version 3.04 (Maddison and Maddison 1992Citation). In the heuristic search TBR branch swapping algorithm and MulTrees option were in effect. Collapse zero length-branches option was on. Maxtrees option was set to 100. Unconstrained and constrained trees were compared using the Kishino-Hasegawa test (Kishino and Hasegawa 1989Citation) and the Wilcoxon signed-ranks test (Templeton 1983Citation).


    RESULTS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 LITERATURE CITED
 
Within the 104 species of the hymenochaetoid clade the length of the selected DNA fragment ranged between 852 b (Coltricia perennis) and 884 b (Phellinus robiniae). Within the russuloid species the length of the fragment ranged between 863 b (Stereum hirsutum) and 870 b (Russula violacea). Sequences from conspecific isolates were identical, even when originating from different continents as for example Coltrica perennis (Europe; North America), Onnia tomentosa (Europe; North America), or Phellopilus nigrolimitatus (Europe; Asia). Only one sequence per species was included in the final analysis. The alignment of the 107 sequences resulted in 919 sites with 433 variable characters, 334 of which were parsimony informative.

The results of our study (Figs. 1, 2) were mostly congruent with those of Wagner and Fischer (2001)Citation. The two large taxa Phellinus s.l. and Inonotus s.l. formed no monophyletic clades but were split into several smaller groups, which in some cases comprised members of the two taxa side by side. The generic subgroups within the European poroid Hymenochaetales as suggested by Wagner and Fischer (2001)Citation were mostly verified as highly supported separate groups. The non-European species were either integrated into these groups or formed new separate ones.



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 FIG. 1. Strict consensus tree (2273 steps) of 144 best trees obtained from parsimony analysis of nuc-lsu rDNA sequences of 104 ingroup taxa and the outgroups Bondarzewia montana, Russula violacea, and Stereum hirsutum. The tree was rooted with the outgroups. Bootstrap analysis was performed with 100 replicates; only bootstrap values higher than 50% are indicated above the branches. Partly dashed bracket of Phellinus s.s. indicates the uncertain position of some species within this genus as explained in the text. Accepted generic names within the ingroup are bold typed

 


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 FIG. 2. Phylogram obtained by neighbor-joining analysis of nuc-lsu rDNA sequences of 104 ingroup taxa and the outgroups Bondarzewia montana, Russula violacea, and Stereum hirsutum. The tree was rooted with the outgroups. Bootstrap analysis was performed with 1000 replicates. Bootstrap values higher than 50% are indicated above the branches. Scale bar at the bottom indicates the percentage of difference between sequences. Partly dashed bracket of Phellinus s.s. indicates the uncertain position of some species within this genus as explained in the text. Accepted generic names within the ingroup are bold typed.

 
In the first step of the MP analysis, 144 trees were found on two different islands (Maddison 1991Citation), each with 2273 steps, consistency index (CI) 0.31, retention index (RI) 0.68, and rescaled consistency index (RC) 0.21. In the second step, no shorter trees were found. Topologies of the strict consensus of the 144 most parsimonious trees (Fig. 1) and the NJ tree (Fig. 2) were mostly congruent.

Both trees (Figs. 1, 2) showed a monophyletic hymenochaetoid clade (MP and NJ 100%), comprising several highly supported subclades. In the following, the designations of these clades are according to those given in Figs. 1 and 2.

The DNA data highly supported a Inonotus s.s. clade (MP 89%; NJ 96%), combining species belonging to Inonotus s.l. and Phellinus s.l. and exhibiting a European and non-European distribution. Two distinct subclades were formed by I. obliquus and I. ulmicola (MP and NJ 100%), and P. linteus, P. vaninii, P. weirianus, and P. baumii (MP and NJ 100%). Phellinus pachyphloeus was closely related to I. chishanyenus and I. nidus-pici (MP 82%; NJ 80%).

Phylloporia (6 mostly tropical species, solely P. ribis occurring in Europe; MP 99%; NJ 100%) and Fulvifomes (4 cosmopolitan or tropical species; MP 99%; NJ 93%) together with a group comprising the non-European species Aurificaria luteoumbrina and Inonotus porrectus (MP 99; NJ 100%) formed another large clade (MP 63%; NJ 73%). For both trees, bootstrap values were constantly high within the Fulvifomes clade (>90%).

Inocutis (5 northern hemispheric or tropical species; MP and NJ 100%) and Fomitiporella (3 northern hemispheric or tropical species; MP 98%; NJ 100%) appeared as sister groups (MP 83%; NJ 89%) and in the NJ tree were next related to the clade with Phylloporia, Fulvifomes, Aurificaria luteoumbrina, and Inonotus porrectus.

The Mensularia clade consisted of a core of 3 northern hemispheric species (MP 99; NJ 100%), with the non-European species Inonotus crocitinctus as next related.

The composition of the Phellinus s.s. clade was inconclusive. In both trees a core of 9 species, all occurring in Europe, together with the non-European P. arctostaphyli was highly supported by 100%. However, the inclusion of P. bicuspidatus and P. spiculosus, both non-European, had no support in the MP tree and only low support in the NJ tree (63%), and the inclusion of the northern hemispheric P. conchatus and the non-European P. occidentalis had no bootstrap support in both trees.

The Pseudoinonotus clade comprised two species, i.e., the northern hemispheric P. dryadeus and the Australian P. chondromyelus (NJ 56%); four species, all northern hemispheric, were combined in the next related Fomitiporia clade (MP and NJ 100).

In the MP and NJ trees, Porodaedalea (4 northern hemispheric species; MP and NJ 100%), and Onnia (3 northern hemispheric species; MP 87%; NJ 100%) were supported as sister groups (NJ 77%), next related in the NJ tree to the northern hemispheric Pseudochaete tabacina (61%).

In both trees, all the clades mentioned above were combined in one large clade (MP 54%; NJ 75%). In the MP tree the northern hemispheric Hymenochaete rubiginosa was integrated in this clade.

The 3 cosmopolitan species of Coltricia and the 4 non-European species of Coltriciella were highly supported as sister groups (MP and NJ 100%), with Pyrrhoderma adamantinum, non-European, and Hyphodontia quercina and Schizopora paradoxa, both northern hemispheric, as next related (MP 69%; NJ 98%). These taxa together formed a second large clade (MP 69%; NJ 96%).

In the NJ tree a third large clade (79%) was formed by Fuscoporia (10 species with European and non-European distribution; MP 91%; NJ 96%), Phellinidium, Inonotopsis subiculosa, Pyrrhoderma scaurum, Trichaptum abietinum, Oxyporus populinus, Phellopilus nigrolimitatus, Basidioradulum radula, and Asterodon ferruginosus. In the MP tree no distinct clade was formed by these taxa.

Within Fuscoporia, the non-European species P. gilvus and I. formosanus (MP and NJ 100%), the northern hemispheric species Fuscoporia torulosa and F. wahlbergii (MP 85%; NJ 99%), and the non-European species P. cinchonensis and Fuscoporia montana (MP and NJ 100%) formed distinct subclades.

Phellinidium appeared as polyphyletic, with the type species P. ferrugineofuscum (northern hemispheric) clustering together with P. pouzarii (European) and P. fragrans (non-European; MP 81%; NJ 100%); the non-European species Phellinidium sulphurascens and P. weirii (MP 97%; NJ 100%) were separated by the position of the northern hemispheric Inonotopsis subiculosa and the non-European Pyrrhoderma scaura.

Another group was formed by the northern hemispheric species Phellopilus nigrolimitatus and Basidioradulum radula (MP and NJ 86%).

To evaluate the monophyly of Phellinidium, a constrained analysis was performed leaving the rest of the tree unresolved. The constrained analysis produced 96 trees that were 9 steps longer than the unconstrained trees. The hypothesized monophyly was not rejected by the Kishino Hasegawa test (P = 0.2166–0.2788) and the Wilcoxon signed ranks-test (P = 0.1614–0.3123).


    DISCUSSION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 LITERATURE CITED
 
Based on a number of distinct characters, the Hymenochaetales sensu Oberwinkler are generally considered as a natural entity (Donk 1948Citation, Jahn 1963Citation, 1981Citation, Domanski et al 1973Citation, Oberwinkler 1977Citation, Fiasson and Niemelä 1984Citation, Julich 1984Citation, Corner 1991Citation, Ryvarden 1991Citation, Hansen and Knudsen 1997Citation). However, the phylogenetic analyses presented in this study strongly suggest that the Hymenochaetales represent no monophyletic group, and in this way its taxonomic concept becomes vague. Similar to results of earlier studies (Hibbett and Donoghue 1995Citation, Hibbett et al 1997Citation, Langer 1998Citation, 2001Citation, Hibbett and Thorn 2001Citation), our analyses result in a highly supported large clade, comprising not only the representatives of the Hymenochaetales, but also Hyphodontia quercina, Schizopora paradoxa, Oxyporus populinus, Basidioradulum radula, and Trichaptum abietinum. In several aspects the latter taxa do not conform with the taxonomic concept of the Hymenochaetales. Although they occur on wood, produce a white rot, and develop resupinate to pileate basidiocarps with a corticioid, irpicoid, or poroid hymenophore, they are divergent by the lack of the xanthochroic reaction, the more or less hyaline hyphae, and the lack of setae. Most striking, all these species, except Oxyporus, have clamped hyphae. As a common character for all species within the hymenochaetoid clade, hitherto exclusively non-perforated parenthesomes were demonstrated for the septal pore caps (Traquair and McKeen 1978Citation, Moore 1980Citation, Oberwinkler 1985Citation, Langer and Oberwinkler 1993Citation, Keller 1997Citation, Müller et al 2000Citation). Such parenthesomes are most often observed within heterobasidiomycetes such as the Auriculariales and Dacrymycetales (Lu and McLaughlin 1991Citation, Wells 1994Citation, Hibbett and Thorn 2001Citation), whereas perforated parenthesomes occur within the homobasidiomycetes (Hibbett and Thorn 2001Citation). Results of phylogenetic studies suggest non-perforated parenthesomes to be plesiomorphic within the homobasidiomycetes (Hibbett and Donoghue 1995Citation, Hibbett et al 1997Citation, Langer 1998Citation, 2001Citation, Hibbett and Thorn 2001Citation). These studies also verified the general view that septal ultrastructure represents a conservative character (Moore 1980Citation) and six out of eight resolved major clades were found to be homogeneous in their parenthesome type (Hibbett and Thorn 2001Citation). The data at hand point out a revision of the concept of the Hymenochaetales, which then probably has to be reduced to the characters provided by the septal ultrastructure. However, extensive studies on this aspect are still missing, and appropriate data are restricted to few taxa only.

Within the large hymenochaetoid clade, some deeper nodes are well supported in our trees (Figs. 1, 2). For instance, good support is evident for the clade comprising Inonotus s.s., Phylloporia, Fulvifomes, Inocutis, Fomitiporella, Aurificaria, Phellinus s.s., Pseudoinonotus, Fomitiporia, Porodaedalea, Onnia, Mensularia, and Pseudochaete, all of which are in accordance with the classic concept of the Hymenochaetales sensu Oberwinkler (1977)Citation. This clade is congruent with the results of Wagner and Fischer (2001)Citation, where it has been designated as clade "A". Wagner and Fischer (2001Citation, 2002Citation) reported a holocoenocytic behavior of the vegetative mycelium for taxa of this clade; however, such data are still missing for many species. The species comprised in this clade are predominantly parasitic and with the exception of Porodaedalea, Onnia, and Fomitiporia hartigii usually occur on deciduous trees. Both holocoenocytic behavior of the vegetative mycelium and parasitism on deciduous trees have been suggested as derived characters in former studies (Boidin 1971Citation, Hacskaylo 1971Citation, Fiasson and Niemelä 1984Citation, Malloch 1987Citation, Hibbett and Thorn 2001Citation), and this is supported by the topologies of our trees (Figs. 1, 2).

The lineage comprising Coltricia, Coltriciella, and Pyrrhoderma adamantinum is clearly separated from the remaining taxa of the Hymenochaetales. Based on the species included in our studies, this clade is reduced to taxa without setae. For a better understanding of the particular relationships the inclusion of additional species belonging to the more closely allied taxa Hyphodontia and Schizopora is essential.

The remaining taxa within the hymenochaetoid clade form a more heterogeneous clade and appear as intermingled with Basidioradulum, Oxyporus, and Trichaptum (Figs. 1, 2), indicating a polyphyletic origin. The Hymenochaetales included in this clade are more often saprophytic and occur on coniferous wood; in addition, they mostly show a binucleate nuclear behavior, in this way pointing to a plesiomorphic position within the Hymenochaetales. The close relationship between Phellopilus and Basidioradulum may be interpreted as follows: a) Phellopilus nigrolimitatus represents a primary species within the Hymenochaetales, having just developped the particular characteristics of the Hymenochaetales, b) these characteristics have been lost in some parallel lineages, and, c) the characteristics of the Hymenochaetales have independently evolved in separate lineages.

As another striking result, our study clearly demonstrates the polyphyletic origin of Phellinus s.l. and Inonotus s.l. For both taxa several distinct clades are resolved, representing natural groups which are in accordance with the mostly European-based taxonomical concept suggested previously (Wagner and Fischer 2001Citation); in addition, new groups become obvious. Besides the DNA data, for most of the non-European species the available information is restricted to morphology and anatomy, whereas data derived from sexuality, cytology, or pigmentation are often missing. Nevertheless, most of the subgroups within Phellinus s.l. and Inonotus s.l. are clearly delimited (see Table II 2 ).


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TABLE II. Synoptic key for genera of Phellinus s.l. and Inonotus s.l

 

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TABLE II. Continued

 
The present study confirms the generic status of Phylloporia, Inocutis, Inonotus, Phellinus, Pseudoinonotus, Fomitiporia, Porodaedalea, Onnia, Mensularia, Fuscoporia, Inonotopsis, Phellopilus, and Coltricia. Distinct new groups are Fulvifomes, Fomitiporella, and Coltriciella. The taxonomic status of Phellinidium (Kotlaba 1968Citation, Fiasson and Niemelä 1984Citation, Dai 1995Citation, 1999Citation) and Pyrrhoderma (Imazeki 1966Citation, Corner 1991Citation, Dai 1999Citation) remains uncertain. A synoptic key for genera of Phellinus s.l. and Inonotus s.l. is offered in Table II.

Until now, Inonotus s.s. comprised taxa with a monomitic hyphal system and annual basidiocarps (Fiasson and Niemelä 1984Citation, Wagner and Fischer 2001Citation). However, our new data suggest that the genus should be treated in a wider sense, comprising taxa with monomitic and annual basidiocarps as well as taxa with dimitic and perennial basidiocarps; in addition, intermediate forms occur in this genus. As a common character, colored basidiospores, negative in Melzer's reagent, are found. Shapes of spores range from ellipsoid to subglobose, setae are mostly present and abundant, and basidiocarps are pileate, effused-reflexed or resupinate. Phellinus pachyphloeus and P. tropicalis represent intermediate forms, with P. pachyphloeus developing perennial fruit bodies with a monomitic hyphal system (Fidalgo 1968Citation, Dai 1999Citation), and P. tropicalis developing annual fruit bodies with a dimitic hyphal system (Larsen and Cobb-Poulle 1990Citation). Fidalgo (1968)Citation suggests P. lamaensis, P. noxius, P. melanodermus, P. magnosporus, and P. portoricensis, all characterized by the occurrence of setal hyphae, as closely related to P. pachyphloeus. Molecular data of these taxa are not available and so no taxonomic statement is provided here. Dai (1999)Citation described the subgenus Phellinidiopsis within Phellinus, comprising taxa with annual or perennial basidiocarps, monomitic hyphal structure, hyphoid setae (=setal hyphae) and thickwalled and colored basidiospores. Besides P. pachyphloeus, also P. tricolor and P. poeltii have been included in this subgenus, while some other taxa with hyphoid setae, such as Phellinus pilatii, Inonotus glomeratus, I. nidus-pici, I. pruinosus, and I. quercustris are suggested as closely related. In our analyses only I. nidus-pici is supported as related to P. pachyphloeus, with I. pruinosus, I. glomeratus, and I. quercustris as more distant. The hyphoid setae of all these taxa resemble those of Phellinidium, but the latter is different by its thin-walled and hyaline basidiospores. Within Inonotus s.s., hyphoid setae are also present in I. chishanyenus (Chang and Chou 1998Citation), I. rodwayi, and I. pegleri, but no distinct subgroup is formed by these taxa. Apparently hyphoid setae are widespread within Inonotus and have evolved or were lost in several different lineages. In our trees, species with or without hyphoid setae occur side by side; for example, I. quercustris, with hyphoid setae, is next to I. cuticularis, without hyphoid setae, and I. plorans, without hyphoid setae, is next to I. rodwayi, with hyphoid setae. The occurrence of setae, hymenial or hyphoid, is not a continuous feature within Inonotus s.s.; for example, they are inconstant in I. hispidus or even missing in I. plorans. Mainly based on the existence of colored basidiospores, P. vaninii and P. baumii have been included in Phellinus subgen. Fulvifomes by Dai (1999)Citation; in our analyses however, these species are clearly placed within Inonotus s.s. After all, we suggest the following taxa to be transferred to Inonotus s.s.:

Inonotus baumii (Pilát) T. Wagner et M. Fischer comb. nov.

{equiv} Phellinus baumii Pilát, Bull Soc Mycol France 48: 25, 1932 (basionym).

Inonotus linteus (Berk. et Curt.) T. Wagner et M. Fischer comb. nov.

{equiv} Polyporus linteus Berk. & Curt., Proc Amer Acad Arts (Boston) 4: 122, 1860 (basionym).

{equiv} Phellinus linteus (Berk. & Curt.) Teng, Fungi of China, p. 467, 1964.

Inonotus pachyphloeus (Pat.) T. Wagner et M. Fischer comb. nov.

{equiv} Polyporus pachyphloeus Pat., J Bot (Paris) 3: 257, 1889 (basionym).

{equiv} Phellinus pachyphloeus (Pat.) Pat., Essai Taxon, p. 97, 1900.

Inonotus tropicalis (M. Lars. et Lomb.) T. Wagner et M. Fischer comb. nov.

{equiv} Phellinus tropicalis M. Lars. & Lomb., Mycologia 80: 73, 1988 (basionym).

= Poria rickii Bres., Ann Mycol 18: 37, 1920.

Inonotus vaninii (Ljub.) T. Wagner et M. Fischer comb. nov.

{equiv} Phellinus vaninii Ljub., Bot Mater Otd Sporov Rast Bot Inst Komarova Akad Nauk SSSR 15: 115, 1962 (basionym).

Inonotus weirianus (Bres.) T. Wagner et M. Fischer comb. nov.

{equiv} Fomes weirianus Bres., Studi Trentini 2: 55, 1926 (basionym).

{equiv} Phellinus weirianus (Bres.) Gilbn., J Arizona Acad Sci 7: 137, 1972.

Phylloporia is a mainly tropical genus with stipitate, sessile, or resupinate basidiocarps, which are annual or perennial. Often a tomentum is formed on the surface, separated from the context by a thin black zone. The hyphal system varies between monomitic and dimitic. Setae are lacking throughout. Basidiospores are subcylindrical to ellipsoid, slightly thickwalled, pale yellow and non-dextrinoid. Taxa of Phylloporia occur on deciduous wood, often on thin branches or even leaves, like the type species, P. parasitica. At the present 12 species are accepted within Phylloporia (Ryvarden 1972Citation, Wagner and Ryvarden 2002Citation). Whereas our results clearly place P. pectinatus within Phylloporia, Dai (1999)Citation places it in Phellinus subgen. Fulvifomes.

Fulvifomes, positioned as sistergroup to Phylloporia, is similar by the lack of setae and the occurrence of thickwalled, yellowish and non-dextrinoid basidiospores, which, however, are larger and ellipsoid to subglobose. Basidiocarps of Fulvifomes are different by exhibiting a distinct dimitic hyphal system and a distinct crust on the surface. Based on these features, Kotlaba and Pouzar (1978)Citation described the Phellinus rimosus complex (=Fulvifomes), including P. badius, P. rimosus and P. robiniae. Dai (1999)Citation suggests the subgenus Fulvifomes, comprising 19 taxa with or without setae, whereas our data show the group to be strictly without setae. Morphological and anatomical data as well as the phylogenetic trees (Figs. 1, 2) clearly support the relationship of the following taxa to Fulvifomes:

Fulvifomes kawakamii (M. Lars., Lomb. et Hodges) T. Wagner et M. Fischer comb. nov.

{equiv} Phellinus kawakamii M. Lars., Lomb. & Hodges, Mycologia 77: 346, 1985 (basionym).

Fulvifomes nilgheriensis (Mont.) T. Wagner et M. Fischer comb. nov.

{equiv} Polyporus nilgheriensis Mont., Ann Sci Nat Bot 18: 12, 1842 (basionym).

{equiv} Phellinus nilgheriensis (Mont.) Cunn., New Zealand Dept Sci Ind Res Bull 164: 26, 1965.

In our trees the genus Aurificaria, represented by Aurificaria luteoumbrina, is very close to Phylloporia and Fulvifomes. Setae are lacking in species of Aurificaria, basidiospores are ellipsoid to subglobose, hyaline to dull brown, and negative in Melzer's reagent. Distinct characters are the stipitate basidiocarps and the olivaceous brown coloring of the basidiospores in KOH (Gilbertson and Ryvarden 1986Citation). Basidiocarps are terrestrial or lignicolous, the hyphal system is monomitic. Ryvarden and Johansen (1980)Citation suggest the genus to be closely related to Inonotus. Our phylogenetic analyses (Figs. 1, 2) show I. porrectus as next related to Aurificaria luteoumbrina, which is confirmed by morphological and anatomical features. Basidiocarps of I. porrectus are substipitate and monomitic, basidiospores are ellipsoid to subglobose, reddish brown and negative in Melzer's reagent, and setae are lacking. Both I. porrectus and A. luteoumbrina occur on deciduous trees. Specific for the former are the contorted and branching hyphae on the pileus surface. Additional molecular data of species of Aurificaria are necessary to further resolve the affinities of I. porrectus.

Inocutis, another well supported group, comprises I. rheades and related species and is characterized by the lack of setae. All species of Inocutis have ellipsoid, non-dextrinoid, yellowish to brownish basidiospores and a distinct monomitic hyphal system. Basidiocarps are annual. The northern hemispheric species, I. rheades, I. tamaricis, and I. dryophilus, exhibit a unique pigment pattern and a marmorated mycelial core with sclerid hyphae (Fiasson 1982Citation, Fiasson and Niemelä 1984Citation). Such a mycelial core has not been reported for the subtropical species Inonotus ludovicianus and I. jamaicensis; no pigment data are available for these taxa. As a common character, only deciduous trees occur as substrate in this group. Our results indicate the following taxa to be included in Inocutis:

Inocutis jamaicensis (Murrill) T. Wagner et M. Fischer comb. nov.

{equiv} Inonotus jamaicensis Murrill, Bull Torrey Bot Cl 31: 593–602, 1904 (basionym).

Inocutis ludovicianus (Pat.) T. Wagner et M. Fischer comb. nov.

{equiv} Xanthochrous ludovicianus Pat., Bull Soc Mycol Fr 24: 6, 1908 (basionym).

{equiv} Inonotus ludovicianus (Pat.) Murrill, South Polyp 41, 1915.

Murrill (1907)Citation described the genus Fomitiporella, including 9 species, with Fomitiporella umbellata (= Phellinus umbrinellus) as type species. Main characters of this genus are perennial basidiocarps and brownish, ellipsoid to globose basidiospores. Murrill (1907)Citation restricted Fomitiporella to taxa with resupinate basidiocarps and this is the case in P. umbrinellus and P. cavicola; however, basidiocarps are effused-reflexed in P. caryophyllii. Most genera within the Hymenochaetales combine taxa with different shapes of basidiocarps and often resupinate, effused-reflexed, pileate, substipitate or stipitate taxa occur side by side in the phylogenetic trees. Additional common features of F. umbellata, P. caryophyllii, and P. cavicola are the dimitic hyphal system, the lack of setae and basidiospores which are negative in Melzer's reagent. Whereas Dai (1999)Citation placed P. umbrinellus in the subgenus Fulvifomes, our data show it as distinct. Apparently Fomitiporella is clearly delimited from the other genera within the Hymenochaetales, and therefore should be accepted as a genus, including the following taxa:

Fomitiporella caryophylii (Racib.) T. Wagner et M. Fischer comb. nov.

{equiv} Trametes caryophylii Racib., Parasitische Algen und Pilze Javas III p. 17, 1900 (basionym).

{equiv} Phellinus caryophylii (Racib.) Cunn., New Zealand Dept Sci Ind Res Bull 164: 238, 1965.

Fomitiporella cavicola (Kotl. et Pouz.) T. Wagner et M. Fischer comb. nov.

{equiv} Phellinus cavicola Kotl. & Pouz., Czech Mycol 48 (2): 155, 1995 (basionym).

Within the Phellinus s.s. group a core is formed by the type species, P. igniarius, and its closest relatives (Niemelä 1972Citation, 1974Citation, 1975Citation, 1977Citation, Fischer 1995Citation). The inclusion of P. bicuspidatus, P. spiculosus, P. conchatus, and P. occidentalis in this group is only weakly supported by our molecular data and so the affinities of these taxa remain uncertain. Dai (1999)Citation and Wagner and Fischer (2001)Citation placed P. conchatus within the Phellinus s.s. group, whereas Fiasson and Niemelä (1984)Citation and Fischer (1996)Citation discuss a close relationship to Porodaedalea. The members of the P. igniarius group examined by Fiasson (1982)Citation showed a specific pigment pattern, different from that found in P. conchatus. The Phellinus s.s. group, including P. bicuspidatus, P. spiculosus, P. conchatus, and P. occidentalis, is characterized by a distinct dimitic hyphal system, the development of a crust on the pileus surface and the occurrence of hymenial setae. The ellipsoid to subglobose basidiospores are hyaline and negative in Melzer's reagent. Only deciduous trees are reported as substrate.

Pseudoinonotus is well delimited by its large, thickwalled, globose, hyaline to faintly yellow basidiospores which are positive in Melzer's reagent and strongly cyanophilous. Hymenial setae are usually frequent and often a crust is developed on the pileus surface. Basidiocarps are annual and the hyphal system is intermediate between monomitic and dimitic. Species of Pseudoinonotus occur both on angiosperms and gymnosperms.

Within Phellinus s.l., Fomitiporia forms a quite distinct group and its generic status was accepted by Fiasson and Niemelä (1984)Citation, Fischer (1996)Citation, Dai (1999)Citation, and Wagner and Fischer (2001)Citation. It is quite similar to Pseudoinonotus in terms of basidiospores and hyphal system; however, setae are rare or absent and basidiocarps are perennial. The context is brass colored, and the hymenium bears ampulla-shaped cystidioles. Fischer (1996)Citation reported an increased DNA content of the nuclei in taxa of Fomitiporia. Substrata within this group are angiosperms and gymnosperms.

A close relationship between Porodaedalea and Onnia was already observed by Wagner and Fischer (2001)Citation. The two genera are similar by their preference for coniferous trees as substrata, the cause of a distinct pocket rot of the heartwood, the duplex structure in the context, the occurrence of hymenial setae, and the ellipsoid to subglobose, hyaline and indextrinoid basidiospores. Porodaedalea is distinct by perennial and dimitic basidiocarps, the development of a crust on the pileus surface, and the roundish to labyrinthine pores. Basidiocarps are resupinate, effused-reflexed or pileate, while they are substipitated to stipitated in Onnia. Phellinus cancriformans clearly is supported as belonging to Porodaedalea.

Porodaedalea cancriformans (M. Lars., Lomb. et Aho) T. Wagner et M. Fischer comb. nov.

{equiv} Phellinus pini var. cancriformans M. Lars., Lomb. & Aho, Canad J Forest Res 9: 33, 1979 (basionym).

{equiv} Phellinus cancriformans (M. Lars., Lomb. & Aho) M. Lars. & Lomb., Fungiflora 3: 43, 1990.

The generic status of Mensularia was re-evaluated by Wagner and Fischer (2001)Citation. The group is characterized by annual and monomitic basidiocarps occurring on hardwoods; shape of fruit bodies varies from resupinate to pileate, basidiospores are ellipsoid, hyaline and dextrinoid, and setae are abundant. Although the affinity of I. crocitinctus to this group is not strongly supported by the molecular data, the similarity of the anatomical features is striking, and a close relationship was already suggested by Gilbertson and Ryvarden (1986)Citation. So we suggest transferring I. crocitinctus to Mensularia:

Mensularia crocitincta (Berk. et Curt.) T. Wagner et M. Fischer comb. nov.

{equiv} Polyporus crocitinctus Berk. & Curt., J Linn Soc Bot 10: 311, 1868 (basionym).

{equiv} Inonotus crocitinctus (Berk. & Curt.) Ryvarden, Norw J Bot 19: 232, 1972.

Both morphologically and anatomically, Fuscoporia represents a more heterogeneous group. The shape of basidiospores varies from allantoid to cylindrical to ellipsoid, but throughout the genus they are hyaline, thin-walled, and non-dextrinoid. The resupinate to pileate basidiocarps are annual to perennial, setae are abundant and the hyphal system is monomitic to dimitic; they occur on coniferous and deciduous trees. For East Asia, Dai (1999)Citation describes 12 species as belonging to this group, which he regards as a subgenus of Phellinus s.l. In accordance with Dai (1999)Citation, our molecular data place Phellinus gilvus within Fuscoporia, and this is supported by the homothallic mode of reproduction and the formation of fruiting bodies in culture occurring both in P. gilvus and several taxa of Fuscoporia. Encrusted hyphae, though easily overlooked, are described as a distinct feature within Fuscoporia (Fiasson and Niemelä 1984Citation, Dai 1999Citation, Niemelä et al 2001Citation, Wagner and Fischer 2001Citation). So far, no such structures have been observed in Inonotus formosanus and P. cinchonensis, two additional taxa placed within Fuscoporia (Figs. 1, 2). However, occurrence of abundant hymenial setae and cylindrical or ellipsoid basidiospores, which are hyaline, thin-walled and non-dextrinoid, point to an affinity to Fuscoporia. Therefore, we propose the following transfers:

Fuscoporia cinchonensis (Murrill) T. Wagner et M. Fischer comb. nov.

{equiv} Pyropolyporus cinchonensis Murrill, Mycologia 2: 195, 1910 (basionym).

{equiv} Phellinus cinchonensis (Murrill) Ryvarden, Norw J Bot 19 (3–4): 234, 1972.

Fuscoporia formosana (T. T. Chang et W. N. Chou) T. Wagner et M. Fischer comb. nov.

{equiv} Inonotus formosanus T. T. Chang & W. N. Chou, Myc Res 102: 789, 1998 (basionym).

Fuscoporia gilva (Schw. : Fr.) T. Wagner et M. Fischer comb. nov.

{equiv} Boletus gilvus Schw., Schrift Nat Ges Leipzig 1: 96, 1822 (basionym).

{equiv} Phellinus gilvus (Schw. : Fr.) Pat., Essai Taxon, p. 97, 1900.

Because of the phylogenetic position of Inonotopsis subiculosa and Pyrrhoderma scaurum, species of Phellinidium are spread over two separate subgroups. However, the constrained analysis did not reject the monophyly of Phellinidium. Main characteristics of Phellinidium are the annual to perennial basidiocarps, which are resupinate to pileate and monomitic, the abundant hyphoid setae in the trama and the context, the cystidia in the hymenium and the hyaline and thin-walled spores, which are non-dextrinoid and ranging from allantoid to cylindrical or ellipsoid (Fiasson and Niemelä 1984Citation, Dai 1995Citation, 1999Citation). In P. ferrugineofuscum, P. pouzarii, and P. fragrans, spores are allantoid to oblong cylindrical, whereas they are ellipsoid in Phellinidium sulphurascens and P. weirii. This divergence correlates well with the splitting of Phellinidium observed in our study (Figs. 1, 2). The ongoing discussions related to the taxonomic status of P. sulphurascens and P. weirii clearly demonstrate the problems inherent of the traditional generic concepts of Phellinus s.l. and Inonotus s.l. Based on a morphological concept, it is essentially a matter of taste if the two species should be placed within Phellinus or Inonotus (Kotlaba and Pouzar 1978Citation, Ryvarden and Gilbertson 1993–1994Citation, Larsen et al 1994Citation). Although they are very similar by anatomical and morphological features, basidiocarps are annual in P. sulphurascens and perennial in P. weirii.

Anatomically, Inonotopsis subiculosa is different from the former group by the total lack of setae. Basidiospores are hyaline, thin-walled and non-dextrinoid. The consistency of the annual basidiocarps is soft and cottony, and the hyphal system is monomitic. Inonotopsis subiculosa occurs on coniferous wood.

The characteristics of Pyrrhoderma are the lack of setae, the subglobose, hyaline and non-dextrinoid basidiospores, and a two-layered crust on the pileus surface. Basidiocarps of P. scaurum are annual and monomitic. Another species of Pyrrhoderma, P. adamantinum, is placed in a phylogenetically distant position together with Hyphodontia quercina and Schizopora paradoxa, and comes out as more closely related to Coltricia and Coltriciella. Pyrrhoderma adamantinum shares the typical generic characteristics as described above but exhibits perennial basidiocarps. Pyrrhoderma sendaiense, the type species, was not available for this study and so the taxonomical status of Pyrrhoderma remains unsolved.

Phellopilus produces perennial basidiocarps with a dimitic or trimitic hyphal system. Hymenial setae are always present, basidiospores are thin-walled, hyaline, narrowly obclavate to cylindrical and non-dextrinoid. Phellopilus nigrolimitatus typically has skeleto-binding hyphae in the context (Dai 1999Citation) and occurs on coniferous wood. Most astonishing is the close relationship between P. nigrolimitatus and Basidioradulum radula (Figs. 1, 2). Apart from the occurrence of non-perforated parenthesomes, Basidioradulum shares no common features with the Hymenochaetales. Basidiocarps are membraneous to resupinate, the hymenophore is odontoid to raduloid, yellowish cream to ochraceous, and the hyphae are hyaline and with clamps. Setae do not exist in Basidioradulum, but cylindric to moniliform cystidia are present. Basidiospores are cylindric to allantoid, hyaline and non-amyloid. Like P. nigrolimitatus, Basidioradulum is restricted to coniferous trees.

The hydnoid Asterodon is positioned next to Phellopilus, whereas the two representatives of the corticioid genera Hymenochaete and Pseudochaete show no distinct relationship to any of the preceeding groups. The phylogenetic relationships of Asterodon, Hymenochaete and Pseudochaete have been discussed previously (Parmasto 2000Citation, Wagner 2001Citation, Wagner and Fischer 2002Citation).

Coltricia characteristically exhibits annual and stipitated basidiocarps with a monomitic hyphal system, growing on the ground. The hymenophore usually is poroid, but varies from poroid to cyclolamellate in C. montagnei. Basidiospores are yellow, ellipsoid, and dextrinoid. Setae are absent in the European and North American species, but are present in tropical species (Ryvarden and Johansen 1980Citation, Corner 1991Citation). Our study was restricted to taxa without setae; in our opinion the inclusion of taxa with setae in Coltricia is questionable. Species of Coltricia are mostly described as terrestrial, sometimes also as being connected with decayed wood. A mycorrhizal association was reported for Coltricia perennis (Danielson 1984Citation), but there have been no further studies on this aspect.

Coltriciella is the sister group to Coltricia, but is separated by verruculous, pale yellowish and ellipsoid basidiospores. Setae are missing. Basidiocarps are pendant or stipitate with a monomitic hyphal system, they occur on rotten deciduous and coniferous wood.

All in all, our expanded dataset, based on a worldwide scale of taxa of the Hymenochaetales clearly supports the idea that Phellinus s.l. and Inonotus s.l. form no natural entities (Wagner and Fischer 2001Citation); instead of this a subdivision into smaller subgroups is evident. Whereas features like the shape of fruit bodies and setae are not suitable for a separation of these subgroups, more reliable conclusions can be drawn from features like the pattern of sexuality, the morphology and color reactions of the basidiospores, the occurrence of tramal and hymenial setae, and the type of mitism (Wagner and Fischer 2001Citation). Our new data, however, demonstrate that the type of mitism is also not homogeneous within the phylogenetically defined subgroups, for instance within Inonotus s.s., Phylloporia, and Fuscoporia. In addition, Inonotus s.s. is demonstrated to comprise species with and without setae. Future studies should concentrate on, for instance, the pattern of sexuality, pigmentation, or culture behavior.

In our study, the deeper nodes within the hymenochaetoid clade show mostly only weak or no bootstrap support, and so more conclusive statements concerning the origin and the classification above generic level cannot be made. Better support could be reached by including additional taxa of the non-Hymenochaetales and by combining sequences from various genetic regions, such as nuc-ssu rDNA, nuc-lsu rDNA, mt-ssu rDNA, and mt-lsu rDNA.


    ACKNOWLEDGMENTS
 
Special thanks go to Helmut Besl, Manfred Binder, Andreas Bresinsky, Yu-Cheng Dai, Lothar Krieglsteiner, Ewald Langer, Norbert Luschka, Tuomo Niemelä, Ingo Nuss, Erast Parmasto, Wolfgang Paulus, and Leif Ryvarden for providing specimens.


    FOOTNOTES
 
1 Corresponding author, towag{at}web.de Back

2 michael.fischer{at}wbi.bwl.de Back

Accepted for publication April 4, 2002.


    LITERATURE CITED
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
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