2024 Volume 66 Issue 1 Pages 88-108
We reevaluated the species belonging to the genus Pyrrhoderma that were collected from Japan and Malaysia based phylogenetic analyses and morphological investigations. We found that Pyr. sendaiense is distinct from Pyr. adamantinum. Pyrrhoderma species with setal hyphae include Pyr. lamaoense, Pyr. noxium, Pyr. sublamaensis, and Pyr. williamsii. Pyrrhoderma noxium, synonymized with Pyr. sublamaense in earlier studies, was distinct from Pyr. sublamaense. All isolates from trees damaged by brown root rot were accommodated in the same clade with Pyr. noxium, and the cause of the disease was confirmed as Pyr. noxium. Pyrrhoderma williamsii resembles Pyr. lamaoense but is distinguished by a glabrous pileus surface and abundant hymenial setae. Fulvoderma species are similar to some Pyrrhoderma species but are distinguished by the duplex context separated by a thin crust composed of nonagglutinated hyphae. Some Inonotus species produce setal hyphae in the trama and context like some Pyrrhoderma species. However, the hyphae of these Inonotus species are acuminate at the tip, tapered toward the base, and often swollen toward the tip, whereas those of the Pyrrhoderma species are cylindrical and mostly equal. The following new combinations are proposed: Pyrrhoderma williamsii and Fulvoderma vallatum.
Pyrrhoderma Imazeki was erected by Imazeki (1966) and is typified by Pyr. sendaiense (Yasuda) Imazeki (basionym: Polyporus sendaiensis Yasuda). This genus was characterized by the stipitate to substipitate (“subsessile” in the original description) basidiocarps, thick and rigid crust on the pileus and stipe surface, yellowish-brown context, colorless and subglobose basidiospores, and what was considered a monomitic hyphal system (not clearly shown in the text but suggested by the drawings given in the original description) without clamp connections on generative hyphae (Imazeki, 1966). The type species was described by Yasuda (1923) based on a specimen collected from Japan and occurs on dead trees of Fagus species (Imazeki, 1966). Pyrrhoderma adamantinum (Berk.) Imazeki is another species included in the original description of this genus. Both species have been differentiated mainly by the shape of basidiocarps, distribution area, and host trees (Imazeki, 1966; Imazeki & Hongo, 1989).
Pyrrhoderma had long been considered a small genus containing only two species (Imazeki & Hongo, 1989). However, Ryvarden (1990) added Pyr. scaurum (Lloyd) Ryvarden (as “Pyr. scaura”) to the genus because it has similar basidiospore and hyphal characteristics. Pyrrhoderma scaurum has frequently substipitate to stipitate basidiocarps with a distinct crust-like layer near the pileus surface (Imazeki & Hongo, 1989) as in Pyrrhoderma species. The treatment by Ryvarden (1989) was followed by Núñez and Ryvarden (2000), who accepted the three species as members of Pyrrhoderma in Hymenochaetaceae, and provided a key to the three species. Dai (2010) took Pyr. sendaiense as a synonym of Pyr. adamantinum and accepted only Pyr. adamantinum and Pyr. scaurum in this genus. Zhou et al. (2018) analyzed Pyrrhoderma and its allies phylogenetically and emended its genus concept, which resulted in the inclusion of Phellinus lamaoensis (Murrill) Pat. and Ph. noxius (Corner) G. Cunn. in this genus. In addition, Pyr. scaurum was reported as phylogenetically distinct from Pyrrhoderma and Fulvoderma L.W. Zhou & Y.C. Dai was described to accommodate this and its allied species.
Pyrrhoderma noxium (Corner) L.W. Zhou & Y.C. Dai is a serious root rot pathogen that causes brown root rot in many tropical areas (Akiba et al., 2015; Ann et al., 2002; Sahashi et al., 2015; Yuan et al., 2023). This fungus was confused with Pyr. lamaoense until Corner (1932) erected Fomes noxius Corner, describing that it lacks hymenial setae and has rounded setal hyphae in the trama, whereas Pyr. lamaoense has hymenial setae and narrower and tapered setal hyphae in the trama. Later, mycologists followed these characteristics to discriminate between these two species (e.g., Fidalgo, 1968; Ryvarden & Johansen, 1980). Fidalgo (1968) considered these species as members of “pachyphloeus group” with setal hyphae (as “setal skeletal hyphae”) in the context and trama (dissepiments), and accepted the following species in this group: Ph. lamaoensis, Ph. magnosporus (Lloyd) Fidalgo, Ph. melanodermus (Pat.) Fidalgo, Ph. noxius, Ph. pachyphloeus (Pat.) Pat., and Ph. portoricensis (Overh.) Fidalgo. Many of these species are recorded from tropical areas of Asia and America, and no or only limited sequences are available for some of them, which makes their phylogenetic position unclear.
Zhou et al. (2018) phylogenetically analyzed Pyr. lamaoense-noxium complex and described two new species with setal hyphae (as “hyphoid setae”)―Pyr. hainanense L.W. Zhou & Y.C. Dai and Pyr. yunnanense L.W. Zhou & Y.C. Dai―and Pyr. thailandicum L.W. Zhou & Y.C. Dai without setal hyphae. They did not provide descriptions of the voucher specimens of “Pyr. lamaoense” and “Pyr. noxium”, but discriminated between these two species from the hyphal arrangement in the context and spore shape in the key provided. They mentioned the lack of hymenial setae in both species, but this is not consistent with the traditional discrimination characteristics of the two as mentioned above. Later, Zhou et al. (2023) described Pyr. nigrum Meng Zhou, Yuan Yuan & Vlásk (as “Pyr. nigra”) representing “Pyrrhoderma sp.” in Zhou et al. (2018).
In this study, we investigated phylogenetic positions of the species belonging to Pyrrhoderma emended by Zhou et al. (2018) and their possible relatives. We studied the morphological characteristics for the voucher specimens of the sequences in detail and characterized the detected clades. Other specimens with similar morphologies were examined to complete the characteristics for the taxa representing the clades. We examined several authentic specimens, and then provided adequate names for the detected clades. Morphological characterization was performed for the genus Pyrrhoderma, comparing it with species belonging to Fulvoderma and Inonotus P. Karst. with perennial and/or woody basidiocarps and setal hyphae, which morphologically resemble some Pyrrhoderma species.
The morphological characteristics of the voucher specimens of the cultures used for molecular phylogenetic studies, as well as other specimens with similar morphological characteristics and some authentic specimens possibly conspecific to these species, were examined. Microscopic characteristics of dried specimens mounted in 5% (w/v) KOH solution or Melzer's reagent were examined. The following abbreviations were used for basidiospore measurements, r = ratio of length/width of a basidiospore, R = arithmetic mean of r, and n = number of measured basidiospores. Herbaria with specimens were abbreviated according to Index Herbariorum (http://sweetgum.nybg.org/science/ih/). All the specimens without indication of herbarium codes are stored in the Mycological Herbarium of Forestry and Forest Products Research Institute (TFM). The main parts of the newly collected Malaysian specimens are stored in the herbarium of Forest Research Institute Malaysia (KEP).
Forest zones used in description of distribution follow Kira (1991): cool-temperate, warm-temperate, subtropical, and tropical.
2.2. Molecular phylogenyDNA was extracted from cultured mycelia using DNeasy Plant Mini Kit (Qiagen, Valencia, CA, USA), following the manufacturer's instructions, as described in Ota et al. (2014).
We analyzed sequences from four genetic markers: 1) internal transcribed spacer (ITS) region of nuclear ribosomal RNA (rRNA), 2) rRNA large subunit (LSU), 3) part of the translation elongation factor 1 alpha (tef1-α) gene, and 4) region between domains 6 and 7 of the second largest subunit of the RNA polymerase II (rpb2) gene. The primers used were 1) LR0R (Rehner & Samuels, 1994) and LR5 (Vilgalys & Hester, 1990) for LSU, 2) ITS1-F and ITS4-B (Gardes & Bruns, 1993) for ITS, 983F and 2218R (Rehner & Buckley, 2005) for tef1-α, and 4) bRPB2-6F and bRPB2-7.1R (Matheny, 2005) or bRPB2-a8.0R (Binder et al., 2010) for rpb2. PCR amplification was performed using a S1000 Thermal Cycler (Bio-Rad, Hercules, CA, USA) with the following conditions: 5 min at 95 °C; followed by 35 cycles of 30 s at 95 °C, 30 s at 55 °C, and 45 s at 72 °C; and final extension for 10 min at 72 °C for ITS and LSU. For tef1-α and rpb2, the touchdown PCR protocol described in Justo and Hibbett (2011) was used. PCR products were purified using Wizard® SV 96 PCR Clean-Up System (Promega, Madison, WI, USA). Direct sequencing of PCR products was performed using BigDye™ Terminator Cycle Sequencing Kit v.3.1 (Applied Biosystems, Foster City, CA, USA) with forward and reverse primers and was analyzed using an ABI 3130xl Genetic Analyzer (Applied Biosystems). Primers 1577F and 1567R (Rehner & Buckley, 2005) were used for the tef1-α amplicon. Some of the resulting ITS sequences included ambiguous base calls, possibly due to heterozygosity. These PCR products were cloned using pGEM®-T Easy Vector Systems (Promega) and transformed into competent cells (E. coli JM109). The DNA of up to four transformed clones from each sample was amplified and sequenced as described above. Sequences were assembled and edited using Pregap4 (Bonfield & Staden, 1996) and Gap4 (Bonfield et al., 1995).
In addition to newly generated sequences, additional sequences mainly used in Zhou et al. (2016, 2018) and Stewart et al. (2020) were derived from the DDBJ/EMBL/GenBank database and included for phylogenetic analysis (Supplementary Table S1). The analyses were performed for five datasets. 1) The LSU dataset included LSU sequences of species belonging Hymenochataceae, and Hyphodontia pallidula (Fr.) J. Erikss. was selected as an outgroup taxon based on the results of Larsson et al. (2006). 2) The Pyrrhoderma-ITS dataset included ITS sequences of Pyrrhoderma species, and Cylindrosporus flavidus (Berk.) L.W. Zhou was selected as an outgroup taxon. 3) The Fulvoderma-ITS dataset included ITS sequences of Fulvoderma species, and Coniferiporia spp. were selected as an outgroup taxon. 4) The Inonotus-ITS dataset included ITS sequences of Inonotus species, and Tropicoporus spp. were selected as an outgroup taxon. 5) The Pyrrhoderma-combined dataset included ITS, LSU, tef1-α, and rpb2 sequences of Pyrrhoderma species, and Coniferiporia sulphurascens (Pilát) L.W. Zhou & Y.C. Dai was selected as an outgroup taxon.
The sequences were initially aligned using MAFFT 7 (Katoh & Standley, 2013) with the G-INS-i option. Trailing ends of the alignment were trimmed. When required, the alignments were manually edited in Jalview 2.1 (Waterhouse et al., 2009). For ITS and LSU alignments, poorly aligned regions were removed using trimAl (Capella-Gutierrez et al., 2009) with automated1 option. For tef1-α, intron regions were removed from the alignment.
Phylogenetic analyses with aligned sequences were performed using the Bayesian (BI) and maximum likelihood (ML) analyses. BI was performed using MrBayes 3.2.7 (Ronquist et al., 2012). The base substitution model was determined for each locus Modeltest-NG (Darriba et al., 2020) using the Akaike information criterion model selection criterion. The models selected were as follows: GTR+G+I for LSU dataset, the Inonotus-ITS dataset, and LSU and rpb2 of the Pyrrhoderma-combined dataset; GTR+G for the Pyrrhoderma-ITS dataset, Fulvoderma-ITS dataset, and ITS of the Pyrrhoderma-combined dataset; SYM+G+I for tef1-α of the Pyrrhoderma-combined datasets. For BI analysis, four chains were run for 3 × 106 generations. Markov chains were sampled at intervals of 100 generations (Larget & Simon, 1999). Two independent runs were performed and the first 25% of the trees were discarded as burn-in. A 50% majority-rule consensus tree and posterior probabilities were computed from the remaining trees. ML analyses were performed using RAxML-NG (Kozlov et al., 2019). Bootstrap analyses were performed with 1000 bootstrap replicates.
The aligned datasets and resulting trees are deposited in TreeBase under the accession number S31506. The sequences generated in this study were deposited in DDBJ/EMBL/GenBank database (Accession numbers, LC822054-LC822189; Table 1).
| Species | Isolate no. | Vaucher specimen no. | Locality | GenBank accession nos. | |||
| ITS | LSU | tef1-α | rpb2 | ||||
| Coniferiporia sulphurascens | FFPRI421047 | F-11774 | Kamikawa, Hokkaido, Japan | LC822054 | LC822089 | LC822122 | LC822157 |
| Cylindrosporus flavidus | FFPRI421048 | F-14520 | Iwaki, Fukushima, Japan | LC822055 | LC822090 | LC822123 | LC822158 |
| Fulvoderma scaurum | FFPRI421049 | F-15146 | Takashima, Shiga, Japan | LC822056 | LC822091 | LC822124 | LC822159 |
| FFPRI421050 | F-29592 | Semboku, Akita, Japan | LC822057 | LC822092 | LC822125 | LC822160 | |
| Fulvoderma vallatum | FFPRI421051 | F-15749 | Kyoto, Kyoto, Japan | LC822058 | LC822093 | LC822126 | LC822161 |
| FFPRI421052 | F-16674 | Kyoto, Kyoto, Japan | LC822059 | LC822094 | LC822127 | LC822162 | |
| FFPRI421053 | F-17133 | Iriomote Is., Okinawa, Japan | LC822060 | LC822095 | LC822128 | LC822163 | |
| Inonotus boninensis | FFPRI421054 T | F-15903 T | Anijima Is., Tokyo, Japan | LC822061 | LC822096 | LC822129 | LC822164 |
| Inonotus pachyphloeus | FFPRI421055 | F-16283 | Ishigaki Is., Okinawa, Japan | LC822062 | LC822097 | LC822130 | LC822165 |
| Inonotus tricolor | FFPRI421056 | F-10383 | Kimotsuki, Kagoshima, Japan | LC822063 | LC822098 | LC822131 | - |
| FFPRI421057 | F-10384 | Miyakonojo, Miyazaki, Japan | LC822064 | LC822099 | LC822132 | - | |
| Pyrrhoderma adamantinum | FFPRI421058 | F-19256 | Omura, Nagasaki, Japan | LC822065 | LC822100 | LC822133 | LC822166 |
| Pyrrhoderma lamaoense | FFPRI411162 | F- 29146 | Iriomote Is., Okinawa, Japan | LC822066 | LC822101 | LC822134 | LC822167 |
| FFPRI421059 | F-29148 | Iriomote Is., Okinawa, Japan | LC822067 | LC822102 | LC822135 | LC822168 | |
| FFPRI421060 | F-29149 | Iriomote Is., Okinawa, Japan | LC822068 | LC822103 | LC822136 | LC822169 | |
| FFPRI421061 | F-29150 | Iriomote Is., Okinawa, Japan | LC822069 | LC822104 | LC822137 | LC822170 | |
| FFPRI421062 | F-29322 | Okinawa Is., Okinawa, Japan | LC822070 | LC822105 | LC822138 | LC822171 | |
| FRIM 744 | F-27225 | Endau Rompin, Johor, Malaysia | LC822071 | LC822106 | LC822139 | LC822172 | |
| FFPRI421063 | F-16623 | Iriomote Is., Okinawa, Japan | LC822072 | LC822107 | LC822140 | LC822173 | |
| FFPRI421064 | F-16925 | Iriomote Is., Okinawa, Japan | LC822073 | LC822108 | LC822141 | LC822174 | |
| Pyrrhoderma noxium | FFPRI421065 | F-29199 | Ishigaki Is., Okinawa, Japan | LC822074 | LC822109 | LC822142 | LC822175 |
| FFPRI421066 | BR | Amamioshima Is. Kagoshima, Japan | LC822075 | LC822110 | LC822143 | LC822176 | |
| FFPRI411160 | BR | Kikai Is., Kagoshima, Japan | LC822076 | LC822111 | LC822144 | LC822177 | |
| FFPRI421067 | BR | Okinawa Is., Okinawa, Japan | LC822077 | LC822112 | LC822145 | LC822178 | |
| FFPRI411125 | BR | Chichijima Is., Tokyo, Japan | LC822078 | LC066605 | LC822146 | LC822179 | |
| FFPRI421068 | BR | Hahajima Is., Tokyo, Japan | LC822079 | LC822113 | LC822147 | LC822180 | |
| FFPRI421069 | BR | Iriomote Is., Okinawa, Japan | LC822080 | LC822114 | LC822148 | LC822181 | |
| FRIM 749 | KEP FRI62981 | Endau Rompin, Johor, Malaysia | LC822081 | LC822115 | LC822149 | LC822182 | |
| FFPRI421070 (= WD-1223) | F-2388 | Minamiosumi, Kagoshima, Japan | LC822082 | LC049950 | LC822150 | LC822183 | |
| Pyrrhoderma sendaiense | FFPRI421071 | F-16592 | Kitaibaraki, Ibaraki, Japan | LC822083 | LC822116 | LC822151 | LC822184 |
| FFPRI421072 | F-16696 | Asahi, Yamagata, Japan | LC822084 | LC822117 | LC822152 | LC822185 | |
| Pyrrhoderma sublamaense | FRIM 731 | KEP FRI62940 | Endau Rompin, Johor, Malaysia | LC822085 | LC822118 | LC822153 | LC822186 |
| Pyrrhoderma williamsii | FFPRI421073 | F-16927 | Iriomote Is., Okinawa, Japan | LC822086 | LC822119 | LC822154 | LC822187 |
| FFPRI421074 | F-17159 | Iriomote Is., Okinawa, Japan | LC822087 | LC822120 | LC822155 | LC822188 | |
| FFPRI421075 | F-17161 | Iriomote Is., Okinawa, Japan | LC822088 | LC822121 | LC822156 | LC822189 | |
BR Isolated from decayed root samples affected from brown root rot. T Type materials.
Cultures sequenced in this study are stored in the culture bank of Forestry and Forest Products Research Institute (FFPRI) or Forest Research Institute Malaysia (FRIM).
The LSU dataset included 81 sequences and resulted in an alignment of 851 characters. The Pyrrhoderma-ITS, Fulvoderma-ITS, and Inonotus-ITS datasets included 69, 20, and 22 sequences and resulted in an alignment of 515, 596, and 554 characters, respectively. Pyrrhoderma-combined data set included 40 sequences and resulted in an alignment of 3172 characters. The topologies of the resulting trees from BI and ML were congruent. The BI trees are shown in Figs. 1, 2, 3, 4, 5.
Among the newly sequenced cultures, all of those provisionally determined as “Pyr. lamaoense” and Pyr. noxium in our herbaria or culture banks were included in the Pyrrhoderma clade with high support (Fig. 1) that coincided with the results of Zhou et al. (2018). Pyrrhoderma sendaiense is a distinct clade from Pyr. adamantinum, indicating that they are distinct species (Figs. 2, 5). Our “Pyr. lamaoense” and Pyr. noxium isolates were divided into four clades. One comprised cultures from basidiocarps determined as Pyr. noxium in Japan and Malaysia, those from trees damaged by brown root rot, and “Pyrrhoderma sp.” by Zhou et al. (2018) (= Pyr. nigrum, Zhou et al., 2023). Those provisionally determined as “Pyr. lamaoense” were divided into three clades: one corresponded with Pyr. lamaoense, one with “Pyr. noxium” defined by Zhou et al. (2018), and one does not coincide with any clade of Zhou et al. (2018) (Fig. 2).
Our results show that F. scaurum is not related to Pyrrhoderma spp., as indicated earlier by Zhou et al. (2018) (Fig. 1). Our sequence data indicated that one Japanese isolate of “F. scaurum” was accommodated in the clade of “F. australe” (scaurum clade 1) and the other was in the clade of “F. scaurum” (scaurum clade 2), as investigated by Zhou et al. (2018) (Fig. 3). Inonotus vallatus Núñez & Ryvarden and Phellinus coronadensis Rizzo, Gleser & Burds. are closely related with F. scaurum and accommodated in the Fulvoderma clade (Figs. 1, 3). Inonotus pachyphloeus (Pat.) T. Wagner & M. Fisch., I. boninensis T. Hatt. & Ryvarden, and I. tricolor (Bres.) Y.C. Dai are accommodated in the Inonotus clade (Figs. 1, 4), although all have setal hyphae and the monomitic hyphal system like several Pyrrhoderma species.
3.2. Morphological characterizations of the cladesOur phylogenetic analyses confirmed that Pyr. sendaiense and Pyr. adamantinum are two distinct species. These findings are consistent with those reported in Japan (Imazeki, 1966; Imazeki & Hongo, 1989). Morphological and ecological differences were clearly summarized by Imazeki (1966), which coincides with our direct observations and herbarium records. Morphological characteristics of the voucher specimens of one clade coincided with those of the holotype and the original description of F. noxius given by Corner (1932). Thus, we conclude that Pyr. noxium is a suitable name to represent this clade (noxium clade). All the cultures obtained from trees damaged by brown root rot were accommodated in this clade, and we reconfirmed that Pyr. noxium is a suitable name for the causal fungus of this disease as is widely used. Pyrrhoderma nigrum is conspecific with Pyr. noxium sharing similar characteristics given in the original description (Zhou et al., 2023). Regarding the other three clades containing specimens with setal hyphae, the morphological characteristics of the voucher specimens coincided with the authentic specimens of Pyropolyporus lamaoensis Murrill (= lamaoense clade), Fomes sublamaensis Lloyd (= sublamaense clade), and Pyropolyporus williamsii Murrill (= williamsii clade), respectively.
All species in the Pyrrhoderma clade share the following characteristics: 1) pileus (if present) covered by a rigid crust composed of dark and highly agglutinated hyphae; 2) (corky to) woody and yellowish-brown context (often brighter colored compared with tubes); 3) woody to flinty and grayish brown to dark brown tubes; 4) monomitic hyphal system in context (although several species have setal hyphae in addition to generative hyphae); 5) monomitic hyphal system in the trama with or without setal hyphae (but highly agglutinated in several species); 6) setal hyphae in the trama and context (if present) almost equal, tapered or rounded at the tip; and 7) subglobose to ellipsoid and colorless basidiospores. Other characteristics are common to many of other Hymenochaetaceae species.
Species in the Fulvoderma clade share 1) stipitate to sessile basidiocarps; 2) duplex context with upper tomentum and lower corky and light yellowish-brown context separated by a thin and black crust; 3) crust composed of non-agglutinated hyphae; 4) corky and yellowish-brown tubes composed of non-agglutinated hyphae; 5) monomitic hyphal system in the context without setal hyphae; 6) subdimitic to dimitic hyphal system in the trama without setal hyphae; and 7) subglobose and colorless basidiospores.
Species in the Inonotus clades are characterized by 1) sessile to resupinate basidiocarps; 2) context (or subiculum) and tubes sappy-fibrous to sappy-corky when fresh and more or less shrunken and fibrous-corky or brittle-corky when drying; 3) monomitic hyphal system both in the trama and context; 4) acuminate setal hyphae, often swollen toward the tip and contracted toward the base; and 5) basidiospores subglobose to ellipsoid, becoming yellowish to brown when matured.
3.3. Characteristics of Pyrrhoderma and its componentsPyrrhoderma Imazeki, Trans. Mycol. Soc. Japan 7: 4 (1966).
Type species: Pyrrhoderma sendaiense (designated by Imazeki, 1966).
Basidiocarps perennial or annual, stipitate, sessile to resupinate. All or most parts of pileus (and stipe, if present) covered by a distinct crust, pileus surface glabrous or with short appressed tomentum. Context woody hard to corky, bright yellowish brown to yellowish brown, often with white mycelial strands and/or crustose lines inside of the context. Tubes stratified or not, corky to woody or flinty composed of agglutinated hyphae, often dark grayish brown to almost black in fresh condition drying grayish brown. Pores regular.
Hyphal system monomitic in both of trama and context, with setal hyphae in some species. Tramal hyphae highly agglutinated or not. Setal hyphae (if present) almost equal, not swollen towards the tip, tapered or rounded at the tip. Crust on pileus surface composed of interwoven, agglutinated, and dark-colored hyphae. Hymenial setae absent or present. Basidiospores ellipsoid to subglobose, colorless, inamyloid, but frequently not seen in dried specimens.
Associated with a white rot or a white pocket rot with large pockets.
Remarks: Zhou et al. (2018) emended the genus concept, but we selected concise characteristics to represent the genus as follows: 1) basidiocarps perennial or annual (but usually persistent for several months in the field); 2) pileus surface covered with a crust composed of highly agglutinated hyphae; 3) context corky to woody; 4) hyphal system monomitic both in the trama and context, with or without setal hyphae, and tramal hyphae highly agglutinated in some species; 5) setal hyphae almost equal, tapered, or rounded at the tip; and 6) basidiospores ellipsoid to subglobose and colorless, inamyloid.
Pyrrhoderma adamantinum (Berk.) Imazeki, Trans. Mycol. Soc. Japan 7: 5 (1966).
≡ Polyporus adamantinus Berk., Hooker's J. Bot. Kew Gard. Misc. 6: 141 (1854).
= Pyrrhoderma musashiense (P. Henn.) Imazeki (nom. inval.) auct. non P. Henn.: Ito, Mycol. Fl. Japan 4: 389 (1955).
Basidiocarps annual to perennial, sessile (usually with a contracted base) to stipitate with a short lateral stipe. Pileus semicircular to spathulate, occasionally irregular, applanate to convex, up to 15 cm long, 12 cm wide, and 4 cm thick; pileus surface glabrous, mostly smooth, often indistinctly sulcate, occasionally umbonate near the base, grayish brown, dark grayish brown to dark brown, often zonate with differently colored zones; pileus margin entire, thick and rounded. Context hard corky to woody, bright yellowish brown to yellowish brown, often with white mycelial strands and black, discontinuous and crustose lines inside of the context near the base, with a distinct crust on pileus surface up to 1 mm thick. Tubes brittle-corky to woody, yellowish brown, often not clearly stratified, up to 10 mm deep in total, often decurrent on stipe. Pores angular, 6-7 pores/mm, dissepiments entire, pore surface grayish brown to brown. Stipe (if present) cylindrical to irregular, glabrous, grayish brown to dark brown, up to 5 cm long, up to 2 cm wide.
Hyphal system monomitic. Tramal hyphae parallel, partly agglutinated, but outline of each hypha mostly clear; tramal generative hyphae thin- to thick-walled, pale yellow to brown, 2-6 µm diam; contextual generative hyphae thin- to slightly thick-walled, occasionally branched, simple-septate, colorless to light brown, inamyloid, 2-7 µm diam. Skeletal and setal hyphae absent. Crust composing hyphae thick-walled, reddish brown, semiparallel to interwoven, agglutinated. Hymenial setae absent. Basidiospores subglobose, colorless, 6.5-7.5 × 5-7.5 µm according to Imazeki (1966), (5.6-)6-7(-8) × (4-)4.5-5.9(-6) µm according to Dai (2010).
Associated with a white rot.
Specimens examined: INDIA. Darjeeling, 6 May 1960 (F-24559). JAPAN. Kagoshima Pref., Kimotsuki, Sata, 19 Oct 1966, leg. K. Aoshima (F-24574); Miyazaki Pref., Nobeoka, Mt. Mukabaki, 1 Oct 1999, leg. S. Kurogi (F-20011); Nagasaki Pref., Nagasaki, Kompira-san, 30 Jan 2000, leg. Y. Wada (F-24564); Nagasaki Pref, Oomura, Oct 1998, leg. K. Yoshida (F-19256, voucher of FFPRI421058); Shimane Pref., Matsue, on Symplocos kuroki Nagamasu, 20 Sep 1963, leg. K. Aoshima (F-24560; F-24577; F-24578), the same place, 15 Oct 1971, leg. Y. Hayashi (F-11418; F-24575); Yamaguchi Pref., Onoda, 29 Jun 1997, leg. M. Izawa (F-18435).
Remarks: This fungus has often been confused with Pyr. sendaiense but is differentiated by the frequently perennial, sessile to shortly stipitate basidiocarps (annual and distinctly stipitate in Pyr. sendaiense); frequently grayish and often zonate pileus surface (cinnamon to brown and azonate in Pyr. sendaiense); thicker crust up to 1 mm thick (0.1-0.2 mm thick in Pyr. sendaiense), larger basidiospores measuring 6.5-7.5 × 5-7.5 µm (5-6.5 × 4-5 µm in Pyr. sendaiense) and warm temperate to subtropical distribution (cool temperate and restricted to Fagus in Pyr. sendaiense).
Pyrrhoderma lamaoense (Murrill) L.W. Zhou & Y.C. Dai, Mycologia 110: 882 (2018).
Figs. 6B, C, 7B, 8A, 9A, C, 10A.
≡ Pyropolyporus lamaoensis Murrill, Bull. Torrey bot. Club 34: 479 (1907).
Basidiocarps annual to perennial, effused-reflexed to resupinate, occasionally sessile, often widely effused on substrates. Pileus elongated in effused specimens, semicircular to irregular in sessile specimens, applanate to triquetrous, occasionally imbricate, up to 5 cm wide from margin to base, up to 2 cm thick; pileus surface appressed-tomentose, tomentum cover all or most part of pileus, tomentum up to 0.5 mm thick, densely-sulcate with conspicuous concentric sulci, occasionally becoming rough in old specimens, reddish brown to brown; pileus margin entire, acute or round. Context corky to woody, bright yellowish brown to yellowish brown, with a thin black crust up to 0.5 mm thick below thin and brown tomentum. Tubes woody to flinty, dark grayish brown when fresh drying light brown to grayish brown, stratified or not, up to 1 cm deep in total. Pores angular to round, 7-9 pores/mm, dissepiments entire, pore surface dark grayish brown drying light brown to grayish brown.
Hyphal system monomitic. Tramal hyphae interwoven and highly agglutinated, thick-walled, reddish brown, tramal hyphal system difficult to observe, but young tubes are composed of generative hyphae and scattered setal hyphae; tramal setal hyphae abundant, almost equal, tapered at the tip, dark brown, some curved then project into hymenium, 3.5-6.5 µm diam; contextual generative hyphae thin- to thick-walled, occasionally branched, simple-septate, colorless to light brown, inamyloid, 2-5 µm diam; contextual setal hyphae abundant, thick-walled to almost solid, almost equal, tapered at the tip, brown to dark brown, 3.5-6.5 µm diam. Crust composing hyphae thick-walled, reddish brown, interwoven and highly agglutinated. Hymenial setae scattered to sparce, often confused with tips of setal hyphae, ventricose to subulate, thick-walled, dark brown, 20-38 × 5-8.5 µm. Basidiospores usually not seen in dried specimens, oblong ellipsoid, colorless, inamyloid, 3.2-4.3 × 2-2.4 µm (according to Dai, 2010).
Associated with a white pocket rot with large pockets.
Specimens examined: PHILIPPINES. Luzon, Lamao Riv., Nov 1904, leg. R. S. Williams (NY, holotype). JAPAN. Okinawa Pref., Iriomote I., Nakama Riv., 8 Sep 1993, leg. T. Hattori (hereinafter referred to as “TH”, F-16623, voucher of FFPRI421063); Okinawa Pref., Iriomote I., Urauchi Riv., 25 Sep 1993, leg. TH (F-16925, voucher of FFPRI421064); the same place, 7 Dec 2010, leg. TH (F- 29146, voucher of FFPRI411162; F-29148, voucher of FFPRI421059; F-29149, voucher of FFPRI421060; F-29150, voucher of FFPRI421061); Okinawa Pref., Okinawa I., Mt. Yonaha-dake, 1 Sep 2014, leg. TH (F-29322, voucher of FFPRI421062). MALAYSIA. Johor, Endau Rompin National Park, 3 Sep 2009, leg. TH & S. S. Lee (F-27225, voucher of FRIM 744). Negri Sembilan, Pasoh For Res, 1 Apr 1993, leg. TH (F-16778).
Remarks: This species is a part of “Ph. lamaoensis” in the traditional usage (e.g. Corner, 1932; Fidalgo, 1968; Ryvarden & Johansen, 1980), and is morphologically characterized by the frequently effused-reflexed to almost resupinate and widely effused basidiocarps, small pileus (up to 5 cm wide and 2 cm thick, if present), densely sulcate pileus surface with an appressed tomentum, thin crust up to 0.5 mm thick below the tomentum, and abundant setal hyphae in the trama measuring 3.5-6.5 µm wide in this complex (Table 2). Hyphal system in the context can be described as dimitic if setal hyphae are considered short skeletal hyphae.
| P. lamaoense | P. noxium | P. sublamaense | P. williamsii | |
| Basidiocarp shape | Frequently effused-reflexed to resupinate, occasionally sessile | Sessile, effused-reflexed to resupinate | Usually sessile | Usually sessile |
| Pileus surface | Densely sulcate, with appressed tomentum | Broadly sulcate, glabrous | Broadly sulcate, glabrous | Broadly sulcate, glabrous or with appressed tomentum near margin |
| Pileus size | Up to 5 cm wide | Up to 25 cm × 13.5 cm | Up to 20 × 15 cm | Up to 15 × 10 cm |
| Crust thickness | -0.5 mm | -1 mm | -1.5 mm | -2.5 mm |
| Setal hyphae in context | Tip tappered, 3.5-5.5 µm wide | Tip tappered to rounded, 7-14 µm wide | Tip tappered, 4-6.5 µm wide | Tip tappered to rounded, 6-10 µm wide |
| Setal hyphae in trama | Tip tappered, 3.5-6.5 µm wide, abundant | Tip rounded, 8-25 µm wide, scattered | Tip tappered, 3.5-6.5 µm wide, abundant | Tip tappered to rounded, 6-11 µm wide, abundant |
| Hymenial setae | 20-38 × 6-12 µm, scattered | Absent | Absent | 30-50 × 6.5-12 µm, abundant |
| Pathogenecity on trees | Saprophitic | Pathogenic | Saprophitic | Saprophitic |
The clade of Pyrrhoderma lamaoense detected by Zhou et al. (2018) coincides with this species. Zhou et al. (2018) did not provide a detailed description of this fungus, but mentioned that it lacks hymenial setae within “the key to species of Pyrrhoderma”. According to our observations, however, hymenial setae are present in the holotype of Pyropolyporus lamaoensis as well as the voucher specimens of our isolates accommodated in the clade of Pyr. lamaoense in Zhou et al. (2018) and other specimens sharing the same morphological characteristics indicated above. The occurrence of hymenial setae in “Phellinus lamaoensis” was also widely recognized in the earlier studies of Corner (1932), Fidalgo (1968), and Ryvarden and Johansen (1980).
This species is common in Okinawa, a subtropical area of Japan and lowland areas of Malaysia. “Phellinus lamaoensis” was also reported from Africa and Central and South America (Fidalgo, 1968; Ryvarden & Johansen, 1980), but a reexamination of the specimens from these areas is required to determine the real distribution area of this species.
Pyrrhoderma noxium (Corner) L.W. Zhou & Y.C. Dai, Mycologia 110: 882 (2018).
Fig. 6D, E, 7C, 8B, C, 9D, 10B.
≡ Fomes noxius Corner, Gardens' Bulletin, Strait Settlements 5: 324 (1932).
= Pyrrhoderma nigrum Meng Zhou, Yuan Yan & Vlasák, Frontiers in Cellular and Infection Microbiology 12 (no. 1100044): 08 (as ‘nigra’; nomen invalidum, Art. F.5. 1, Shenzhen Code) (2023).
Basidiocarps usually perennial, pileate, effused-reflexed to resupinate, often widely effused on substrates. Pileus (if present) semicircular to irregular, elongated in effused specimens, convex, up to 25 cm long, 13.5 cm wide (according to Corner, 1932), up to 5 cm thick; pileus surface glabrous to matt, often sulcate with broad zones, brown, dark brown to almost black, growing margin cream to light brown; pileus margin entire, rounded. Context woody, bright yellowish brown to yellowish brown, with a distinct crust up to 1 mm thick. Tubes woody to flinty, dark grayish brown to almost black when fresh drying grayish brown, often not clearly stratified, single layer up to 5 mm deep, up to 15 mm deep in total. Pores angular to round, 7-9 pores/mm, dissepiments entire, pore surface dark grayish brown to almost black drying grayish brown.
Hyphal system monomitic. Tramal hyphae interwoven and highly agglutinated, thick-walled, reddish brown; tramal setal hyphae sparce to scattered, almost equal, mostly rounded, some slightly tapered at the tip, dark brown, some curved then project into hymenium, 8-14 to 18-25 µm diam (varied according to specimens), contextual generative hyphae thin- to moderately thick-walled, occasionally branched, simple-septate, colorless to light brown, inamyloid, 2.5-5 µm diam; contextual setal hyphae abundant, thick-walled to almost solid, almost equal, tapered to rounded at the tip, brown to dark brown, 7-14 µm diam. Crust composing hyphae thick-walled, reddish brown, interwoven and highly agglutinated. Hymenial setae absent. Basidiospores subglobose to broadly ellipsoid, colorless, 3.5-4.5 × 3-3.5 µm (according to Corner, 1932).
Type of rot: Associated with a white pocket rot with large pockets.
Specimens examined: SINGAPORE. Singapore Botanic Gardens, leg. E. J. H. Corner (K, isotype). JAPAN. Kagoshima Pref., Kimotsuki, Sata, 31 Oct 1950, leg. R. Imazeki (F-2388, voucher of FFPRI421070); Okinawa Pref., Ishigaki I., Banna, 2 Oct 1993, leg. TH (F-16962); Ishigaki I., Omoto-dake, on Casuarina equisetifolia J. et G. Forst., 26 Oct 2011, leg. TH (F-29199, voucher of FFPRI421065); Tokyo Pref., Bonin Is., Chichijima I, Yoake-yama, on dead wood by brown root rot, 2 Nov 2012, leg. TH, Y. Ota, & H. Masuya (F-28595); Bonin Is., Hahajima I., Omoto-hama, on dead wood by brown root rot, 5 Nov 2012, leg. TH (F-28653); Hahajima I., Kuwanoki-yama, 14 Nov 2013, leg. TH, Y. Ota, & H. Masuya (F-28859). MALAYSIA. Johor, Endau Rompin National Park, 3 Sep 2009, leg. TH & S. S. Lee (KEP FRI62981, voucher of FRIM 749, dup. F-27258).
Remarks: This fungus causes brown root rot. The fungus is characterized by a glabrous pileus surface, frequently with a light colored growing margin, dark grayish brown to almost black pore surface in fresh condition, broad (up to 25 µm diam) and round-tipped setal hyphae in the trama, and a complete lack of hymenial setae across Pyrrhoderma spp. (Table 2). The macromorphology of this fungus is quite variable, and resupinate to widely effused specimens are similar to Pyr. lamaoense, whereas distinctly pileate specimens resemble Pyr. sublamaense. It coincides with “Pyrrhoderma sp.” in Zhou et al. (2018), and the clade they applied “Pyr. noxium” actually represents Pyr. sublamaense.
Pyrrhoderma sendaiense (Yasuda) Imazeki, Trans. Mycol. Soc. Japan 7: 4 (1966).
Figs. 6F, G, 7D, 8D, 11.
≡ Polyporus sendaiensis Yasuda, Bot. Mag. Tokyo 37: 128 (1923).
Basidiocarps annual, laterally stipitate with a distinct stipe. Pileus semicircular, reniform or spathulate, applanate, up to 8 cm long, 6 cm wide, and 15 mm thick; pileus surface glabrous, mostly smooth, often sulcate, azonate, cinnamon to brown; pileus margin entire, acute to obtuse. Context hard corky to woody, bright yellowish brown to yellowish brown, frequently with white mycelial strands inside of pileus context near the base and/or stipe context, with a distinct crust fully covering pileus and stipe 0.1-0.2 mm thick. Tubes brittle-corky to woody, yellowish brown, up to 3 mm deep. Pores round to angular, 6-7 pores/mm, dissepiments entire, pore surface grayish brown to dark grayish brown. Stipe cylindrical, occasionally irregular, concolorous with pileus surface, up to 10 cm long and 2 cm wide.
Hyphal system monomitic. Tramal hyphae parallel, partly agglutinated; tramal generative hyphae thin- to thick-walled, occasionally branched, simple-septate, pale yellow to light brown, inamyloid, 2.5-6 µm diam; contextual generative hyphae thin- to slightly thick-walled, occasionally branched, simple-septate, pale yellow to light brown, inamyloid, 3-7 µm diam. Skeletoid hyphae and setal hyphae absent. Crust composing hyphae thick-walled, reddish brown, interwoven and agglutinated. Hymenial setae absent. Basidia 4-sterigmate, 18-25 × 7-10 µm. Basidiospores short ellipsoid, with a large guttula, colorless, inamyloid, 5-6.5 × 4-5 µm, 5.7 × 4.5 µm on average, R = 1.26, r: 1.2-1.38, n = 20.
Type of rot: Associated with a white rot.
Specimens examined: JAPAN. Miyagi Pref., Sendai, 21 Sep 1913, leg. A. Yasuda (holotype, TNS; isotype, TFM); Aomori Pref., Towada, on Fagus crenata Blume, 24 Sep 1964, leg. Y. Hayashi (F-24570); Ehime Pref., Omogo, Kaneyama-dani, 22 Nov 1996, leg. T. Okino (F-19243); Ibaraki Pref., Kitaibaraki, Ogawa, 5 Aug 1992, leg. K. Okabe (F-16592, voucher of FFPRI421071); the same place, on F. crenata, 14 Sep 1999, leg TH (F-19297); the same place, 11 Aug 2004, leg. TH (F-21267); Ibaraki Pref., Mt. Tsukuba, on F. crenata, 28 Jul 1998, leg. TH (F-18914); Kanagawa Pref., Yamakita-machi, Miho, on F. crenata, 22 Oct 1969, leg. K. Nanamiya (F-24567); Mie Pref., Misugi-cho, Kawakami, 7 Sep 1965, leg. K. Aoshima (F-24568); Miyazaki Pref., Morotsuka, 17 Nov 1999, leg. S. Kurogi (F-20024); Niigata Pref., Matsunoyama, 13 Sep 1964, leg. K. Aoshima (F-24561; F-24562; F-24563; F-24566; F-24571; F-24573; F-24579); Yamagata Pref., Mt. Asahi, 28 Oct 1992, leg. TH (F-16695, voucher of FFPRI421072); Yamagata Pref., Mt. Gassan, 30 Oct 1992, leg. TH (F-16714).
Remarks: This species is peculiar with distinctly stipitate basidiocarps, similar to that in many of Ganoderma and Amauroderma spp. Therefore, Yasuda (1923) described it as a member of the Amaurodermus group in Polyporus, where spores were incorrectly described as “ellipsoid, rough and very pale colored.” This is the only species in Pyrrhoderma that is distributed in cool temperate regions and specific to Fagus trees.
Pyrrhoderma sublamaense (Lloyd) Y.C. Dai & F. Wu, in Wu, Zhou, Vlasák & Dai, Fungal Diversity 113: 151 (as ‘sublamaensis’) (2022).
Figs. 6H, I, 7E, 8E, 9E, 10C.
≡ Fomes sublamaensis Lloyd, Mycol. Writ. 7 (Lett. 66): 1128 (1922).
= Pyrrhoderma noxium (Corner) L.W. Zhou & Y.C. Dai auct. non Corner: Zhou et al., Mycologia 110: 882 (2018).
Basidiocarps probably perennial, sessile. Pileus semicircular, applanate, up to 20 cm long, 15 cm wide, and 4 cm thick; pileus surface glabrous, smooth, sulcate or not, rusty brown, dark brown to almost black, light brown near the margin; pileus margin thin and entire. Context woody, bright yellowish brown to yellowish brown, with white mycelial strands inside of the context, with a distinct crust up to 1.5 mm. Tubes woody to flinty, dark grayish brown when fresh drying grayish brown, not clearly stratified, up to 3 cm deep in total. Pores round to angular, 8-10 pores/mm, dissepiments entire, pore surface dark grayish brown drying grayish brown.
Hyphal system monomitic. Tramal hyphae interwoven and highly agglutinated, thick-walled, reddish brown, tramal hyphal system difficult to observe; tramal setal hyphae abundant, mostly equal, tapered at the tip, dark brown, some curved then project into hymenium, 3.5-6.5 µm diam; contextual generative hyphae thin- to moderately thick-walled, occasionally branched, simple-septate, colorless to light brown, inamyloid, 2.5-5 µm diam; contextual setal hyphae abundant, thick-walled to almost solid, mostly equal, tapered at the tip, brown to dark brown, 4-6.5 µm diam. Crust composing hyphae thick-walled, reddish brown, interwoven and highly agglutinated. Hymenial setae absent. Basidia not seen. Basidiospores not seen.
Type of rot: not examined.
Specimens examined: PHILIPPINES. Luzon, Mt. Maquiling, 1 Nov 1920, leg. O. A. Reinking (holotype, BPI 310585). MALAYSIA. Johor, Endau Rompin National Park, 2 Sep 2009, leg. TH & S. S. Lee (KEP FRI62940, voucher of FRIM 731; dup. F-27197); Negri Sembilan, Pasoh For Res, 15 Apr 1993, leg. TH (F-16822).
Remarks: Ryvarden (1989) considered F. sublamaensis as a prior name of Pyr. noxium, whereas Fidalgo (1968) and Abe et al. (1995) took this as a synonym of Pyr. lamaoense. Wu et al. (2022) combined the epithet ‘sublamaensis’ with Pyrrhoderma to replace Pyr. noxium following Ryvarden (1989); however, Pyr. sublamaense is a distinct species both from Pyr. lamaoense and Pyr. noxium, as indicated above.
Macroscopically, it is similar to the sessile form of Pyr. noxium by the glabrous and dark colored pileus surface. However, the setal hyphae in the trama of Pyr. noxium are wide (8-14 to 18-25 µm wide), mostly rounded, and less abundant. This species may also pass as Pyr. lamaoense because of the pointed setal hyphae measuring 3.5-6.5 µm wide in the trama, but it lacks appressed tomentum on the pileus surface, has a semicircular pileus up to 15 cm wide, and lacks hymenial setae unlike Pyr. lamaoense (Table 2). This fungus lacks typical hymenial setae; however, tips of setal hyphae projecting into the hymenium or young and short setal hyphae may be considered hymenial setae. Phylogenetically, it coincides with “Pyr. noxium” treated in Zhou et al. (2018), but the holotype of Pyr. noxium is apparently distinct from this fungus.
Pyrrhoderma williamsii (Murrill) T. Hatt., comb. nov.
MycoBank no.: MB854318.
Basionym: Pyropolyporus williamsii Murrill, Bull. Torrey Bot. Club 34: 479 (1907).
Basidiocarps perennial, sessile, occasionally effused-reflexed when produced on the underside of the substrate. Pileus semicircular to elongated, occasionally irregular, triquetrous to convex, up to 15 cm long, 10 cm wide, and 5 cm thick; pileus surface glabrous to matt, occasionally indistinctly appressed-hairy near the margin, broadly sulcate, often densely sulcate near the margin, occasionally cracked, grayish brown, reddish brown to dark brown; pileus margin entire, obtuse. Context woody, light brown to reddish brown, often with white mycelial strands inside of the context, with a distinct crust on pileus up to 2.5 mm thick. Tubes woody to flinty, brown to dark brown when fresh drying grayish brown, stratified or indistinctly stratified, up to 30 mm deep in total. Pores angular to round, 7-9 pores/mm, dissepiments entire.
Hyphal system monomitic. Tramal hyphae interwoven, highly agglutinated, thick-walled, reddish brown; tramal setal hyphae abundant, mostly equal, tapered to rounded at the tip, dark brown, some curved then project into hymenium, 6-11 µm diam; contextual generative hyphae thin- to thick-walled, occasionally branched, simple-septate, colorless to light brown, inamyloid, 2.5-5 µm diam; contextual setal hyphae abundant, thick-walled to almost solid, mostly equal, tapered to rounded at the tip, dark brown, 6-10 µm diam. Crust composing hyphae thick-walled, reddish brown, interwoven and highly agglutinated. Hymenial setae ventricose, abundant, distinct from tips of setal hyphae, 30-50 × 6.5-12 µm. Basidiospores not seen.
Type of rot: Associated with a white pocket rot with large pockets.
Specimens examined: PHILIPPINES. Luzon Lamao Riv., Dec 1903, leg. R. S. Williams (NY, holotype). JAPAN. Okinawa Pref., Iriomote I., Urauchi Riv., 26 Sep 1993, leg. TH (F-16927, voucher of FFPRI421073); the same place, 21 Jun 1994, leg. TH (F-17159, voucher of FFPRI421074; F-17161, voucher of FFPRI421075).
Remarks: Pyropolyporus williamsii was considered a synonym of Pyr. lamaoense (Corner, 1932; Fidalgo, 1968; Ryvarden, 1985) and represents a part of “Phellinus lamaoensis” in the traditional usage. Pyrrhoderma williamsii is morphologically distinct from Pyr. lamaoense, characterized by a larger pileus of up to 15 × 10 cm (up to 5 cm wide in Pyr. lamaoense), mostly glabrous pileus surface (appressed-tomentose and densely sulcate in Pyr. lamaoense), thick crust on pileus surface up to 2.5 mm thick (up to 0.5 mm thick in the latter), wider setal hyphae in trama measuring 6-11 µm diam (3.5-6.5 µm diam in Pyr. lamaoense), and abundant hymenial setae measuring 30-50 × 6.5-12 µm (scattered to sparce, 20-38 × 5-8.5 µm in Pyr. lamaoense). Moreover, this is distinct from Pyr. sublamaense by the presence of hymenial setae and wider setal hyphae (Table 2). Pyrrhoderma hainanense is phylogenetically close to this fungus, sharing similar wide setal hyphae (Zhou et al., 2018). Pyrrhoderma hainanense is keyed out at the key “1. Basidiocarps resupinate” provided by Zhou et al. (2018), but can produce effused-reflexed or distinctly sessile basidiocarps, according to the original description. Further studies are required to determine their identities.
3.4. A key to the species of Pyrrhoderma1. Setal hyphae absent. ...... 2.
1. Setal hyphae present at least in trama. ...... 4.
2. Basidiocarps sessile; context fragile when fresh, drying corky; pores 3-5/mm (Zhou et al., 2018; specimen not seen)...... P. thailandicum
2. Basidiocarps stipitate to sessile; context corky to woody, pores smaller. ...... 3.
3. Basidiocarps annual, laterally stipitate with a distinct stipe; pileus up to 15 mm thick; basidiospores short ellipsoid, 5-6.5 × 4-5 µm; distributed in cool temperate areas, on Fagus spp. ...... P. sendaneinse
3. Basidiocarps annual to perennial, sessile to stipitate, stipe often indistinct; pileus up to 40 mm thick; basidiospores subglobose, 6.5-7.5 × 5-7.5 µm; distributed in warm temperate and subtropical areas, on various hardwood trees...... P. adamantinum
4. Hymenial setae absent...... 5
4. Hymenial setae present...... 6
5. Basidiocarps perennial, sessile, effused-reflexed to resupinate; setal hyphae in trama scattered, mostly rounded at the tip, 8-14 to 18-25 µm diam...... P. noxium
5. Basidiocarps perennial, sessile; setal hyphae in trama abundant, tapered at the tip, 4-6.5 µm diam...... P. sublamaense
5. Basidiocarps annual (to perennial), resupinate (to effused-reflexed or sessile in perennial specimens); setal hyphae in trama tapered, 6-10 µm diam (Zhou et al., 2018; specimen not seen). ...... P. hainanense
6. Basidiocarps annual to perennial, effused-reflexed to resupinate or sessile; pileus up to 5 cm wide; (if pileate) pileus surface densely sulcate with appressed tomentum above crust; crust up to 0.5 mm thick; setal hyphae in trama 3.5-6.5 µm diam; hymenial setae sparce to scattered, 20-38 × 5-8.5 µm. ...... P. lamaoense
6. Basidiocarps perennial, sessile, occasionally effused-reflexed but distinctly pileate; pileus up to 10 cm wide; pileus surface glabrous or with appressed tomentum near margin, broadly sulcate; crust up to 2.5 mm thick; setal hyphae in trama 6-11 µm diam; hymenial setae abundant, 30-50 × 6.5-12 µm. ...... P. williamsii
6. Basidiocarps annual, sessile, effused-reflexed or resupinate; setal hyphae in trama 5-8 µm diam; hymenial setae 16-45 × 5-12 µm (Zhou et al. 2018; specimen not seen). ...... P. yunnanense
3.5. Species in other genera examinedFulvoderma L.W. Zhou & Y.C. Dai, Mycologia 110: 876 (2019).
Type species: Fulvoderma australe L.W. Zhou & Y.C. Dai
Basidiocarps annual to perennial, stipitate to substipitate or sessile. Pileus dimidiate to spathulate, reniform or circular; pileus surface matt to felty, light yellowish brown, yellowish brown to reddish brown. Context corky-leathery when fresh, drying felty-corky, with a thin and black crust composed of non-agglutinated hyphae below tomentum, and then duplex with upper tomentum and corky context separated by a thin black line. Hymenophore poroid, regular. Hyphal system monomitic in context, subdimitic to dimitic in trama. Hymenial setae absent or present. Basidiospores subglobose to short ellipsoid, colorless, inamyloid.
Remarks: Zhou et al. (2018) differentiated this genus from Pyrrhoderma by the yellowish pileus surface in the original description; however, F. vallatum shows reddish brown pileus surface without yellowish coloration. They reported that Fulvoderma lacks hymenial setae, but hymenial setae are present in F. vallatum and Ph. coronadensis (Rizzo et al., 2003), with Ph. coronadensis a possible member of this genus.
Fulvoderma scaurum (Lloyd) L.W. Zhou & Y.C. Dai sensu lato, Mycologia 110: 879.
≡ Fomes scaurus Lloyd, Mycol. Writ. 4, Lett. 44: 11 (1913).
≡ Polyporus scaurus (Lloyd) Lloyd, Mycol. Writ. 4, Lett. 56: 8 (1915).
= Onnia cumingii (Berk.) Imazeki, auct. Imazeki: Bull. Tokyo Sci. Mus. 6: 110 (1943), non Berk.
Specimens examined: JAPAN. Miyagi Pref., Sendai, leg. A. Yasuda (TFM, isotype); Akita Pref., Semboku, Nyuto Hot Spring, 1 Oct 2023, leg. TH (F-29592, voucher of FFPRI421050); Hokkaido Pref., Chitose, Lake Shikotsu-ko, 10 Aug 1963, leg. K. Aoshima (F-22693); the same place, 14 Sep 1966, leg. K. Aoshima (F-22695); Hokkaido Pref., Tomakomai, Maruyama, 2 Sep 1992, leg. Y. Hayashi (F-22699); Hokkaido Pref., Yubari, Numa-no-sawa, 19 Sep 1990, leg. TH. (F-15810); Ibaraki Pref., Kitaibaraki, Ogawa, 3 Oct 1997, leg. TH (F-18006); the same place, 9 Aug 2004, leg. TH (F-21243); Ishikawa Pref., Shiramine, 7 Nov 1999, leg. Y. Yamashita (F-20071); Iwate Pref., Appi-Kogen, 4 Oct 1989, leg. Y. Abe et al. (F-15206); Nagano Pref., Kiso, Kaida, 10 Sep 1994, leg. TH (F-17209); Nagano Pref., Azumi, Mt. Norikura, 25 Aug 1991, leg. TH (F-16236); Shiga Pref., Kutsuki, Asahinomori, leg. TH (F-15146, voucher of FFPRI421049); Tottori Pref., Mt. Daisen, 5 Aug 1990, leg. TH (F-15724).
Remarks: Although the basionym of this fungus is often referred as Pol. scaurus after Ryvarden (1990), the fungus is conspecific to Fomes scaurus Lloyd (Lloyd, 1913). According to Lloyd (1915), the holotype of Pol. scaurus is “A fine collection which we are enabled to draw a better description than from previous sendings (=specimens used for description of F. scaurus). Therefore, F. scaurus is the correct basionym of this fungus.
Zhou et al. (2018) described “F. australe” allied to “F. scaurum”. They mentioned that the former has smaller pores (5-6/mm), narrower contextual hyphae (3.5-8 µm wide), interwoven tramal hyphae, and a “tropical to subtropical” distribution, whereas the latter has larger pores (4-5/mm), wider hyphae (7-12 µm wide), parallel tramal hyphae, and “temperate” distribution. Note that “subtropical” and “temperate” used by Zhou et al. (2018) does not follow Kira (1991), in which climatic zones for East Asian forests were characterized, but roughly represent “warm temperate” and “cool temperate” zones used by Kira (1991), respectively. The isotype of Fomes scaurus has small pores (7-8/mm) and interwoven tramal hyphae that do not coincide with the description of “F. scaurum” provided by Zhou et al. (2018). In addition, F-29592, the voucher specimen of the Japanese isolate accommodated in “scaurum clade 2” with the Chinese “F. scaurum,” has small pores (6-8 /mm), narrower contextual hyphae (2-7.5 µm wide), and semiparallel tramal hyphae. These findings do not agree with the above characterizations.
According to our observation, in “F. scaurum” specimens from various regions of Japan, including cool temperate and warm temperate areas, pore size varies from 5-6 to 7-9 pores/mm, and no specimen showed large pores measuring 4-5 pores/mm. The width of the contextual hyphae varies from 2-7.5 to 3-12 µm, with none measuring 7-12 µm. The arrangement of tramal hyphae was semiparallel to interwoven. We conclude that no clear difference exists in pore size, width of contextual hyphae, and arrangement of tramal hyphae between cool and warm temperate populations of “F. scaurum” in Japan. Perhaps, pore and hyphal sizes indicated by Zhou et al. (2018) referred to an inaccurate description by Ryvarden and Núñez (2000), who provided the same size for pores and contextual hyphae.
Here, we hesitate to make a nomenclatural conclusion on “F. scaurum” and “F. australe” before examining more specimens with molecular information and those collected in and around the type locality, namely Sendai and other lowland areas of middle-southern Tohoku Region, Japan.
Fulvoderma vallatum (Berk.) T. Hatt., comb. nov.
MycoBank: MB854321.
Basionym: Polyporus vallatus Berk., Hooker's J. Bot. Gard. Misc. 6: 138 (1854).
= Polyporus orientalis Lloyd, Mycol. Writ. 3, Synop. stip. polyp.: 193 (1912).
Basidiocarps annual, centrally to excentrically, occasionally laterally stipitate with a short stipe. Pileus circular, dimidiate to reniform, occasionally spathulate, applanate, up to 15 cm diam, or up to 20 cm long and 15 cm wide, up to 2 cm thick near the base; pileus surface matt to appressed tomentose, broadly sulcate, light brown to reddish brown; pileus margin entire, obtuse to acute. Context corky-leathery drying felty-corky, light brown; with a thin crust below superficial tomentum, crust black, up to 0.2 mm thick; tomentum fibrous-corky, concolorous or slightly darker than lower context, up to 4 mm thick. Tubes corky, light brown, up to 3 mm deep. Pores round to angular, 6-7 to 8-9 pores/mm, dissepiments entire, pore surface light grayish brown to brown. Stipe cylindrical to irregular, concolorous with pileus surface, up to 6 cm long, up to 3 cm wide.
Hyphal system monomitic in context, dimitic in trama. Tramal hyphae interwoven, non-agglutinated; tramal generative hyphae thin-walled, occasionally branched, simple-septate, colorless to pale brown, 1.5-3 µm diam; tramal skeletal hyphae thick-walled to almost solid, unbranched, light brown to rusty brown, inamyloid, 2.5-4 µm; contextual generative hyphae thin- to thick-walled, occasionally branched, simple-septate, colorless to rusty brown, inamyloid, 2.5-5 µm diam; setal hyphae absent both in context and trama. Crust composing hyphae non-agglutinated, mostly thick-walled, some hyphae almost straight, mostly unbranched, light brown to brown, semi-parallel, 3.5-5.5 µm diam, mixed with other hyphae sinuous with conspicuous side branches, up to 4 µm diam. Tomentum composing hyphae loosely interwoven, pileus surface not palisade, hyphal tips pointed, acuminate. Hymenial setae sparce to abundant, subulate to ventricose, occasionally hooked, 20-35 × 6-12 µm. Basidia 4-sterigmate, 10-15 × 5-6 µm. Basidiospores subglobose to short ellipsoid, colorless, inamyloid, 3-4.5 × 2.5-3.5 µm, 3.8 × 3 µm on average, R = 1.26, r: 1.17-1.31, n = 20.
Type of rot: white pocket rot with fine pockets.
Specimens examined: JAPAN. Kyoto Pref., Kyoto, Fushimi, 26 Sep 1990, leg. TH (F-15749, voucher of FFPRI421051); Kyoto, Kiyomizu, on Pinus densiflora Sieb. & Zucc., 27 Sep 1992, leg. M. Inaba (F-16674, voucher of FFPRI421052); Kyoto, Yoshida-yama, on P. densiflora, 12 Jul 1988, leg. TH (F-15352); Miyazaki Pref., Ebino, Ebino-kogen, 1 Nov 1975, leg. K. Aoshima (F22737); Miyazaki Pref., Miyazaki, Shizen-Kyuyorin, 13 Oct 1978, leg. K. Aoshima et al. (F-22737); Nara Pref., Nara, on P. densiflora, Feb 1962, leg. K. Aoshima (F-22736); Okinawa Pref., Iriomote I., Nakama Riv., on Pinus luchuensis Mayr., 19 Jun 1994, leg. TH (F-17133; voucher of FFPRI421053); Okinawa Pref., Miyako I., Shimoji, on P. luchuensis, 22 Jun 2004, leg. Y. Kawabe (F-21196); Kochi Pref., Kochi, Asakura, on P. densiflora, Dec 1968, leg. Y. Jinno (F-22734); Tottori Pref., Tottori, Oochidani, 12 Oct 1966, leg. K. Aoshima et al. (F-22735).
Remarks: This species is characterized by stipitate basidiocarps, the presence of crust as a thin and black line under the tomentum, and its occurrence on the roots or trunk base of Pinus spp. Laterally stipitate specimens may resemble F. scaurus sensu lato, but the latter always occurs on hardwood trees and lacks hymenial setae. This fungus often causes a decline in Pinus spp. (Hemmi & Nojima, 1928).
Inonotus boninensis T. Hatt. & Ryvarden, Mycotaxon 49: 210 (1993).
? = Inonotus griseus L.W. Zhou, Mycotaxon 130: 664 (2015)
Specimens examined: JAPAN. Bonin Is., Anijima I., leg. TH (F-15903, isotype, voucher of FFPRI421054).
For a detailed description, see Hattori and Ryvarden (1993).
Remarks: This species is accommodated in the Inonotus clade. Inonotus griseus is phylogenetically very close to this fungus and can be conspecific. It is distinct from Pyrrhoderma spp. in having setal hyphae with a distinctly pointed tip and a tapered base, up to 25 µm diam in the trama, and colored basidiospores. Tubes are sappy-corky when fresh, drying hard corky to woody, and shrunken then pore surface is cracked.
Inonotus melanodermus (Pat.) Zmitr., Malysheva & Spirin, Nov. sist. Niz. Rast. 40: 161 (2006).
≡ Xanthochrous melanodermus Pat., Ann. Jard. Bot. Buitenzorg, suppl. 1: 113 (1887).
Specimens examined: INDONESIA. Java, Foret de Tjibodas (FH, holotype).
For detailed descriptions, see Fidalgo (1968) and Ryvarden and Johansen (1980) as Phellinus melanodermus (Lloyd) Fidalgo.
Remarks: No sequence is available for this fungus. Wu et al. (2022) transferred this fungus to Ochrosporellus Bondartseva & S. Herrera without molecular analysis or direct examination on specimens. We have kept this fungus in Inonotus because it shares morphological similarity with I. pachyphloeus in having perennial basidiocarps, sappy-corky context drying fibrous-corky, broad setal hyphae with a distinctly acuminate tip and a tapered base, and subglobose and colored basidiospores at maturity.
Inonotus melanodermus differs from I. pachyphloeus by the lack of hymenial setae (e.g., Fidalgo, 1968; Ryvarden & Johansen, 1980). However, Corner (1991) objected and indicated the following points to differentiate this fungus from I. pachyphloeus: 1) pileus applanate, never really ungulate, with thinner flesh, shorter tubes and tube-layers each separated by a thin black crust; 2) spores ochraceous in the mass; 3) hymenial setae straight; 4) extrahymenial setae (setal hyphae) shorter and in the dissepiments not so wide; 5) hyphae distinctly dimitic in the context; 6) surface of pileus at first with a deeper pile of hyphal ends and without extrahymenial setae; 7) dissepiments agglutinated; and 8) the montane habitat.
According to our studies on type materials and other specimens, 1) I. melanodermus lacks hymenial setae, although young setal hyphae in trama can be considered straight hymenial setae; 2) setal hyphae of I. melanodermus are shorter (120-250 µm long in trama and 200-350 µm long in context) than those of I. pachyphloeus (250-400 µm long in trama and 380-900 µm long in context) as well as sparser; 3) most of the contextual hyphae of I. melanodermus are irregularly thick-walled with obscure occurrence of septa, whereas those of I. pachyphloeus are typical generative hyphae with a thin- to slightly thick-wall and frequent septa; 4) dissepiments are somewhat (but not distinctly) agglutinated in both species; and 5) spore masses can be also ochraceous in I. pachyphloeus.
Inonotus melanodermus is a poorly studied species with limited available specimens, and easily misidentified in the case of inexperienced determination due to the lack of hymenial setae. Voucher specimens must be examined in detail to avoid taxonomic confusion by referring to incorrectly identified specimens and cultures.
Inonotus pachyphloeus (Pat.) T. Wagner & M. Fisch., Mycologia 94: 1009 (2002).
≡ Polyporus pachyphloeus Pat., J. Bot., Paris 3: 257 (1889).
Specimens examined: FIJI. Fiji Isl. (FH, lectotype). JAPAN. Okinawa Pref., Ishigaki I., Yonehara, 18 Sep 1991, leg. TH (F-16283; voucher of FFPRI421055). MALAYSIA. Negri Senbilan, Pasoh Forest Reserve, 15 Mar 1997, leg. TH (TFM F-17786).
For detailed descriptions, see Fidalgo (1968) and Ryvarden and Johansen (1980) as Phellinus pachyphloeus.
Remarks: Wu et al. (2022) transferred this fungus to Ochrosporellus; however, it is a confirmed member of Inonotus sensu stricto, as already shown by Wagner and Fischer (2002) and Zhou et al. (2016). Although its context has often been described as woody or woody hard (e.g., Fidalgo, 1968; Ryvarden & Johansen, 1980), it is sappy-corky in fresh condition, drying shrunken and fibrous-corky, as in many Inonotus species. Wide and swollen setal hyphae with an acuminate tip and a tapered base, and colored basidiospores at maturity coincide with those of several Inonotus species with setal hyphae.
Inonotus tricolor (Bres.) Y.C. Dai, Fungal Diversity 45: 290 (2010).
≡ Poria tricolor Bres., Hedwigia 51: 316 (1912).
Specimens examined: JAPAN. Kagoshima Pref., Uchinoura, Hetsuka, 14 Oct 1963, leg. K. Aoshima (F-10383, voucher of FFPRI421056); the same place, 29 Oct 1998, leg. TH (F-19235); Miyazaki Pref., Miyakonojo, Mt. Aoi-dake, leg. K. Aoshima (F-10384, voucher of FFPRI421057).
For a description, see Ryvarden and Johansen (1980) as Phellinus tricolor (Bres.) Kotl.
The setal hyphae of I. tricolor are similar to those of many Inonotus species; however, unlike most Inonotus species, it has woody hard tubes and context (subiculum). Wu et al. (2022) used phylogenetic analysis to transferred this fungus to Ochrosporellus.
‘Phellinus’ hoehnelii (Bres.) Ryvarden, A Preliminary Polypore Flora of East Africa: 173 (1980).
≡ Fomes hoehnelii Bres., Annls mycol. 10: 499 (1912).
= Fomes magnosporus Lloyd, Mycol. Writ. 6 (Mycol. Not. 64): 1014 (1920).
For detailed descriptions, see Fidalgo (1968) as Phellinus magnosporus (Lloyd) Fidalgo and Ryvarden and Johansen (1980).
Specimens examined: PHILIPPINES. Luzon I., Bataan Prov., Lamao (BPI, holotype of F. magnosporus).
Remarks: No sequence is available for this fungus. Wu et al. (2022) transferred this fungus to Ochrosporellus without performing molecular analysis or direct examination of specimens. This fungus shares similarly shaped setal hyphae with many of Inonotus species, but has woody context unlike that of most Inonotus species.
The hyphal system is an important trait for characterizing genera in Hymenochaetaceae. Inonotus includes most poroid species in Hymenochaetaceae with a monomitic hyphal system and fleshy to fibrous context, whereas Phellinus Quél. includes those with a dimitic hyphal system and corky to woody context in traditional usage (e.g., Ryvarden, 1991). This dualistic genus concept was challenged by molecular phylogenetic studies, resulting in the recognition of various genera to accommodate species traditionally classified in Inonotus and Phellinus (e.g., Wagner & Fischer, 2002). The hyphal system is still considered important for characterizing the morphology of genera detected by phylogenetic analyses, for example, most species belonging to Inoderma P. Karst., Inocutis Fiasson & Niemelä, Phylloporia Murrill, Onnia P. Karst., and Mensularia Lázaro Ibiza have a monomitic hyphal system in the context, whereas those in Fomitiporia Murrill, Phellinus, and Porodaedalea Murrill have a dimitic hyphal system (Wu et al., 2022).
Despite their corky to woody context, species in Pyrrhoderma have monomitic hyphal systems both in the context and the trama. Other notable characteristics of this genus include 1) horny crust composed of agglutinated hyphae on the pileus surface (if pileate); 2) cylindrical and mostly equal setal hyphae in the trama and context, excluding Pyr. adamantinum, Pyr. sendaiense and Pyr. thailandicum that lack setal hyphae; and 3) subglobose to ellipsoid, colorless and inamyloid basidiospores.
Fulvoderma species resemble some Pyrrhoderma species in the woody to corky context with a superficial crust, excluding Pyr. thailandicus (fragile when fresh and drying corky); a monomitic hyphal system in the context; and subglobose to ellipsoid and colorless basidiospores. According to Zhou et al. (2018), the yellow brown pileus surface in Fulvoderma is distinctive from that of Pyrrhoderma, but F. vallatum lacks yellowish coloration on the pileus surface, indicating that color shade of the pileus surface may not be a key characteristic to differentiate these two genera. According to our observation, the tramal hyphal system is distinctive between these genera: subdimitic to dimitic with thick-walled skeletoid or skeletal hyphae in Fulvoderma and monomitic (but highly agglutinated in matured specimens of several species) in Pyrrhoderma. In addition, the context of Fulvoderma species is duplex, with the upper tomentum composed of loosely interwoven hyphae and the lower corky context separated by a thin crust composed of dark and nonagglutinated hyphae, whereas in Pyrrhoderma, the pileus surface is covered by a thick and horny crust.
Inonotus pachyphloeus was reconfirmed to be a member of Inonotus s.s., and is not related to Pyr. lamaoense and Pyr. noxium, although those species were often considered members of Phellinus, with morphological similarities in the hyphal characteristics (Corner, 1932; Fidalgo, 1968). Our study revealed that I. boninensis and I. tricolor, species with setal hyphae and a monomitic hyphal system, are also accommodated in the Inonotus clade. Several species with setal hyphae are confirmed members of Inonotus sensu stricto after phylogenetic studies: I. glomeratus (Peck) Murrill, I. patouillardii (Rick) Imazeki, I. quercustris M. Blackw. & Gilb., and I. rickii (Pat.) D.A. Reid (Wagner & Fischer, 2002; Zhou et al., 2015). These species have 1) fibrous, sappy-fibrous, to sappy-corky context (if pileate) and/or tubes in fresh condition, drying more or less shrunken and fibrous-corky or brittle-corky in most species, 2) acuminate setal hyphae, often swollen near the tip and/or tapered toward the base, and 3) more or less colored basidiospores at maturity (Gilbertson & Ryvarden, 1986; Ryvarden, 2005; Ryvarden & Johansen, 1980). By contrast, Pyrrhoderma species have 1) woody to corky context even in fresh condition (except for Pyr. thailandicus), 2) cylindrical and almost equal setal hyphae in trama and context (if present), and 3) colorless basidiospores.
Wu et al. (2022) erected Rigidonotus Y.C. Dai, F. Wu, L.W. Zhou, Vlasák & B.K.Cui (type species: R. glomeratus (Peck) Y.C. Dai, F. Wu, L.W. Zhou, Vlasák & B.K. Cui) to accommodate R. glomeratus and R. pruinosus (Bondartsev) Y.C. Dai, F. Wu, L.W. Zhou, Vlasák & B.K. Cui and accepted Ochrosporellus (type species: O. portoricensis) to accommodate 10 other species. Both of these genera include several “Inonotus” species with setal hyphae. Of the species transferred to Ochrosporellus, I. pachyphloeus was not accommodated in the clade defied as Ochrosporellus and several other species were transferred without detailed investigation. We will continue to use Inonotus according to Zhou et al. (2016) for now.
Specimens of Pyr. sublamaense and Pyr. williamsii have been determined as Ph. lamaoensis (= Pyr. lamaoense) or Ph. noxius (= Pyr. noxium). Fidalgo (1968) considered F. sublamaensis and Pyropolyporus williamsii as synonyms of Ph. lamaoensis, whereas Ryvarden (1985; 1989) concluded F. sublamaensis as a prior name for Ph. noxius and P. williamsii as a synonym of Ph. lamaoensis. These four species are similar in that they have frequently perennial basidiocarps and presence of setal hyphae, but are distinguished mainly by the basidiocarp shape (distinctly pileate vs. frequently effused), pileus surface structure (presence of upper tomentum), crust thickness, diameter of setal hyphae in trama, and presence of hymenial setae (summarized in Table 2). Pyrrhoderma noxium causes brown root rot, a serious disease of crops such as Hevea brasiliensis Muell. Arg., Camellia sinensis (L.) Kuntze, and Tectona grandis L.f. Zhou et al. (2018) misapplied this name to Pyr. sublamaensis, a saprotrophic fungus, and later Zhou et al. (2023) proposed Pyr. nigrum to represent Pyr. noxium. These treatments can cause serious confusion about the scientific name of this important pathogen (e.g., Garfinkel et al., 2020), but we reconfirmed Pyr. noxium as the correct name for this pathogen. This is the only species in Pyrrhoderma that causes serious diseases in trees.
Both Pyr. lamaoense and Pyr. noxium were considered widely distributed in tropical areas (Fidalgo, 1968; Ryvarden & Johansen, 1980). As shown by Zhou et al. (2018) and our study, however, some additional species exist among those determined as “Pyr. lamaoense” and “Pyr. noxium” in the tropical and subtropical areas of East and Southeast Asia. To further understanding this group, it is necessary to make detailed investigations on their phylogeny and morphological characterizations as indicated above on samples from various regions. The distribution and ecological characteristics, including pathogenicity, of each species can be evaluated based on correctly identified specimens from various regions. In many cases, it is difficult to extract DNA from dried and outdated specimens of Pyrrhoderma spp. to obtain good sequences. Cultures and/or basidiocarp samples kept in suitable buffer should be used for the molecular analysis on this group.
Pyrrhoderma sendaiense and Pyr. adamantinum, the original members of this genus, have nonflinty tubes, lack setal hyphae, are associated with a white rot, and are distributed mainly in temperate areas. Pyrrhoderma sendaiense was treated as conspecific with Pyr. adamantinum in some studies (Dai, 2010; Zhou et al., 2018); however, they actually represent two distinct species with different basidiocarp shape, basidiospore size, distribution, and host range. Pyrrhoderma sendaiense is hitherto known only from cool temperate areas of Japan and is highly specific to Fagus trees. The type locality of Pyr. adamantinum was mentioned as “Khasia Mountains and Sikkim; Darjeeling” (Berkeley, 1854). Imazeki et al. (1966) reported this fungus from Batasi (2150 m alt), Darjeeling in India, indicating that it is distributed in highland areas in the Himalayas. Known localities of this fungus in Japan and China are in warm temperate areas, with those in China described as subtropical areas (Dai, 2010), which roughly coincide with warm temperate areas defined by Kira (1991), and it is hitherto unknown from tropical lowland areas of Southeast Asia. The host range of Pyr. adamantinum remains unclear, however, it is likely to grow on various dead hardwood trees. The species has not been reported in regions where Fagus trees are distributed.
The authors declare no conflicts of interest. All the experiments undertaken in this study comply with the current laws of Japan.
This study was financially supported, in part, by a fund to T. H. provided by Institute for Fermentation, Osaka and by a Grant-in-Aid for Scientific Research (no. 25292096) from the Japan Society for the Promotion of Science. We would like to thank Forest Research Institute Malaysia and the Malaysian Government for funding the project Inventory and Survey of Selected Macrofungi in Peninsular Malaysia. We also thank the curators of the following herbaria: Farlow Reference Library and Herbarium of Cryptogamic Botany, Harvard University (FH), U.S. National Fungus Collections, Systematic Botany and Mycology Laboratory (BPI), Royal Botanic Gardens, Kew (K) for loan of specimens. Photographs of Fomes sublamaensis holotype were provided by Dr. Y. Abe (FFPRI). This study was undertaken with permission from Forestry Agency, Ministry of Agriculture and Fisheries, and Ministry of the Environment.
