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Research Article
Three new species of Phanerochaete (Polyporales, Basidiomycota)
expand article infoSheng-Hua Wu‡§, Che-Chih Chen§, Chia-Ling Wei§
‡ National Museum of Natural Science, Taichung, Taiwan
§ National Chung Hsing University, Taichung, Taiwan

Corresponding author: Sheng-Hua Wu ( shwu@mail.nmns.edu.tw )

Academic editor: Bao-Kai Cui
© 2018 Sheng-Hua Wu, Che-Chih Chen, Chia-Ling Wei.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Wu S-H, Chen C-C, Wei C-L (2018) Three new species of Phanerochaete (Polyporales, Basidiomycota). MycoKeys 41: 91-106. https://doi.org/10.3897/mycokeys.41.29070
Open Access

Abstract

Phanerochaete canobrunnea, P. cystidiata and P. fusca are presented as new species, supported by morphological studies and two sets of phylogenetic analyses. The 5.8S+nuc 28S+rpb1 dataset shows the generic placement of the three species within the phlebioid clade of Polyporales. The ITS+nuc 28S dataset displays relationships for the new taxa within Phanerochaete s.s. Phanerochaete canobrunnea grew on angiosperm branches in subtropical Taiwan and is characterised by greyish brown hymenial surface, brown generative hyphae and skeletal hyphae and absence of cystidia. Phanerochaete cystidiata grew on angiosperm branches above 1000 m in montane Taiwan and SW Yunnan Province of China and is characterised by cream to yellowish hymenial surface and more or less encrusted leptocystidia. Phanerochaete fusca grew on angiosperm branches at 1700 m in Hubei Province of China and is characterised by dark brown hymenial surface, leptocystidia, brown subicular hyphae and colourless to brownish basidiospores.

Keywords

China, corticioid fungi, multi-marker phylogeny, Phanerochaetaceae , Taiwan

Introduction

The genus Phanerochaete P. Karst., typified by P. alnea (Fr.) P. Karst., belongs to the Polyporales of the Basidiomycota and encompasses, when taken in a broad sense (Eriksson et al. 1978; Burdsall 1985; Wu 1990), over 150 names (Index Fungorum 2018). Phanerochaete spp. are typically recognised by its membranaceous, effuse, smooth hymenial surface (some are tuberculate, odontioid-hydnoid or merulioid-poroid), mostly monomitic hyphal system, simple-septate generative hyphae or with rare clamp connections in the subiculum, clavate basidia and ellipsoid to cylindrical, thin-walled and smooth basidiospores, which are inamyloid and non-dextrinoid. Phanerochaete is widely distributed and occurs on twigs, branches or trunks of angiosperms or gymnosperms, causing white rot in wood.

Phanerochaete recently has been shown to be a polyphyletic group, containing members placed throughout the phlebioid clade of Polyporales (Binder et al. 2005; Wu et al. 2010; Floudas and Hibbett 2015; Miettinen et al. 2016; Justo et al. 2017). Phanerochaete s.l. comprises some segregate genera: Efibula Sheng H. Wu, Hydnophlebia Parmasto, Phaeophlebiopsis Floudas & Hibbett, Phlebiopsis Jülich, Rhizochaete Gresl., Nakasone & Rajchenb. and Scopuloides (Massee) Höhn. & Litsch. (Burdsall 1985; Wu 1990; Greslebin et al. 2004; Wu et al. 2010; Floudas and Hibbett 2015).

The field survey of the corticioid fungi from Taiwan and mainland China conducted in 2014, 2015 and 2017, have revealed three new species of Phanerochaete s.s. presented herein, based on morphological and phylogenetic evidence.

Materials and methods

Morphological studies

Voucher specimens are deposited at the herbarium of National Museum of Natural Science of ROC (TNM). We used three mounting media for microscopic studies: 5% potassium hydroxide (KOH) with 1% phloxine was used for observation and measurements; Melzer’s reagent (IKI) was utilised to determine amyloidity and dextrinoidity and Cotton blue (CB) was utilised to check cyanophily. A standard method of measurement for microscopic characters follows Wu (1990). Below abbreviations were used when presenting statistic measurements of basidiospores: L = mean basidiospore length, W = mean basidiospore width, Q = variation in L/W ratio, n = number of measured spores. The terminology of microscopic characters followed Wu (1990).

DNA extraction and sequencing

Dried specimens or mycelia were first ground into a fine powder using liquid nitrogen and a TissueLyser II (Qiagen, Hilden, Germany). DNA was then extracted using the Plant Genomic DNA Extraction Miniprep System (Viogene-Biotek Corp., New Taipei, Taiwan) according to the manufacturer’s instructions. The rDNA ITS1-5.8S-ITS2 (ITS) was amplified using primer pairs ITS1/ITS4 (White et al. 1990). The D1-D2 domain of nuc 28S rDNA (nuc 28S) was amplified using primer pair LR0R/LR5 (http://www2.clarku.edu/faculty/dhibbett/Protocols_Folder/Primers/Primers.pdf). RNA polymerase II largest subunit (rpb1) was amplified using the primer pair RPB1-Af/RPB1-Cr (Stiller and Hall 1997; Matheny et al. 2002). Both RPB1-2.1f and RPB1-2.2f were used as alternative primers to pair with RPB1-Cr (Frøslev et al. 2005). The PCR protocols for ITS, nuc 28S and rpb1 followed Wu et al. (2018). PCR products were directly purified and sequenced by the MB Mission Biotech Company (Taipei, Taiwan). We determined the identity and accuracy of newly obtained sequences by comparing them to sequences in GenBank and assembled them using BioEdit (Hall 1999). Newly obtained sequences were then submitted to GenBank (https://www.ncbi.nlm.nih.gov/genbank/; Table 1).

Table 1.
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Species and sequences used in the phylogenetic analyses. Newly generated sequences are shown in bold.

Taxon Strain/Specimen ITS (contains 5.8S) nuc 28S rpb1
Bjerkandera adusta HHB-12826-Sp KP134983 KP135198 KP134784
Byssomerulius corium FP-102382 KP135007 KP135230 KP134802
Candelabrochaete africana FP-102987-Sp KP135294 KP135199 KP134872
Ceraceomyces serpens HHB-15692-Sp KP135031 KP135200 KP134785
Ceriporia alachuana FP-103881-Sp KP135341 KP135201 KP134845
Ceriporia purpurea KKN-223-Sp KP135044 KP135203 KP134788
Efibula americana FP-102165 KP135016 AY684165 AY864873
Emmia lacerata FP-55521-T KP135024 KP135202 KP134805
Gloeoporus pannocinctus L-15726-Sp KP135060 KP135214 KP134867
Hydnophlebia chrysorhiza FD-282 KP135338 KP135217 KP134848
Hyphoderma litschaueri FP-101740-Sp KP135295 KP135219 KP134868
Hyphoderma mutatum HHB-15479-Sp KP135296 KP135221 KP134870
Hyphodermella rosae FP-150552 KP134978 KP135223 KP134823
Meruliopsis alnbostramineus HHB-10729 KP135051 KP135229 KP134787
Phaeophlebiopsis peniophoroides FP-150577 KP135417 KP135273 KP134813
Phanerochaete aculeata Wu 880701-2 – GQ470636 –
Phanerochaete affinis KHL11839 EU118652 EU118652 –
Phanerochaete alnea OM8110 KP135171 – –
Phanerochaete arizonica RLG-10248-Sp KP135170 KP135239 KP134830
Phanerochaete australis HHB-7105-Sp KP135081 KP135240 KP134840
Phanerochaete bambusicola Wu 0707-2 MF399404 MF399395 LC314324
Phanerochaete brunnea He1873 KX212220 KX212224 –
Phanerochaete burtii HHB-4618 KP135117 KP135241 KP134829
Phanerochaete calotricha Vanhanen-382 KP135107 – KP134826
Phanerochaete canobrunnea CHWC 1506-17 LC412093 LC412102 –
CHWC 1506-39 LC412094 LC412103 –
CHWC 1506-66 LC412095 LC412104 –
Phanerochaete carnosa HHB-9195-Sp KP135129 KP135242 KP134831
Phanerochaete chrysosporium HHB-6251-Sp KP135094 KP135246 KP134842
Phanerochaete citrinosanguinea FP-105385 KP135100 KP135234 KP134824
Phanerochaete concrescens LE < RUS>:287,008 KP994375 – –
Phanerochaete cumulodentata H:6,033,465 LN833868 – –
VL212 JF440574 – –
Phanerochaete cystidiata GC 1708-358 LC412096 LC412101 LC412107
Wu 1708-326 LC412097 LC412100 LC412108
Phanerochaete ericina HHB-2288 KP135167 KP135247 KP134834
Phanerochaete exilis HHB-6988 KP135001 KP135236 KP134799
Phanerochaete fusca Wu 1409-161 LC412098 LC412105 LC412109
Wu 1409-163 LC412099 LC412106 LC412110
Phanerochaete incarnata WEI 16-078 MF399407 MF399398 LC314327
Phanerochaete krikophora HHB-5796-Sp KP135164 KP135268 KP134837
Phanerochaete laevis HHB-15519-Sp KP135149 KP135249 KP134836
Phanerochaete livescens FD-106 KP135070 KP135253 KP134841
Phanerochaete magnoliae HHB-9829-Sp KP135089 KP135237 KP134838
Phanerochaete odontoidea Wu 9310-8 MF399408 MF399399 LC314328
Phanerochaete porostereoides He1902 KX212217 KX212221 –
He1908 KX212218 KX212222 –
Phanerochaete pseudomagnoliae PP-25 KP135091 KP135250 KP134839
Phanerochaete pseudosanguinea FD-244 KP135098 KP135251 KP134827
Phanerochaete rhodella FD-18 KP135187 KP135258 KP134832
Phanerochaete robusta Wu 1109-69 MF399409 MF399400 LC314329
Phanerochaete sacchari Wu 880313-6 – GQ470654 –
Phanerochaete sanguinea HHB-7524 KP135101 KP135244 KP134825
Phanerochaete sanguineocarnosa FD-359 KP135122 KP135245 KP134828
Phanerochaete sordida FD-241 KP135136 KP135252 KP134833
Phanerochaete stereoides VPCI207312 KF291012 – –
Wu 9708-118 – GQ470661 –
Phanerochaete subceracea FP-105974-R KP135162 KP135255 KP134835
Phanerochaete subodontoidea Wu 0106-35 MF399411 MF399402 LC314331
Phanerochaete taiwaniana Wu 0112-13 MF399412 MF399403 LC314332
Phanerochaete thailandica 2015_07 MF467737 – –
Phanerochaete velutina Kotiranta21402 KP135179 – –
Phlebia centrifuga HHB-9239-Sp KP135380 KP135262 KP134844
Phlebia chrysocreas HHB-6333-Sp KP135358 KP135263 KP134861
Phlebia fuscoatra HHB-10782-Sp KP135365 KP135265 KP134857
Phlebia radiata AFTOL-484 AY854087 AF287885 AY864881
Phlebia uda FP-101544-Sp KP135361 KP135232 KP134859
Phlebiopsis gigantea FP-70857-Sp KP135390 KP135272 KP134821
Pirex concentricus OSC-41587 KP134984 KP135275 KP134843
Rhizochaete radicata FD-123 KP135407 KP135279 KP134816
Scopuloides rimosa HHB-7042 KP135350 KP135282 KP134853
Terana caerulea FP-104073 KP134980 KP135276 KP134865

Phylogenetic analyses

We included two datasets for phylogenetic analyses. The 5.8S+nuc 28S+rpb1 was compiled for inferring generic classification of target species within the phlebioid clade of Polyporales. The ITS+nuc 28S was compiled for getting better resolutions on species level within Phanerochaete s.s. The selection of strains and species consulted Wu et al. (2010), Floudas and Hibbett (2015), Volobuev et al. (2015), Liu and He (2016), Miettinen et al. (2016) and Wu et al. (2018). MAFFT v. 7 was used to align sequences of each marker with default settings (Katoh and Standley 2013). The resulting alignments were manually adjusted in MEGA 7 (Kumar et al. 2016). Hyphoderma litschaueri (Burt) J. Erikss. & Å. Strid and H. mutatum (Peck) Donk, were chosen as the outgroup in the 3-marker dataset. Phlebiopsis gigantea (Fr.) Jülich was chosen as the outgroup in the 2-marker dataset. Final datasets were deposited at TreeBASE (submission ID 23083).

For both datasets, Maximum Likelihood (ML) and Bayesian Inference (BI) analyses were performed, respectively, using RAxML BlackBox (Stamatakis et al. 2014) and MrBayes v. 3.2.6 (Ronquist et al. 2012) at the CIPRES Science Gateway (Miller et al. 2010; http://www.phylo.org/). For BI analysis, jModeltest 2.1.10 (Darriba et al. 2012) was first carried out to determine the best-fit substitution model for each marker based on Akaike Information Criterion (AIC). The GTR+I+G was used as the substitution model for the entire alignment of the 3-marker dataset, while, for the 2-marker dataset, the HKY+I+G and the GTR+I+G were used for the alignments of ITS and nuc 28S, respectively. The parameters for BI analyses were as follows: ngen = 10000000, samplefreq = 100, nchains = 4, nst = 6 for GTR, nst = 2 for HKY, rates = invgamma, burn-in = 25000. Fifty percent majority-rule consensus phylograms with posterior probability values (PP) were obtained when the average standard deviation of split frequencies was below 0.001. For ML analysis, the best-scoring tree with values of bootstrap (BS) was constructed using the GTR model with one hundred rapid bootstrap inferences. Gaps were regarded as missing data. Phylograms were visualised and edited by TreeGraph 2 (Stöver and Müller 2010) and Adobe Illustrator (Adobe Systems, Inc).

Results

Phylogenetic analyses

The 5.8S+nuc 28S+rpb1 dataset consisted of 58 sequences of 2481 characters including gaps, of which 931 sites were parsimony informative. The ITS+nuc 28S dataset consisted of 45 sequences of 2199 characters including gaps, of which 220 sites were parsimony informative. Topologies of phylogenetic trees of each dataset inferred from BI and ML methods were similar and, thus, only ML trees were shown (Figs 1, 2). In the 3-marker analyses (Fig. 1), three main subclades of the phlebioid clade of Polyporales, annotated as three families, Irpicaceae, Meruliaceae and Phanerochaetaceae, could be recognised in the ingroup (BS = 75–97%, PP = 1). Sequences of three new species were nested within the lineage of Phanerochaete s.s. of Phanerochaetaceae (BS = 100%, PP = 1). In the 2-marker analyses (Fig. 2), sequences of each of three new species formed well-supported monophyletic group (BS = 97–100%, PP = 1). Phanerochaete canobrunnea, P. cystidiata and P. fusca were allied to P. thailandica Kout & Sádlíková, P. ericina (Bourdot) J. Erikss. & Ryvarden and P. porostereoides S.L. Liu & S.H. He, respectively, based on available sequences.

Figure 1. 

Phylogram inferred from Maximum likelihood analysis of the concatenated 5.8S+nuc 28S+rpb1 dataset of representative taxa in the phlebioid clade of Polyporales. Branches are labelled with Maximum likelihood bootstrap values ≥70% and Bayesian posterior probabilities ≥0.9. Studied taxa are shaded with greyish boxes. Scale bar = substitutions per site.

Figure 2. 

Phylogram inferred from Maximum likelihood analysis of the concatenated ITS+nuc 28S dataset of taxa in Phanerochaete s.s. Nodes are labelled with Maximum likelihood bootstrap values ≥70% and Bayesian Posterior probabilities ≥0.9. Studied taxa studied are shaded with greyish boxes. Scale bar = substitutions per site.

Taxonomy

Phanerochaete canobrunnea Sheng H. Wu, C.C. Chen & C.L. Wei, sp. nov.

MycoBank No: MycoBank No: 827411
Figs 3A, 4

Diagnosis

Phanerochaete canobrunnea is recognised by brown generative hyphae and brown skeletal hyphae, in combination with absence of cystidia.

Holotype

TAIWAN. Nantou County: Yuchih Township, Lienhuachih, 23°55'N, 120°53'E, 715 m alt., on angiosperm branch, coll. W.C. Chen, C.C. Chen & C.L. Wei, 23 Jun 2015, CHWC 1506-17 (TNM F0029207).

Etymology

From canus+brunneus (= greyish-brown), referring to the colour of the hymenial surface.

Description

Basidiome resupinate, effuse, loosely adnate, membranaceous, 250–500 μm thick in section. Hymenial surface pale greyish-brown, slightly darkening in KOH, smooth, sometimes cracked; margin concolorous or brownish, slightly fibrillose or determinate.

Hyphal system dimitic; generative hyphae mostly simple-septate, single or double clamp connections occasionally present in subiculum. Subiculum fairly uniform, with fairly loose texture, 200–400 μm thick; generative hyphae interwoven, brown, more or less straight, moderately ramified, rarely encrusted, 4–9 (–11) μm diam., thin- to thick-walled, walls up to 1.5 μm thick, anastomoses occasional; skeletal hyphae interwoven, brown, more or less straight, un-ramified or ramified, 2–5 μm diam., usually subsolid or thick-walled, walls up to 1.5 μm, adventitious septa occasionally present. Hymenial layer thickening, with dense texture, 50–100 μm thick; hyphae more or less vertical, brownish to subcolourless, 3–6 μm diam., thin-walled. Cystidia lacking. Basidia subclavate to clavate, 15–25 × 5–6 μm, 4-sterigmate. Basidiospores ellipsoid to narrowly ellipsoid, adaxially flattened, smooth, thin-walled, IKI –, CB –, mostly 4.2–5.8 × 2.5–3 μm. [(4–) 4.5–5.8 (–6) × (2.5–) 2.7–3 (–3.2) μm, L = 5.10±0.54 μm, W = 2.86±0.18 μm, Q = 1.78 (n = 30) (CHWC 1506-17); (4–) 4.2–5 (–5.8) × (2.3–) 2.5–2.8 (–3) μm, L = 4.63±0.42 μm, W = 2.66±0.17 μm, Q = 1.75 (n = 30) (CHWC 1506-39)].

Additional specimens examined (paratypes)

TAIWAN. Nantou County: Yuchih Township, Lienhuachih, 23°55'N, 120°53'E, 715 m alt., on angiosperm branch, coll. W.C. Chen, C.C. Chen & C.L. Wei, 23 Jun 2015, CHWC 1506-39 (TNM F0029217); CHWC 1506-66 (TNM F0029236).

Distribution

Known from subtropical Taiwan.

Remarks. Amongst the few species in Phanerochaete having brown subicular hyphae, only P. canobrunnea and P. thailandica possess skeletal hyphae [described as “quasi-binding hyphae” in the protologue of P. thailandica, Sadlikova and Kout (2017)]. These two species are also closely related according to the phylogenetic analyses (Fig. 2). However, P. thailandica bears leptocystidia and has larger basidiospores (7–8 × 4–4.5 µm) (Sadlikova and Kout 2017). Phanerochaete brunnea Sheng H. Wu resembles P. canobrunnea in lacking cystidia and having similar basidiospores, but its hyphal system is monomitic (Wu 1990). These two species are phylogenetically not closely related (Fig. 2).

Figure 3. 

Basidiomes. A Phanerochaete canobrunnea (holotype, CHWC 1506-17) B P. cystidiata (holotype, GC 1708-358) C P. fusca (holotype, Wu 1409-161). Scale bar:1cm.

Figure 4. 

Phanerochaete canobrunnea (holotype, CHWC 1506-17) A profile of basidiome section B lower part of basidiome section C generative hyphae D skeletal hyphae E basidia F basidiospores. Scale bars: 100 μm (A); 10 μm (B–F).

Phanerochaete cystidiata Sheng H. Wu, C.C. Chen & C.L. Wei, sp. nov.

MycoBank No: MycoBank No: 827412
Figs 3B, 5

Diagnosis

Phanerochaete cystidiata is characterised by having a fibrillose margin of the basidiome and apically narrow or tapering leptocystidia that are more or less encrusted. Additionally, crystal masses are present in the hymenial layer.

Holotype

TAIWAN. Nantou County: Aowanta, 23°57'N, 121°10'E, 1200 m alt., on angiosperm branch, coll. C.C. Chen, 28 Aug 2017, GC 1708-358 (TNM F0031801).

Etymology

From cystidiatus, referring to the presence of cystidia of this species.

Description

Basidiome resupinate, effuse, adnate, membranaceous, 120–250 (–330) μm thick in section. Hymenial surface creamish-yellow, brownish in KOH, smooth to occasionally slightly tuberculate (due to crystal masses in hymenial layer), sometimes cracked; margin whitish or concolorous, fibrillous to fimbriate, occasionally determinate.

Hyphal system monomitic; hyphae simple-septate, clamp connections rarely present in subiculum. Subiculum fairly uniform, with somewhat loose to fairly dense texture, usually very dense near the substrate, 70–150 μm thick; hyphae more or less horizontal, colourless, fairly straight, moderately ramified, occasionally strongly encrusted with crystals, 3–6 (–7) μm diam., with 0.8–1.5 μm thick walls, anastomoses occasional. Hymenial layer thickening, with fairly dense texture, 50–100 (–180) μm thick, occasionally stratified; hyphae more or less vertical, colourless, 2.5–5 μm diam., thin-walled. Crystal masses occasionally abundant in hymenial layer. Leptocystidia numerous, immersed or emergent, cylindrical, median part usually slightly swollen and slightly thick-walled, with narrow or tapering apices, sparsely to heavily encrusted, (35–) 40–60 × 4–5.5 μm. Basidia subclavate to narrowly clavate, usually guttulate when mature, 20–30 × 4.5–5.5 μm, 4-sterigmate. Basidiospores ellipsoid to narrowly ellipsoid, adaxially flattened, smooth, thin-walled, guttulate, IKI–, CB–, mostly 4–5.3 × 2.5–3 μm. [4–5 (–5.5) × (2.5–) 2.7–3 (–3.3) μm, L = 4.59±0.43 μm, W = 2.86±0.18 μm, Q = 1.61 (n = 30) (GC 1708-358); (4–) 4.2–5 (–5.5) × 2.5–3 (–3.2) μm, L = 4.72±0.40 μm, W = 2.79±0.20 μm, Q = 1.70 (n = 30) (Wu 1708-326)].

Additional specimens examined (paratypes)

CHINA. Yunnan Province: Wenshan Zhuang and Miao Autonomous Prefecture, Maguan County, Dalishu Township, Lake, 23°07'04"N, 104°08'17"E, 1800 m alt., on angiosperm branch, coll. C.C. Chen, 7 Aug 2017, GC 1708-76 (TNM F0031803). TAIWAN. Nantou County: Aowanta, 23°57'N, 121°10'E, 1200 m alt., on angiosperm branch, coll. S.H. Wu, 28 Aug 2017, Wu 1708-326 (TNM F0031802).

Distribution

Known from China (Yunnan Province) and Taiwan (type locality).

Remarks

Phanerochaete ericina is the most closely related species (Figs 1, 2), but differs in having brownish hymenophore, frequently branched narrow hyphae (quasi-binding hyphae) and cystidia that are not encrusted (Wu 1990). Phanerochaete burtii (Romell) Parmasto, P. carnosa (Burt) Parmasto, P. calotricha (P. Karst.) J. Erikss. & Ryvarden, P. citrinosanguinea Floudas & Hibbett, P. pseudosanguinea Floudas & Hibbett, P. sanguinea (Fr.) Pouzar and P. sanguineocarnosa Floudas & Hibbett also have a more or less fimbriate margin of the basidiomes, apically narrow or tapering cystidia and similar-sized basidiospores; however, their cystidia are not or only rarely encrusted. These species form a strongly supported monophyletic group, while P. cystidiata is phylogenetically distantly related to this group (Figs 1, 2).

Figure 5. 

Phanerochaete cystidiata (holotype, GC 1708-358) A profile of basidiome section B basidiome section C leptocystidia D basidia E basidiospores. Scale bars: 100 μm (A); 10 μm(B–E).

Phanerochaete fusca Sheng H. Wu, C.C. Chen & C.L. Wei, sp. nov.

MycoBank No: MycoBank No: 827413
Figs 3C, 6

Diagnosis

Phanerochaete fusca is characterised by smooth to tuberculate dark brown hymenial surface, monomitic hyphal system with brown subicular hyphae and leptocystidia with narrow or tapering apices. Additional diagnostic features: hyphae and cystidia usually with adventitious septa, subicular hyphae sometimes swollen at hyphal ends and basidia becoming thick-walled and brownish when old.

Holotype

CHINA, Hubei Province: Shennongjia Forest Area, Wenshui Forest Farm, 31°44'N, 110°20'E, 1700 m alt., on angiosperm branch, coll. S.H. Wu, 19 Sep 2014, Wu 1409-161 (TNM F0029722).

Etymology

From fuscus (= dark brown), referring to the colour of the hymenial surface.

Description

Basidiome resupinate, effuse, adnate, membranaceous, 250–580 μm thick in section. Hymenial surface dark brown, slightly darkening in KOH, smooth to tuberculate, not cracked; margin concolorous, more or less separable, determinate.

Hyphal system monomitic; hyphae simple-septate, clamp connections rarely present in subiculum. Subiculum fairly uniform, with dense texture, 200–480 μm thick; hyphae more or less horizontal, brown, fairly straight, moderately ramified, usually swollen at hyphal ends, usually encrusted near subhymenium, (2.5–) 3–7 (–7.5) μm diam., with slightly thick to up to 2 μm thick walls, with small oily drops, usually with adventitious septa. Hymenial layer thickening, with dense texture, 50–100 μm thick; hyphae more or less vertical, brownish to subcolourless, 2.5–4 μm diam., slightly thick-walled. Leptocystidia numerous, originating from hymenial layer, projecting, cylindrical with narrow or tapering apices, sometimes encrusted, subcolourless to brownish, usually with 1 or 2 adventitious septa, 50–70 × 3.5–5.5 (–6) μm, with thin to up to 1 μm thick walls. Basidia clavate or occasionally narrowly clavate, subcolourless to brownish, sometimes with an adventitious septum, 22–50 × 5–6 μm, with thin to up to 1 μm thick walls, 4-sterigmate. Basidiospores narrowly ellipsoid to subcylindrical, adaxially slightly concave, smooth, thin- to slightly thick-walled, colourless to sometimes brownish, IKI –, CB –, mostly 5.7–7.3 × 3–3.5 μm. [(5.3–) 5.7–7.3 (–7.8) × (2.8–) 3–3.5 (–3.7) μm, L = 6.63±0.64 μm, W = 3.24±0.28 μm, Q = 2.05 (n = 30) (Wu 1409-161)].

Additional specimen examined (paratype)

CHINA. Hubei Province: Shennongjia Forest Area, Wenshui Forest Farm, 31°44'N, 110°20'E, 1700 m alt., on angiosperm branch, coll. S.H. Wu, 19 Sep 2014, Wu 1409-163 (TNM F0029723).

Distribution

Known from China (Hubei Province).

Remarks

Phanerochaete stereoides Sheng H. Wu resembles P. fusca in having brown subicular hyphae and leptocystidia. However, hymenial surface of the former is pale greyish-brown, while the latter is dark brown. Moreover, cystidia of P. stereoides are uniformly thin-walled and colourless, not with 1 or 2 adventitious septa. These two species are not closely related according to the phylogenetic analyses (Fig. 2). Phanerochaete porostereoides is the most closely related species (Fig. 2). Like P. fusca, it has brown subicular hyphae, but differs by lacking cystidia and by smaller basidiospores [(4.5–) 4.7–5.3 (–5.5) × (2.3–) 2.5–3.1 (–3.3) μm], according to Liu and He (2016).

Figure 6. 

Phanerochaete fusca (holotype, Wu 1409-161) A profile of basiome section B basidiome section C leptocystidia D subicular hyphae, usually swollen at hyphal ends E basidia F basidiospores. Scale bars: 100 μm (A); 10 μm (B–F).

Acknowledgments

This study was financed by Ministry of Science and Technology of Taiwan (ROC) (Grant no 107-2621-B-178-002-MY3). The authors thank Dr. Xiang-Hua Wang (Kunming Institute of Botany, China) for providing help in the field trips in SW Yunnan Province, China. We are also grateful to Ms. Siou-Zhen Chen (TNM) for managing studied specimens and to Shin-Yi Ke (TNM) for the help in DNA sequencing work.

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