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A contribution to Porogramme (Polyporaceae, Agaricomycetes) and related genera

Abstract

The polypores with shallow pores from tropical Asia and America are studied. Our molecular phylogeny based on the internal transcribed spacer (ITS), the large subunit nuclear ribosomal RNA gene (nLSU), the translation elongation factor 1-α gene (TEF1), and the largest subunit of RNA polymerase II (RPB1) demonstrates six clades are formed among Porogramme and related genera. Two new genera, Cyanoporus and Pseudogrammothele, are established, and the six clades represent Porogramme, Cyanoporus, Grammothele, Epithele, Theleporus, and Pseudogrammothele, respectively. The molecular clock analyses estimate the divergence times of the six clades based on a dataset (ITS + LSU + TEF1 + RPB1 + RPB2), and we recognize the mean stem ages of the six genera are earlier than 50 Mya. Three new species in Porogramme were morphologically and phylogenetically confirmed, and they are described as P. austroasiana, P. cylindrica, and P. yunnanensis. Phylogenetic analysis shows that type species of Tinctoporellus and Porogramme are nested in the same clade, and Tinctoporellus is treated as a synonym of Porogramme. Based on our phylogeny, twelve new combinations are proposed, and the differences between the new species and similar or related species are discussed.

Introduction

Porogramme, typified by P. albocincta, is characterized by the resupinate, bluish gray, reddish to almost black basidiome with an irpicoid to poroid hymenophore, hymenium restricted to the base of tubes, a monomitic hyphal system, generative hyphae with clamp connections and dextrinoid, the absence of cystidia and dendrohyphidia, ellipsoid to cylindrical, thin-walled, neither amyloid nor dextrinoid basidiospores, a white rot ecology, with the substrate becoming reddish beneath the basidiomes (Ryvarden and Johansen 1980).

Theleporus (typified by T. cretaceus), Grammothele (typified by G. lineata), Epithele (typified by E. typhae), and Porogramme are similar in sharing hymenia restricted to the base of tubes, and these genera are traditionally called corticioid fungi (Ryvarden 1979; Ryvarden and Johansen 1980; Larsson 2007). Tinctoporellus, typified by T. epimiltinus, is similar to above four genera, but differs by the hymenium being present at both the base and vertical wall of tubes, and was considered a true polypore (Ryvarden 1979). Epithele differs from Grammothele, Theleporus, and Porogramme by the smooth hymenophore and thick-walled basidiospores, Theleporus differs from Grammothele and Porogramme in the pale basidiome and in not reddening substrate. Grammothele differs from Porogramme by the presence of dendrohyphidia.

Species in Porogramme, Theleporus, Grammothele, Epithele, and Tinctoporellus are mostly distributed in tropical or subtropical areas (Ryvarden and Johansen 1980; Wu et al. 2022). Recently, more new species in above genera were described (Yuan and Wan 2012; Zhou and Dai 2012; Nakasone 2013; Ryvarden 2015, 2018, 2019; Yuan 2015; Wu et al. 2016; Hyde et al. 2019; Decock and Ryvarden 2020, 2021). The five genera were previously proved to belong to Polyporaceae based on molecular phylogeny (Binder et al. 2005; Zhou and Dai 2012; Justo et al. 2017). However, phylogenetic relationships between Porogramme and Tinctoporellus, Epithele, Grammothele and Theleporus were not analyzed, and their species diversity is not well known.

Based on samples from Brazil, China, Malaysia, Singapore, Sri Lanka, and Vietnam, phylogenetic analyses on Porogramme and Tinctoporellus, Epithele, Grammothele and Theleporus are carried out. Three new species belonging to Porogramme are detected, and their illustrated description are given, the new definition of the genus is outlined. In addition, two new genera and twelve new combinations are proposed.

Materials and methods

Morphological studies

Voucher specimens examined are deposited in the collection of the Institute of Microbiology, Beijing Forestry University (BJFC). Morphological descriptions are based on field notes and voucher specimens. Sections of basidiome were studied microscopically according to Cui et al. (2019), and examined at 1000 × using a Nikon Eclipse 80i microscope.

The following abbreviations are used in the descriptions: KOH = 5% potassium hydroxide, IKI = Melzer’s reagent, IKI– = neither amyloid nor dextrinoid, CB = Cotton Blue, CB +  = cyanophilous, CB– = acyanophilous, L = mean spore length (arithmetic average of all spores), W = mean spore width (arithmetic average of all spores), Q = variation in the L/W ratios between the specimens studied, n (a/b) = number of spores (a) measured from given number (b) of specimens. Special color terms follow Anonymous (1969) and Petersen (1996).

Molecular sequencing

A cetyl trimethylammonium bromide rapid plant genome extraction kit (Demeter Biotechnologies Co., Ltd, Beijing) was used to extract total genomic DNA from purified isolates, and performed the polymerase chain reaction (PCR) according to the manufacturer’s instructions with some modifications (Cui et al. 2019). The DNA was amplified with the primers: ITS5/ITS4 for ITS.

(White et al. 1990), LR0R/LR7 for nLSU (Vilgalys and Hester 1990), RPB1-Af/RPB1-Cr for.

RPB1 (Matheny et al. 2002), fRPB2-5F/fRPB2-7cR for RPB2 (Liu et al. 1999; Matheny 2005), and EF1-983F/EF1-1567R for TEF1 (Rehner and Buckley 2005). The PCR procedures for ITS, nLSU, RPB1, RPB2 and TEF1 followed Shen et al. (2019) and Ji et al. (2022). DNA sequencing was performed at Beijing Genomics Institute, and the newly generated sequences were deposited in the GenBank database.

Phylogenetic analysis

Sequences generated for this study were aligned with additional sequences downloaded from GenBank (Table 1) using BioEdit (Hall 1999) and ClustalX (Thompson et al. 1997). The data matrixes were edited in Mesquite v3.70 software (Maddison and Maddison 2021). Trametes suaveolens was used as outgroup. Alignment was manually adjusted to allow maximum alignment and to minimize gaps. Sequence alignment was deposited at TreeBase (http://purl.org/phylo/treebase/).

Table 1 Taxa information and GenBank accession numbers of the sequences used in this study

Maximum Likelihood (ML) and Bayesian inference (BI) were employed to perform phylogenetic analysis using the jModeltest v.2.17 to determine the best-fit evolution model for the combined dataset of ITS + nLSU + TEF1 + RPB1 sequences for estimation. Phylogenetic analysis approaches followed Zhao et al. (2015). The ML phylogenies were inferred from the combined dataset using RAxML 7.2.8 (GitHub, San Francisco, CA, USA), the default settings of the GTR + I + G model were used for all parameters in the ML analysis (Stamatakis 2006). The ML bootstrap values (ML) of the nodes were obtained using the GTRCAT model with 1000 bootstrap replicates (Hills and Bull 1993).

The BI analyses were conducted with MrBayes 3.2.6 (Ronquist 2003). Four Markov chains were run for 2,000,000 generations until the split deviation frequency value was ≤ 0.01 and trees were sampled every 1000 generations. The first 25% of sampled trees were discarded as burn-in, whereas the remaining trees were used to construct a 50% majority consensus tree and calculate Bayesian posterior probabilities (BPPs).

Branches that received bootstrap support for BS (bootstrap support for ML) values and BPPs (Bayesian posterior probabilities for BI) simultaneously ≥ 50% and ≥ 0.8 were considered as significantly supported, respectively. Phylogenetic tree was visualized with the program FigTree v. 1.4.3 (http://tree.bio.ed.ac.uk/software/figtree/).

Divergence time estimation

The divergence times were estimated with the BEAST v2.6.5 software package (Bouckaert et al. 2019) with a dataset composed of ITS + nLSU + TEF1 + RPB1 + RPB2 sequences (Table 1). Sequences of the species are adopted partly from the topology established by Song and Cui (2017). An XML file was generated with BEAUti (version 2). The rates of evolutionary changes at nuclear acids were estimated using ModelTest (version 3.7) with the GTR substitution model (Posada and Crandall 1998). A log-normal distribution was employed for molecular clock analysis and the tree prior was set to Yule speciation. Three fossil calibrations, Archaeomarasmius leggettii (Hibbett et al. 1995; 1997), Quatsinoporites cranhamii (Smith et al. 2004; Berbee and Taylor 2010) and Paleopyrenomycites devonicus (Taylor et al. 1999; 2005), representing the minimum divergence time of Agaricales (90 Mya), Hymenochaetaceae (125 Mya), and between Ascomycota and Basidiomycota (400 Mya), respectively, were used as calibrations. After 10,000,000 generations, the first 10% of the sampled trees were removed as burn-in. The log file was checked for convergence with Tracer (version 1.52), and the trees file was interpreted to a maximum clade credibility (MCC) tree with TreeAnnotator (version 2.6.5), annotating clades with more than 0.8 Bayesian posterior probability (BPP).

Results

Molecular phylogeny

The combined dataset included sequences from 69 fungal specimens representing 32 taxa. Best model for the combined ITS + nLSU + TEF1 + RPB1 dataset estimated and applied in the Bayesian analysis: GTR + I + G, lset nst = 6, rates = invgamma; prset statefreqpr = dirichlet (1, 1, 1, 1). Bayesian analysis resulted in an average standard deviation of split frequencies = 0.003213. Both ML and BI trees resulted in similar topologies, thus only the topology from the ML analysis is presented along with statistical values from the ML (≥ 50%) and BPPs (≥ 0.8) algorithms (Fig. 1). From the phylogenetic tree, four new well-supported lineages in Porogramme clade (Clade A) were formed: Three specimens (Dai 19624, 19634 and 21202) from Malaysia, and Sri Lanka named as Porogramme austroasiana; three specimens (Dai 12222, 12236 and 12259) from Yunnan of China named as P. yunnanensis; four samples (Dai 18526A, 18529A, 18544A and 22348) from subtropical China named as P. cylindrica; three samples (Dai 17445, 17460 and WX2014-26) from Brazil represent P. subargentea.

Fig. 1
figure 1

Phylogeny of Porogramme and related species generated by Maximum Likelihood based on dataset ITS + nLSU + TEF1 + RPB1. Bootstrap supports for Maximum Likelihood (ML) and Bayesian Posterior Probabilities (BPPs) are higher than 50% (ML) and 0.8 (BPPs) on the branches. New taxa are in bold

Samples of so-called Grammothele fuligo formed a clade (Clade B) closely related to Porogramme, Grammothele, Epithele, and Theleporus. So, a new genus, Cyanoporus, is set up for the clade. These samples formed three lineages nested in the clade representing C. camptogrammus, C. fuligo, and C. aff. fuligo, respectively.

Three samples of Cui 6539, Dai 17821 and 21932 from southern China and Singapore formed a new lineage in the Grammothele clade (Clade C) with a robust support (100% ML and 1.00 BPP), and they represent G. duportii. Two samples of Grammothele separabillima H.S. Yuan from southern China formed a clade (Clade F) with a robust support (100% ML and 1.00 BPP) in our phylogeny (Fig. 1), thus the new genus, Pseudogrammothele, is established to accommodate the unique species.

Divergence time estimation of Porogramme and related genera

The combined dataset for the molecular clock analysis included 51 taxa, of which 33 belonged to Polyporaceae. The results of divergence time estimation (Fig. 2) show that Polyporaceae emerged in a mean stem age of 152.9 Mya [95% highest posterior density (HPD) of 113.4–195.6 Mya] and a mean crown age of 113.2 Mya (95% HPD of 80.3–152.4 Mya). Among the six clades of Porogramme and related genera, Pseudogrammothele separabillima grouped with Polyporus squamosus and evolved from the same ancester dated to 79.1 Mya. The Theleporus clade and Epithele clade diverged at 79.2 Mya and 72.9 Mya, respectively. Then, the Cyanoporus clade, species growing only on monocotyledons which previously treated as Grammothele fuligo, diverged at 62.1 Mya. The Porogramme clade, including the species of Porogramme and Tinctoporellus, sister to the Grammothele clade, and both of them diverged at 54.3 Mya. Consequently, the mean stem ages of the six major clades are well supported as allied lineages originated during the middle Paleogene period which is consistent with previous studies of Ji et al. (2022).

Fig. 2
figure 2

Estimated divergence times of Porogramme and related genera generated by molecular clock analyses using a combined dataset ITS + nLSU + TEF1 + RPB1 + RPB2. Estimated mean divergence time (Mya) and posterior probabilities (PP) > 0.8 are annotated at the internodes. The 95% highest posterior density (HPD) interval of divergence time estimates is marked by horizontal blue bars

Taxonomy

Porogramme austroasiana Y.C. Dai, W.L. Mao & Yuan Yuan, sp. nov., (Figs. 3 and 4).

Fig. 3
figure 3

Basidiome of Porogramme austroasiana (holotype). Bar = 1.0 cm

Fig. 4
figure 4

Microscopic structures of Porogramme austroasiana (drawn from holotype). a. Basidiospores; b. Basidia; c. Basidioles; d. Dendrohyphidia; e. Hyphae from subiculum; f. Hyphae from trama

MycoBank no.: MB 846852.

Etymology: Austroasiana (Lat.): refers to the species being found in South Asia.

Diagnosis: The irregular and partly split pores, thin-walled generative hyphae with both clamps and simple septa, arboriform branched skeletal hyphae, clavate basidia sometimes constricted at middle, oblong ellipsoid to narrowly ovoid basidiospores measuring 3.8–4.5 × 2.1–2.5 μm differentiate the species in Porogramme.

Type: Sri Lanka: Avissawella, Salgala Forest, N 6° 95′, E 80° 20′, on fallen angiosperm trunk, 3 March 2019, Y.C. Dai 19624 (BJFC031301—holotype).

Description: Basidiome annual, resupinate, difficult to separate from the substrate, hard and brittle when dry, to 7.5 cm long, 4.5 cm wide and 0.6 mm thick at the center. Pore surface cream to pale buff when fresh and dry; sterile margin distinct, white when fresh, cream when dry; pores round to angular, irregular and partly split, 2–5 per mm; dissepiments thin, entire. Hymenium present at both vertical tube-walls and the base of tubes. Subiculum pale buff, resinous, to 0.1 mm thick. Tubes concolorous with pore surface, corky, to 0.5 mm long. Hyphal system dimitic; generative hyphae with both clamp connections and simple septa; skeletal hyphae IKI–, CB–; tissues unchanged in KOH. Subicular generative hyphae frequent, hyaline, thin-walled, moderately branched, 1.5–2.5 µm diam; skeletal hyphae dominant, pale yellowish, thick-walled with a narrow to medium lumen, frequently arboriform branched, flexuous, interwoven, 1–2.5 µm diam. Tramal generative hyphae frequent, hyaline, thin-walled, occasionally branched, 1.5–2 µm diam; skeletal hyphae dominant, pale yellowish, distinctly thick-walled with a medium to wide lumen, arboriform branched, flexuous, interwoven, 1.5–2.5 µm diam. Cystidia and cystidioles absent. Dendrohyphidia hyaline, thin-walled. Basidia clavate, sometimes constricted at middle, with 4 sterigmata and a basal clamp connection, 11–15 × 3–5 µm; basidioles dominant, clavate to pyriform, slightly smaller than basidia. Some irregular-shaped crystals present among hymenium. Basidiospores oblong ellipsoid to narrowly ovoid, hyaline, thin-walled, smooth, IKI–, CB–, (3.6–)3.8–4.5(–5) × (2.0–)2.1–2.5(–2.6) µm, L = 4.11 µm, W = 2.22 µm, Q = 1.82–1.85 (n = 60/2).

Additional specimens examined: Malaysia: Selangor: Kota Damansara, Community Forest Reserve, N 3° 16′, E 101° 58′, on fallen angiosperm trunk, 7 December 2019, Y.C. Dai 21202 (BJFC032856). Singapore: Bukit Timah Nature Reserve, N 1° 35′, E 103° 77′, on fallen angiosperm trunk, 19 July 2017, Y.C. Dai 17817 (BJFC025349). Sri Lanka: Avissawella: Salgala Forest, N 6° 95′, E 80° 20′, on fallen angiosperm trunk, 3 March 2019, Y.C. Dai 19634 (BJFC031311).

Porogramme cylindrica Y.C. Dai, W.L. Mao & Yuan Yuan, sp. nov., (Figs. 5 and 6).

Fig. 5
figure 5

Basidiome of Porogramme cylindrica (holotype). Bar = 1.0 cm

Fig. 6
figure 6

Microscopic structures of Porogramme cylindrica (drawn from holotype). a. Basidiospores; b. Basidia; c. Basidioles; d. Dendrohyphidia; e. Hyphae from subiculum; f. Hyphae from trama

MycoBank no.: MB 846851.

Etymology: Cylindrica (Lat.): refers to the species having cylindrical basidiospores.

Diagnosis: Differs from other Porogramme species by the big pores measuring 2–4 per mm, generative hyphae with both clamp connections and simple septa, non-dextrinoid skeletal hyphae, and the cylindrical basidiospores measuring 8–10 × 3.1–3.8 µm.

Type: China: Guangdong: Zhaoqing, Dinghushan Nature Reserve, N 23° 17′, E 112° 54′, on fallen branch of Schima, 28 April 2018, Y.C. Dai 18544A (BJFC027012—holotype).

Description: Basidiome annual, resupinate, inseparable, corky when fresh, corky to brittle when dry, to 5 cm long, 1.8 cm wide, and 0.8 mm thick at center; sterile margin thinning out, very narrow to almost lacking. Pore surface white when fresh, straw yellow when dry; pores angular, 2–4 per mm; dissepiments thin, entire to slightly lacerate. Subiculum white, corky, to 0.1 mm thick. Tubes concolorous with pore surface, corky, to 0.7 mm long. Hyphal system dimitic; generative hyphae with both clamp connections and simple septa; skeletal hyphae IKI–, CB + ; tissues unchanged in KOH. Subicular generative hyphae dominant, hyaline, thin-walled, occasionally branched, 2–3 µm diam; skeletal hyphae frequent, hyaline, thick-walled with a narrow to medium lumen, moderately branched, flexuous, interwoven, 2–3 µm diam. Tramal generative hyphae frequent, hyaline, thin-walled, occasionally branched, 1.5–2 µm diam; skeletal hyphae dominant, hyaline, thick-walled with a medium to wide lumen, moderately branched, flexuous, interwoven, 1.5–3 µm diam. Cystidia and cystidioles absent. Dendrohyphidia frequent at dissepiment edges. Hyphal pegs occasionally present at dissepiment edge. Basidia clavate, with four sterigmata and a basal clamp connection, 19–23 × 4.5–7 µm; basidioles in shape similar to basidia, but slightly smaller. Some irregular-shaped crystals frequently present among hymenium. Basidiospores cylindrical tapering at apiculus, hyaline, thin-walled, smooth, IKI–, CB–, (7.5–)8–10(–10.2) × (3–)3.1–3.8(–4.2) µm, L = 8.99 µm, W = 3.31 µm, Q = 2.72–2.75 (n = 60/2).

Additional specimens examined: China: Fujian: Fuzhou, Fuzhou National Forest Park, N 26° 16′, E 119° 29′, on fallen angiosperm branch, 4 June 2021, Y.C. Dai 22348 (BJFC036936). Guangdong: Zhaoqing, Dinghushan Nature Reserve, N 23° 17′, E 112° 54′, on fallen branch of Schima, 28 April 2018, Y.C. Dai 18526A (BJFC026994), 18529A (BJFC026997).

Porogramme yunnanensis Y.C. Dai, W.L. Mao & Yuan Yuan, sp. nov., (Figs. 7 and 8).

Fig. 7
figure 7

Basidiome of Porogramme yunnanensis (holotype). Bar = 1.0 cm

Fig. 8
figure 8

Microscopic structures of Porogramme yunnanensis (drawn from holotype). a. Basidiospores; b. Basidia; c. Basidioles; d. Cystidioles; e. Dendrohyphidia; f. Hyphae from subiculum; g. Hyphae from trama

MycoBank no.: MB 846850.

Etymology: Yunnanensis (Lat.): refers to the species being found in Yunnan, China.

Diagnosis: Porogramme yunnanensis is characterized by annual to biennial and resupinate basidiome, white pores when fresh, yellowish when dry, entire dissepiments, a monomitic hyphal system, tissues almost unchanged in KOH, the presence of fusiform cystidioles and abundant dendrohyphidia, ellipsoid to drop-shaped basidiospores measuring 3.7–5 × 2–2.6 µm.

Type: China: Yunnan: Pu'er, Laiyang River Forest Park, N 22° 78′, E 100° 97′, on fallen angiosperm trunk, 6 June 2011, Y.C. Dai 12222 (BJFC010505 – holotype).

Description: Basidiome annual to biennial, resupinate, inseparable, corky and without odor or taste when fresh, becoming hard corky upon drying, to 7 cm long, 3 cm wide, and 1.6 mm thick at center; sterile margin distinct, yellowish brown when fresh. Pore surface pure white when fresh, honey when dry; pores round to angular, 4–6 per mm; dissepiments thick, entire. Hymenium present at both the vertical tube-walls and the base of tubes. Subiculum pale buff, resinous, to 1 mm thick. Tubes concolorous with the pore surface, corky, to 0.6 mm long. Wood reddening under basidiome. Hyphal system monomitic; generative hyphae with clamp connections, CB + ; tissues unchanged in KOH. Subicular generative hyphae hyaline, thin-walled, moderately branched, interwoven, 1.5–2.5 µm diam. Tramal generative hyphae hyaline, thin-walled, frequently branched, interwoven, 1–2.5 µm diam. Dendrohyphidia present in hymenium. Cystidioles fusiform, thin-walled, smooth, 11–15 × 2.5–4 mm. Basidia clavate, with four sterigmata and a basal clamp connection, 13–16.0 × 4–5.5 µm; basidioles in shape similar to basidia, but smaller. Small tetrahedric or polyhedric crystals frequently present among hymenium. Basidiospores ellipsoid tapering to apiculus, hyaline, thin-walled, smooth, IKI–, CB–, (3.2–)3.7–5.0(–5.1) × (1.9–)2.0–2.6(–3.0) µm, L = 4.20 µm, W = 2.31 µm, Q = 1.82–1.85 (n = 60/2).

Additional specimens examined: China: Yunnan: Pu'er, Laiyang River Forest Park, N 22° 78′, E 100° 97′, on fallen angiosperm trunk, 6 June 2011, Y.C. Dai 12236 (BJFC010519), 12259 (BJFC010542), 12261 (BJFC010544).

The following eight taxa nested in the Porogramme clade, and their combinations are proposed:

Porogramme aurantiaca (A.M.S. Soares) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846848.

Basionym: Grammothele aurantiaca A.M.S. Soares, Fungal Divers. 96: 212 (2019).

Porogramme brasiliensis (Ryvarden) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846846.

Basionym: Grammothele brasiliensis Ryvarden, Syn. Fung. 33: 38 (2015); as 'brasilensis'.

Porogramme bubalina (H.S. Yuan) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846845.

Basionym: Tinctoporellus bubalinus H.S. Yuan, Mycol. Prog. 11: 949 (2012).

Porogramme epimiltina (Berk. & Broome) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846844.

Basionym: Polyporus epimiltinus Berk. & Broome, J. Linn. Soc., Bot. 14: 54 (1875).

Synonym: Tinctoporellus epimiltinus (Berk. & Broome) Ryvarden, Trans. Br. mycol. Soc. 73: 18 (1979).

Porogramme hinnulea (H.S. Yuan) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846843.

Basionym: Tinctoporellus hinnuleus H.S. Yuan, Mycol. Prog. 11: 950 (2012).

Porogramme micropora (A.M.S. Soares & W.K.S. Xavier) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846841.

Basionym: Grammothele micropora A.M.S. Soares & W.K.S. Xavier, Fungal Divers. 96: 212 (2019).

Porogramme subargentea (Speg.) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846840.

Basionym: Poria subargentea Speg., Revista Argent. Hist. Nat. 1: 104 (1891).

Synonym: Grammothele subargentea (Speg.) Rajchenb., Mycotaxon 17: 280 (1983).

Material examined: Brazil: Pernambuco: Recife, Charles Darwin Ecological Reserve, S 8° 40′, W 34° 52′, on fallen angiosperm trunk, 18 May 2017, Y.C. Dai 17445 (BJFC024976), 17460 (BJFC024991).

Remarks : Porogramme subargentea.

was originally described as Poria subargentea from South America (Spegazzini 1891). Then Rajchenberg (1983) combined it into Grammothele according to its dextrinoid skeletal hyphae, abundant dendrohyphidia and cylindric basidiospores. Afterwards, Reck and Silveira (2009) found its hymenium covers the vertical tube walls and the substrate with reddish zones. These features are similar to Porogramme epimiltina, but phylogenetically it is closer to P. cylindrica rather than P. epimiltina (Fig. 1).

Porogramme venezuelica (Ryvarden) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov.

MycoBank no.: MB 846839.

Basionym: Grammothele venezuelica Ryvarden, Syn. Fung. 33: 42 (2015).

Based on our study, Tinctoporellus merged in Porogramme, and some species previously addressed in Grammothele are combined in Porogramme. We definite Porogramme as following.

Basidiome resupinate. Hymenophore cream, bluish gray, reddish to almost black, irpicoid to poroid. Hymenium present at both the vertical tube-walls and the base of tubes or restricted to the base of tubes. Hyphal system monomitic or dimitic, generative hyphae with clamp connections or with both clamp connections and simple septa, hyphae dextrinoid or not. Cystidia absent. Dendrohyphidia present in most species. Basidiospores ellipsoid to cylindrical, thin-walled, IKI–, CB–. Ecology a white rot and reddening substrate in most species.

Cyanoporus Y.C. Dai, W.L. Mao & Yuan Yuan, gen. nov.

MycoBank no.: MB 846831.

Etymology: Cyanoporus (Lat.): refers to the genus having bluish pores.

Type: Cyanoporus fuligo (Berk. & Broome) Y.C. Dai, W.L. Mao & Yuan Yuan.

Description: Basidiome annual, resupinate, adnate, corky to coriaceous. Pore surface bluish gray to dark blue. Hyphal system dimitic; generative hyphae with clamp connections; skeletal hyphae IKI–, CB–. Hymenium restricted to the base of tubes. Basidiospores ellipsoid, hyaline, thin-walled, smooth, IKI–, CB–. Causing a white rot, usually growing on monocotyledons.

Cyanoporus fuligo (Berk. & Broome) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov., (Figs. 9 and 10).

Fig. 9
figure 9

Basidiome of Cyanoporus fuligo (Y.C. Dai 21936). Bar = 1.0 cm

Fig. 10
figure 10

Microscopic structures of Cyanoporus fuligo (Y.C. Dai 21936). a. Basidiospores; b. Basidia; c. Basidioles; d. Hyphae from trama

MycoBank no.: MB 846834.

Basionym: Polyporus fuligo Berk. & Broome, Bot. J. Linn. Soc. 14: 53 (1875).

Synonym: Grammothele fuligo (Berk. & Broome) Ryvarden, Trans. Br. mycol. Soc. 73: 15 (1979).

Description: Basidiome annual, resupinate, adnate, inseparable, leathery to corky when fresh, corky when dry; to 13 cm, 2.5 cm wide and 0.3 mm thick at center. Pore surface bright grayish blue when fresh, becoming dark blue upon drying; pores angular, 8–12 per mm; dissepiments thin, entire. Sterile margin thinning out, pale bluish gray, to 1 mm wide. Hymenium restricted to the base of tubes. Subiculum dark brown, hard corky, very thin, to 0.04 mm thick. Tubes hard corky, to 0.26 mm long, tube walls whitish under a lens, but trama dark brown. Hyphal system dimitic; generative hyphae with clamp connections; skeletal hyphae IKI–, CB–; tissues becoming pale olivaceous to dark brown in KOH. Subicular hyphae is similar to those in trama. Tramal generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1.5–2.5 μm diam; skeletal hyphae dominant, pale to dark brown, thick-walled with a narrow lumen to subsolid, occasionally branched, subparallel along the tubes to loosely interwoven, 1.5–3 μm diam. Cystidia and cystidioles absent. Dendrohyphidia not seen. Basidia clavate, with four large sterigmata and a basal clamp connection, 19–23 × 4–6 μm; basidioles in shape similar to basidia, but smaller. Some irregular-shaped crystals present among hymenium. Basidiospores ellipsoid, hyaline, thin-walled, smooth, IKI–, CB–, (4.2–)4.5–6(–6.8) × (2.3–)2.6–3.2(–3.5) μm, L = 5.15 μm, W = 2.91 μm, Q = 1.76–1.77 (n = 60/2).

Specimens examined: China: Hainan: Haikou, Jinniuling Park, N 20° 01′, E 110° 32′, on dead bamboo, 7 November 2020, Y.C. Dai 21936 (BJFC035835), 21937 (BJFC035836), 21950 (BJFC035848). Hunan: Yongzhou, Xiaoxiang Park, 26° 49′, E 111° 58′, on dead bamboo, 3 November 2019, Y.C. Dai 21117 (BJFC032777).

Cyanoporus camptogrammus (Pat.) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov., (Figs. 11 and 12).

Fig. 11
figure 11

Basidiome of Cyanoporus camptogrammus (Y.C. Dai 22099). Bar = 1.0 cm

Fig. 12
figure 12

Microscopic structures of Cyanoporus camptogrammus (Y.C. Dai 22099). a. Basidiospores; b. Basidia; c. Basidioles; d. A cystidiole; e. A dendrohyphidium; f. Agglutinated skeletal hyphae; g. Hyphae from trama

MycoBank no.: MB 846835.

Basionym: Porogramme camptogramma Pat., Bull. Soc. mycol. Fr. 29: 208 (1913).

Description: Basidiome annual, resupinate, adnate, inseparable, leathery to corky; to 13 cm, 8 cm wide and 0.2 mm thick at center. Pore surface grayish blue when fresh, darkening upon drying; pores angular, 5–8 per mm; dissepiments thin, entire. Sterile margin wide to narrow, white, to 1 mm wide. Hymenium restricted to the base of tubes. Subiculum dark brown, corky, very thin, to 0.05 mm thick. Tubes corky, to 0.15 mm long, tube walls bluish white under a lens, but trama dark brown. Hyphal system dimitic; generative hyphae with clamp connections; skeletal hyphae IKI–, CB–; tissues becoming olivaceous to dark in KOH. Subicular hyphae is similar to those in trama. Tramal generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 2–2.5 μm diam; skeletal hyphae dominant, as brown bundles of strongly agglutinated hyphae, thick-walled with a wide lumen, rarely branched, subparallel along the tubes to loosely interwoven, 2.5–4 μm diam. Cystidioles present. Dendrohyphidia present in hymenium. Basidia clavate, with four large sterigmata and a basal clamp connection, 18–21 × 4.5–6 μm; basidioles in shape similar to basidia, but smaller. Some irregular-shaped crystals present among hymenium. Basidiospores oblong ellipsoid to cylindrical, hyaline, thin-walled, smooth, IKI–, CB–, (6–)6.4–7.9(–8.2) × (2.5–)2.9–3.5(–4) μm, L = 7.17 μm, W = 3.17 μm, Q = 2.23–2.26 (n = 60/2).

Specimens examined: China: Guangdong: Zhanjiang, Campus of Guangdong Ocean University, N 40° 00′, E 116° 21′, on living tree of palm, 4 June 2019, Y.C. Dai 19693 (BJFC031369). Hainan: Haikou, Jinniuling Park, N 20° 01′, E 110° 32′, on dead palm, 7 November 2020, Y.C. Dai 21948 (BJFC035847); Sanya, Fairyland, N 18° 18′, E 109° 12′, on dead palm, 15 November 2020, Y.C. Dai 22099 (BJFC035991). Vietnam: Ho Chi Minh, Reunification Palace, N 10° 77′, E 106° 69′, on dead palm, 10 October 2017, Y.C. Dai 18296 (BJFC025818).

Pseudogrammothele Y.C. Dai, W.L. Mao & Yuan Yuan, gen. nov.

MycoBank no.: MB 846836.

Etymology: Pseudogrammothele (Lat.): refers to the genus resembling Grammothele.

Type: Pseudogrammothele separabillima (H.S. Yuan) Y.C. Dai, W.L. Mao & Yuan Yuan.

Description: Basidiome annual, resupinate, easily separate from the substrate, leathery when fresh soft corky when dry. Pore surface yellowish brown to pale luteous. Subiculum duplex with a distinct black line separating the two layers. Hymenium restricted to the base of tubes. Hyphal system dimitic; generative hyphae with clamp connections; skeletal hyphae IKI–, CB + . Basidiospores oblong ellipsoid, hyaline, thin-walled, smooth, usually with a large guttule, IKI–, CB + . Causing a white rot, growing on fallen angiosperm twig.

Pseudogrammothele separabillima (H.S. Yuan) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov. (Fig. 13).

Fig. 13
figure 13

Basidiome of Pseudogrammothele separabillima (Y.C. Dai 22599). Bar = 1.0 cm

MycoBank no.: MB 846837.

Basionym: Grammothele separabillima H.S. Yuan, Phytotaxa 213: 50 (2015).

Description: Basidiome annual, resupinate, resupinate, effused, often elongated along thin branches, easily separate from the substrate, leathery when fresh, soft corky when dry, Sterile margin white. Pore surface yellowish brown to pale luteous; pores distinct, entire, angular, 4–6 per mm; dissepiments thin, finely pruinose. Subiculum duplex, upper layer concolourous with pore surface, lower layer dark brown. Hymenium restricted to the base of tubes. Hyphal system dimitic; generative hyphae with clamp connections; skeletal hyphae IKI–, CB + . Dendrohyphidia present. Basidia clavate, bearing four sterigmata and a basal clamp connection, 23–31 × 8–12 μm; basidioles in shape similar to basidia, but slightly smaller. Basidiospores oblong ellipsoid, hyaline, thin-walled, smooth, usually with a large guttule, IKI–, CB + , 9.8–11.4 × 6.4–7.3 μm.

Specimens examined: China: Yunnan: Jinghong, Xishuangbanna Botanic Garden, N 22° 1′, E 100° 54′, on fallen angiosperm branch, 7 July 2021, Y.C. Dai 22599 (BJFC037173); Mengla County, Yulinggu Forest Park, N 21° 27′, E 101° 34′, on fallen angiosperm twig, 4 July 2021, Y.C. Dai 22568 (BJFC037142).

Grammothele duportii (Pat.) Y.C. Dai, W.L. Mao & Yuan Yuan, comb. nov. (Figs. 14 and 15).

Fig. 14
figure 14

Basidiome of Grammothele duportii (Y.C. Dai 21932). Bar = 1.0 cm

Fig. 15
figure 15

Microscopic structures of Grammothele duportii (Y.C. Dai 21932). a. Basidiospores; b. Basidia and basidioles; c. Cystidioles; d. Dendrohyphidia; e. A hyphal peg; f. Hyphae from subiculum; g. Hyphae from trama

MycoBank no.: MB 846838.

Basionym: Porogramme duportii Pat., Bull. Soc. mycol. Fr. 29: 208, 1913; as 'duporti'.

Description: Basidiome annual resupinate, adnate, corky to coriaceous, without special odor or taste when fresh, becoming hard corky and light in weight upon drying, to 9.5 cm long, 2.5 cm wide, and 1.4 mm thick at center; sterile margin narrow to almost lacking. Pore surface grayish white to sordid gray or violet gray; pores angular to irregular, 2–3 per mm; dissepiments thin, entire to lacerate. Hyphal pegs frequent, dotted-looking. Hymenium present at both the vertical tube-walls and the base of tubes. Subiculum buff, corky, becoming dark and resinous with age, to 0.6 mm thick. Tubes short, rigid corky when dry, to 0.8 mm long, under a lens the walls almost black, the bottom of tubes with white mycelia. Hyphal system dimitic; generative hyphae with clamp connections; skeletal hyphae IKI–, CB–; tissues darkening in KOH. Subicular generative hyphae infrequent, hyaline, thin-walled, rarely branched, flexuous, 2–2.5 µm diam; skeletal hyphae dominant, pale to dark brown, thick-walled with a narrow to medium lumen, frequently branched, strongly flexuous, interwoven, 2–3 µm diam. Tramal generative infrequent, hyaline, thin-walled, moderately branched, 1.5–2 µm diam; skeletal hyphae dominant, pale to dark brown, thick-walled with a narrow lumen to subsolid, frequently branched, mostly flexuous, interwoven, 1.5–3 µm diam. Dendrohyphidia frequently present, hyaline, thin-walled, moderately to strongly branched. Hyphal pegs often apically encrusted with large crystals, some hyphal pegs projected from tube trama or submerged in trama. Cystidia absent, two kinds of cystidioles present, one fusoid, slightly smaller than the basidioles, another hyphal-like, occurring in the hymenium, simulating narrow and cylindrical cystidioles. Basidia clavate, with four sterigmata and a basal clamp connection, 18–24 × 4–7 µm; basidioles dominant, in shape similar to basidia, but smaller. Big rhomboid or polyhedric crystals frequently present among hymenium. Basidiospores oblong ellipsoid tapering at apiculus, hyaline, thin-walled, smooth, IKI–, CB–, (5.2–)5.3–7(–7.2) × (2–)2.1–2.9(–3) µm, L = 6.03 µm, W = 2.48 µm, Q = 2.43–2.45(n = 60/2).

Specimens examined: China: Hainan: Changjiang County, Bawangling Nature Reserve, N 19° 05′, E 109° 05′, on fallen angiosperm trunk, 10 May 2009, B.K. Cui 6539 (BJFC004392); Haikou, Jinniuling Park, N 20° 01′, E 110° 32′, on fallen angiosperm branch, 7 November 2020, Y.C. Dai 21932 (BJFC035831). Singapore: Bukit Timah Nature Reserve, N 1° 35′, E 103° 77′, on fallen angiosperm trunk, 19 July 2017, Y.C. Dai 17821 (BJFC025353); on rotten wood, 20 July 2017, Y.C. Dai 17878 (BJFC025410).

Discussion

Our phylogeny confirmed the close relationship among Porogramme, Grammothele, Epithele, Theleporus, and Tinctoporellus (Fig. 1), and six clades were formed. The clade A is named as Porogramme clade, and the type species of Porogramme (P. albocincta) and Tinctoporellus (T. epimiltinus) nested in the clade. Porogramme (1900) is an earlier name than Tinctoporellus (1979) and has a priority, so, we merge Tinctoporellus into Porogramme. The clade B is named as Cyanoporus clade. Species growing on monocotyledons (palm, bamboo etc.) are included in this clade. Although Cyanoporus fuligo was treated as Grammothele fuligo and Porogramme fuligo, but our phylogeny shows Cyanoporus forms an independent clade closely related to Porogramme, Grammothele, Epithele, and Theleporus. So, the genus Cyanoporus is proposed to accommodate Cyanoporus fuligo and related taxa. The clade C is named as Grammothele clade, and its type species, G. lineata, is included in the clade. The clade D is named as Epithele clade, most species with DNA data in Epithele are included in the clade, including the type species Epithele typhae. The clade E is named as Theleporus clade, most species in Theleporus are included in the clade although DNA data of its type species, T. cretaceus, are unavailable. The clade F is named as Pseudogrammothele clade, the single species Pseudogrammothele separabillima was originally described in Grammothele due to its anatomical characteristics fit the definition of the genus (resupinate basidiome with brownish pore surface, a dimitic hyphal system with hyaline to yellowish skeletal hyphae and the presence of dendrohyphidia, Yuan 2015). However, easily separating from the substrate, the distinct pores, duplex subiculum and large and cyanophilous basidiospores with guttules indicate the difference from Epithele, Grammothele, Porogramme, and Theleporus (Nakasone 2013; Yuan 2015). Moreover, the divergence time estimation shows P. separabillima diverged at 79.1 Mya and evolved from the same ancester with Polyporus squamosus. Thus, the genus Pseudogrammothele, is proposed to accommodate Pseudogrammothele separabillima.

Recent molecular phylogenies demonstrated that hymenophore is not a key feature for separation of genera, and species with corticioid and poroid hymenophore are nested in the same genus, for instance, Antrodia (Runnel et al. 2019) and Hymenochaete (He and Dai 2012). Our phylogeny on Porogramme, Tinctoporellus, Grammothele, and Theleporus reveals the similar conclusion, the corticioid genus Porogramme and poroid genus Tinctoporellus nested in the same clade.

Phylogenetically, Porogramme austroasiana formed an independent lineage (Fig. 1). Morphologically, Porogramme austroasiana resembles Grammothele lacticolor Ryvarden by sharing resupinate basidiome with poroid hymenophore, approximately the same-sized pores and basidiospores (2–5 per mm, 3.8–4.5 × 2.1–2.5 µm vs. 3–4 per mm, 3–4 × 2–2.5 µm). However, G. lacticolor differs from P. austroasiana by the presence of hyphal pegs, reddening substrate, weakly dextrinoid skeletal hyphae, and distributed in central America (Ryvarden 2015).

Morphologically, Porogramme cylindrica may be confused with P. austroasiana and P. bubalina in having approximately the same pores size (2–5 per mm). However, the latter two species have distinctly smaller basidiospores (3.8–4.5 × 2.1–2.5 µm in P. austroasiana, 4.7–5.4 × 2.8–3.3 µm in P. bubalina vs. 8–10 × 3.1–3.8 µm in P. cylindrica, Yuan and Wan 2012). Porogramme yunnanensis is similar to P. hinnulea in having the same-sized pores (4–6 per mm), the presence of dendrohyphidia and ellipsoid basidiospores, but the latter has a dimitic hyphal system and wider basidiospores (4.5–5.2 × 2.5–3 µm vs. 3.7–5.0 × 2.0–2.6 µm, Yuan and Wan 2012).

Phylogenetically, Porogramme cylindrica is closely related to P. yunnanensis (Fig. 1), but the former has a dimitic hyphal structure and the absence of cystidioles, while the latter has a monomitic hyphal system and the presence of fusoid cystidioles.

Phylogenetically, Porogramme subargentea formed an independent lineage (Fig. 1) with a robust support (100% ML and 1.00 BPP). Morphologically, P. subargentea share similar cylindric basidiospores with P. cylindrica, but the latter species has non-dextrinoid skeletal hyphae and longer basidiospores (8–10 × 3.1–3.8 vs. 5.2–8.3 × 2.6–3.1 µm, Rajchenberg 1983).

In our phylogeny, a sample of Porogramme albocincta (FP102875sp) from Puerto Rico formed an independent lineage with Porogramme micropora (WX2014-116) from Brazil with a relatively high support (88% ML). Although the voucher specimen of Porogramme albocincta (FP102875sp) was not examined morphologically, P. micropora may be confused with P. albocincta due to the dark bluish gray basidiome and very small pores (8–20 per mm) according to Ryvarden (1979) and Hyde et al. (2019), we treated P. albocincta (FP102875sp) as ‘P. micropora’ based on our phylogeny.

Cyanoporus fuligo was originally described from Sri Lanka on dead palm, and Ryvarden has a general description of the species (Ryvarden 1979). According to our study it seems to be a species complex, and two species are existed, samples (Dai 21117, 21936, 21937, 21950) with small pores formed an independent lineage with a robust support (100% ML and 1.00 BPP), and samples with relatively big pores (Dai 19693, 21948, 22099, 22117) formed another independent lineage with a robust support (100% ML and 1.00 BPP). The pores in the former lineage are 8–12 per mm which are almost invisible to the naked eye, so, it fits the original description of Polyporus fuligo: “pores quite invisible to the naked eye, so that it looks like a Corticium”. Therefore, samples of Dai 21117, 21936, 21937 and 21950 are treated as Cyanoporus fuligo.

Six taxa were treated as synonyms of Cyanoporus fuligo (Ryvarden and Johansen 1980, MycoBank: https://www.mycobank.org/page/Simple%20names%20search; Index Fungorum: http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=314701). Among them, Porogramme camptogramma Pat. was described on bamboo from northern Vietnam (Patouillard 1913). Its original description as “pores about 6 per mm, spore oblong to oblong ellipsoid, 5.5–8 × 2.5–3.5 µm”. In our study, samples of Dai 18296, 19693, 21948, 22099, 22117 from tropical China and Vietnam have pores of 5–8 per mm and basidiospores of 6.4–7.9 × 2.9–3.5 µm. These important features fit Porogramme camptogramma well. So, we treated these samples as Cyanoporus camptogramma.

Grammothele lineata was originally described from Cuba (Berkeley and Curtis 1869), and Ryvarden and Johansen (1980) give a general description of the species. According to our study, it seems to be a species complex, and three species are existed and formed three independent lineages (Fig. 1): G. lineata sensu stricto from tropical America (samples Dai 18485 and WX2014-208 from Brazil, molecular data from its type locality are unavailable so far), G. denticulata Y.C. Dai & L.W. Zhou from China (Zhou and Dai 2012) and a taxon represented by Southeast Asian samples of Cui 6539, Dai 17821 and 21932.

Nine taxa were treated as synonyms of Grammothele lineata (Ryvarden and Johansen 1980, MycoBank: https://www.mycobank.org/page/Simple%20names%20search; Index Fungorum: http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=168936), among them, Porogramme duportii was described from northern Vietnam (Patouillard1913). Its original description as “pores chalk white with grayish reflection, about 0.25 mm thick, subhymenial white, pores diameter 200–250 µm (dissepiments not included), hyphal pegs present in tube walls”. Our Asian samples of Cui 6539, Dai 17821 and 21932 fit P. duportii well, so, we combined this taxon as Grammothele duportii. G. duportii are very similar to G. lineata, and the Chinese samples were treated as the latter previously (Dai et al. 2011), but differs from G. lineata by the slightly wider basidiospores (5.3–7 × 2.1–2.9 µm vs. 4.5–6 × 1.5–2.5 µm, Ryvarden and Johansen 1980) and the presence of two kinds of cystidioles.

In addition, three new combinations Porogramme brasiliensis, P. micropora, and P. venezuelica are proposed based on phylogenetic analysis only, because we did not study their voucher materials (Fig. 1). Porogramme aurantiaca, another new combination from tropical America (samples Dai 17401 and WX2014-115), has reddish zones beneath basidiome which matches the morphological characteristics of Porogramme.

According to our phylogeny, the genus Epithele formed an independent clade with a robust support (100% ML and 1.00 BPP), and another related genus Theleporus, a few known species in the genus with molecular sequences formed an independent clade related to Porogramme, Grammothele, and Epithele with a relatively low support (51% ML). However, its type species, Theleporus cretaceus from South Africa (Fries 1849), is not analyzed because its DNA data are not available so far. To confirm its affinity, more samples, especially material of T. cretaceus from type locality is badly needed. Moreover, the two genera,Theleporus, and Epithele, occurred in a mean stem age of 79.2 Mya and 72.9 Mya, respectively, the estimation results are in accord with the results carried out by Ji et al. (2022) that the mean stem ages of the six major clades of Polyporus are approximately 47–60 Mya (Fig. 2).

Recently, dating analyses have provided a deep insight into the evolution of Polyporales (Song and Cui 2017; Zhao et al. 2017; Ji et al. 2022). Our analysis of divergence time estimation suggests that Polyporales occurred in a mean stem age of 187.6 Mya and Polyporaceae of which species mostly growing on the angiosperm woods possibly emerged in a mean stem age of 152.9 Mya (Fig. 2). Moreover, species preferring to grow on gymnosperm woods in Polyporales emerged in an earlier mean stem age of 164.6 Mya. Considering many botanists confirmed the crown age for the angiosperms was at least 160 Mya, our divergence time estimation of the six clades of Porogramme and related genera corresponded with the previous study (Ji et al. 2022) that the mean stem ages of six major clades of Polyporus are approximately 47–60 Mya, the mean stem ages of the six genera we recognize all earlier than 50 Mya (Fig. 2), thus, it is reasonable to recognize the six clades (Porogramme, Grammothele, Cyanoporus, Epithele, Theleporus, and Pseudogrammothele) as independent genera.

Conclusion

Six clades represent Porogramme, Grammothele, Cyanoporus, Epithele, Theleporus, and Pseudogrammothele are recognized based on phylogenetic analysis and morphological examination on samples from tropical or subtropical Asia and America (Fig. 1), among them Cyanoporus and Pseudogrammothele are proposed as new genera. Tinctoporellus is merged into Porogramme because the type species of both genera are nested in the same clade. Three new species of Porogramme are described and illustrated, and the definition of the genus is revised. Twelve new combinations in Cyanoporus, Grammothele, Porogramme, and Pseudogrammothele are proposed. The molecular clock analyses also support the six clades as independent genera due to the mean stem ages of the six genera we recognize all earlier than 50 Mya (Fig. 2).

Based on morphological and phylogenetic analyses on Porogramme, Grammothele, Cyanoporus, Epithele, Theleporus, and Pseudogrammothele, their phylogenetic relationships and general morphological characteristics are outlined. In our phylogeny, the six genera belong to Polyporales and being closely related with each other (Fig. 1). Among them, Cyanoporus, proposed as a new genus, is characterized by its bluish pores, hymenium restricted to the base of tubes, rarely branched and subparallel skeletal hyphae along tubes and usually growing on monocotyledons. Another new genus, Pseudogrammothele, characterized by its basidiome is easily separated from the substrate, distinct pores, duplex subiculum and large and cyanophilous basidiospores with guttules, so, differs it from Epithele, Grammothele, Porogramme, and Theleporus. Epithele and Theleporus are similar by sharing hymenia restricted to the base of tubes, while Epithele is distinguished by its basically smooth hymenophore, hyphal pegs composed of trama hyphae and usually thick-walled basidiospores. Hyphal pegs are also common in most species of Grammothele, while Grammothele has more or less poroid hymenophore and thin-walled basidiospores. Upon the recombination of Tinctoporellus, Porogramme and several species traditionally belong to Grammothele, Porogramme is characterized by hymenium present at both the vertical tube-walls and the base of tubes or restricted to the base of tubes, a monomitic or dimitic hyphal system, generative hyphae with clamp connections or with both clamp connections and simple septa, hyphae dextrinoid or not and reddening substrate in most species.

Availability of data and materials

All sequence data generated for this study can be accessed via GenBank: https://www.ncbi.nlm.nih.gov/genbank/. Alignments are available at TreeBase (http://www.treebase.org; submission ID: 29977).

Abbreviations

BI:

Bayesian inference

BJFC:

Herbaria of the Institute of Microbiology, Beijing Forestry University

BPP:

Bayesian posterior probability

BS:

Bootstrap

CB:

Cotton blue

GTR + I + G:

General time reversible + proportion invariant + gamma

IKI:

Melzer’s reagent

ITS:

Nuclear ribosomal internal transcribed spacer

KOH:

5% Potassium hydroxide

MCC:

Maximum clade credibility

ML:

Maximum likelihood

Mya:

Million years ago

PCR:

Polymerase chain reaction

RPB1:

Largest subunit of RNA polymerase II

RPB2:

Second largest subunit of RNA polymerase II

TEF1:

Translation elongation factor 1-α

References

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Acknowledgements

We are grateful to Miss Xing Ji, Hong-Min Zhou and Mr. Heng Zhao (Beijing Forestry University) for providing sequences and assisting the molecular clock analysis.

Funding

The research is supported by National Natural Science Foundation of China (Project Nos. U1802231, 32000010).

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Design of the research: Y-CD, YY and W-LM; performance of the research: W-LM and Y-DW; data analysis and interpretation: W-LM, Y-DW, Y-CD and YY; collect the materials: Y-CD, Y-DW and H-GL; writing and revising the manuscript: W-LM, Y-DW, H-GL, Y-CD and YY. All authors have read and agreed to the published version of the manuscript.

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Correspondence to Yuan Yuan or Yu-Cheng Dai.

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Mao, WL., Wu, YD., Liu, HG. et al. A contribution to Porogramme (Polyporaceae, Agaricomycetes) and related genera. IMA Fungus 14, 5 (2023). https://doi.org/10.1186/s43008-023-00110-z

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Keywords

  • Polyporaceae
  • Phylogeny
  • Taxonomy
  • Wood-rotting fungi
  • Five new taxa