The examined specimens were deposited at the herbarium of the Institute of Microbiology, Beijing Forestry University (BJFC), and some duplicates were deposited at the Institute of Applied Ecology, Chinese Academy of Sciences, China (IFP). Morphological descriptions and abbreviations used in this study followed Cui et al. (2019) and Shen et al. (2019).

The procedures for DNA extraction and polymerase chain reaction (PCR) used in this study were the same as described by Han et al. (2016) and Liu et al. (2019, 2022). The ITS regions were amplified with the primer pairs ITS4 and ITS5, the nLSU regions were amplified with the primer pairs LR0R and LR7, the nSSU regions were amplified with the primer pairs NS1 and NS4, the mtSSU regions were amplified with the primer pairs MS1 and MS2, the RPB2 gene was amplified with the primer pairs fRPB2-f5F and bRPB2-7.1R, and the TEF gene was amplified with the primer pairs EF1-983F and EF1-1567R (White et al., 1990; Matheny, 2005; Rehner and Buckley, 2005).

The PCR cycling schedules for different DNA sequences of ITS, nLSU, nSSU, mtSSU, RPB2, and TEF genes used in this study followed those used in Liu et al. (2019); Shen et al. (2019), Zhu et al. (2019), and Ji et al. (2022) with some modifications. The PCR products were purified and sequenced at Beijing Genomics Institute, China, with the same primers. All newly generated sequences were submitted to GenBank and are listed in Table 1.

Sequences were aligned with additional sequences downloaded from GenBank (Table 1) using BioEdit (Hall, 1999) and ClustalX (Thompson et al., 1997). Alignment was manually adjusted to allow maximum alignment and to minimize gaps. Sequence alignment was deposited at TreeBase (submission ID 29193).¹ The sequences of Laetiporus sulphureus (Bull.) Murrill and L. zonatus B.K. Cui & J. Song, obtained from GenBank, were used as outgroups for the phylogenetic analyses of Fomitopsis.

Phylogenetic analyses approaches used in this study followed Sun et al. (2020) and Liu et al. (2021b). The congruences of the 6-genes (ITS, nLSU, nSSU, mtSSU, RPB2, and TEF) were evaluated with the incongruence length difference (ILD) test (Farris et al., 1994) implemented in PAUP* 4.0b10 (Swofford, 2002), under heuristic search and 1,000 homogeneity replicates. Maximum parsimony (MP) analysis was performed in PAUP* version 4.0b10 (Swofford, 2002). Clade robustness was assessed using a bootstrap (BT) analysis with 1,000 replicates (Felsenstein, 1985). Descriptive tree statistics tree length (TL), consistency index (CI), retention index (RI), rescaled consistency index (RC), and homoplasy index (HI) were calculated for each Most Parsimonious Tree (MPT) generated. Maximum Likelihood (ML) analysis was performed in RAxmL v.7.2.8 with a GTR + G + I model (Stamatakis, 2006). Bayesian inference (BI) was calculated by MrBayes 3.1.2 (Ronquist and Huelsenbeck, 2003) with a general time reversible (GTR) model of DNA substitution and a gamma distribution rate variation across sites determined by MrModeltest 2.3 (Posada and Crandall, 1998; Nylander, 2004). The branch support was evaluated with a bootstrapping method of 1,000 replicates (Hillis and Bull, 1993).

Branches that received bootstrap supports for MP, ML greater than or equal to 75%, and Bayesian posterior probabilities (BPP) greater than or equal to 0.95 were considered as significantly supported. The phylogenetic tree was visualized using FigTree v1.4.2.²

The combined 6-gene sequences dataset for phylogenetic analyses had an aligned length of 4,626 characters including gaps (610 characters for ITS, 1,346 characters for nLSU, 526 characters for mtSSU, 1,009 characters for nSSU, 648 characters for RPB2, 487 characters for TEF), of which 3,113 characters were constant, 240 were variable and parsimony-uninformative, and 1,273 were parsimony-informative. MP analysis yielded 12 equally parsimonious trees (TL = 6,756, CI = 0.366, RI = 0.722, RC = 0.264, HI = 0.634). The best model for the concatenate sequence dataset estimated and applied in the Bayesian inference was GTR + I + G with equal frequency of nucleotides, lset nst = 6 rates = invgamma; prset statefreqpr = dirichlet (1,1,1,1). Bayesian analysis resulted in a concordant topology with an average standard deviation of split frequencies = 0.008762. ML analysis resulted in a similar topology as MP and Bayesian analyses, and only the ML topology is shown in Figure 1. The phylogenetic trees inferred from ITS + nLSU + nSSU + mtSSU + RPB2 + TEF gene sequences were obtained from 103 fungal samples representing 65 taxa of Fomitopsis and its related genera within the antrodia clade. Also, 64 samples representing 30 taxa of Fomitopsis clustered together and separated from other genera.

Fomitopsis resupinata B.K. Cui & Shun Liu, sp. nov. (Figures 2A, 3).

MycoBank: MB 842873.

Diagnosis — Fomitopsis resupinata is characterized by its resupinate basidiomata with cream to buff pore surface when fresh, becoming pinkish buff to honey-yellow upon drying and cylindrical to slightly allantoid basidiospores (7.2–9 × 2.7–3.3 μm).

Holotype — CHINA. Hainan Province, Changjiang County, Bawangling Nature Reserve, on fallen trunk of Mangifera infica, 9 May 2009, Dai 10819 (BJFC 010395).

Etymology — “resupinata” (Lat.): refers to the resupinate basidiomata.

Fruiting body — Basidiomata annual, resupinate, not easily separated from substrate, without odor or taste when fresh, becoming corky and light in weight upon drying; up to 9 cm long, 8.4 cm wide, and 8 mm thick at center. Pore surface cream to buff when fresh, becoming pinkish buff to honey-yellow upon drying; pores round to angular, 4–6 per mm; dissepiments slightly thick, entire. Context very thin, corky, cream to buff, up to 3 mm thick. Tubes concolorous with pore surface, corky, up to 5 mm long. Tissues unchanged in KOH.

Hyphal structure — Hyphal system dimitic; generative hyphae bearing clamp connections; skeletal hyphae IKI–, CB–.

Context — Generative hyphae infrequent, hyaline, thin-walled, rarely branched, 2–3.4 μm in diam; skeletal hyphae dominant, yellowish brown to cinnamon brown, thick-walled with a narrow lumen to subsolid, unbranched, straight, interwoven, 3.2–5.5 μm in diam.

Tubes — Generative hyphae infrequent, hyaline, thin-walled, rarely branched, 1.9–3 μm in diam; skeletal hyphae dominant, yellowish brown to cinnamon brown, thick-walled with a wide to narrow lumen, unbranched, more or less straight, interwoven, 2–5 μm in diam. Cystidia absent; cystidioles occasionally present, fusoid, hyaline, thin-walled, 13.2–22 × 3.2–4.3 μm. Basidia clavate, bearing four sterigmata and a basal clamp connection, 13.5–17.4 × 4.8–6.2 μm; basidioles dominant, similar to basidia but smaller.

Spores — Basidiospores cylindrical to slightly allantoid, hyaline, thin-walled, smooth, IKI–, CB–, (7–)7.2–9(–9.5) × (2.6–)2.7–3.3(–3.5) μm, L = 8.14 μm, W = 2.93 μm, Q = 2.46–3.52 (n = 60/2).

Type of rot — Brown rot.

Notes — Phylogenetically, Fomitopsis resupinata was closely related to F. durescens (Overh. ex J. Lowe) Gilb. & Ryvarden, F. nivosa and F. ostreiformis (Berk.) T. Hatt (Figure 1). They share similar sized pores, but F. durescens differs in its pileate basidiomata with a white to cream pore surface when fresh, ochraceous when dry, smaller and narrower cylindrical basidiospores (6–8 × 1.5–2.5 μm; Gilbertson and Ryvarden, 1986); F. nivosa differs by having pileate basidiomata with a cream to pale sordid brown or tan pore surface, and has a distribution in Asia, North America, and South America (Núñez and Ryvarden, 2001; Han et al., 2016); F. ostreiformis differs in its effused reflexed to pileate basidiomata, soft when fresh, hard when dry, a trimitic hyphal system, smaller and cylindrical basidiospores (4.2–5.6 × 1.4–2.6 μm; De, 1981). Fomitopsis bambusae Y.C. Dai, Meng Zhou & Yuan Yuan and F. cana B.K. Cui, Hai J. Li & M.L. Han also distribute in Hainan Province of China, but F. bambusae differs by having bluish-gray to pale mouse-gray pore surface when fresh, becoming mouse-gray to dark gray when dry, smaller pores (6–9 per mm), smaller and cylindrical to oblong ellipsoid basidiospores (4.2–6.1 × 2–2.3 μm), and grows on bamboo (Zhou et al., 2021); F. cana differs by having cream to straw colored pore surface when young which becoming mouse-gray to dark gray with age, a trimitic hyphal system, smaller and cylindrical to oblong-ellipsoid basidiospores (5–6.2 × 2.1–3 μm; Li et al., 2013).

Additional specimen (paratype) examined — CHINA. Hainan Province, Wanning County, on fallen angiosperm trunk, 14 May 2009, Cui 6697 (BJFC 004551).

Fomitopsis srilankensis B.K. Cui & Shun Liu, sp. nov. (Figures 2B,C, 4).

MycoBank: MB 842874.

Diagnosis — Fomitopsis srilankensis is characterized by its resupinate to effused-reflexed or pileate basidiomata with pale mouse-gray to honey-yellow pileal surface when dry, buff to cinnamon-buff pore surface when dry, and cylindrical basidiospores (5.5–6.6 × 1.9–2.5 μm).

Holotype — Sri Lanka. Wadduwa, South Bolgoda Lake, on angiosperm stump, February 28, 2018, Dai 19539 (BJFC 031218).

Etymology — “srilankensis” (Lat.): refers to the species occurrence in Sri Lanka.

Fruiting body — Basidiomata annual, resupinate to effused-reflexed or pileate, without odor or taste, becoming corky and light in weight upon drying. Pilei applanate, semicircular to elongated, projecting up to 2.5 cm, 1.3 cm wide, and 7 mm thick at base; resupinate part up to 8.6 cm long, 2.8 cm wide and 1.8 mm thick at center. Pileal surface pale mouse-gray to honey-yellow when dry, glabrous, sulcate, azonate; margin obtuse, concolorous with the pileal surface. Pore surface buff to cinnamon-buff when dry; pores round to angular, 5–8 per mm; dissepiments thick, entire. Context cream to pinkish buff, corky, up to 4 mm thick. Tubes concolorous with pore surface, corky, up to 3 mm long. Tissues unchanged in KOH.

Hyphal structure — Hyphal system dimitic; generative hyphae bearing clamp connections; skeletal hyphae IKI–, CB–.

Context — Generative hyphae infrequent, hyaline, thin-walled, rarely branched, 2–3.4 μm in diam; skeletal hyphae dominant, yellowish brown to cinnamon brown, thick-walled with a wide to narrow lumen, occasionally branched, more or less straight, interwoven, 2.4–5.8 μm in diam.

Tubes — Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1.9–3 μm in diam; skeletal hyphae dominant, yellowish brown to cinnamon brown, thick-walled with a wide to narrow lumen, occasionally branched, more or less straight, interwoven, 2–5 μm in diam. Cystidia absent; cystidioles occasionally present, fusoid, hyaline, thin-walled, 10.5–15.5 × 2.4–3.2 μm. Basidia clavate, bearing four sterigmata and a basal clamp connection, 8.9–15.8 × 4.8–6.2 μm; basidioles dominant, similar to basidia but smaller.

Spores — Basidiospores cylindrical, hyaline, thin-walled, smooth, IKI–, CB–, (5.3–)5.5–6.6(–6.7) × (1.7–)1.9–2.5 μm, L = 6.11 μm, W = 2.16 μm, Q = 2.52–2.96 (n = 60/2).

Type of rot — Brown rot.

Notes — In the phylogenetic tree, Fomitopsis srilankensis grouped together with F. cana, F. meliae (Underw.) Gilb. and F. submeliae (Figure 1). Morphologically, they share similar sized pores, but F. cana differs in having pale mouse-gray to dark gray pileal surface, cream to straw colored pore surface when young and turning mouse-gray to dark gray with age, a trimitic hyphal system and wider basidiospores (5–6.2 × 2.1–3 μm; Li et al., 2013); F. meliae differs in having pileate basidiomata, glabrous to minutely tomentose pileal surface, ochraceous pore surface and larger basidiospores (6–8 × 2.5–3 μm; Gilbertson, 1981; Núñez and Ryvarden, 2001); F. submeliae differs from F. srilankensis by its cream pileal surface when fresh, becoming buff to buff yellow when dry, cream to pinkish buff pore surface when fresh, becoming cream to clay-buff when dry and smaller basidiospores (4–5 × 1.9–2.4 μm).

Additional specimen (paratype) examined — Sri Lanka. Wadduwa, South Bolgoda Lake, on fallen angiosperm trunk, February 28, 2018, Dai 19528 (BJFC 031207).

Fomitopsis submeliae B.K. Cui & Shun Liu, sp. nov. (Figures 2D, 5).

MycoBank: MB 842875.

Diagnosis — Fomitopsis submeliae is characterized by its effused-reflexed basidiomata with several small imbricate pilei protruding from a large resupinate part, pale mouse-gray to grayish brown pileal surface when dry, cream to clay-buff pore surface when dry, and cylindrical to oblong-ellipsoid basidiospores (4–5 × 1.9–2.4 μm).

Holotype — MALAYSIA. Kuala Lumpur, Forest Eco-Park, on fallen angiosperm trunk, 14 April 2018, Dai 18559 (BJFC 026848).

Etymology — “submeliae” (Lat.): refers to the new species resembling Fomitopsis meliae in morphology.

Fruiting body — Basidiomata annual, effused-reflexed with several small imbricate pilei protruding from a large resupinate part, inseparable from the substrate, corky, without odor or taste when fresh, corky to fragile and light in weight when dry. Single pileus up to 2 cm, 3.8 cm wide, and 6 mm thick at base; resupinate part up to 12 cm long, 4.5 cm wide, and 2.4 mm thick at center. Pileal surface cream when fresh, becoming buff to buff yellow when dry, rough, azonate; margin cream to buff, acute, incurved. Pore surface cream to pinkish buff when fresh, becoming cream to clay-buff when dry; pores round to angular, 4–7 per mm; dissepiments thick, entire to slightly lacerate. Context cream to buff, corky, up to 4 mm thick. Tubes concolorous with pore surface, corky to fragile, up to 2 mm long. Tissues unchanged in KOH.

Hyphal structure — Hyphal system dimitic; generative hyphae bearing clamp connections; skeletal hyphae IKI–, CB–.

Context — Generative hyphae infrequent, hyaline, thin-walled, rarely branched, 2–3.5 μm in diam; skeletal hyphae dominant, hyaline to pale yellowish, thick-walled with a wide to narrow lumen, rarely branched, more or less straight, interwoven, 2.6–6.4 μm in diam.

Tubes — Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1.8–3 μm in diam; skeletal hyphae dominant, hyaline, thick-walled with a wide to narrow lumen, rarely branched, more or less straight, interwoven, 2–5 μm in diam. Cystidia absent; cystidioles occasionally present, fusoid, hyaline, thin-walled, 14.5–18 × 3.2–5 μm. Basidia clavate, bearing four sterigmata and a basal clamp connection, 15.8–21.5 × 4.8–6.5 μm; basidioles dominant, similar to basidia but smaller.

Spores — Basidiospores cylindrical to oblong-ellipsoid, hyaline, thin-walled, smooth, IKI–, CB–, (3.8–)4–5(–5.2) × 1.9–2.4(–2.6) μm, L = 4.49 μm, W = 2.11 μm, Q = 1.92–2.42 (n = 90/3).

Type of rot — Brown rot.

Notes — Five samples of Fomitopsis submeliae from China, Malaysia, and Vietnam formed a highly supported subgroup (99% ML, 100% MP, 1.00 BPP), and then grouped with F. cana, F. meliae and F. srilankensis (Figure 1). Morphologically, F. cana differs by having effused-reflexed and grayish basidiomata, pale mouse-gray to dark gray pileal surface, a trimitic hyphal system and larger basidiospores (5–6.2 × 2.1–3 μm; Li et al., 2013); F. meliae differs in having pileate basidiomata with an ochraceous pore surface and larger basidiospores (6–8 × 2.5–3 μm; Gilbertson, 1981; Núñez and Ryvarden, 2001); F. srilankensis differs in its pale mouse-gray to honey-yellow pileal surface, buff to cinnamon-buff pore surface when dry and larger basidiospores (5.5–6.6 × 1.9–2.5 μm). Fomitopsis subtropica B.K. Cui & Hai J. Li also distributes in China, Malaysia, and Vietnam, but F. subtropica differs from F. submeliae by having smaller pores (6–9 per mm) and smaller basidiospores (3.2–4 × 1.8–2.1 μm), a trimitic hyphal system (Li et al., 2013); in addition, it is distant from F. submeliae in the phylogenetic analyses (Figure 1).

Additional specimens (paratypes) examined — CHINA. Hainan Province, Baoting County, Tropical Garden, on fallen angiosperm trunk, May 27, 2008, Dai 9719 (IFP 007971); Qiongzhong County, Limushan Forest Park, on fallen angiosperm trunk, 24 May 2008, Dai 9544 (BJFC 007830); on rotten angiosperm wood, May 24, 2008, Dai 9535 (BJFC 010339); Dai 9543 (BJFC 010338); on angiosperm wood, May 24, 2008, Dai 9525 (BJFC 007818). VIETNAM. Hochiminh, Botanic Garden, on angiosperm stump, October 12, 2017, Dai 18324 (BJFC 025847).

Fomitopsis yimengensis B.K. Cui & Shun Liu, sp. nov. (Figures 2E,F, 6).

MycoBank: MB 842876.

Diagnosis — Fomitopsis yimengensis is characterized by its pileate, solitary or imbricate basidiomata with pinkish buff, clay-buff to grayish-brown pileal surface, cream to pale cinnamon pore surface, thin-walled to slightly thick-walled generative hyphae in context, cylindrical basidiospores (6–7.2 × 2–3 μm).

Holotype — CHINA. Shandong Province, Mengyin County, on stump of Pinus sp., July 28, 2007, Cui 5027 (BJFC 003068).

Etymology — “yimengensis” (Lat.): refers to the species distributed in Yimeng Mountains.

Basidiomata — Basidiomata annual, pileate, solitary or imbricate, without odor or taste when fresh, becoming hard corky and light in weight when dry. Pilei semicircular to flabelliform, projecting up to 2.8 cm long, 5.7 cm wide, and 1.7 cm thick at base. Pileal surface pinkish buff, clay-buff to grayish-brown, glabrous or with irregular warts, azonate; margin obtuse, cream to honey-yellow. Pore surface cream to pale cinnamon; pores round, 4–6 per mm; dissepiments thick, entire. Context cream to buff-yellow, corky, up to 1.2 cm thick. Tubes concolorous with pore surface, hard corky, up to 5 mm long. Tissues unchanged in KOH.

Hyphal structure — Hyphal system dimitic; generative hyphae bearing clamp connections; skeletal hyphae IKI–, CB–.

Context — Generative hyphae infrequent, hyaline, thin-walled to slightly thick-walled, occasionally branched, 2.2–4 μm in diam; skeletal hyphae dominant, yellowish brown to cinnamon brown, thick-walled with a wide to narrow lumen, occasionally branched, straight, 2.2–6.2 μm in diam.

Tubes — Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1.9–3.3 μm in diam; skeletal hyphae dominant, hyaline to pale yellowish, thick-walled with a wide to narrow lumen, rarely branched, more or less straight, 1.9–4 μm in diam. Cystidia absent, but fusoid cystidioles occasionally present, hyaline, thin-walled, 13.8–18 × 2.8–4.2 μm. Basidia clavate, with a basal clamp connection and four sterigmata, 15.5–18 × 4.9–6.5 μm; basidioles dominant, similar to basidia but smaller.

Spores — Basidiospores cylindrical, hyaline, thin-walled, smooth, IKI–, CB–, 6–7.2 × 2–3(–3.1) μm, L = 6.64 μm, W = 2.71 μm, Q = 2.13–2.78 (n = 90/3).

Type of rot — Brown rot.

Notes — Three samples of F. yimengensis were successfully sequenced and formed a well-supported lineage (93% ML, 97% MP, 1.00 BPP), and then grouped with F. caribensis B.K. Cui & Shun Liu and F. palustris (Berk. & M.A. Curtis) Gilb. & Ryvarden (Figure 1). Morphologically, F. caribensis differs by having cream to pinkish buff pore surface when dry, round to angular and smaller pores (6–9 per mm), growth on angiosperm trees and distribution in the Caribbean regions (Liu et al., 2019); F. palustris differs in having malodorous fresh fruiting bodies, larger pores (2–4 per mm) and basidia (24–28 × 6–7 μm), and growth on angiosperm trees (Núñez and Ryvarden, 2001). Fomitopsis yimengensis and F. bondartsevae (Spirin) A.M.S. Soares & Gibertoni have similar basidiospores, but F. bondartsevae differs from F. yimengensis by having effused reflexed to pileate basidiomata, larger pores (2–3 per mm), a trimitic hyphal system and growth on Tilia cordata (Spirin, 2002). Fomitopsis iberica Melo & Ryvarden also grows on Pinus sp., but it differs from F. yimengensis by having larger pores (3–4 per mm), a trimitic hyphal system, larger cystidioles (20–27 × 4–5–5 μm), and has a distribution in Europe (Melo and Ryvarden, 1989).

Additional specimens (paratypes) examined — CHINA. Shandong Province, Mengyin County, Dongchangming, on stump of Pinus sp., July 28, 2007, Cui 5031 (BJFC 003072); Mengyin County, Mengshan Forest Park, on fallen trunk of Pinus sp., August 6, 2007, Cui 5111 (BJFC 003152).