Abstract

Introduction

Trechispora P. Karst. (Hydnodontaceae, Trechisporales) was typified with Trechispora onusta P. Karst. (Karsten, 1890). It is characterized by the resupinate to effused basidiomata with smooth to hydnoid to poroid hymenophore, a monomitic or dimitic hyphal structure with clamped generative hyphae having typical ampullaceous septa, and short cylindric basidia and smooth to verrucose or aculeate basidiospores (Karsten, 1890; Bernicchia and Gorjón, 2010). About 49 species are currently known in Trechispora worldwide (Liberta, 1966, 1973; Larsson, 1994, 1995, 1996; Ryvarden, 2002; Trichiès and Schultheis, 2002; Miettinen and Larsson, 2006; Ordynets et al., 2015; Xu et al., 2019) and Index Fungorum¹ and MycoBank².

Larsson (2007) addressed the classification of corticioid fungi and revealed that Trechispora farinacea (Pers.) Liberta grouped with Trechispora hymenocystis (Berk. and Broome) K.H. Larss., in which both species nested within the family Hydnodontaceae Jülich. Based on the large subunit nuclear ribosomal RNA gene (nLSU) datasets, Albee-Scott and Kropp (2010) supported to transfer Hydnodon thelephorus (Lév.) Banker to Trechispora as Trechispora thelephora (Lév.) Ryvarden. The order Trechisporales was studied employing the internal transcribed spacer (ITS) and nLSU regions, in which it suggested that Porpomyces Jülich, Sistotremastrum J. Erikss., Subulicystidium Parmasto, and Trechispora belonged to a highly supported clade and Trechispora belongs to Hydnodontaceae and was closely related to Brevicellicium K.H. Larss. and Hjortstam (Telleria et al., 2013). A phylogenetic study of Trechispora was addressed and demonstrated that Trechispora cyatheae Ordynets, Langer and K.H. Larss. and Trechispora echinocristallina Ordynets, Langer and K.H. Larss. clustered into Trechispora as new members, inferred from the combined data of the ITS and LSU datasets (Ordynets et al., 2015). The phylogeny of Trechisporales was inferred from a combined dataset of ITS-nLSU sequences and showed that Porpomyces, Scytinopogon Singer, and Trechispora grouped together and nested within family Hydnodontaceae (Liu et al., 2019). Phylogram generated from analysis of ITS sequence dataset of Trechispora showed that Trechispora echinospora Telleria was sister to the clade formed by Trechispora araneosa (Hohn. and Litsch.) K.H. Larss., T. farinacea, T. hymenocystis, and Trechispora mollusca (Pers.) Liberta with a low support (Phookamsak et al., 2019). The ITS + nLSU dataset comprised 22 species and revealed that Trechispora yunnanensis C.L. Zhao formed a monophyletic lineage within Trechispora and was closely related to Trechispora byssinella (Bourdot) Liberta and Trechispora laevis K.H. Larss. (Xu et al., 2019).

During the studies on wood-inhabiting fungi in southern China, three species of Trechispora could not be assigned to any described species. Obtaining sequences from the new taxa, the authors examine taxonomy and phylogeny of three new species within the genus Trechispora, based on the ITS and nLSU sequences.

Materials and Methods

Results

Molecular Phylogeny

In the ITS dataset, the sequences from 43 fungal specimens representing 25 species were included. The dataset had an aligned length of 1034 characters, of which 521 characters are constant, 86 are variable and parsimony-uninformative, and 427 are parsimony-informative. MP analysis yielded 26 equally parsimonious trees (TL = 2048, CI = 0.4561, HI = 0.5439, RI = 0.6174, RC = 0.2816). Best model for the ITS 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 and ML analysis resulted in a similar topology to MP analysis, with an average standard deviation of split frequencies = 0.009985 (BI).

The phylogeny (Figure 1) inferred from ITS sequences showed that Trechispora bambusicola was sister to Trechispora stevensonii (Berk. and Broome) K.H. Larss, and Trechispora fimbriata grouped with Trechispora nivea. T. fissurata grouped with T. echinospora Telleria, M. Dueñas, I. Melo, and M.P. Martín.

Open in a separate window

FIGURE 1

Maximum Parsimony strict consensus tree illustrating the phylogeny of three new species and related species in Trechispora based on ITS sequences. Branches are labeled with maximum likelihood bootstrap values > 70%, parsimony bootstrap proportion values > 50%, and Bayesian posterior probabilities > 0.95, respectively.

In the ITS + nLSU dataset, it included sequences from 49 fungal specimens representing 27 species. The dataset had an aligned length of 2256 characters, of which 1387 characters are constant, 188 are variable and parsimony-uninformative, and 681 are parsimony-informative. MP analysis yielded 100 equally parsimonious trees (TL = 2811, CI = 0.4963, HI = 0.5037, RI = 0.6409, RC = 0.3180). Best model for the ITS 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 and ML analysis resulted in a similar topology to MP analysis, with an average standard deviation of split frequencies = 0.009991 (BI).

The phylogenetic tree (Figure 2) inferred from ITS + nLSU sequences demonstrated 27 species of Trechispora and revealed that T. bambusicola formed a single lineage and then grouped with Trechispora rigida (Berk.) K.H. Larss. and T. stevensonii. T. fimbriata was sister to T. nivea. T. fissurata grouped with T. thelephora (Lév.) Ryvarden.

Open in a separate window

FIGURE 2

Maximum Parsimony strict consensus tree illustrating the phylogeny of three new species and related species in Trechispora based on ITS + nLSU sequences. Branches are labeled with maximum likelihood bootstrap values > 70%, parsimony bootstrap proportion values > 50%, and Bayesian posterior probabilities > 0.95, respectively.

Taxonomy

Trechispora bambusicola C.L. Zhao, sp. nov.

MycoBank no.: MB 838612 (Figures 3, ​,44).

Open in a separate window

FIGURE 3

Basidiomata of Trechispora bambusicola (holotype): Bars: (A) 2 cm; (B) 1 mm.

Open in a separate window

FIGURE 4

Microscopic structures of Trechispora bambusicola (drawn from the holotype): (A) Section of hymenium. (B) Basidiospores. (C) Basidia and basidioles. Bars: (A,C) 10 μm; (B) 5 μm.

Holotype—China, Yunnan Province, Pu’er, Laiyanghe National Forest Park, on dead bamboo, 30 September 2017, CLZhao 3305 (SWFC).

Etymology—Bambusicola (Lat.): referring to occurrence on bamboo stump.

Basidiomata

Annual, adnate, soft, and fragile, without odor or taste when fresh, becoming granulose upon drying, up to 15 cm long and 5 cm wide, 50–300 μm thick. Hymenial surface odontioid, aculei cylindrical to conical, blunt, 0.3–0.5 mm long, white to cream when fresh, turn to cream to buff upon drying. Margin white to cream.

Hyphal structure

Monomitic, generative hyphae with clamp connections, hyaline, thick-walled, up to 0.7 μm, richly branched, 2–3 μm in diameter, IKI−, CB−; hyphae unchanged in KOH.

Hymenium

Cystidia and cystidioles absent; basidia shortly cylindrical to subclavate with median constriction, with 4-sterigmata and a basal clamp connection, 9–13 × 2.5–5 μm, basidioles dominant, in shape similar to basidia, but slightly smaller.

Basidiospores

Ellipsoid, hyaline, thick-walled, ornamented, sparse aculei, sharp, IKI−, CB−, (2.6−)2.9–3.5(−3.9) × 2–2.7 μm, L = 3.18 μm, W = 2.41 μm, Q = 1.26–1.38 (n = 60/2).

Type of rot

White rot.

Additional specimen examined

CHINA, Yunnan Province, Pu’er, Laiyanghe National Forestry Park, on dead bamboo, 30 September 2017, CLZhao 3302 (SWFC).

Trechispora fimbriata C.L. Zhao, sp. nov.

MycoBank no.: MB 838613 (Figures 5, ​,66).

Open in a separate window

FIGURE 5

Basidiomata of Trechispora fimbriata (holotype). Bars: (A) 5 mm; (B) 1 mm.

Open in a separate window

FIGURE 6

Microscopic structures of Trechispora fimbriata (drawn from the holotype). (A) Basidiospores. (B) Basidia and basidioles. (C) Section of hymenium. Bars: (A) 5 μm; (B,C) 10 μm.

Holotype—China, Yunnan Province, Puer, Jingdong County, Wuliangshan National Nature Reserve, on the angiosperm trunk, October 5, 2017, CLZhao 4154 (SWFC).

Etymology—Fimbriata (Lat.): refers to the fimbriate margin of the basidiomata.

Basidiomata

Annual, adnate, without odor or taste when fresh, becoming fragile upon drying, up to 10 cm long and 3 cm wide, 100–200 μm thick. Hymenial surface hydnoid, with aculei, cylindrical, blunt, 0.4–0.7 mm long, white to pink when fresh, turn to pink to buff upon drying. Margin white to cream, thinning out, fimbriate.

Hyphal system

Monomitic, generative hyphae with clamp connections, hyaline, thick-walled, up to 0.6 μm, branched, 2–4 μm in diameter, IKI−, CB−; hyphae unchanged in KOH.

Hymenium

Cystidia and cystidioles absent; basidia shortly cylindrical with median constriction, with 4–6 sterigmata and a basal clamp connection, 7–11.5 × 3.5–5 μm, basidioles dominant, in shape similar to basidia, but slightly smaller.

Basidiospores

Ellipsoid, hyaline, thick-walled, ornamented, sparse aculei, sharp, IKI−, CB−, (2.5−)3–3.6(−3.8) × 2.4–3.2 μm, L = 3.25 μm, W = 2.63 μm, Q = 1.17–1.38 (n = 90/3).

Type of rot

White rot.

Additional specimens examined

China, Yunnan Province, Yuxi, Xinping County, Mopanshan National Forestry Park, on living tree of angiosperm, August 9, 2018, CLZhao 7969 (SWFC); on angiosperm trunk, October 15, 2018, CLZhao 9006 (SWFC).

Trechispora fissurata C.L. Zhao, sp. nov.

MycoBank no.: MB 838614 (Figures 7, ​,88).

Open in a separate window

FIGURE 7

Basidiomata of Trechispora fissurata (holotype). Bars: (A) 1 cm; (B) 1 mm.

Open in a separate window

FIGURE 8

Microscopic structures of Trechispora fissurata (drawn from the holotype). (A) Basidiospores. (B) Basidia and basidioles. (C) Section of hymenium. Bars: (A) 5 μm; (B,C) 10 μm.

Holotype—China, Yunnan Province, Puer, Jingdong County, Wuliangshan National Nature Reserve, on angiosperm trunk, October 6, 2017, CLZhao 4571 (SWFC).

Etymology—Fissurata (Lat.): refers to the cracking fissures on hymenial surface.

Basidiomata

Annual, adnate, without odor or taste when fresh, becoming cracking upon drying, up to 8 cm long and 4.5 cm wide, 400–800 μm thick. Hymenial surface hydnoid, with aculei, cylindrical to conical, sharp, 0.5–0.9 mm long, cream to straw yellow when fresh, turn to cream to yellow upon drying. Margin cream to yellow.

Hyphal system

Monomitic, generative hyphae with clamp connections, hyaline, thick-walled, up to 0.8 μm, branched, 2.5–5 μm in diameter, IKI−, CB−; hyphae unchanged in KOH.

Hymenium

Cystidia and cystidioles absent; basidia shortly clavate to tubular, with 4-sterigmata and a basal clamp connection, 8–10.5 × 2.5–4.5 μm, basidioles dominant, in shape similar to basidia, but slightly smaller.

Basidiospores

Ellipsoid, hyaline, thick-walled, ornamented, dense aculei, sharp, IKI−, CB−, (3−)3.3–4(−4.3) × (2.5−)2.8–3.5(−3.9) μm, L = 3.67 μm, W = 3.19 μm, Q = 1.13–1.17 (n = 60/2).

Type of rot

White rot.

Additional specimen examined

CHINA, Yunnan Province, Yuxi, Xinping County, Mopanshan Forestry Park, on the fallen angiosperm branch, January 17, 2017, CLZhao 995 (SWFC).

Discussion

Phylogenetically, Phookamsak et al. (2019) introduced the phylogram generated from BI analysis of ITS sequence dataset of Trechispora sequences and included most taxa in this genus, in which it implied the phylogenetic relationship among species of Trechispora. In the present study, based on the ITS sequences (Figure 1), T. bambusicola was sister to T. stevensonii (Berk. and Broome) K.H. Larss; T. fimbriata grouped with T. nivea; T. fissurata grouped with T. echinospora Telleria, M. Dueñas, I. Melo, and M.P. Martín. Further ITS + nLSU dataset (Figure 2) revealed that T. bambusicola formed a single lineage and then grouped with T. rigida and T. stevensonii; T. fimbriata was sister to T. nivea; T. fissurata grouped with T. thelephora. However, T. rigida differs in its dirty white to buff hymenophore (Larsson, 1996). T. stevensonii is separated from T. bambusicola by the smooth to hydnoid hymenophore and larger basidiospores (4–4.5 × 3–3.5 μm; Larsson, 1995). T. nivea differs from T. fimbriata by the white to light ochraceous hymenial surface (Persoon, 1794). T. echinospora differs from T. fissurata by the farinaceous to grandinioid hymenophore and larger, globose basidiospores (3.3–4 × 2.8–3.5 μm; Phookamsak et al., 2019) and T. thelephora differs in its pileate to stipitate with light yellow brown surface and larger (4–5 × 3.4–4.5 μm; Albee-Scott and Kropp, 2010).

In the present study, three new species, T. bambusicola, T. fimbriata, and T. fissurata spp. nov. are found from rotten wood. Morphologically, T. bambusicola is similar to T. cyatheae Ordynets, Langer and K.H. Larss. by sharing the characteristics of soft and fragile basidiomata. However, T. cyatheae differs from T. bambusicola by having farinaceous to grandinioid hymenophore and thin-walled generative hyphae (Ordynets et al., 2015).

Trechispora fimbriata has similar characteristics of having the fimbriate margin with Trechispora canariensis Ryvarden and Liberta, Trechispora clancularis (Park.-Rhodes) K.H. Larss., Trechispora microspora (P. Karst.) Liberta, Trechispora stellulata (Bourdot and Galzin) Liberta, and Trechispora subhelvetica (Parmasto) Liberta. However, T. canariensis differs in its arachnoid to pelliculose hymenophore and larger basidiospores (5–7 × 3–3.5 μm; Ryvarden and Liberta, 1978); T. clancularis differs in the poroid to irpicoid hymenophore and slightly cyanophilous basidiospores (Larsson, 1994); T. stellulata differs in the arachnoid to byssoid hymenophore with whitish hymenial surface (Liberta, 1966); and T. subhelvetica differs in the narrower basidiospores (3–4 × 2–2.5 μm; Parmasto, 1965).

Trechispora fissurata resembles several species with similar features of having the hydnoid hymenophore and a monomitic hyphal system: T. nivea (Pers.) K.H. Larss., T. stevensonii (Berk. and Broome) K.H. Larss., and Trechispora verruculosa (G. Cunn.) K.H. Larss., but T. nivea by the white to pale ochraceous hymenial surface and thin-walled generative hyphae encrusted with granular crystals (Bernicchia and Gorjón, 2010); T. stevensonii by the white to ochraceous hymenial surface and larger basidiospores (4–4.5 × 3–3.5 μm; Larsson, 1995); T. verruculosa by the slightly cyanophilous and larger basidiospores (4.5–5.5 × 3.5–4.5 μm; Larsson, 1996).

Currently, eight species of Trechispora have been reported from China (Dai, 2011; Xu et al., 2019), Trechispora alnicola, Trechispora cohaerens, T. farinacea, T. microspora, T. nivea, Trechispora polygonospora Ryvarden, Trechispora subsphaerospora (Litsch.) Liberta, and T. yunnanensis, and one species of T. yunnanensis was found in Yunnan Province of China and it differs from three new species by having a smooth to farinaceous hymenial surface and larger basidiospores (7–8.5 × 5–5.5 μm; Xu et al., 2019). Three new taxa do not closely group together in phylogenetic trees, and morphologically, T. bambusicola differs from T. fimbriata and T. fissurata by having granulose basidiomata with cream to buff hymenial surface and growth on dead bamboo. T. fimbriata differs in its fimbriate margin of the basidiomata with pink to buff hymenial surface.

In addition, the ectomycorrhizal fungi (EcM) play an important role in ecosystems based on their mutualistic association with many groups of plants (Heijden et al., 2015). Vanegas-León et al. (2019) discovered the Trechisporales basidiomes and root colonization from T. thelephora basidiome. In the present study, T. fissurata was sister to T. thelephora based on ITS + nLSU phylogenetic analysis (Figure 2), which implied that both species have close evolutionary relationship. However, T. fissurata grows on deeply decayed wood, and T. thelephora is a soil-inhabiting fungus. Therefore, future investigations in both inhabiting types are needed to determine whether the natural selection or other factors pushes the different direction on inhabiting soil/wood among Trechispora.

In the habitat and distribution, Hibbett et al. (2014) revealed that most species of Trechispora is considered as soil-inhabiting. Later, some species were found on deeply decayed wood fungi (Bernicchia and Gorjón, 2010; Dai, 2011). However, some species in Trechispora are a typical feature of ectomycorrhizal fungi as frequently forming basidiomes on soil (Dunham et al., 2007; Vanegas-León et al., 2019). In the neotropical and subtropical region, the ectomycorrhizal basidiomes are found; however, the researches on the new taxa related to wood-decaying fungi of Trechispora from China are poorly reported. Further studies may focus on the relationships between the plants and species from Trechispora and try to better understand the evolutionary directions between soil-inhabiting and decayed wood fungi of Trechispora; many fungal studies on phylogeny and application were from these areas, which will be useful to push future researches for the genus Trechispora (Dai, 2011; Cui et al., 2019; Shen et al., 2019; Zhu et al., 2019; Richter et al., 2019; Angelini et al., 2020; Bao et al., 2020).

Disclosure

All the experiments undertaken in this study comply with the current laws of the People’s Republic of China.

Data Availability Statement

The data presented in the study are deposited in the https://www.ncbi.nlm.nih.gov/GenBank and https://www.mycobank.org/page/Home/MycoBank repository accession number of GenBank (ITS MW544021-MW544027 and nLSU MW520171-MW520177) and MycoBank (MB 838612-MB 838614).

Author Contributions

C-LZ collected the species. WZ performed the molecular phylogenetic analyses. Both authors were responsible for the morphological analysis and description of the collections, planned, organized, and evaluated critically the experimental parts, wrote the manuscript, contributed to the article, and approved the submitted version.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Abbreviations

References