Additions to the Knowledge of Corticioid Xylodon (Schizoporaceae, Hymenochaetales): Introducing Three New Xylodon Species from Southern China

Abstract

Three wood-inhabiting fungal species, Xylodon gossypinus, X. macrosporus, and X. sinensis spp. nov. were collected from southern China, with the similar function to decompose rotten wood, which are here proposed as new taxa based on a combination of morphological features and molecular evidence. Xylodon gossypinus is characterized by the resupinate basidiomata with cotton hymenophore, and ellipsoid basidiospores; X.macrosporus is characterized by the resupinate basidiomata having the cracking hymenophore with pale yellowish hymenial surface, and larger basidiospores 8–10.5 × 7.5–9 µm; and X. sinensis differs by its grandinioid hymenial surface and subglobose basidiospores measuring as 3–5 × 2.5–4 µm. Sequences of ITS and nLSU rRNA markers of the studied samples were generated, and phylogenetic analyses were performed with maximum likelihood, maximum parsimony, and Bayesian inference methods. The ITS+nLSU analysis in Hymenochaetales revealed that the three new species clustered into the Schizoporaceae family, located in genus Xylodon; based on the ITS dataset, X. gossypinus was a sister to X. ussuriensis; X. macrosporus closely grouped with X.follis with a high support; and X.sinensis was retrieved as two sisters to X. attenuatus and X. yarraensis with a lower support.

A Phylogenetic and Taxonomic Study on Xylodon (Hymenochaetales): Focusing on Three New Xylodon Species from Southern China

“…Zhou by the cracked hymenophore. However, Xylodon australis is diverse from X. laceratus by its membranous basidiomata with a brown hymenial surface with an olive tint and subulate, sinuous, or moniliform cystidia (40-60 × 10-20 µm) [22]; X. gamundiae is different than X. laceratus by its suburniform to sinuous basidia (20-30 × 4-5 µm) and cylindrical to subcylindrical basidiospores (6-6.5 × 3-3.5 µm) [56]; X. macrosporus differs from X. laceratus by its ellipsoid to broad ellipsoid, larger basidiospores (8-10.5 × 7.5-9 µm) [32]; X. rhododendricola could be delimited from X. laceratus by its odontioid, buff-yellow hymenophore, and usually encrusted with crystals leptocystidia (30-35 × 3-3.5 µm) [3]; X. subserpentiformis is distinguishable from X. laceratus by its snake-like sinuous tramacystidia (45-50 × 4.5-5.5 µm) and utriform or subclavate basidia (20-25 × 4.5-5.5 µm) [3].…”

“…In their geographical distribution and ecological preferences, the members of Xylodon are widespread and primarily wood decomposers, causing a white-rot of woody substrates, which are widely distributed in various forest ecosystems from boreal, temperate, subtropical, to tropical zones [16,55]. Some taxa of Xylodon have been collected on rotten trunks and stumps of conifers and angiosperms, bamboo, and ferns [3,12,32,34,44,[56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72].…”

“…Molecular phylogeny of the genus Xylodon based on the ITS-alone dataset included sequences from 61 fungal specimens representing 55 species, revealed that X. gossypinus, X. macrosporus, and X. sinensis were grouped into three different subclades of Xylodon. X. gossypinus grouped closely with X. ussuriensis Viner; X. macrosporus grouped with X. follis with high supports, and X. sinensis grouped to a clade comprising X. attenuatus and X. yarraensis with lower supports [32]. In the current study (Figure 1), our three undescribed taxa nested into the genus Xylodon, in which X. laceratus was a sister to X. heterocystidiatus; X. montanus closely grouped with X. subclavatus and X. xinpingensis with a high supports; X. tropicus was retrieved as a sister to X. hastifer.…”

“…Hjortstam & Ryvarden, X. gossypinus and X. pumilius in having the moniliform cystidia. However, Xylodon anmashanensis differentiates from X. montanus by its cracked, odontioid hymenophore and three kinds of cystidia: hyphoid or subulate cystidia (22-53 × 2.5-4.5 µm), moniliform and submoniliform cystidia (20-60 × 3-5 µm) [15]; X. brevisetus is diverse from X. montanus by its odontioid hymenophore, clavate to cylindrical basidia (20-25 × 4-5 µm) [25]; X. crassisporus could be delimited from X. montanus by its odontioid, pale yellow or very pale brown hymenophore, and the capitate cystidia (27-75 × 2-5 µm) [56]; X. gossypinus differs from X. montanus by its flocculent basidiomata and capitate cystidia (16-23.5 × 2.5-5 µm) [32]; X. pumilius is distinguishable from X. montanus by its ochraceous hymenophore, capitate cystidia (30-45 × 4-5 µm) and broadly ellipsoid to broadly, thick-walled basidiospores (5-6 × 4-5 µm) [56].…”

“…Maximum parsimony strict consensus tree illustrating the phylogeny of Xylodon species based on ITS sequences showed that X. gossypinus C.L. Zhao [32].…”