Research Article |
Corresponding author: Bao-Kai Cui ( cuibaokai@yahoo.com ) Academic editor: María P. Martín
© 2019 Xing Ji, Dong-Mei Wu, Shun Liu, Jing Si, Bao-Kai Cui.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Ji X, Wu D-M, Liu S, Si J, Cui B-K (2019) Crassisporus gen. nov. (Polyporaceae, Basidiomycota) evidenced by morphological characters and phylogenetic analyses with descriptions of four new species. MycoKeys 57: 61-84. https://doi.org/10.3897/mycokeys.57.38035
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A new poroid wood-inhabiting fungal genus, Crassisporus gen. nov., is proposed on the basis of morphological characters and molecular evidence. The genus is characterized by an annual growth habit, effused-reflexed to pileate basidiocarps with pale yellowish brown to yellowish brown, concentrically zonate or sulcate, and velutinate pileal surface, a trimitic hyphal system with clamped generative hyphae, tissues turning to dark in KOH, oblong to broadly ellipsoid, hyaline, smooth, and slightly thick-walled basidiospores. Phylogenetic analysis based on ITS+nLSU sequences indicate that Crassisporus belongs to the core polyporoid clade. The combined ITS+nLSU+mtSSU+EF1-α+RPB2 sequences dataset of representative taxa in the Polyporaceae demonstrate that Crassisporus is grouped with Haploporus but forms a monophyletic lineage. In addition, four new species of Crassisporus, C. imbricatus, C. leucoporus, C. macroporus, and C. microsporus are described.
core polyporoid clade, molecular phylogeny, polypore, taxonomy, wood-decaying fungi
Polyporales is one of the most diverse orders of Basidiomycota including more than 1800 described species in 216 genera and 13 families (
During the investigations of species diversity and phylogeny of Polyporales, four new species were found that did not belong to any known genus, for which reason, a new genus is established to accommodate them. Morphologically, these four taxa do not fit any of the known polypore taxa. To confirm the position of the new genus, phylogenetic analyses of the new genus and related taxa within Polyporales were carried out based on the internal transcribed spacer (ITS) regions, the large subunit nuclear ribosomal RNA gene (nLSU), the small subunit mitochondrial rRNA gene sequences (mtSSU), the translation elongation factor 1-α gene (EF1-α), and the second largest subunit of RNA polymerase II (RPB2).
The studied specimens were deposited at the herbarium of the Institute of Microbiology, Beijing Forestry University (
A CTAB rapid plant genome extraction kit (Aidlab Biotechnologies Co. Ltd, Beijing) was used to extract total genomic DNA from dried specimens, and performed the polymerase chain reaction (PCR) according to the manufacturer’s instructions with some modifications (
Species, specimens and GenBank accession numbers of sequences used in this study.
Species | Sample no. | Locality | GenBank accessions | ||||
---|---|---|---|---|---|---|---|
ITS | nLSU | mtSSU | EF1-α | RPB2 | |||
Abortiporus biennis | EL 65-03 | Sweden | JN649325 | JN649325 | – | – | – |
Abundisporus fuscopurpureus | Cui 10950 | China | KC456254 | KC456256 | KF051025 | KF181154 | – |
A. pubertatis | Dai 11310 | China | KC787568 | KC787575 | KF051031 | KF181125 | |
Dai 11927 | China | KC787569 | KC787576 | KF051034 | KF181128 | – | |
A. sclerosetosus | MUCL 41438 | Singapore | FJ411101 | FJ393868 | – | – | – |
A. violaceus | Ryvarden 32807 | Finland | KF018127 | KF018135 | KF051038 | KF181132 | – |
Antrodia albida | CBS 308.82 | USA | DQ491414 | AY515348 | – | – | – |
A. macra | MUAF 887 | Czech Republic | EU340898 | – | – | – | – |
Bjerkandera adusta | NBRC 4983 | Unknown | AB733156 | AB733333 | – | – | – |
Cinereomyces lindbladii | KHL 12078 | Norway | FN907906 | FN907906 | – | – | – |
Climacocystis borealis | KHL 13318 | Estonia | JQ031126 | JQ031126 | – | – | – |
Coriolopsis brunneoleuca | Cui 13911 | China | MK116480a | MK116489a | MK116498a | – | MK124544a |
C. brunneoleuca | Dai 12180 | China | KC867414 | KC867432 | – | – | KF274655 |
C. polyzona | BKW004 | Ghana | JN164978 | JN164790 | – | JN164881 | JN164856 |
C. retropicta | Cui 13849 | China | MK116481a | MK116490a | MK116499a | MK122979a | MK124545a |
Cui 14030 | China | MK116482a | MK116491a | MK116500a | MK122980a | MK122987a | |
Crassisporus imbricatus | Cui 6556 | China | KC867351 | KC867426 | – | – | – |
C. imbricatus | Dai 10788 | China | KC867350 | KC867425 | KX838374 | – | – |
C. leucoporus | Cui 16801 | Australia | MK116488a | MK116497a | MK116507a | MK122986a | MK122993a |
C. macroporus | Cui 14465 | China | MK116485a | MK116494a | MK116504a | MK122983a | MK122990a |
Cui 14468 | China | MK116486a | MK116495a | MK116505a | MK122984a | MK122991a | |
C. microsporus | Cui 16221 | China | MK116487a | MK116496a | MK116506a | MK122985a | MK122992a |
Daedaleopsis confragosa | Cui 6892 | China | KU892428 | KU892448 | KX838381 | KX838418 | KU892507 |
D. hainanensis | Cui 5178 | China | KU892435 | KU892462 | KX838413 | KX838441 | KU892495 |
Datronia mollis | RLG6304sp | USA | JN165002 | JN164791 | – | JN164901 | JN164872 |
Earliella scabrosa | PR1209 | Puerto Rico | JN165009 | JN164793 | – | – | JN164866 |
Fomes fomentarius | ES 2008-3 | Sweden | JX109860 | JX109860 | – | – | – |
Fomitella supina | JV0610 | Guatemala | KF274645 | KF274646 | – | – | – |
F. supina | Ryvarden 39027 | Puerto Rico | KF274643 | – | – | – | – |
Fomitopsis betulina | Dai 11449 | China | KR605798 | KR605737 | KR605998 | KR610726 | KR610816 |
F. pinicola | Cui 10405 | China | KC844852 | KC844857 | KR605961 | KR610690 | KR610781 |
Fragiliporia fragilis | Dai 13080 | China | KJ734260 | KJ734264 | – | – | – |
F. fragilis | Dai 13559 | China | KJ734261 | KJ734265 | – | – | – |
Yuan 5516 | China | KJ734263 | KJ734267 | – | – | – | |
Funalia gallica | Dai 10977 | China | KC867378 | KC867452 | – | – | KU182651 |
F. trogii | RLG4286Sp | USA | JN164993 | JN164808 | – | JN164898 | JN164867 |
Gelatoporia subvermispora | BRNU 592909 | Czech Republic | FJ496694 | FJ496706 | – | – | – |
Grammethelopsis subtropica | Cui 9035 | China | JQ845094 | JQ845097 | KF051030 | KF181124 | – |
Cui 9041 | China | JQ845096 | JQ845099 | KF051039 | KF181133 | – | |
Haploporus latisporus | Dai 11873 | China | KU941847 | KU941871 | KU941896 | KU941934 | KU941918 |
H. latisporus | Dai 10562 | China | KU941848 | KU941872 | KU941897 | KU941935 | KU941919 |
H. odorus | Yuan 2365 | China | KU941846 | KU941870 | KU941895 | KU941933 | KU941917 |
Dai 11296 | China | KU941845 | KU941869 | KU941894 | KU941932 | KU941916 | |
H. subtrameteus | Dai 4222 | China | KU941849 | KU941873 | KU941898 | KU941936 | KU941920 |
Cui 10656 | China | KU941850 | KU941874 | KU941899 | KU941937 | KU941921 | |
Heterobasidion annosum | PFC 5327 | Greece | KC492915 | – | – | KC571655 | – |
Hexagonia apiaria | Cui 6447 | China | KC867362 | KC867481 | MG847228 | MG867697 | KF274660 |
H. apiaria | Dai 10784 | China | KX900635 | KX900682 | KX900732 | KX900822 | MG867677 |
H. hirta | Dai 5081 | China | – | KC867486 | – | – | – |
Cui 4051 | China | KC867359 | KC867471 | – | – | – | |
Hornodermoporus latissimus | Cui 6625 | China | HQ876604 | JF706340 | KF051040 | KF181134 | – |
Dai 12054 | China | KX900639 | KX900686 | KF218297 | KF286303 | – | |
H. martius | MUCL 41677 | Argentina | FJ411092 | FJ393859 | – | – | – |
MUCL 41678 | Argentina | FJ411093 | FJ393860 | – | – | – | |
Hydnopolyporus fimbriatus | LR 40855 | Puerto Rico | JN649347 | JN649347 | – | – | – |
Hypochnicium lyndoniae | NL 041031 | UK | JX124704 | JX124704 | – | – | – |
Laetiporus montanus | Cui 10011 | China | KF951274 | KF951315 | KX354570 | KX354617 | KT894790 |
L. sulphureus | Cui 12388 | China | KR187105 | KX354486 | KX354560 | KX354607 | KX354652 |
Lenzites betulina | HHB9942Sp | USA | JN164983 | JN164794 | – | JN164895 | JN164860 |
Megasporia ellipsoidea | Cui 13854 | China | MK116483a | MK116492a | MK116501a | MK122981a | MK122988a |
M. major | Cui 10253 | China | JQ314366 | JQ780437 | MK116502a | – | – |
Megasporoporiella rhododendri | Cui 10745 | China | MK116484a | MK116493a | MK116503a | MK12298222982a | MK122989a |
M. subcavernulosa | Cui 14247 | China | MG847213 | MG847222 | MG847234 | MG867705 | MG867685 |
Microporus affinis | Cui 7714 | China | JX569739 | JX569746 | KX880696 | – | KF274661 |
M. vernicipes | Dai 9283 | China | KX880618 | KX880658 | KX880701 | KX880926 | – |
M. xanthopus | Cui 8284 | China | JX290074 | JX290071 | KX880703 | KX880878 | JX559313 |
Neodatronia sinensis | Dai 11921 | China | JX559272 | JX559283 | – | – | JX559320 |
Neofomitella fumosipora | Cui 8816 | China | JX569734 | JX569741 | KX900766 | – | – |
Cui 13581a | China | KX900664 | KX900714 | KX900767 | KX900848 | KX900815 | |
N. rhodophaea | TFRI 414 | Unknown | EU232216 | EU232300 | – | – | – |
Obba rivulosa | KCTC 6892 | Canada | FJ496693 | FJ496710 | – | – | – |
Perenniporia hainaniana | Cui 6364 | China | JQ861743 | JQ861759 | KF051044 | KF181138 | – |
P. hainaniana | Cui 6365 | China | JQ861744 | JQ861760 | KF051045 | KF181139 | – |
P. medulla-panis | MUCL 49581 | Poland | FJ411088 | FJ393876 | – | – | – |
Cui 14515 | China | MG847214 | MG847223 | – | MG867707 | MG867687 | |
P. substraminea | Cui 10177 | China | JQ001852 | JQ001844 | KF051046 | KF181140 | – |
Cui 10191 | China | JQ001853 | JQ001845 | KF051047 | KF181141 | – | |
Perenniporiella chaquenia | MUCL 47648 | Argentina | FJ411084 | FJ393856 | – | HM467610 | – |
P. micropora | MUCL 43581 | Cuba | FJ411086 | FJ393858 | – | HM467608 | – |
P. neofulva | MUCL 45091 | Cuba | FJ411080 | FJ393852 | – | HM467599 | – |
P. pendula | MUCL 46034 | Cuba | FJ411081 | FJ393853 | – | HM467601 | – |
Phanerochaete chrysosporium | BKM-F-1767 | USSR | HQ188436 | GQ470643 | – | – | – |
Phlebia unica | KHL 11786 | Sweden | EU118657 | EU118657 | – | – | – |
Pycnoporus cinnabarinus | Dai 14386 | China | KX880629 | KX880667 | KX880712 | KX880885 | KX880854 |
Skeletocutis amorpha | Miettinen 11038 | Finland | FN907913 | FN907913 | – | – | – |
Stereum hirsutum | NBRC 6520 | Unknown | AB733150 | AB733325 | – | – | – |
Trametes conchifer | FP106793Sp | USA | JN164924 | JN164797 | – | JN164887 | JN164849 |
T. pubescens | FP101414Sp | USA | JN164963 | JN164811 | – | JN164889 | JN164851 |
T. tephroleuca | Cui 7987 | China | KC848293 | KC848378 | KX880755 | KX880934 | KX880869 |
T. versicolor | FP135156Sp | USA | JN164919 | JN164809 | – | JN164878 | JN164850 |
Truncospora detrita | MUCL 42649 | French Guyana | FJ411099 | FJ393866 | – | – | – |
T. macrospora | Cui 8106 | China | JX941573 | JX941596 | KX880763 | KX880920 | KX880871 |
Yuan 3777 | China | JX941574 | JX941597 | – | – | – | |
T. ochroleuca | MUCL 39726 | China Taiwan | FJ411098 | FJ393865 | – | – | – |
Cui 5671 | China | JX941584 | JX941602 | KF218309 | KF286315 | – | |
T. ohiensis | MUCL 41036 | USA | FJ411096 | FJ393863 | – | – | – |
Tyromyces chioneus | Cui 10225 | China | KF698756 | KF698745 | – | – | – |
T. kmetii | Penttilä 13474 | China | KF705040 | KF705041 | – | – | – |
Vanderbylia fraxinea | DP 83 | Italy | AM269789 | AM269853 | – | – | – |
MUCL 39326 | France | FJ411094 | FJ393861 | – | – | – | |
V. robiniophila | Cui 5644 | China | HQ876609 | JF706342 | KF051051 | KF181145 | MG867691 |
Cui 7144 | China | HQ876608 | JF706341 | KF051052 | KF181146 | – | |
V. vicina | MUCL 44779 | Ethiopia | FJ411095 | FJ393862 | – | – | – |
Whitfordia scopulosa | Dai 10739 | China | KC867364 | KC867482 | KX880766 | KX880922 | MG867692 |
Sequences used for phylogenetic analyses in this study are listed in Table
Phylogenetic analyses used in this study followed the approach of
RAxML v. 7.2.6 (
MrModeltest v. 2.3 (
Phylogenetic trees were viewed using FigTree v. 1.4.2 (http://tree.bio.ed.ac.uk/software/figtree/). Branches that received bootstrap support for maximum parsimony (MP), maximum likelihood (ML) and Bayesian posterior probabilities (BPP) greater than or equal to 75% (MP and ML) and 0.95 (BPP) were considered as significantly supported, respectively.
The combined 2-gene dataset included sequences from 68 fungal samples representing 59 taxa. The dataset had an aligned length of 2111 characters, of which 1249 characters were constant, 196 were variable and parsimony-uninformative, and 666 were parsimony-informative. MP analysis yielded 37 equally parsimonious trees (TL = 4143, CI = 0.345, RI = 0.617, RC = 0.213, HI = 0.655). Best model for the combined 2-gene dataset estimated and applied in the BI was GTR+I+G, lset nst = 6, rates = invgamma; prset statefreqpr = dirichlet (1,1,1,1). MP, ML and BI analyses yielded similar tree topologies with an average standard deviation of split frequencies = 0.006293 (BI), and the ML topology is shown in Figure
The combined 5-gene (ITS, nLSU, mtSSU, EF1-α, RPB2) dataset included sequences of 82 fungal samples representing 57 taxa. The dataset had an aligned length of 4306 characters, of which 2521 characters were constant, 258 were variable and parsimony-uninformative, and 1527 were parsimony-informative. MP analysis yielded 1 equally parsimonious tree (TL = 8989, CI = 0.339, RI = 0.620, RC = 0.210, HI = 0.661). Bayesian and ML analyses resulted in a similar topology as the MP analysis, with an average standard deviation of split frequencies = 0.006328 (BI); and the ML topology is shown in Figure
Phylogeny of Crassisporus and related species obtained for more representative taxa in the Polyporaceae based on combined sequences dataset of ITS+nLSU+mtSSU+EF1-α+RPB2. Topology is from ML analysis with parsimony bootstrap support values (≥50 %), maximum likelihood bootstrap support values (≥50 %), and Bayesian posterior probability values (≥0.95).
Differs from other genera by the combination of effused-reflexed to pileate basidiocarps, pale yellowish brown to yellowish brown, concentrically zonate or sulcate, velutinate pileal surface, a trimitic hyphal system with clamped generative hyphae, tissues darkening in KOH, and oblong to broadly ellipsoid, hyaline, smooth and slightly thick-walled basidiospores.
Crassisporus (Lat.): referring to thick-walled basidiospores.
Crassisporus macroporus B.K. Cui & Xing Ji.
Basidiocarps annual, effused-reflexed to pileate. Pileal surface pale yellowish brown, yellowish brown to umber-brown when dry, concentrically zonate or sulcate, velutinate. Pore surface usually white, cream buff to cinnamon-buff when fresh, buff, pale yellowish brown to yellowish brown when dry. Context pale yellowish brown to yellowish brown, leathery to corky when dry. Tubes concolorous with the context, corky when dry. Hyphal system trimitic with clamped generative hyphae, skeletal hyphae hyaline to pale yellowish brown, binding hyphae hyaline to pale yellowish brown, negative in Melzer’s reagent, tissues turning to black in KOH. Cystidia absent, thin-walled cystidioles usually present. Basidiospores oblong to broadly ellipsoid, hyaline, smooth, slightly thick-walled, IKI-, CB-. Causing a white rot.
Crassisporus imbricatus is characterized by imbricate basidiocarps, pale greyish-brown pore surface when dry, round to angular pores (3–5 per mm), and oblong ellipsoid basidiospores (10–14 × 4.5–6.2 μm).
CHINA. Hainan Province, Changjiang County, Bawangling Nature Reserve, on dead angiosperm tree, 9 May 2009, Dai 10788 (
Imbricatus (Lat.): referring to the imbricate basidiocarps.
Fruitbody: Basidiocarps annual, effused-reflexed to pileate, imbricate, soft corky, without odor or taste when fresh, leathery to corky upon drying. Pilei semicircular or elongated, projecting up to 1.5 cm, 3.5 cm wide, and 2.5 mm thick at base. Pileal surface yellowish brown, velutinate, concentrically zonate. Pore surface buff when fresh, becoming pale greyish brown when dry; sterile margin indistinct, pores round to angular, 3–5 per mm; dissepiments slightly thick, entire to slightly lacerate. Context yellowish brown, leathery, up to 2.5 mm thick. Tubes concolorous with context, corky, up to 1.5 mm long.
Hyphal structure: Hyphal system trimitic; generative hyphae bearing clamp connections; skeletal and binding hyphae IKI-, CB-; tissues turning to black in KOH.
Context: Generative hyphae infrequent, hyaline, thin-walled, unbranched, 2–3.5 μm in diam.; skeletal hyphae dominant, hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, rarely branched, straight, interwoven, occasionally simple-septate, 2.5–5.5 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 1.2–2.5 μm in diam.
Tubes: Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1.5–3 μm in diam.; skeletal hyphae dominant, hyaline to pale yellowish brown, thick-walled, occasionally branched, strongly interwoven, rarely simple-septate, 1.5–3.5 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 1–2 μm in diam. Cystidia and cystidioles absent. Basidia clavate, bearing four sterigmata and a basal clamp connection, 19–32 × 9–12 μm; basidioles dominant, in shape similar to basidia, but distinctly smaller.
Spores: Basidiospores oblong ellipsoid, hyaline, slightly thick-walled, smooth, IKI-, CB-, 10–14(–15) × 4.5–6.2(–6.6) μm, L = 12.33 μm, W = 5.34 μm, Q = 2.27–2.36 (n = 60/2).
White rot.
CHINA. Hainan Province, Changjiang County, Bawangling Nature Reserve, on fallen branch of Pinus latteri, 10 May 2009, Cui 6556 (
Crassisporus leucoporus is characterized by a white pore surface when fresh, round to angular pores (3–4 per mm) and oblong ellipsoid basidiospores (8.4–11.2 × 4.2–5.4 μm).
AUSTRALIA. Queensland, Cairns, Roadside of Mount Whitfield Park, on fallen angiosperm branch, 18 May 2018, Cui 16801 (
Leucoporus (Lat.): referring to the white pore surface when fresh.
Fruitbody: Basidiocarps annual, effused-reflexed to pileate, corky, without odor or taste when fresh, soft leathery to corky upon drying. Pilei semicircular or elongated, projecting up to 1.5 cm, 3 cm wide, and 6 mm thick at base. Pileal surface yellowish brown to umber-brown, finely velutinate, concentrically sulcate. Pore surface white when fresh, becoming cream, clay buff to pale yellowish brown when dry; sterile margin distinct, cream to pale yellowish brown, up to 1.5 mm wide; pores round to angular, 3–4 per mm; dissepiments slightly thick, entire. Context pale yellowish brown to fulvous, leathery, up to 3 mm thick. Tubes pale yellowish brown, corky, up to 2.5 mm long.
Hyphal structure: Hyphal system trimitic; generative hyphae bearing clamp connections; skeletal and binding hyphae IKI-, CB-; tissues turning to black in KOH.
Context: Generative hyphae infrequent, hyaline, thin-walled, unbranched, 1.1–2.6 μm in diam.; skeletal hyphae in context dominant, pale yellowish brown, thick-walled with a narrow to wide lumen, unbranched, straight, interwoven, occasionally simple-septate, 1.8–3.9 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 0.7–2.2 μm in diam.
Tubes: Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1–2.8 μm in diam.; skeletal hyphae dominant, hyaline to pale yellowish brown, thick-walled with a narrow to wide lumen, occasionally branched, more or less straight, strongly interwoven, 0.9–3.3 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 0.8–2.1 μm in diam. Cystidia absent, cystidioles fusoid, sometimes septate at the tips, hyaline, thin-walled, 16.7–28.1 × 5.1–6.3 μm. Basidia clavate, bearing four sterigmata and a basal clamp connection, 18.1–29.2 × 6.4–9.8 μm; basidioles dominant, in shape similar to basidia, but smaller.
Spores: Basidiospores oblong ellipsoid, hyaline, smooth, slightly thick-walled, IKI-, CB-, (7.9–)8.4–11.2(–11.5) × (4–)4.2–5.4(–5.7) μm, L = 9.49 μm, W = 4.79 μm, Q = 1.99 (n = 60/1).
Crassisporus macroporus is characterized by cream-buff to cinnamon-buff colored pore surface with distinct sterile margin when fresh, large pores (2–3 per mm) with thin dissepiments, a trimitic hyphal system with cyanophilous skeletal hyphae, the presence of fusoid cystidioles, and oblong ellipsoid basidiospores (9.5–13.2 × 4–6.2 μm).
CHINA. Guangxi Autonomous Region, Huanjiang County, Mulun Nature Reserve, on fallen angiosperm branch, 10 July 2017, Cui 14468 (
Macroporus (Lat.): referring to the large pores.
Fruitbody: Basidiocarps annual, effused-reflexed to pileate, corky to leathery, without odor or taste when fresh, soft leathery upon drying. Pilei flabelliform, semicircular or elongated, projecting up to 1.5 cm, 4 cm wide and 5 mm thick at base; resupinate part up to 7 cm long, 4 cm wide, and 5 mm thick at center. Pileal surface buff to yellowish brown when fresh, becoming yellowish brown upon drying, finely velutinate, concentrically sulcate. Pore surface cream, buff to cinnamon-buff when fresh, becoming buff, pale yellowish brown to yellowish brown when dry; sterile margin distinct, buff to pale yellowish brown, up to 2 mm wide; pores round to angular, 2–3 per mm; dissepiments thin, entire to lacerate. Context yellowish brown to pale yellowish brown, leathery, up to 1.5 mm thick. Tubes pale yellowish brown, corky, up to 2 mm long.
Hyphal structure: Hyphal system trimitic; generative hyphae bearing clamp connections; skeletal and binding hyphae IKI-, CB+; tissues turning to black in KOH.
Context: Generative hyphae infrequent, hyaline, thin-walled, unbranched, 1.5–3.5 μm in diam.; skeletal hyphae dominant, pale yellowish brown, thick-walled with a narrow lumen to subsolid, unbranched, more or less straight, interwoven, occasionally simple-septate, 2–5.5 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 1–3 μm in diam.
Tubes: Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1–2 μm in diam.; skeletal hyphae dominant, hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, occasionally branched, more or less straight, strongly interwoven, 1.5–3 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 0.8–2 μm in diam. Cystidia absent, cystidioles fusoid, hyaline, thin-walled, 13–20 × 4.5–6 μm. Basidia clavate, bearing four sterigmata and a basal clamp connection, 17–28 × 7–8 μm; basidioles dominant, in shape similar to basidia, but smaller.
Spores: Basidiospores oblong ellipsoid, hyaline, smooth, slightly thick-walled, IKI-, CB-, 9.5–13.2(–14) × 4–6.2(–6.5) μm, L = 11.24 μm, W = 4.96 μm, Q = 2.26–2.31 (n = 60/2).
White rot.
CHINA. Guangxi Autonomous Region, Huanjiang County, Mulun Nature Reserve, on dead angiosperm tree, 10 July 2017, Cui 14465 (
Crassisporus microsporus is characterized by pileate basidiocarps, small pores (5–7 per mm), and small, broadly ellipsoid basidiospores (4–5 × 3–3.7 μm).
CHINA. Yunnan Province, Ruili, Mori Tropical Rainforest Park, on living angiosperm tree, 17 September 2017, Cui 16221 (
Microsporus (Lat.): referring to the small basidiospores.
Fruitbody: Basidiocarps annual, pileate, sessile, corky, without odor or taste when fresh, soft leathery to corky upon drying. Pilei semicircular, projecting up to 2 cm, 4 cm wide, and 4.5 mm thick at base. Pileal surface pale yellowish brown to yellowish brown, finely velutinate, concentrically sulcate. Pore surface cream, buff to cinnamon-buff when fresh, buff, pale yellowish brown to yellowish brown when dry; sterile margin distinct, buff, up to 1 mm wide; pores round to angular, 5–7 per mm; dissepiments slightly thick, entire. Context pale yellowish brown to yellowish brown, leathery to corky when dry, up to 1.5 mm thick. Tubes concolorous with context, soft corky to corky, up to 3 mm long.
Hyphal structure: Hyphal system trimitic; generative hyphae bearing clamp connections; skeletal and binding hyphae IKI-, CB-; tissues turning to deep brown in KOH.
Context: Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, 1.2–3.5 μm in diam.; skeletal hyphae dominant, hyaline to pale yellowish brown, thick-walled with a narrow lumen, rarely branched, straight, interwoven, occasionally simple-septate, 2.5–6 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 0.8–2.5 μm in diam.
Tubes: Generative hyphae infrequent, hyaline, thin-walled, rarely branched, 1.2–3 μm in diam.; skeletal hyphae dominant, hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, moderately branched, more or less straight, strongly interwoven, 1.5–3 μm in diam.; binding hyphae hyaline to pale yellowish brown, thick-walled with a narrow lumen to subsolid, flexuous, frequently branched, interwoven, 0.8–2.5 μm in diam. Cystidia absent, cystidioles fusoid, hyaline, thin-walled, 12.5–18 × 4–5.5 μm. Basidia clavate, bearing four sterigmata and a basal clamp connection, 14–21 × 4.5–6 μm; basidioles in shape similar to basidia, but distinctly smaller.
Spores: Basidiospores broadly ellipsoid, hyaline, smooth, slightly thick-walled, IKI-, CB-, 4–5(−5.2) × (−2.8)3–3.7(−3.9) μm, L = 4.5 μm, W =3.23 μm, Q = 1.4 (n = 60/1).
In the present study, Crassisporus is proposed based on morphological characters and phylogenetic analyses. In the ITS+nLSU analysis, Crassisporus was nested in the core polyporoid clade with strong support (100% MP, 100% ML, 1.00 BPP; Fig.
Morphologically, the four Crassisporus species can be easily distinguished from each other. Crassisporus microsporus differs from other species by its small pores (5–7 per mm), and small broadly ellipsoid basidiospores (4–5 × 3–3.7 μm). Except for C. imbricatus, C. leucoporus, C. macroporus, and C. microsporus, all have fusoid cystidioles in the hymenium; moreover, C. imbricatus produces imbricate basidiocarps. Previously, the type specimen of C. imbricatus was identified as Coriolopsis byrsina (Mont.) Ryvarden based on morphological characters (
Phylogenetically, Haploporus groups together with Crassisporus (Figs
Crassisporus is similar to Hexagonia Fr. and Neofomitella Y.C. Dai, Hai J. Li & Vlasák, because these genera share pileate brown basidiocarps, a trimitic hyphal system with clamped generative hyphae, and tissues becoming dark in KOH. However, Hexagonia is distinguished from Crassisporus by its larger hexagonal pores and thin-walled basidiospores (
Both Perenniporia Murrill and Crassisporus have hyaline and thick-walled basidiospores, but species of Perenniporia have cyanophilous, and variable dextrinoid skeletal hyphae. In addition, Perenniporia usually has truncate basidiospores (
Truncospora Pilát is similar to Crassisporus in having pileate basidiocarps and variable presence of cystidioles. However, Truncospora is distinguished from Crassisporus by variable dextrinoid and cyanophilous skeletal hyphae and truncate, strongly dextrinoid basidiospores (
Abundisporus Ryvarden and Crassisporus share effused-reflexed or pileate basidiocarps, but Abundisporus differs by its pale-umber to deep-purplish-brown or greyish- to umber-brown context, dimitic hyphal system, and pale-yellowish basidiospores (
Perenniporiella Decock & Ryvarden also has annual, pileate basidiocarps, and hyaline, thick-walled basidiospores, but it differs from Crassisporus in having a dimitic hyphal system (
Grammothelopsis Jülich is similar to Crassisporus in having thick-walled basidiospores; however, it differs from Crassisporus in its resupinate to effused basidiocarps with shallow irregular pores, and variable dextrinoid skeletal hyphae (
1 | Cystidioles absent | C. imbricatus |
– | Cystidioles present | 2 |
2 | Basidiospores broadly ellipsoid | C. microsporus |
– | Basidiospores oblong ellipsoid | 3 |
3 | Pore surface cream, buff to cinnamon-buff when fresh, pores 2–3 per mm | C. macroporus |
– | Pore surface white when fresh, pores 3–4 per mm | C. leucoporus |
We express our gratitude to Drs Tom May (Royal Botanic Gardens Victoria, Australia) and Yu-Cheng Dai (Beijing Forestry University) for arrangement of and assistance during field collections. The research was financed by the National Natural Science Foundation of China (Project Nos. 31670016, 31870008) and Beijing Forestry University Outstanding Young Talent Cultivation Project (No. 2019JQ03016).