A new species of Wrightoporiopsis, W. irregularis sp. nov, is described and illustrated from southern China. It is characterized by annual, pileate, imbricated and sulphur yellow basidiocarps, irregular hymenophore varying from poroid to hydnoid, a monomitic hyphal structure in context but dimitic in the trama, generative hyphae bearing clam connections, indextrinoid skeletal hyphae, the absence of gloeocystidia, cystidia and gloeoplerous hyphae, the presence of fusoid cystidioles, ellipsoid, thin-walled, finely asperulate, strongly amyloid, and acyanophilous basidiospores measuring 2.8–3.3×2.2–2.5μm. Phylogenetic analysis based on the combined ITS (internal transcribed spacer region) and nLSU (the large nuclear ribosomal RNA subunit) dataset demonstrated W. irregularis is a new lineage in Wrightoporiopsis.

Keywords: hericiaceae, taxonomy, wood-inhabiting fungi

Wrightoporiopsis YC Dai, Jia J Chen & BK Cui, typified by W. neotropica (Ryvarden) YC Dai, Jia J Chen & BK Cui, was recently established by Chen et al.¹ Some of taxa in the genus were previously treated under Wrightoporia Pouzar.^2–4 However, Phylogenetic analysis demonstrated that Wrightoporiopsis is distant from Wrightoporia sensu stricto, and these two genera in fact belong to two families, Hericiaceae and Wrightoporiaceae, respectively.¹ Wrightoporiopsis is characterized by pileate, yellow to yellowish-brown basidiocarps, a dimitic hyphal system with generative hyphae bearing clamp connections, skeletal hyphae usually dextrinoid, basidiospores ellipsoid to subglobose, hyaline, finely asperulate, strongly amyloid, and causing a white rot.¹

During a field trip in Hainan Province of southern China, a yellowish specimen with poroid to hydnoid hymenophore was collected, it has a dimitic hyphal structure with generative hyphae bearing clamp connections, and asperulate, amyloid basidiospores, so it belongs to Wrightoporia sensu lato based on these morphological characters, and was not recorded in China.⁵ After phylogenetic analysis of ITS+nLSU sequences and re-examination morphology in laboratory, it turn out to represent a new species of Wrightoporiopsis. In this paper its illustrated description is given and an identification key to accepted species of Wrightoporiopsis is provided.

Morphology

The studied specimens are deposited in the herbaria of the Institute of Microbiology, Beijing Forestry University (BJFC). Morphological descriptions are based on field notes and herbarium specimens. Microscopic analyses follow Chen et al.,¹ and Dai.⁶ Special color terms follow Anonymous⁷ and Petersen.⁸ In the text, the following abbreviations were used: KOH stands for 5% potassium hydroxide, CB stands for Cotton Blue, CB– stands for acyanophilous, IKI stands for Melzer’s reagent, IKI– stands for negative in Melzer’s reagent, IKI+ stands for amyloid in Melzer’s reagent, L stands for arithmetic average of all spore length, W stands for arithmetic average of all spore width, Q for L/W ratio, n (a/b) stands for measured from given number of spores (a) number of specimens (b).

Molecular phylogeny

The genomic DNA were obtained from dried specimens using the CTAB rapid plant genome extraction kit (Aidlab Biotechnologies, Co., Ltd., Beijing) following the manufacturer's instructions.^1,9 The internal transcribed spacer (ITS) regions were amplified with the primers ITS4 and ITS5,¹⁰ and the nuclear large subunit (nLSU) ribosomal RNA gene regions with the primers LR0R and LR7.¹¹ The PCR procedure for ITS and nLSU was follows Chen.¹ The amplicon purified and sequenced by the Beijing Genomics Institute, China with the same primers as in amplifications. All newly generated sequence was deposited in GenBank (http://www.ncbi.nlm.nih.gov).

In addition to the newly generated sequences, additional ITS and nLSU sequences of Wrightoporiopsis and related species from previous studies¹ were obtained from GenBank (Table 1) to explore the phylogenetic position of our specimen. All sequences were aligned using ClustalX v.1.83¹² and manually adjusted in BioEdit.¹³ Before the phylogenetic analysis, ambiguous regions at the beginning and the end of the alignment were deleted and gaps were manually adjusted to optimize the alignment. The edited alignment was deposited at TreeBase (http://purl.org/phylo/treebase; submission ID 23041).

Phylogenetic analysis was following to previous studies.^1,14 Maximum parsimony (MP), Bayesian inference (BI) and Maximum likelihood (ML) methods were used to perform the phylogenetic analysis. The three phylogenetic methods resulted in similar topologies for each dataset. Thus, only the topology from the MP analysis is presented. Branches that received bootstrap support from maximum parsimony (MP), maximum likelihood (BS) and Bayesian posterior probabilities (BPP) greater than or equal to 85% (MP and BS) and 0.95 (BPP) were considered as significantly supported.

Phylogenetic analyses

A total of 60 ITS (30) and nLSU (30) sequences included sequences from 31 fungal collections representing 16 species (Table 1) in this study, were used in the phylogenetic analyses. The alignment, generated by the ITS+nLSU dataset, contained 2147 characters. MP tree yielded four similar topologies (TL=1496, CI=0.606, RI=0.816, RC=0.494, HI=0.394). BI resulted in a similar consensus tree as the MP tree achieving an average standard deviation of split frequencies <0.01 after 2.5 million generations. ML tree also resulted in a topology similar to that with MP tree, and so only show the MP tree. BT values (≥80%) and BPPs (≥0.95) are shown at the nodes (Figure 1).

Hericium abietis (Weir ex Hubert) K.A. Harrison and Hericium coralloides (Scop.) Pers. were used as outgroups because they are closely related to Wrightoporiopsis according previous studies.^1,14 Based on the phylogenetic tree inferred from the combined ITS+nLSU dataset (Figure 1), shows that the newly sequence specimen formed a distinct lineage within Wrightoporiopsis clade, and, so we described a species of the Wrightoporiopsis.

Wrightoporiopsis irregularis YC Dai, Q Chen & XH Ji, sp. nov. (Figure 2 & Figure 3)