The Morphological Characteristics and Phylogenetic Analyses Revealed an Additional Taxon in Heteroradulum (Auriculariales)

Jia-Jin Li,Chao-Mao Liu,Chang-Lin Zhao

doi:10.3390/d14010040

Abstract

Auriculariales is diverse, embracing a number of corticioid, poroid, and hydnoid genera. The present study covers a new wood-inhabiting fungal species of Heteroradulum niveum sp. nov that is proposed on the basis of a combination of morphological features and molecular evidence. The species is characterized by the resupinate basidiomata, a monomitic hyphal system with generative hyphae with clamp connections; tubular cystidia; two- to four-celled basidia; and allantoid, colorless, thin-walled, smooth, IKI–, CB–, basidiospores (6.5–13.5 × 2.7–5.5 µm). Sequences of ITS and nLSU rRNA gene regions of the specimens were generated, and phylogenetic analyses were carried out with methods of maximum parsimony, maximum likelihood, and Bayesian inference. These phylogenetic analyses inferred from ITS+nLSU indicated that H. niveum is nested in Heteroradulum within Auriculariales. Further study within Heteroradulum on the basis of ITS+nLSU dataset revealed that it formed a monophyletic lineage with a strong support (100% BS, 100% BP, 1.00 BPP) and then grouped with H. yunnanensis.

Highlights

The Auriculariales is a characteristic order of Agaricomycetes (Basidiomycota), in which it has been introduced to embrace a number of corticioid, poroid, and hydnoid genera on the basis of a result of morphological, phylogenetic, and cytological studies [1,2,3]
The molecular systematics involving Heteroradulum based on the internal transcribed spacer (ITS) regions and the large subunit nuclear ribosomal RNA gene sequences revealed that the taxonomy and phylogeny of the Auriculariales with stereoid basidiocarps were employed, in which H. adnatum Spirin & Malysheva and H. semis Spirin & Malysheva were described as new taxa [4]
We present morphological and molecular phylogenetic evidence that supports the recognition of a new species within the Heteroradulum, on the basis of the internal transcribed spacer (ITS) region nLSU sequences

Summary

Introduction

The Auriculariales is a characteristic order of Agaricomycetes (Basidiomycota), in which it has been introduced to embrace a number of corticioid, poroid, and hydnoid genera on the basis of a result of morphological, phylogenetic, and cytological studies [1,2,3].The Auriculariales are wood decomposers inhabiting various hosts, from the tropics to the subarctic zone, in which some of them are able to survive under extreme climatic conditions [4]. The delimitation of Auriculariales has been principally based on the characteristics observed under optical and electron microscopy and supports by molecular analyses [5]. Heteroradulum Lloyd ex Spirin & Malysheva was typified by H. kmetii (Bres.) Spirin &. Seven species have been accepted in Heteroradulum worldwide [4,6,7,8,9,10,11]. The molecular systematics involving Heteroradulum based on the internal transcribed spacer (ITS) regions and the large subunit nuclear ribosomal RNA gene (nLSU) sequences revealed that the taxonomy and phylogeny of the Auriculariales with stereoid basidiocarps were employed, in which H. adnatum Spirin & Malysheva and H. semis Spirin & Malysheva were described as new taxa [4]. Möller [12] was revised, which showed that Heteroradulum grouped with Exidiopsis (Bref.) Möller [13] and Tremellochaete

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Conclusion