Taxonomic circumscription of melanconis-like fungi causing canker disease in China.

Xinlei Fan,Jadson D.P Bezerra,Zhuo Du,Chengming Tian

doi:10.3897/mycokeys.42.29634

Xinlei Fan, Jadson D.P Bezerra + Show 2 more

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https://doi.org/10.3897/mycokeys.42.29634

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Abstract

Melanconis-like species comprise latent fungal pathogens with a wide range of woody hosts. Taxonomy of these pathogens is difficult due to their uninformative descriptions and similar asexual morphology. Based on molecular phylogenies, many species of this group were placed in various families of Diaporthales. In this study, eight species of melanconis-like fungi were isolated from Betulaalbosinensis, B.platyphylla (Betulaceae), Cornuscontroversa (Cornaceae), Corylusmandshurica (Betulaceae) and Juglansregia (Juglandaceae) in China. These species were phylogenetically placed in three families of Diaporhthales, i.e. Juglanconisjuglandina, J.oblonga (Juglanconidaceae), Melanconiellabetulicolasp. nov., M.corylinasp. nov. (Melanconiellaceae), Melanconisbetulae, Ms.itoana, Ms.stilbostoma (Melanconidaceae) and one new genus, Sheathospora (Melanconiellaceae). Sheathospora is proposed to accommodate Melanconiellacornuta with conical and discrete pycnidia with aseptate, hyaline, cylindrical to ellipsoidal conidia with distinct hyaline sheath on branches of Cornuscontroversa. Combined analyses of ITS, LSU, CAL, RPB2 and TEF1-α sequence data were used to construct the molecular phylogeny. Additionally, we provided separate phylogenetic trees for three families (Juglanconidaceae, Melanconidaceae and Melanconiellaceae) to show the species distribution of melanconis-like fungi in China.

Highlights

Melanconium (Diaporthales) was introduced by Link (1809) from dead branches of Fagus with M. atrum Link as the generic type. Corda (1837) extended this genus to 28 species
Tree topologies of all genera computed from the maximum parsimony (MP), Maximum Likelihood (ML) and Bayesian analyses were similar for the individual gene region and in the combined dataset
During the investigation of melanconis-like fungi in China, we identified eight species residing in three families (Juglanconidaceae, Melanconidaceae and Melanconiellaceae) of Diaporthales

Summary

Introduction

Melanconium (Diaporthales) was introduced by Link (1809) from dead branches of Fagus with M. atrum Link as the generic type. Corda (1837) extended this genus to 28 species. Melanconium (Diaporthales) was introduced by Link (1809) from dead branches of Fagus with M. atrum Link as the generic type. Sutton (1980) summarised more than 200 binomials that have been described in Melanconium, whereas no generic revision is available due to the uninformative descriptions and illustrations, few morphological characteristics, misplacement or poor condition of original specimens and lacking of ex-type cultures. Melanconium species has serious obstacles for appropriate interpretation and is phylogenetically distributed throughout the Diaporthales, especially in Juglanconidaceae, Melanconidaceae and Melanconiellaceae. The genus Melanconium may be synonymous with Melanconis and would have priority, the true identity of the generic type, M. atrum, is obscure and it was recommended to protect Melanconis over Melanconium (Rossman et al 2015)

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