Five Novel Taxa from Freshwater Habitats and New Taxonomic Insights of Pleurotheciales and Savoryellomycetidae.

Wei Dong,Mingkwan Doilom,Huang Zhang,Zhangyong Dong,Nakarin Suwannarach,Gennuo Wang,Er-Fu Yang,Xiandong Yu,Kevin D Hyde,Rajesh Jeewon

doi:10.3390/jof7090711

Abstract

Pleurotheciales is the largest order in Savoryellomycetidae with a large proportion of species known from freshwater habitats. In order to investigate the phylogenetic relationships of taxa within Pleurotheciales and contribute to their diversity, submerged wood was collected from freshwater habitats in China (Yunnan Province) and Thailand. Two dematiaceous, sporodochial hyphomycetes and one annulatascales-like ascomycete with unusual morphology as compared to extant ones were discovered. They were subjected to DNA-based phylogenetic analyses and the results revealed three distinct lineages in Savoryellomycetidae. This morpho-phylo taxonomic study supports the establishment of five novel taxa including two novel genera, Obliquifusoideum and Saprodesmium, and three novel species, Coleodictyospora muriformis, Obliquifusoideum guttulatum and Saprodesmium dematiosporum. Coleodictyospora muriformis and S. dematiosporum are placed in Pleurotheciales, while O. guttulatum is referred to Savoryellomycetidae genera incertae sedis. The phylogenetic relationships are also presented for Coleodictyospora and Pseudocoleodictyospora, which raises an intriguing taxonomic issue. These two genera are positioned in two different classes, viz Sordariomycetes and Dothideomycetes, although they are quite similar except for the presence of a conidial sheath. This study expands our knowledge of the fungal diversity of freshwater fungi, and also indicates that Pleurotheciales species are mostly found in freshwater habitats.

Highlights

Savoryellomycetidae currently accommodates four orders, Conioscyphales, Fuscosporellales, Pleurotheciales and Savoryellales
Pseudocoleodictyospora to accommodate three hyphomycetous species collected from the bark of living Tectona grandis and three hyphomycetous species collected from the bark of living
The presence of conidial sheath as a criterion for delimiting two genera is interesting as this is often used for species delimitation in classification, such as species in Astrosphaeriella, Dictyosporium, Kirschsteiniothelia and Natipusilla [48]

Summary

Introduction

Savoryellomycetidae currently accommodates four orders, Conioscyphales, Fuscosporellales, Pleurotheciales and Savoryellales. This is based on evidence from phylogenetic analyses and divergence time studies with the order having a stem age estimated as 268 MYA [1]. The four orders clustered as a robust clade in all studies [1,2,3]. Pleurotheciales, with a single-family Pleurotheciaceae [4], is the largest order in Savoryellomycetidae. Multi-locus phylogenetic relationships of Pleurotheciaceae species were investigated to better understand their taxonomy [3,4,6,7,8,9,10] and as a result, eleven genera were accepted in the family [11]

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Conclusion