Taxonomy and phylogeny of lignicolous freshwater fungi from plateau lakes in Yunnan Province, China

Abstract Yunnan Province is located in southwestern China, at the core and intersection of the “Himalaya”, “Indo-Burma” and “Mountains of Southwest China” biodiversity hotspots. It is the most biodiverse province in China, acting as a major center for the origin and diversification of numerous species, and of which lignicolous freshwater fungi are one of the rich bioresources. As a part of our ongoing studies on freshwater fungi in Yunnan Province China, we collected lignicolous freshwater ascomycetes from Yunnan plateau lakes, combining morphological characteristics and multi-gene phylogenetic analysis (including, ITS, LSU, SSU, tef 1-α, tub 2 and rpb 2) to identify the species and reveal their phylogenetic placement. A total of 293 freshwater ascomycetes were collected, and through rigorous analysis, 126 species were identified, spanning three classes, 24 orders, 39 families, and 70 genera. Most of these fungi belong to Dothideomycetes and Sordariomycetes , with a few of Eurotiomycetes . Based on morphological and phylogenetic analyses, we introduce two new genera, Neomoromyces and Rostraeuseptisporum , and 40 new species, viz . , Apiospora fuxianhuensis , A. lacustris , Atractospora hydei , Chaetopsina hydei , C. septata , Chloridium hydei , Ch. yunnanense , Dematiosporium hydei , D. muriforme , Dictyocheirospora yunnanensis , Distoseptispora dujuanhuensis , Di. hongheensis , Di. jingdongensis , Halobyssothecium hydei , Hongkongmyces hydei , Kirschsteiniothelia hydei , Mytilinidion hydei , Neomoromyces hydei , Obliquifusoideum hydei , Ophioceras yunnanense , Plagiascoma hydei , Pseudodactylaria lacustris , Pseudostanjehughesia hydei , Rostraeuseptisporum hydei , Sporidesmiella dujuanhuensis , S. guttulata , S. hongheensis , S. hydei , S. lacustris , Sporidesmium dianchiense , Sp. distoseptatum , Sp. dujuanhuense , Sp. hongheense , Sp. lacustris , Sp. kunmingense , Sp. yangzonghaiense , Sp. yilonghuense , Thysanorea hydei , Tetraploa verrucosa , Xylolentia hydei . Detailed morphological descriptions and illustrations of these species are provided, along with a discussion of their phylogenetic relationships and distinctive morphological characters. Furthermore, five new combinations are introduced, viz . , Pseudodactylaria flammulicornuta (≡ Dodactylaria flammulicornuta ), P. palmae (≡ Do. palmae ), P. tunicata (≡ Do. tunicata ), P. uliginicola (≡ Do. uliginicola ) and Pseudostanjehughesia verrucosa (≡ Ceratosporium verrucosum ). Based on molecular sequence data and morphological characteristics, Dictyocheirospora aquadulcis and Dic. lithocarpi have been synonymized with Dic. heptaspora , Dic. alangii synonymized with Dic. appendiculata ; Dictyosporium lakefuxianense synonymized with Pseudodictyosporium wauense , Distoseptispora nanchangensis synonymized with Distoseptispora aquatica , Chaetopsina beijingensis synonymized with Ch. fulva . Ten new geographical records are reported in China and 10 species are first reported from freshwater habitats, and 6 species are newly reported both from China and from freshwater habitats. This study fills a gap in the research on fungal diversity in Yunnan Province, and improves our understanding of their ecological roles in freshwater ecosystems. Phylogenetic analysis provides a reliable molecular framework for the classification of lignicolous freshwater fungi, supporting the reassessment of fungal taxonomy and ensuring a more objective and evolutionarily natural classification of species. This work is dedicated to Professor Kevin D. Hyde on his 70th birthday, in recognition of his lifetime contributions to mycology and his extensive research and training of students. His wide-ranging work on freshwater fungi is highlighted in this paper.