A novel coniothyrium-like genus in <i>Coniothyriaceae</i> ( <i>Pleosporales</i>) from salt marsh ecosystems in Thailand

Abstract

In this study, a novel coniothyrium-like genus <italic>Coniothyrioides</italic> is introduced to <italic>Coniothyriaceae</italic> based on a fresh fungal collection from salt marsh habitats in Thailand. Coniothyrium-like taxa are taxonomically controversial and have been classified into different families in <italic>Pleosporales</italic> such as <italic>Didymosphaeriaceae</italic> (<italic>Alloconiothyrium</italic> and <italic>Paraconiothyrium</italic>), <italic>Coniothyriaceae</italic> (<italic>Coniothyrium</italic>) and <italic>Didymellaceae</italic> (<italic>Microsphaeropsis</italic>). However, our novel genus shares similar morphology to some key characters in <italic>Coniothyriaceae</italic> in having dark, globose pycnidia, uni-locular conidiomata, a central ostiole, a peridium of <italic>textura</italic> <italic>angularis</italic> cells, and doliiform conidiogenous cells with a periclinal thickening at the apex, while conidial morphologies are diverse. The presence of setae arising from the outer peridial wall is the main difference between <italic>Coniothyrioides</italic> and other closely related <italic>Coniothyriaceae</italic> genera. Phylogenetically, LSU-SSU-ITS sequence analyses confirm the placement of this novel genus as a distinct lineage within <italic>Coniothyriaceae</italic>. Species boundaries were defined, based on morphology and multi-gene phylogenetic analyses using maximum likelihood and Bayesian inference analyses. The comprehensive descriptions and micrographs are provided. Our findings expand the taxonomic knowledge of <italic>Ascomycota</italic> in salt marsh ecosystems.