<i>Thyridium intestinalis</i> sp. nov.: A New Coprophilous Fungal Species Isolated from Cattle Feces in South Korea

The genus <i>Thyridium</i> has undergone significant taxonomic revision in recent years, including the incorporation of <i>Phialemoniopsis</i> and the establishment of the order <i>Thyridiales</i>. During a recent survey of coprophilous fungi in South Korea, we isolated a distinctive ascomycete from Hanwoo cattle feces that exhibited unique morphological and physiological traits. An integrative taxonomic approach combining morphological, physiological, and molecular evidence supports its recognition as a novel species. Multilocus phylogenetic analyses based on concatenated sequences (internal transcribed spacer (ITS), large subunit nuclear (LSU), <i>β</i>-tubulin, and actin) placed the new species within a monophyletic clade in <i>Thyridium</i>, distinct from all previously described taxa, with strong support values. Morphologically, <i>T. intestinalis</i> is characterized by flamingo-pink colonies on potato dextrose agar (PDA), distinctive branching patterns of conidiophores, and oval to cylindrical conidia, distinguishing it from closely related species. Physiologically, it exhibits a distinctive enzymatic profile with strong esterase (C4), leucine arylamidase, and N-acetyl-<i>β</i>-glucosaminidase activities. This study represents the first report of <i>Thyridium</i> from coprophilous habitats in East Asia, significantly expanding our understanding of the ecological plasticity and host associations. The enzymatic activity of <i>T. intestinalis</i> may shed light on its adaptation to herbivore-associated environments and may indicate its potential relevance to biomass degradation.