<i>Neostagonosporella sasae</i> (<i>Phaeosphaeriaceae</i>, <i>Pleosporales</i>), a newly described species from bamboo leaves in Japan

Although approximately 300 species of bambusicolous fungi have been described in Japan, Neostagonosporella and related taxa have not been reported. In this study, a Neostagonosporella-like fungus was collected from living leaves of Sasa borealis and unidentified bamboos in Japan and described as a new species (Neostagonosporella sasae) based on morphological examinations and phylogenetic analyses. This species is characterized by multiloculate ascostromata, trabeculate pseudoparaphyses, cylindrical to fusiform hyaline 5–6-septate ascospores, phialidic conidiogenesis, and two types of conidia: 3–6-septate cylindrical macroconidia and aseptate or rarely 1-septate ellipsoidal microconidia. These characteristics resemble those of N. bambusicola and N. sichuanensis. However, N. sasae differs from N. bambusicola in its substrates (vs. dead leaves of bamboo), trabeculate pseudoparaphyses, and shorter ascospores, and from N. sichuanensis in its substrates (vs. living to nearly dead stems and branches of Phyllostachys heteroclada), shorter ascospores, and larger microconidia. Phylogenetic analyses showed that N. sasae formed a robust monophyletic clade within the Neostagonosporella lineage but were separated from other known species of this genus. Furthermore, we revised the genus definition to incorporate additional ecological and morphological characteristics: bamboo leaves as substrates (previously limited to stems and branches), and cellular pseudoparaphyses (previously limited to trabeculate forms).