Abstract
Cinnamomum cassia is a renowned medicinal and aromatic plant with significant economic importance and broad pharmacological applications. This study investigates the taxonomy and diversity of endophytic fungi belonging to the order Diaporthales, isolated from this plant in Guangdong Province, China. A total of six isolates were obtained from healthy leaves. These isolates were examined using morphological characteristics and multilocus phylogenetic analyses based on the internal transcribed spacer (ITS), large subunit ribosomal RNA gene (LSU), and translation elongation factor 1-alpha (tef1). Phylogenetic reconstructions inferred from maximum likelihood and Bayesian inference, together with morphological evidence, revealed that the isolates represent three distinct and previously undescribed species, which are herein described as Gnomoniopsis luodingensis sp. nov. (Gnomoniaceae), Ternstroemiomyces cinnamomi sp. nov., and Ternstroemiomyces zhaoqingensis sp. nov. (Ternstroemiomycetaceae). These findings expand the known host range of endophytic fungi and provide essential taxonomic data for the fungal community associated with this economically important medicinal plant.