Over the past two decades, numerous novel species have been identified within Dictyosporiaceae, primarily in Dictyocheirospora and Dictyosporium. A recent monograph has revealed that these two genera exhibit a distinct preference for freshwater habitats, particularly in southern China. However, further investigation into the distribution and diversity of the two genera in Guangdong and Guizhou Provinces remains insufficient. In this study, we conducted an analysis of four intriguing cheiroid hyphomycetes collected from flowing rivers in these two regions. Through morphological and phylogenetic analyses incorporating combined LSU, SSU, ITS, and tef1-α sequence data, we have identified them as a novel species in Dictyocheirospora (Dictyoc. submersa sp. nov.), two novel species in Dictyosporium (Dictyos. guangdongense sp. nov. and Dictyos. variabilisporum sp. nov.), and one previously documented species (Dictyos. digitatum). Specifically, the identification of Dictyos. guangdongense is primarily based on its distinct morphology, characterized by complanate, cheiroid, and brown to dark brown conidia, with a hyaline, short, and atrophied appendage arising from the apical cell of the outer row. In addition, the morphological distinctions between Dictyocheirospora and Dictyosporium are further clarified based on our new data. This study also highlights a few phylogenetic matters regarding Dictyosporiaceae.

Pogostemon cablin is one of the well-known Southern Chinese medicinal plants with detoxification, anti-bacterial, anti-inflammatory, and other pharmacological functions. Identification and characterization of phytopathogens on P. cablin are of great significance for the prevention and control of diseases. From spring to summer of 2019 and 2020, a leaf spot disease on Pogostemon cablin was observed in Guangdong Province, South China. The pathogen was isolated and identified based on both morphological and DNA molecular approaches. The molecular identification was conducted using multi-gene sequence analysis of large subunit (LSU), the nuclear ribosomal internal transcribed spacer (ITS), beta-tubulin (β-tubulin), and RNA polymerase II (rpb2) genes. The causal organism was identified as Stagonosporopsis pogostemonis, a novel fungal species. Pathogenicity of Stagonosporopsis pogostemonis on P. cablin was fulfilled via confining the Koch’s postulates, causing leaf spots and stem blight disease. This is the first report of leaf spot diseases on P. cablin caused by Stagonosporopsis species worldwide.

Pestalotiopsis phyllostachydis sp. nov. is introduced during a study of the diversity of bambusicolous fungi in Guangdong Province, China. The new species exhibits similar conidial morphology, pigmentation, and dimensions to its relatives; however, it can be distinguished by the length of its apical and basal appendages. The identification is corroborated by a phylogenetic analysis incorporating combined ITS, tef1-α and tub2 sequence data. A refined description and illustration of P. phyllostachydis are provided, accompanied by a morphological comparison of this new taxon and its closely related taxa compiled in a table. In addition, the common morphological characteristics utilized for interspecific identification are discussed incidentally.

Pogostemon cablin (Lamiaceae) is a component of traditional medicines in Southern China. The identification of P. cablin pathogens is essential for the production and development of this industry. During 2019–2020, a leaf spot on P. cablin was observed in Zhanjiang, Guangdong Province. The pathogen of the leaf spot was isolated and identified using morphological and phylogenetic methods. Phylogenetic analysis was performed using the internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (gapdh), RNA polymerase II (rpb2), translation extension factor 1-alpha (tef1), and Alternaria major allergen 1 (Alt-a1) genes. Based on phylogenetic and morphological studies, this was confirmed to be a novel species of Alternaria pogostemonis, with description and illustrations presented. The pathogenicity test of A. pogostemon was verified by Koch’s postulates as causing leaf spot disease. This is the first report of leaf spot disease in P. cablin caused by the Alternaria species. This study contributes to the knowledge of P. cablin leaf spot diseases.

Hongkongmyces is a genus of particular interest, as its type species was isolated from a biopsy specimen of a patient with an invasive foot infection, making it the only member of Lindgomycetaceae associated with human infections. However, most Hongkongmyces species have been identified as saprobes from freshwater habitats. During our ongoing investigation into the taxonomy and diversity of freshwater fungi in southern China and along a north-south gradient, we discovered a novel species, Hongkongmyces wuhanensis, from a freshwater lake in Wuhan City, China. The classification of the new species is supported by morphological characteristics and multi-locus phylogeny using combined LSU, SSU, ITS and tef1-α rDNA sequence data. Hongkongmyces wuhanensis is distinguished by its narrowly fusiform or vermiform, yellowish brown, mostly 5-septate ascospores. A detailed description, illustration, and an updated phylogenetic tree are presented. In addition, we discuss the possibility of Clohesyomyces being the asexual morph of Aquimassariosphaeria.

Species within Distoseptispora have demonstrated an exceptional rate of expansion with an ongoing investigation of lignicolous microfungi from freshwater and terrestrial habitats. In just one year (2025), a remarkable 36 species were described. However, despite the substantial increase in documented species, our understanding towards the specific/generic delimitation of Distoseptispora remains insufficient. In this study, we explored a mangrove habitat, a special aquatic habitat under salt stress, for Distoseptispora to facilitate a comprehensive understanding of this group. The specimen was collected from an estuarine mangrove wetland at the Hanjiang River in Guangdong Province, China. Multi-locus phylogenetic analysis of a concatenated LSU, ITS, tef1-α, and rpb2 dataset and morphological study identified our new collection as a novel species, Distoseptispora mangrovei. Distoseptispora mangrovei is unique by its short, solitary conidiophores and variable conidia, which are solitary or occasionally catenate, mostly elongated, obclavate, not or slightly constricted at the septa, but sometimes deeply constricted at some septa. Percurrent proliferation from cut ends of conidia is also occasionally observed.