Three new species of Colletotrichum (Glomerellaceae, Glomerellales) based on morphology and multilocus phylogeny from Fujian, China

Colletotrichum species are well-known plant pathogens, and many also exist as endophytes or saprobes on diverse plant hosts. In this study, three novel Colletotrichum species were isolated from diseased leaves of Millettia rugosa , Paederia scandens , and Pleioblastus fortunei in Fujian Province, China, and taxonomically characterized using an integrative taxonomic approach. Species boundaries were delineated through combined molecular phylogenetic reconstruction and morphological comparison with closely allied taxa. Phylogenetic reconstructions were carried out based on concatenated sequence datasets of five loci (ITS, gapdh , chs-1 , act , and tub2 ) using both maximum likelihood (ML) and Bayesian inference (BI) analytical methods. The results indicate that these three species form highly supported, independent monophyletic lineages clearly distinguishable from all previously described Colletotrichum species. Morphological assessment of colony traits, conidiogenous cells, and conidial morphology further confirms their taxonomic novelty by identifying stable phenotypic differences relative to phylogenetically close relatives. Consequently, three new species of Colletotrichum are formally proposed: C. millettii , C. pleioblasti , and C. wuyishanense . Phylogenetically, C. wuyishanense nests within the C. destructivum species complex, whereas C. millettii and C. pleioblasti represent two distinct monophyletic lineages nested within the genus without assignment to any formally described species complex. This study implies that additional undescribed Colletotrichum taxa remain to be uncovered from subtropical plant hosts across China, which will enrich genus-level species diversity and support native plant conservation and anthracnose disease management.