Ophiostomatoid fungi associated with Hylurgus ligniperda, including six new species from eastern China.

Hylurgus ligniperda is a highly successful invader among bark beetles (Scolytinae), and has become established in every continent where its host plants occur. Bark beetles maintain a close symbiotic relationship with ophiostomatoid fungi whose morphology is highly adapted for beetle dispersal, and the presence of these fungal symbionts actively facilitates successful bark beetle invasions. At present, the fungal community associated with H. ligniperda in the newly invaded eastern China is still unknown. The aims of this study were therefore to characterize the ophiostomatoid communities associated with H. ligniperda in China. To achieve this, a total of 435 ophiostomatoid fungal strains were isolated from 326 adult samples collected in galleries and traps. Through morphological analysis and multilocus phylogenetic approaches, 13 species across six genera (Ceratocystiopsis, Graphilbum, Hawksworthiomyces, Leptographium, Masuyamyces, and Ophiostoma) were identified, of which six species were described as new. Fungal recovery rates differed significantly between gallery-derived and trap-collected adults (χ² test, p < 0.01). Furthermore, comparative analysis of ophiostomatoid fungal communities associated with H. ligniperda across five continents revealed distinct and well-defined assemblage patterns in each geographical region. This study elucidates the symbiotic relationship between H. ligniperda and ophiostomatoid fungi during invasion, providing a theoretical foundation for further research on their cooperative invasion and colonization mechanisms.