Additions to Diaporthe (Sordariomycetes, Diaporthaceae) and Neptunomyces (Dothideomycetes, Didymosphaeriaceae) species associated with Itea in Thailand

Itea is an economically and medicinally important plant, widely distributed across China, Japan and Southeast Asia, noted for producing rare sugars. Despite this, endophytic fungi associated with this plant remain poorly studied. This study focuses on the taxonomy and phylogeny of fungi isolated from healthy tissues of Itea japonica and I. riparia in Northern Thailand.

By incorporating morphology, multiloci phylogenetic analyses and nucleotide polymorphism comparison, we establish two novel species, Diaporthe iteae (Diaporthaceae, Sordariomycetes) and Neptunomyces iteae (Didymosphaeriaceae, Dothideomycetes) as well as report a new host and a new geographical record for Diaporthe coracoralinae. Diaporthe iteae sp. nov. was collected from I. japonica, and is recognized within the Diaporthe siamensis species complex (section Sojae).

In addition, D. coracoralinae is reported on I. japonica in Thailand for the first time, occupying a position within section Sojae with an undetermined species complex. Neptunomyces iteae sp. nov. was collected from I. riparia and is classified within the family Didymosphaeriaceae. Updated phylogenetic trees and comprehensive morphological comparisons with closely related taxa are provided and discussed for better resolution of species delimitation.

This study enhances our understanding of fungal diversity on Itea, and provides a taxonomic foundation for future biodiversity, ecological and applied studies.