# Novel Freshwater Ascomycetes from Submerged Plant Debris in the Zújar River (Extremadura Community, Spain)

## TL;DR

This study discovers and describes new freshwater fungi from decaying plant debris in a Spanish river, enhancing understanding of fungal diversity in Mediterranean ecosystems.

## Contribution

Five new freshwater fungal species are described, along with taxonomic revisions in two fungal orders.

## Key findings

- Five new freshwater ascomycete species were identified and described from the Zújar River.
- Polyscytalum submersum is the first record of its genus in the Iberian Peninsula.
- Taxonomic refinements were proposed for the orders Magnaporthales and Conioscyphales.

## Abstract

Freshwater fungi remain insufficiently documented in the Mediterranean river systems despite their key roles in organic-matter turnover. Here, we surveyed filamentous fungi associated with submerged decaying plant debris in the Zújar River (Extremadura, southwestern Spain) using a culture-based approach combined with phenotypic characterization and multilocus phylogenetic analyses (ITS, LSU, rpb1, rpb2 and tef-1α). A total of 49 strains were isolated and identified, revealing a diverse assemblage of Ascomycota. Five taxa are described as new to science: Arachnopeziza torrehermosensis, Conioscypha clavatispora, Neoanungitea torrehermosensis, Ophioceras diversisporum and Polyscytalum submersum. Notably, Polyscytalum submersum represents the first record of the genus for the Iberian Peninsula, while Arachnopeziza torrehermosensis, Neoanungitea torrehermosensis and Ophioceras diversisporum constitute the first records of their respective genera for Spain (and Neoanungitea torrehermosensis also for Europe). In addition, phylogenetic evidence supports taxonomic refinements within the orders Magnaporthales and Conioscyphales, including the establishment of Protophioceras to accommodate Ophioceras sichuanense and the establishment of Protoconioscypha for two previously misclassified Conioscypha species. Overall, this first mycological report of submerged plant debris in the Zújar River substantially expands knowledge of freshwater fungal diversity in the region and provides a refined framework for the taxonomy of several lineages of aquatic-associated ascomycetes.