# Cladobotryum rhodochroum sp. nov. (Hypocreales, Ascomycota): A New Fungicolous Species Revealed by Morphology, Phylogeny, and Comparative Genomics

## TL;DR

A new species of fungus, Cladobotryum rhodochroum, was identified using a combination of morphology, phylogeny, and genomics.

## Contribution

The study introduces a new fungal species supported by integrative morphological, phylogenetic, and genomic data.

## Key findings

- Phylogenetic analysis shows URP strains form a distinct clade related to C. tenue and C. rubrobrunnescens.
- Genomic comparisons reveal significant divergence in transposable elements, mitochondrial architecture, and secondary metabolite potential.
- Morphological differences confirm the distinctness of Cladobotryum rhodochroum from related species.

## Abstract

Species of the ascomycetous genus Cladobotryum (Hypocreales, Hypocreaceae) are ecologically and economically important mycoparasites that cause cobweb disease in cultivated and wild mushrooms. Despite their significance as fungal pathogens and producers of bioactive metabolites, the taxonomy of Cladobotryum remains unresolved due to extensive morphological plasticity, complex teleomorph–anamorph connections, and the presence of cryptic species. This study employs an integrative approach combining micro- and macromorphological characterization, multi-locus phylogeny (ITS, rpb2, and tef-1a), and comparative genomics to clarify the taxonomic position of the Greek isolate Cladobotryum sp. ATHUM 6904, previously designated as an unclassified red-pigmented (URP) strain. Phylogenetic analyses demonstrated that URP strains form a distinct, well-supported clade closely related to C. tenue and C. rubrobrunnescens, yet genetically and morphologically distinct from both. Comparative genomic analyses of isolate ATHUM 6904 and the ex-type strains of C. tenue and C. rubrobrunnescens revealed pronounced divergence in transposable element content, mitochondrial genome architecture, gene order, orthologous gene composition, secondary metabolite biosynthetic potential, and overall genomic distance. Micro- and macromorphological comparisons further supported the differentiation of isolate ATHUM 6904 from both reference species. Based on the combined molecular, morphological, and genomic evidence, the Greek isolate ATHUM 6904 is described as a novel species, Cladobotryum rhodochroum sp. nov.