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Morphological and Phylogenetic Characterization of Raffaelea xyleboricola sp. nov. from Xyleborus Beetles in Korea

Summary

Researchers discovered a new fungal species living inside ambrosia beetles collected from Korean apple orchards. By examining the fungus under a microscope and analyzing its genetic material, they confirmed it was previously unknown to science. This fungus, named Raffaelea xyleboricola, may help scientists better manage beetle-related tree diseases and protect apple orchards.

Background

Ambrosia beetles in the genus Xyleborus maintain mutualistic relationships with fungal symbionts that serve as their principal food source. The genus Raffaelea comprises major fungal symbionts of ambrosia beetles, with previous studies identifying only two Raffaelea species in Korea. This study addresses the need for accurate species-level identification of fungal isolates from ambrosia beetles in Korean apple orchards.

Objective

To characterize and identify a fungal isolate obtained from ambrosia beetles collected in Korean apple orchards through morphological examination and molecular phylogenetic analysis. The study aimed to determine the taxonomic identity and phylogenetic position of the isolate designated ARI-25-A12.

Results

The collected beetles were identified as Xyleborus species, showing 99.0% similarity to Xyleborus pfeili. The fungal isolate ARI-25-A12 exhibited distinctive morphological features including white fur-like colonies, hyaline globose conidia averaging 5.2 × 5.2 μm, and yeast-like sprout cell formation. Phylogenetic analyses based on ITS and concatenated LSU, SSU, and β-tubulin sequences consistently classified ARI-25-A12 as a distinct lineage within the genus Raffaelea, separate from all previously described species.

Conclusion

Based on morphological and molecular phylogenetic evidence, the isolate ARI-25-A12 is described as a novel species designated Raffaelea xyleboricola sp. nov. The species shows distinctive cultural characteristics, including non-mucilaginous white colonies and globose conidia, which differ from related Raffaelea species. Future investigations into the pathogenic potential and geographic distribution of R. xyleboricola in Korea are recommended for effective tree disease management.
  • Published in:Mycobiology,
  • Study Type:Taxonomic characterization study,
  • Source: 10.1080/12298093.2025.2590303, PMID: 41356629
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