Scytalidium terrigenum sp. nov. : a New Species Isolated from Soil in Korea

A fungal strain designated KNUF-23-236 was isolated from a soil sample collected in Maseo-myeon, Seocheon-gun, Chungcheongnam-do, Republic of Korea during a survey of soil-inhabiting fungi. The isolate was identified through cultural, morphological, and molecular analyses. Sequence analyses of the internal transcribed spacer (ITS) regions, the large subunit of nuclear ribosomal RNA (LSU) gene, the small subunit of nuclear ribosomal RNA (SSU) gene, and the RNA polymerase II subunit (RPB2) genes revealed that KNUF-23-236 is closely related to Scytalidium aurantiacum and Scytalidium album. ITS regions and LSU gene sequences showed 97.5% and 98.5% similarity with the closely related species, S. aurantiacum. For S. album, ITS regions and LSU, SSU and RPB2 gene sequences showed 96.9%, 100.0% and 93.8% similarity. However, the strain exhibited clear differences from these two species on the basis of cultural and micromorphological characteristics. Compared with closely related species, KNUF-23-236 exhibited colonies ranging from white to yellow, and it also produced relatively small hyphae measuring 1.4–3.4 μm, arthrospores measuring 2.5–8.9 × 1.7–2.9 μm that showed a transition from hyaline to brown and oval, septate chlamydospores occurring singly or in unbranched chains. Phylogenetic analyses were performed using the ITS regions, LSU, SSU and RPB2 genes. Phylogenetic trees indicated that KNUF-23-236 forms a distinct lineage within the genus Scytalidium. Based on the cultural characteristics, morphological differences and distinct phylogenetic clustering of the strain, we propose Scytalidium terrigenum sp. nov. KNUF-23-236 as a novel species within the genus Scytalidium.