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

During an investigation of soil microfungi in Korea, a fungal strain designated KNUF-23-236 was isolated from a soil sample collected in Seocheon-gun, Chungcheongnam-do, Korea. Molecular analyses using the ITS regions and the LSU, SSU, and RPB2 genes revealed that Scytalidium aurantiacum and Scytalidium album are its close phylogenetic relatives, with sequence similarity levels ranging from 93.8% to 100.0%. However, based on cultural and morphological characteristics strain KNUF-23-236 differs from S. aurantiacum and S. album by having white-to-yellow colonies without reddish pigmentation, smaller hyphae (1.4-3.4 μm vs. 1.6-4.8 μm and 3.2-8.0 μm, respectively), arthrospores that transition from hyaline to brown rather than remaining consistently hyaline, and oval, septate chlamydospores that form singly or in chains, without branching. Furthermore, the phylogenetic trees constructed using the ITS sequence alone, the concatenated ITS and LSU sequences, and the combined sequences of three loci (ITS, SSU, and RPB2) confirmed a distinct phylogenetic position of KNUF-23-236 within the genus Scytalidium. Based on a combination of phylogenetic and morphological evidence, strain KNUF-23-236 is identified as a novel species of the genus, for which the name Scytalidium terrigenum sp. nov. is proposed.