Phialomyces koreanus sp. nov., a Novel Species Isolated from Soil in Korea

To investigate fungal diversity in soil in Korea, soil samples were collected from Geumsan-gun, Chungcheongnam-do. A fungal strain designated as KNUF-23-295 was isolated and cultured on potato dextrose agar (PDA) to examine its morphological characteristics. The strain produced hyaline conidiophores and ampulliform phialides with conidia formed in chains, consistent with the genus Phialomyces. BLAST analysis of the internal transcribed spacer (ITS) sequence showed similarities of 97.3%, 94.6%, and 94.4% with P. macrosporus, P. humicoloides, and P. arenicola, respectively, indicating that strain KNUF-23-295 belongs to the genus Phialomyces. Strain KNUF-23-295 differed from previously described species of Phialomyces in its cultural and morphological characteristics. On PDA, the strain produced a pink pigment and formed relatively small phialides (8.4–20.9 × 2.0–4.7 μm) and conidia (3.5–8.2 × 2.3–4.4 μm). The conidia were observed singly, in short or long chains, and in aggregates. To determine its phylogenetic position within the genus Phialomyces, concatenated phylogenetic analyses were conducted using the ITS, large subunit ribosomal RNA gene (LSU), chaperonin containing TCP1 subunit 8 gene (Cct8), and RNA polymerase II second-largest subunit gene (RPB2) sequences. The phylogenetic trees showed that strain KNUF-23-295 formed a distinct and independent clade within the genus Phialomyces. Based on cultural, morphological, and phylogenetic analyses, strain KNUF-23-295 is proposed as a novel species, Phialomyces koreanus sp. nov. This study represents the first report of the genus Phialomyces in Korea.