Phylogenetic and Morphological Analysis of a Novel Tolypocladium Species Isolated from Soil in South Korea

A fungal strain designated KNUF-22-014, belonging to the family Ophiocordycipitaceae, was isolated from a soil sample collected in Sobaeksan National Park, South Korea. Phylogenetic trees based on the combined sequences of internal transcribed spacer (ITS) regions and the large subunit of 28S rRNA (LSU) gene, as well as on five concatenated loci (LSU, ITS, translation elongation factor 1α, β-tubulin, and subunit 1 of RNA polymerase II), revealed that the isolate falls within the clade containing the genus Tolypocladium but occupies a distinct phylogenetic position. Its closest relative is T. tropicale. Morphologically, strain KNUF-22-014 can be distinguished from T. tropicale by the shape of its phialides (subcylindrical vs. lageniform), its conidiophore type (arborescent or unbranched vs. trichodermatoid), and its larger conidia size (2.1 ± 0.1 µm vs. 1.5 ± 0.1 µm). Phylogenetic analysis and morphological observations indicate that KNUF-22-014 represents a novel species in the genus Tolypocladium, for which the name Tolypocladium sobaeksanense sp. nov. is proposed.