Humicola ovoideum sp. nov. and Pseudohumicola obscura sp. nov., Two Novel Chaetomiaceae Species Reported in Korea

During an investigation of soil micro-fungi in Korea, two fungal strains designated as strains KNU-1816T and KNUF-20-124T were isolated from soil samples collected from Gyeongbuk province. The morphological features of strain KNU-1816T included obovate greenish-yellow ascomata with bristle-like dark-brown hairs and clavate asci with 8 biseriate bilaterally flattened limoniform olivaceous brown ascospores containing an apical germ pore and subhyaline or pale brown conidia. While strain KNUF-20-124T produced aleurioconidia-like conidia and hyaline, Acremonium-like conidiophores. Phylogenetic analyses based on the concatenated nucleotide sequences of the internal transcribed spacer (ITS) regions, partial sequences of the large subunit (LSU) 28S rRNA, RNA polymerase II largest subunit (RPB2), and beta-tubulin (TUB2) placed strains KNU-1816T and KNUF-20-124T within the family Chaetomiaceae, specifically in the genera Humicola and Pseudohumicola, respectively. Each occupied a distinct phylogenetic position separate from known species, thereby warranting their designation as novel species. Here, we describe and illustrate two new species, Humicola ovoideum sp. nov. KNU-1816T and Pseudohumicola obscura sp. nov. KNUF-20-124T, providing detailed morphological descriptions and phylogenetic insights.