Revealing hidden fungal diversity: A new species of Leightoniomyces discovered from historic Herbarium SP-Fungi in Brazil

During a scientific visit to re-examine microfungi deposited in SP-Fungi, part of the Herbarium SP, a specimen previously identified as Leightoniomyces phillipsii and collected from decomposing roots was found to exhibit morphological features not reported in the original description. Detailed microscopic observations revealed consistent differences in conidial morphology, particularly the presence of digitate projections, and in reproductive structures, including connective cells forming short conidial chains. These characters support its recognition as a new species of the rare genus Leightoniomyces. Conidiogenesis is briefly discussed and a key to the known species are also provided. This study highlights the importance of herbarium collections as valuable repositories for detecting overlooked fungal diversity.