Two novel species of Pestalotiopsis on Picea and Tsuga from temperate forests in the United States.

In a 2023 survey evaluating conifers with Rosellinia infections, five Pestalotiopsis fungal strains were isolated from plant samples obtained from Maine, New Hampshire, and Ohio. Based on a multi locus phylogenetic analysis (ITS, TUB, TEF), species-specific base pair substitutions, and morphological characterization, the five isolates were determined to constitute two novel species within the genus Pestalotiopsis. These two new species are introduced here as Pestalotiopsis maineana and Pestalotiopsis neohantoniensis. Pestalotiopsis maineana shares close phylogenetic affinity to P. fusiformis, P. brachiata, and P. hispanica, while P. neohantoniensis shares affinity with P. daliensis, P. chamaeropis, and P. hainanensis. Both new species described herein differ from close relatives based on various morphological characters including the number of basal appendages of the conidia. Further, species-specific base pair substitutions are provided for the TEF locus which had the most resolution when compared to the ITS and TUB loci. To our knowledge, P. maineana is the first species of Pestalotiopsis to be isolated and reported from white spruce (Picea glauca) while P. neohantoniensis is the first species to be isolated and reported from Serbian spruce (Picea omorika) and eastern hemlock (Tsuga canadensis). Overall, this study provides insight into the microfungi associated with conifers in the United States. Citation: Miller ST, Salgado-Salazar CS, Munck I, Castlebury LA (2025). Two novel species of Pestalotiopsis on Picea and Tsuga from temperate forests in the United States. Fungal Systematics and Evolution 16: 265-281. doi: 10.3114/fuse.2025.16.15.