Two novel species of <i>Pestalotiopsis</i> on <i>Picea</i> and <i>Tsuga</i> from temperate forests in the United States

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