The new family Septorioideaceae, within the Botryosphaeriales and Septorioides strobi as a new species associated with needle defoliation of Pinus strobus in the United States.

Recent sampling of eastern white pine (Pinus strobus) affected by white pine needle defoliation (WPND) within the northeastern U.S. has found that a putative new species, closely related to Septorioides pini-thunbergii, was the most frequently isolated species. Septorioides pini-thunbergii is currently the only known species of its genus in the family Botryosphaeriaceae and is associated with needle cast of Pinus thunbergii in Japan. This study aims to complete a morphological description of the putative new species and use DNA sequence data of six gene loci (SSU, LSU, ITS, β-tubulin, EF1, and RPB2) to accurately place the putative new species within the Botryosphaeriales. Morphological comparisons have shown that this putative new species is distinct from S. pini-thunbergii. Comparison of DNA sequence data has further confirmed our morphological findings, indicating the classification of a new species which we describe as Septorioides strobi sp. nov., marking the first report of the genus Septorioides within the U.S. Subsequently, our phylogenetic analysis has further revealed that S. pini-thunbergii and S. strobi do not reside within the Botryosphaereace, but comprise a new family within the order Botryosphaeriales we recognize as Septorioideaceae fam. nov. Taxonomic novelties: New family - Septorioideaceae S. Wyka & K. Broders fam. nov. New species - Septorioides strobi S. Wyka & K. Broders sp. nov.