Abstract
The taxonomy of the family Cucurbitariaceae and its allies, especially Fenestellaceae has received little attention despite its broad relevance. To further clarify phylogenetic relationships between the two families, new collections were made and samples examined morphologically. Morphometric observations reveal two new Fenestella species that are different from other known species and are introduced as Fenestella ostryae sp. nov. and F. mackenziei sp. nov. The asexual morph of F. ostryae is also established from single spore cultures and described. Phylogeny inferred from a combined dataset of ITS, LSU and SSU rDNA sequence also reveals a close association of the new taxa to F. fenestrata, but they are distinct. Sequence analyses also support our previous assumption that Fenestellaceae should be synonymized with Cucurbitariaceae. Pyrenochaeta quercina, Pyrenochaeta unguis-hominis and an additional new cucurbitaria-like isolate constitute a strongly supported monophyletic lineage within Cucurbitariaceae. To better resolve intergeneric level relationships and improve taxonomic issues within Cucurbitariaceae, a new genus, Neocucurbitaria gen. nov. is introduced with Neocucurbitaria acerina as a new species.