Orbispora gen. nov., ancestral in the Scutellosporaceae (Glomeromycetes)

Scutellospora pernambucana and S. projecturata are transferred into Orbispora, our proposed new genus in the arbuscular mycorrhiza-forming Scutellosporaceae (Glomeromycota). Orbispora is recognized by spores formed terminally on sporogenous cells and three spore walls with single mono-lobed hyaline to subhyaline germination orbs on the inner 'germinal' wall that appear identical to the orbs in Kuklospora colombiana, K. kentinensis, and a few Acaulospora species. DNA sequence analyses show the two Orbispora species as ancestral within the sporogenous cell-forming Glomeromycetes. An updated key summarizes the morphological differences among species in the Scutellosporaceae.