Abstract
Hymenobolus agaves has been reported only in Europe and Africa on the American plant Agave americana (Asparagaceae). This fungus has never been found in the native range of its host, in arid ecosystems of northern and central Mexico and Texas, USA. It has been suggested to be a pathogen that can kill its host. The fungus grows on succulent leaf bases of the plant. The morphology - black apothecia with a hymenium that disintegrates when asci mature and dark ornamented ascospores - make this species very distinctive, but it has been collected and reported only a few times since its first description. Its systematic position has been unclear, and it has been treated as incertae sedis, that is of uncertain placement, in Leotiomycetes. With recent collections and additional data on the ecology of H. agaves, we use integrative taxonomy (DNA sequences, morphology, ecology) to show its relationships is with Cenangiaceae.