What is "ambrosiella"

Ambrosiella is a genus of ambrosia fungi within the Ceratocystidaceae family. It was cirumscribed by mycologists Josef Adolph von Arx and Grégoire L. Hennebert in 1965 with Ambrosiella xylebori as the type species. All Ambrosiella species are obligate symbionts of ambrosia beetles. Several former species were moved to Raffaelea or Hyalorhinocladiella and there are currently seven species.