Chionosphaera
Chionosphaera is a genus of fungi in the family Chionosphaeraceae. It has four species.
Taxonomy
The genus was circumscribed by the mycologist Darrell Cox in 1976. He assigned Chionosphaera apobasidialis as the type species. Cox discovered this fungus after incubating dead bur oak tree branches in a moist chamber for a few days and observing the resulting tiny white fruiting bodies emerging between the cracks of the bark. The genus name, which combines the Greek chion with sphaira, refers to the form of the fungus's glistening white fruiting body, which Cox described as a "tiny stalked snowball" when viewed under a microscope.Cox suggested classifying Chionosphaera in the Filobasidiaceae, and proposed emending the description of this family to accommodate this inclusion. Instead, in 1982 the mycologists Franz Oberwinkler and Robert Bandoni proposed the family Chionosphaeraceae, with Chionosphaera as the type genus.
Description
Chionosphaera apobasidialis produces tiny, white, club-shaped structures known as synnemata on the bark of dead branches from trees like bur oak, post oak, and American hornbeam. These structures look similar to those produced by certain types of imperfect fungi and some other basidiomycetes.In laboratory conditions, Chionosphaera apobasidialis can complete its life cycle on various types of growth media. Its spores, called basidiospores, germinate by budding—a process where a new cell forms directly from the parent cell. The fungus requires two different mating types to reproduce sexually. It only forms its fruiting bodies in the lab when grown alongside another fungus, such as a species of Cladosporium or a similar mold.
The basidia of Chionosphaera are a special type known as apobasidia, which are more commonly found in gasteromycetes but are unique in this context among the hymenomycetes, a large group that includes most mushroom-forming fungi.
Species
Chionosphaera apobasidialis Chionosphaera cuniculicola Chionosphaera erythrinae Chionosphaera phylaciicolaTwo lichenicolous former members of the genus were transferred to the genus Crittendenia in 2021.