Annulohypoxylon annulatum

"Annulohypoxylon annulatum" is a pyrenomycete, a carbonaceous fungus that produces its ascospores in perithecia, and then shoots them out through an opening called the ostiole. "Annulohypoxylon" was derived from the original genus "Hypoxylon" in 2005 and is distinguished by their flat, disk-like rings encircling the ostioles.