Annulohypoxylon.
Fungi > Division Ascomycota > Class Sordariomycetes > Order Xylariales > Family Xylariaceae.
Genus Annulohypoxylon has 70 species.
27 of these were previously in the closely related Hypoxylon genus.
They have flask-shaped peritheca in a black fruiting body.
The ostioles are just visible on the surface.
Annulohypoxylon differ from Hypoxylon species by having a ring around the ostiole.
J.F.
