Hyalorbilia fagi

A minute ascomycete occurring scattered on a decorticated fallen trunk of Fagus sylvatica.

Medullary excipulum composed of a thin layer of globose to ellipsoidal hyphae, underlain by a thick layer of cylindrical, very elongate hyphae, parallelly arranged, hyaline and thick-walled; these ectal excipulum hyphae are key to distinguishing the species from potential confusions in the genus Orbilia, which has globose ectal excipular hyphae.

Asci cylindrical, 8-spored, only up to 45 µm long and up to 3.5 µm wide, with a simple base (lacking croziers), covered by a congophilic gel layer over the entire hymenial surface.

Paraphyses scarce, simple, filiform, narrower than the asci.

Ascospores cylindrical to allantoid, smooth, hyaline, thin-walled, with two darker guttules situated at both poles.

Herbarium material available: JTP1995/23.