Hysterographium fraxini

A species characterized by its enormous asci and muriform spores.

Asci cylindric-clavate, bitunicate, 8-spored, with biseriate to irregular arrangement within the ascus, up to 180 µm long and 35-40 µm wide, inamyloid in Melzer's reagent.

Paraphyses filiform, very slender, up to only 1.5 µm wide, hyaline, branched, covered by an amorphous substance of orange pigments.

Ascospores ellipsoidal, muriform in appearance, with numerous longitudinal and transverse septa, brown with greenish tints under the microscope, with numerous clearly visible refractive oil droplets.

Herbarium material available: JTP1929/23, 2323/24, and 2421/25.