Hypoxylon fraxinophilum

Hypoxylon intermedium, also known as H. fraxinophilum, is a small ascomycete producing spherical perithecial stromata on dead wood of Fraxinus excelsior.

Stromata vary from brick-red to greyish hues, rarely exceeding 5 to 6 mm in diameter. Application of 10% KOH releases a distinctive yellow to greenish-yellow pigment into solution. Mature ascospores are notably large for the genus, occasionally exceeding 20 µm in length.

The specimens presented here were collected between January and May, growing on dead fallen branches of Fraxinus excelsior in Amurrio (Álava).