Hymenoscyphus serotinus

A species typical of beech (Fagus sylvatica) forests, fruiting in gregarious swarms on small fallen branches and twigs. Apothecia measure around 5 mm across when flattened at maturity, typically yellow to cream-yellow, though pure white forms occur.

Macroscopically it resembles numerous congeners, but the distinctly curved, arcuate morphology of its ascospores containing numerous guttules ensures reliable identification.

Specimens examined for this study were gathered in November on beech twigs in Orduña (Bizkaia). Additional macroscopic photographs illustrate previous collections from Entzia-Iturrieta (Álava) and Erroibar (Navarra), also on beech wood in September and October, respectively.