Bryostroma guttulatum

Hosts: Didymodon tophaceus (GBI), D. fallax (only one perithecium seen), Blindia acuta (type host, continental Europe). Difficult to separate from B. halosporum morphologically other than by the size of the ascomata. Possibly a cryptic species complex and best considered in a broad sense.

Single black ascomata in the apices of infected Didymodon tophaceus. Totland Bay, Isle of Wight, late Dec 2025.
Overview of above.
Host shoot with B. guttulatum ascoma.
Outer excipulum in water.
Asci in water.
Hymenium in water.
Ascospore with narrow mucilaginous sheath (most obvious at the apex) in water.