Hosts: Rhizomnium punctatum
Found in an area where the very similar O. similis is locally frequent. Most of what I initially believed to be O. mnii has turned out to be O. similis as the spores are distinctly verrucose. However, the single apothecium here directly from Rhizomnium protonema appears to possess smooth ascospores.
Thank you to Marcel Vega for pointing out that O. mnii spores are much less verrucose than O. similis.
It is still possible that this collection is O. similis was it wasn’t studied thoroughly enough. O. mnii is not currently accepted as present in the British Isles yet. It should be searched for between Oct – Jan on the persistent protonema of Rhizomnium, especially on wood.
Bryophilous fungi 