Pseudomicrodochium bryophilum

Hosts: Cephalozia (Nowellia) curvifolia and Ptilidium pulcherrimum

Many thanks to Peter Döbbeler for confirming the identification. The attachment points between the conidiogeneous cells and the conidia were difficult to visualise confidently. It is likely that this fungus is quite common on hosts on rotting wood, so it is worth searching for on the likes of Cephalozia, Lophocolea, etc.

The wide host range may be explained by the possibility that this fungus derives its nutrients from host cuticle / secreted resources. It does not appear to be intracellular. Therefore, putatively, it shares its host niche with the likes of Bryochiton spp. and Lichenopeltella alpestris agg., which similarly have rather wide host ranges, at least under currently accepted species concepts.

Powdery brownish patches on Cephalozia (Nowellia) curvifolia on rotting wood. Glenashdale Falls, Isle of Arran, VC100 (Scotland).
Rehydrated specimen (5 months in herbarium) showing blackish blotches on shoots and perianths of Cephalozia curvifolia. Leg. C.D. Preston, Sept 2021. VC48, Merioneth, Wales.
A compound image showing infected shoot and (upper inset) sporodochia with conidiogeneous cells and (lower inset) a 2-septate conidium. Note the middle cell is more rounded and thick-walled than the distal cells. From above specimen. Bar = 10 microns.
A group of conidia from the above specimen.
A cluster of conidia from a specimen from Goblin Coombe near Bristol, April 2024. Leg. et det. Greiff.