An update. I returned to the site and collected more of this. It turns out that the fruitbodies are associated with the aerial mycelium of the moss parasite Acrospermum adeanum, which was attacking the moss substrates. I think it may therefore be parasitic on that. I noticed this mycelium previously but did not make the connection. A better sample nicely shows the co-occurance of the Capronia s.l. with the Acrospermum. I screened adjacent Lepraria populations and found them absent of the Capronia. Could still be wrong on the host specificity front but, given the mess of so many hyphae, I doubt I will be able to find convincing cellular evidence of the parasitism.

Another update:

This seems to fit with Bryosphaeria epibrya (Racov.) Döbbeler. Will investigate further.

Bryosphaeria epibrya (Racov.) Döbbeler Ascomata* 95-170 Brown Setose with brown, straight or slightly curved, septate hairs up to 50 long and 3-4 wide. Hairs lower on the fruitbody are more hypha-like. Looks glabrous unless under high magnification Narrowly cylindrical 8 (pseudo-32) Paraphysoids 1-2 wide, thread-like, branched, septate, sparse and fragmenting in mature fruitbodies Ellipsoidal (9-)10-13 x 3-4 Hyaline to brownish 3 (but disintegrating into 4 cells in asci) 4-celled spores dissociate into 4 individual cells = pseudo-32-spored asci; spore fragments apparently exuded from asci in a blackish-brown drop, possibly suggestive of a sheath. Hyphae Colourless to brownish.

Hosts: Anomodon rugelii; Didymodon rigidulus; Brachythecium sp.; Leskea polycarpa; Platygyrium repens; Pylaisia polyantha Saprophytic on decomposing, discoloured plants Döbbeler (1978); Racovitza (1959)

George