Aquacidia antricola (Taylor) Aptroot

     Thallus crustose strongly attached to its substrate, grainy to somewhat rough surface, glaucous green, greenish-gray, green, if not submerged, bright green almost fluorescent if subjected to splashing water, very prominent and conspicuous hypothallus, always present, white, whitish, sometimes bordered with blackish-brown. Apothecia infrequent and sometimes absent, 0.4-0.6 mm in diameter, more or less sessile, convex disc, beige, beige-pinkish, light brown, bordered by a more or less persistent white cottony margin. Asci with 4-5-6-8 spores as a result of the abortion of some spores. Colorless spores, long fusiform, 2-9-septate with a tapering appendage at the ends, very variable in size, 14-28 x 3-4 µm to 25-40 x 3-4 µm according to the authors, 30-50 x 3- 4.5 µm according to our measurements. Presence, especially in sterile individuals, of large sessile pycnidia, globular at the beginning then in irregular cups, white and cottony. Pycnospores of 4-5 x 1-1.5 µm according to our measurements, typically in dumbbells with a constriction in the center. C-, K-, CK-, P-, UV + typically pink. Rare species coming on or under damp siliceous rocks sheltered from direct light, sometimes partially submerged, at the edge of streams and unpolluted rivers, more rarely at the base of old trees sheltered from large roots.

N.B. Same habitat as Bacidia viridifarinosa which might be its sterile sorediated form according to some authors.

NB Very similar (and formerly confused) with Bacidina inundata which has a similar or neighboring habitat but which is distinguished from it by its more granular thallus less bright green, its more numerous apothecia more greyish and without cottony edge, its pycnidia submerged in the thallus and not sessile and its less important hypothallus.