Calicium corynellum was downlisted from England after Yahr (2015) determined the specimens from England were actually C. viride. However, Prieto et al (2020) determined that it is genetically different and show that it occurs scattered in Europe and North America.

New article by Prieto et al. (2020) assessed this sp. vs. C. viride and determined that it is not all C. viride as found by Yahr 2015 in England.
A new site was found in WA state.

Widespread but rare throughout temperate and hemi-boreal Europe, and also recorded from western North America. Easily overlooked and maybe under recorded. Apparently declining in Europe.

Siliceous rocks, steep or vertical and protected from direct rainfall, but in humid situations

In the UK, changing management of churchyards affects humidity. In North America logging impacts sites by changing humidity and temperature regimes.

Taxonomic status uncertain in the UK. Possibly confused with the similar but common and typically epiphytic C. viride.
Taxonomic issues addressed by Prieto et al. 2020, who determined that C. viride and C. corynellum are distinct phylogenetically and morphologically.
Found twice in Oregon Cascades by Rikkinen (2003) and once by Hardman and Stone in Ferry Co., (Colville NF) WA (unpublished, specimen Stone herbarium.)

Simkin, J. 2003. Calicium corynellum. Plantlife Back from the Brink dossier. 216, 28 pp.