ASCOMYCOTA | LECANOROMYCETES > CALICIALES > Caliciaceae

Common name:            -

Synonym:                    Buellia alboatra

Habitat:                         Coastal (for this entry)

Substrata:                     Rock, (trees)

Growth form:                Saxicolous, (corticolous)

Thallus:                  Crustose

Apothecia:                    Lecideine

BLS identity rating:        Graded 2/5 (relatively easy, although microscopic inspection recommended)

Thallus rather variable, often, wide-spreading, can be thin or thick, smooth or uneven, cracked or granulose, whitish to pale grey; apothecia immersed at first, discs initially flat, but becoming slightly raised and convex, black, but often with a whitish pruinose covering, up to 1mm dia., sometimes with a white thalline margin, which can be crenulate.

Diplotomma alboatrum is mostly found on calcareous rock, or stonework, but can also occur on trees with nutrient-rich bark, especially Ulmus and Fraxinus, and sometimes on worked timber. It could be confused with the very similar, closely related Diplotomma chlorophaeum, except that species is more likely to be seen on siliceous rock and walls and, although it occurs on the coast, has mainly been recoded from much further west so, on that basis alone, it's reasonably safe to assume that the photographed specimens shown here are, almost certainly Diplotomma alboatrum. Spot testing would confirm as the featured species doesn't show a K reaction, whereas Diplotomma chlorphaeum will slowly turn red. Some authors actually treat the two species as being synonymous despite the ecological and chemical differences.