ASCOMYCOTA | LECANOROMYCETES > LECANORALES > Psoraceae

Genus Protoblastenia, meaning 'forerunner of Blasternia', which was an earlier name for Caloplaca

Common name:             Members of the genus collectively known as 'orange dot lichens'

Synonyms:                     -

Habitat:                           Urban (for this entry)

Substrata:                      Stone, mortar

Growth forms:               Saxicolous

Thallus:                   Crustose

Apothecia:                     Lecideine

BLS identity rating: Graded 1/5 (identification should be straightforward)

Crustose thallus thin and superficial, more or less areolate, cracked-polygonal; dirty grey-brown to pale greenish-grey; apothecia numerous and usually well distributed, sessile, not in pits, varying in size from 0.3mm to 0.8mm dia., initially flat, but becoming convex, somewhat wart-shaped, margin thin, but soon excluded, colour variable, brownish-red to dull or bright orange, sometimes looking more orange-greenish, particularly when in shade.

Protoblastenia rupestris is a common and widespread species occurring on a wide range of calcareous substrata, including limestone, concrete, mortar and chalk pebbles.

Not to be confused Caloplaca species, particularly those of the superficially similar Caloplaca holocarpa aggregate, which typically have more densely crowded, flat apothecia with persistent margins.