Rhizocarpon subpostumum
- Innhold
- Morphology
- Chemistry
- Habitat
- Comment
Morphology
Thallus cracked to areolate, up to 5 cm diam., thin; hypothallus indistinct; areolae up to 0.5 mm diam., pale grey, dull, angular to irregular; medulla KI–. – Apothecia up to 0.5 mm diam., black, epruinose, orbicular to angular, plane, distinctly marginate; excipulum reddish brown in the rim, paler in inner part, lacking crystals, K+ red; hypothecium medium brown, K–; hymenium colourless, containing crystals dissolving in K; epihymenium olivaceous brown, K–; ascospores 8 per ascus, 3-septate to submuriform, persistently colourless, 17–25 × 9–13 µm. – Conidiomata not seen.
Chemistry
Stictic acid; spot tests: medulla PD+ orange, K+ yellow, C–.
Habitat
On siliceous rock in the lowlands. In Norway known from a single locality (1939).
Comment
A poorly understood species.