Buellia norstictica Imshaug in sched.
Thallus: dispersed whitish areoles on a black prothallus.
Hymenium: greenish at base
Ascospores: 14.5-18 x 8 Ám
Chemistry: atranorin, nostictic acid by TLC
Description & Ecology:
Several collections from the Falkland Islands.
This species is superficially similar to Rhizocarpon immersum (see below) from which it is separated by its simple paraphyses and Lecanora-type asci.
Probably a synonym of Buellia spuria, although the norsticitic acid chemotype may deserve some taxonomic status, possibly as a separate geographical variety (F. Bungartz pers. comm.)