Blastenia crenularia forma = Caloplaca crenularia forma

    Differs from the Caloplaca crenularia s.l. type - to which it was associated because of the colour of its apothecia - by two main characteristics: absence of thallus and apothecia clustured and forming small muriform mounds. The absence of thallus might suggest Caloplaca arenaria but the lack of mature, well-developped ascospores makes it difficult to link it to this latter. The rusty colour of apothecia, the habitat (granite rocks of the foreshore) and the presence of typical Caloplaca crenularia s.l. specimen nearby suggested an affiliation to the Caloplaca crenularia s.l. group. Might also be considered as a maritime Atlantic form of Caloplaca crenularia var. contigua, with no thallus.*