Pisutiella grimmiae (Nyl) S.Y. Kondr., Lökös & Farkas =Caloplaca grimmiae (Nyl.) H. Olivier
Thallus absent or unseen. Apothecia rare or in small clusters, 0.3-1 mm diam., disc plane, orange, brown-orange, redish, margin persistent, dark grey. Ascospores polarilocular, 10-14 x 5,5-7 µm, septum 3-4 µm wide. Photobiont: trebouxioide. Chemical spot tests negative. Rare, growing on Candelariella and notably on Candelariella vitellina on exposed rocks of the seashore. Inconspicuous species, systematically to be searched on Candelariella vitellina thalli developing on coastal rocks where it can be found as small red-orange apothecia circled by a grey margin contrasting with the bright yellow and black of the host species. N.B. Cf. Caloplaca aractina rather similar but with a dark grey thallus.*