Buelliella physciicola Poelt & Hafelner

Commensal or parasite Ascomycota of Phaeophyscia thallus.

     Thallus invisible, ascomycota and host hyphae mixed. Ascomata visible at first as pseudotheca, closed and more or less rounded,opening when mature and then looking like apothecia, 0.2-0.3 mm diam., disc blackish, margin thick, more or less distorted, blackish. Ascii 8-spored, 50-60 x 12-17 µm. Ascospores hyaline at first, pale brownish when old, ellipsoid, 1-septate, 13-17 x 6-8,5 µm. Rare, or usually undetected or hardly visible, growing on the thalli of different Phaeophyscia species and notably on Phaeophyscia orbicularis on dry and well-lit rocks. See also on the same host Pyrenidium actinellum of which the pseudotheca do not open and with ascii 4-spored, ascospores brown-blackish, 3-septate.*