Anamorph: Conidiomata pycnidial, ca 30-35 µm diam., wall dark brown. Conidiogenous cells cylindrical, 3.5-5.5 x 2-5 µm. Conidia 3-4 x 0.5-1.0 µm. Teleomorph: ascomata perithecial, partly immersed in the host thallus or in apothecia in groups of 3 to 10, eventually causing bleaching and destruction of the host; 80-100 (-120) µm diam., globose to subglobose, black in external view. Ascomatal wall dark brownish-black in the upper part and lighter brown or reddish brown below, 6-8 µm thick, slightly thicker (to ca 15 µm) in the ostiolar area, composed of 2-4 layers of angular cells 6-9(-10) µm diam. and 3-5 µm thick. Interascal tissue absent, but the ostiole is lined with periphyses and pendent hyaline apical pseudoparaphyses 12-17 x 1.5-3 µm extend into the perithecial cavity. Asci 40-50 X 10-15 µm, narrowly saccate, sessile or shortly stipitate, thick-walled in the upper part and fissitunicate, not staining in iodine, 8-spored. Ascospores arranged biseriately, (14.5-) 16-19 (-21.5) x (3.5-) 4-5 µm, hyaline, not or slightly constricted at the single median septum, upper cell sometimes wider, with a gelatinous sheath.