Thelidium huuskonenii

Description. Prothallus not visible. Thallus white to grey, endolithic to thinly epilithic, only surrounding perithecia, algal cells, c. 4 - 7 μm, in one specimen surrounded by one dark line. Perithecia 0.18 - 0.32 mm in diam., (1 / 2 -) 3 / 4 - 1 - immersed, leaving shallow to deep pits; c. 80 - 120 perithecia / cm 2. Ostiole pale to dark, plane to depressed, c. 20 - 40 μm wide. Involucrellum absent, apical or covering half of the exciple, 0 - 60 μm thick, appressed to the exciple or clearly diverging from it. Exciple 0.20 - 0.28 mm, wall dark brown to black, c. 15 - 20 μm thick, apex may be thickened to 50 - 80 μm thick. Periphysoids c. 20 - 45 x 1.5 - 2 μm, branching. Asci c. 58 - 74 x 22 - 25 μm, 8 - spored. Ascospores (0 -) 1 - septate, (16.4 -) 18.2 - 20.7 - 23.2 (- 27.6) x (8.0 -) 8.6 - 9.9 - 11.2 (- 14.4) μm (n = 69).