Rhytidhysteron rufulum

A species typical of tropical climates, on decaying ground wood, with hysterothecia 1.5 to 3 mm long and 1 to 1.5 mm wide, black, carbonaceous in appearance, with a longitudinal slit that opens under moist conditions becoming broadly navicular or almost discoid, revealing its orange hymenium.

Outer wall hyphae pseudoparenchymatous, of textura globulosa-angularis, very thick-walled (walls up to 2.4 µm thick), 10 to 12 µm long, 8 to 9 µm wide, with abundant brown pigment inside.

Asci cylindrical, bitunicate, hyaline, eight-spored, 140 to 170 µm long, 12 to 15 µm wide, arranged in a single row within the ascus (uniseriate), and inamyloid in Melzer's reagent.

Pseudoparaphyses filamentous, hyaline, septate, 1.5 to 2.5 µm wide, with apical enlargements of 3.5 to 4 µm, multiple apical branchings, and projecting above the asci.

Ascospores ellipsoidal to fusiform, some slightly allantoid, smooth, thick-walled, dark brown under the microscope, 23 to 31 µm long, 9 to 11 µm wide, containing abundant oil droplets (guttules) inside.