Sowerbyella imperialis

Species characteristic of conifers, fruiting on the ground among needle litter, with cup-shaped ascomata with an undulate margin, 2 to 4 cm in diameter, lemon yellow inside and whitish outside.

Medullary excipulum of textura intricata, formed by hyaline, thin-walled hyphae, interwoven, septate, often with slight enlargements, 6 to 13 µm in diameter.

Ectal excipulum of textura angularis, formed by subglobose hyphae 12 to 29 µm long and 12 to 19 µm wide, hyaline or with faint pale brown intracellular pigment; from the exterior arise hyphoid hairs 5 to 10 µm wide, septate with 3 to 5 septa.

Asci cylindrical, eight-spored, operculate, 145 to 185 µm long, 6 to 9 µm wide, with uniseriate spore arrangement within the ascus, croziers at the base, and inamyloid in Melzer's reagent.

Paraphyses cylindrical, septate, sparsely branched, 2 to 2.5 µm wide, with slight apical enlargements up to 3.5 µm, containing yellowish granular pigment that turns greenish in Melzer's reagent, extending very slightly above the asci.

Ascospores ellipsoidal, hyaline, thick-walled and minutely verrucose, 11.5 to 13.5 µm long, 6 to 7 µm wide, with two large oil droplets (guttules) at the poles, and covered with low warts up to 0.5 µm high, faintly visible under light microscopy.