Thalloidima sedifolium

Squamulose lichen typical of calcareous soils, with a thallus formed by small greyish-green squamules, with discoid, flat to slightly convex apothecia, very dark blue to black, 1.5 to 3 mm in diameter, and without reaction to KOH.

Asci eight-spored (octosporic), clavate, 45 to 55 µm long by 10 to 15 µm wide, with parallel arrangement of spores within the ascus, and with an amyloid reaction of the wall in Melzer's reagent.

Paraphyses filamentous, hyaline, septate, sparsely branched, 1.5 to 2.5 µm wide, with abrupt swellings of the apical cell 4 to 6 µm wide, densely covered at the apex with a dark brown amorphous substance, and barely projecting above the level of the asci.

Ascospores fusiform, smooth, hyaline, thin-walled, 12 to 17 µm long by 3 to 5 µm wide, mature ones generally 1-septate (with a central septum); according to literature smooth, without oil drops, and what is observed inside the ascospores in the image are vacuoles caused by cytoplasmic retraction.