Physcia aipolia

A foliose lichen (leaf-like in appearance), forming rosettes up to 10 cm or more in diameter, characteristic of tree bark, with a whitish-grey thallus tinged with bluish tones, and disc-shaped apothecia 2 to 3 mm in diameter concentrated at the center of the thallus, blackish brown with a slightly raised, whitish margin.

Photobiont consisting of green algae of the genus Trebouxia, with spherical unicellular algae 8 to 15 µm in diameter.

Asci clavate, eight-spored, 70 to 85 µm long, 16 to 20 µm wide, with biseriate to irregular spore arrangement occupying only the upper half of the ascus, and amyloid in Melzer's reagent.

Paraphyses filamentous, septate, simple or with occasional apical bifurcations, 1.5 to 2 µm wide, with slight apical enlargements of 4 to 5 µm, covered at the apex with a brown extracellular parietal pigment that stains reddish violaceous upon addition of KOH.

Ascospores ellipsoidal, with a central septum (two-celled), greenish brown under the microscope, 19 to 23 µm long, 9 to 11 µm wide, thick-walled with the thickening more pronounced at the ends, leaving a completely spherical refractive lumen in each cell.

Herbarium material available: JTP2109/24.