Rhizocarpon hochstetteri  

Thallus grey- to red-brown, moderately thick to thick (0.1-0.35 mm), cracked-areolate; areoles flat to convex, 0.2-1.0 mm diam.; medulla I–.
Anamorph: not known.
Teleomorph: ascomata apothecia, 0.6-1.0 (-1.2) mm diam., frequent, black, flat to slightly convex, sessile when well-developed, or innate among areoles. True exciple persistent, but often poorly formed, sometimes slightly crenate, composed of radiating, dark brown hyphae. Epithecium usually with aeruginose to blue-black pigment (macrocarpa-green; K–, N+ red), but occasionally brown (K–, N–). Hymenium 95-150 μm high. Hypothecium dark brown (arnoldiana-brown). Interascal tissue of cellular pseudoparaphyses, branched and anastomosing, 2.5-3.0 μm diam., swelling at the apex to ca 3.5 μm), with a sharply delimited, brown (atra-brown) cap. Asci 85-100 × 30-35 μm, clavate, fissitunicate, with a well-developed tholus that is K/I– in the lower part and K/I+ blue near the apex, lacking an ocular chamber, Rhizocarpon-type, 8-spored. Ascospores 21-25 × 8.5-12 μm, ovoid to ovoid-ellipsoidal, sometimes slightly curved, 1-septate, usually distinctly constricted at the ± supramedian septum, hyaline, becoming brown when over-mature, with a broad gelatinous sheath.
Chemistry: C–, K± yellow, Pd± orange. Stictic acid or no lichen substances detected by t.l.c.