Thallus cracked-rimose, thin 0.05-0.08 mm thick, olive-brown, usually in a mosaic of other crustose species, pigmented region of cortex 10-12 µm thick, olivaceous (K+ brown, N+ dilute brown), black prothallus visible at edges and sometimes between areoles. Medulla I+ weakly violet Photobiont chlorococcoid, cells globose, thick walled, 10-18 µm diam.
Apothecia immersed to adnate, lirellate, usually straight or slightly curved, 0.4-0.7 mm x 0.1-0.2 mm, but carbonized area of exciple spreading on to adjacent areoles to 0.5 mm across, margin raised and completely obscuring the hymenium. Excipulum brown, composed of cellular hypahae. Hypothecium dilute brown. Hymenium c. 70 µm thick, I+ blue; epihymenial zone brown (K—, N—). Paraphyses richly branched and anastomosing, slender 1.0-1.5 µm wide, apices scarcely swollen, not conglutinate. Asci cylindrical, 40-50 x 10-12 µm, Rimularia-type. Ascospores simple, hyaline, ellipsoid with rounded ends, (9-)11-12(-14) x 6-7(-8) µm.
Conidiomata pycnidia, black, immersed in the thallus 0.05-0.08 mm diam. Conidia bacilliform, 6-8 x 0.8 µm.
Chemistry: No substances detected by TLC.
Reported from Campbell Island and the Auckland Islands (NZ) and from Isla Desolacion (Chile).
Distribution in Google Earth
The new species is most similar to Lithographa graphidioides in that it has a thin thallus that lacks lichen substances. However, the thallus of L. graphidioides is ochraceous (not olivaceous-brown), and the apothecia are also more frequently rounded and have a consistently more exposed hymenium.
Lithographa olivacea most often occurs in a mosaic of other crustose lichens (e.g. Labyrinthia implexa, Pertusaria sp., Placopsis sp., Rimularia maculata (see below), and Tremolecia atrata).
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