in Nimis & Poelt, Studia Geobot., 7, suppl. 1: 73, 1987.
Distribution: C - Sar.
Description: Thallus crustose. episubstratic, pale orange, rimose-areolate, rather thick, forming small, compact, sometimes confluent , up to 5 mm wide patches. Areoles flat, angular, 0.2-0.5 mm in diam. Thallus subparaplectenchymatous throughout, with angular, thick-walled cells; in the algal-free lower medulla they measure 3-6 μm, in the cortex they are horizontally elongate and may reach up to 8 μm. Apothecia orange, one to two per areole, completely immersed in the areoles or weakly emerging, in which case a thin proper margin is evident, otherwise immarginate, with a flat disc. Proper exciple radially expanded at margin, subparaplechtenchymatous, with strongly conglutinated-swollen hyphae; epithecium orange-brown, K+ red; hymenium colourless, c. 50 μm high: paraphyses strongly conglutinated, 2-2.5 μm thick at base, the apical cells only slightly thicker, and (in water) difficult to distinguish, becoming free in K. Asci 8-spored, clavate, functionally unitunicate, apically thickened with a broad internal beak, the inner part of apex and external cap I+ blue, Teloschistes-type. Ascospores 2-celled, polarilocular, hyaline, mostly poorly developed or only partially ripe, broadly ellipsoid, c. 11-12 x 6.5-8.5 μm, the equatorial thickening (“septum”) 2.5-3 μm at maturity. Photobiont chlorococcoid. Spot tests: thallus and apothecia K+ red, C-, KC-, P-. Chemistry: thallus and apothecia with unidentified anthraquinones.
Note: a very peculiar species, hitherto known only from the type locality, on basic siliceous rocks in a dry internal valley of central Sardegna.