Thallus: squamulose squamules: scattered or adjacent, 1.5-4 mm wide, 0.25-0.4 mm thick, rounded or deeply lobate, plane and fully adnate or concave with upturned and often undulate margins, ± distinctly black-rimmed, fastened by conspicuous black rhizines upper surface: medium to dark brown, smooth or somewhat rugulose, dull, margins blackened and often slightly thickened upper cortex: 30-50 µm thick; cells: angular, isodiametrical and c. 5-8 µm in diam. or anticlinally slightly elongated and then up to 11 x 8 µm wide, overlain by an amorphous layer (10-30 µm thick) medulla: white, composed of interwoven hyphae divided into many spherical cells (5-9 µm in diam.), with filamentous parts in thick squamules; algal layer: c. 50-80 µm thick, evenly delimited above, uneven below; algal cells: 5-9 µm in diam., ± in vertical columns lower cortex: paraplectenchymatous, brown-black, 25-40 µm thick; cells: 5-9 µm wide lower surface: black throughout, lacking rhizohyphae, rhizinate; rhizines: externally black, with a white core, 50-100 µm in diam. and up to more than 10 mm long, originating centrally or from most of the underside, usually branched, anchoring and linking squamules Perithecia: broadly pyriform, up to 0.4 mm broad, causing swellings on the underside of squamules; exciple: c. 30 µm thick, black, often pale near the apex; periphyses: 40-60 µm long; hymenial algal cells: globose, 2-3 (-4) µm in diam. or ellipsoid and up to 5 x 3 µm asci: clavate, 1-spored (very rarely 2-spored) ascospores: muriform, yellowish brown to brown, elongate-ellipsoid or narrowly clavate, (55-) 65-92 x 23-36 µm Pycnidia: immersed, up to 0.2 mm wide, roundish, conidiogenous layer convoluted conidia: bacilliform, 3-4.5 x <1 µm. Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on soil in areas with Mediterranean climates World distribution: SW Europe, Australia and SW North America Sonoran distribution: southern California and Baja California. Notes: The 1-spored asci are distinctive.