Thallus immersed, or superficial, thin, continuous or in small flecks; white, grey, dark brown, orange-yellow or purple-red, often with flecks or extensive patches of a yellow, K+ violet pigment. Cortex poorly defined. Photobiont a green alga. Anamorph: no information available. Teleomorph: ascomata perithecia, immersed in pits in rock, or forming projections 100-350 µm diam. Involucrellum absent, or developed around the ostiolar region in immersed perithecia; or thin, spreading from the ostiole and often reaching down to the substrate in projecting perithecia. Peridium hyaline to brown below. Interascal tissue absent, periphyses and periphysoidswell-developed. Hymenial gel I+ red (+ blue at very low concentrations of I), K/I+ blue. Asci ellipsoidal to clavate, K/I–, fissitunicate, wall thickened above, dehiscence by extrusion of a delicate endotunica as a long rostrum, 8-spored. Ascospores arranged irregularly, (20-) 27-35 (-47) × (9-) 11-14 (-17) μm, length/width ratio (1.8-) 2.2-2.8 (-4), ellipsoidal to clavate, 3-septate, thin-walled, smooth, without an epispore, gelatinous sheath or appendages. Chemistry: thallus (yellow areas) K+ purple (quinone-like pigment).