Thallus saxicolous, up to about 5 mm diam. consisting of a beige, thin, undifferentiated hypothallus. Part of the type material is sorediate, but whether these thalli belong to C. tenuis remains unsolved. Apothecia lecanorine, emanating as orange-yellow craters from the hypothallus, up to 0.4 mm diam., initially immersed, later broadly sessile. Disc flat, orange yellow. Margin thick, 80 μm, regular, persistently prominent, shining, more yellow than the disc (Fig. 7). Thalline margin with about 13 μm large algae in a layer below the hymenium. The cortex consists of very glutinized, prosoplectenchymatic tissue with very narrow lumina apparently extending to the surface. Outer 5-10 μm with inspersed anthraquinone granules. Proper margin 25 μm thick below the hymenium, laterally fan-shaped, about 65 μm broad, consisting of prosoplectenchymatic hyphae. Hypothecium about 15 μm thick, hyaline, without oil droplets, consisting of intricately interwowen hyphae. Hymenium 80-90 μm with medium coarse epipsamma. Paraphyses about 1.5 μm thick, simple or sparsely branched, terminally gradually becoming slightly thicker. Spores 11-12 x 5.5-6.5 μm. Septum 2-3 μm.
Discussion. This species, described by Øvstedal (1985), is at present known only from the type specimen. It appears to have grown in a somewhat humid environment. There is a possibility that the specimen is a modification of some other species. However, as the very gelatinized structure of the thalline margin conforms with no other material so far studied by us, we retain it as an accepted taxon.