Trapelia elacista  

Thallus effuse, thin at the margin, sometimes uneven with low convex areas, rapidly becoming cracked, the mature thallus surface plane to slightly uneven, cracks usually numerous, sometimes delimiting discrete ‘islands’; pale grey or pale pinkish grey, at most faintly brownish when young, discontinuous in drier habitats. Prothallus sometimes visible at unimpeded margins, very thin, pale, sometimes absent or at least inconspicuous.
Anamorph: not known.
Teleomorph: ascomata apothecia, variable in size but up to 560 μm diam., often first visible as a pale pruinose disc, sometimes becoming convex, but often beginning to split at the apex before becoming convex. Developing margins often white, slightly roughened or pruinose, sometimes with the margin irregularly crenulate or with white flecks, often excluded when mature; a proportion of apothecia sometimes surrounded with a ± circular fissure with a white-pruinose surface, especially when young, the crack sometimes wide and crater-like; adjacent apothecia sometimes separated by white-pruinose fissures; young apothecia sometimes arising on the degenerating remains of a previous one. Ascospores 14·0–24·5 × 8·0–12·5 μm, ellipsoidal, aseptate, thin-walled, smooth, without an epispore or gelatinous sheath.