Galapagos Species Database

Thallus thin, whitish or grayish, usually distinctly developed on the bark surface, rarely embedded in the substrate and of the same color; surface smooth, ±shiny, not pruinose; Apothecia immersed to erumpent, lirellate; lirellae ±elongate, sparsely branched, undulating to ±stellate, not aggregated into stromatic thallus areas; labia thin, distinct, surrounded by an irregular, narrow thalline rim separated from thallus by a ± distinct fissure; disc expanded, barely concave to flattened, often fissured, with or without white, farinose pruina; exciple laterally and basally distinctly carbonized, basal carbonization typically expanding with age, lateral exciple typically surrounded by large Ca-oxalate crystals; hymenium hyaline, inspers, I–; ascospores pale gray, soon brownish, I+ reddish brown, 8 per ascus, oblong to broadly fusiform, 14-20 x 5-7 µm, transversely septate, regularly 4-celled. Chemistry: No substances found; all spot tests negative.

Specimens of L. sericeum typically have elongated, sparsely branched lirellae with a distinct, carbonized exciple lined with a thin thalline rim typically separated from the surrounding thallus by a discrete fissure. Paler pseudostromatic thallus areas that contain large Ca-oxalate crystals can be present between closely neighboring lirellae, but these lirellae are never aggregated within well developed stromata and they are typically much less branched than in Sarcographa tricosa.