Verrucula helvetica  

Thallus areolate or squamulose-areolate to 4–12 mm diam., or of scattered areoles. Areoles (0.2-) 0.3–0.6 (-0.8) mm diam., 200–300 μm thick, squamules polygonal, more rarely rounded, irregular, grey-brown, more rarely light or bright brown (shade forms), covered by an often scattered white-grey pruina. Cortex 8–11 μm thick, of 1–2 layers of cells with light brown walls, epinecral layer often discontinuous, thin (0–13 μm). Algal layer 55–85 μm thick, with algal cells 8–15 (-18) μm diam. Medulla distinctly I+ violet blue, 100–200 μm thick, fairly dense, hyaline but sometimes brownish below.
Anamorph: conidiomata pycnidia, 105–240 × 45–65 μm, completely immersed, the wall hyaline except for the upper part around the ostiole which is partly brown. Conidia (3-) 4–5 × 1–1.5 μm, bacilliform.
Teleomorph: ascomata perithecia, 140-160 μm diam., Immersed or with the upper quarter protruding from the thallus, 1-4 (-5) in each areole, visible from above due to blackening around the ostiole. Exciple 14–20 μm thick, hyaline, the exposed part brown. Interascal tissue of apical paraphyses 16–24 × 1.5–3 μm in size. Asci (35-) 45–50 × 15–19 μm. Ascospores (12-) 12.5–16.5 (-18) × (5.5-) 7–8.5 (-9.5) μm, ellipsoidal.

Description adapted from Navarro-Rosines et al. (2007).