Verrucaria serpuloides I.M.Lamb
Thallus jet black, matt, with cracks, spreading in irregular patches to 30 cm diam., saxicolous, submerged. Perithecia numerous, evenly scattered, slightly raised, 0.2-0.4 mm diam., ostiole depressed, minute. Ascospores biseriate, broadly ellipsoid, 15-17.5 × 8-9.5 µm.
A: The only truly submerged maritime lichen.
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