Lithothamnion intermedium

Thallus as stony heavily calcified crusts (500–550 μm thick), tightly attached to the substratum, purple-red, with wavy whitish margins and projections, (1)–2–5 mm high, 1–2 mm diam, simple or subdichotomously branched, frequently fusing with adjoining projections. In radial section, hypothallium (bottom cells) composed of several layers of rectangular elongated cells, (7.5)–10–12.5 μm diam., 12.5–15 μm long. Perithallium consist of vertically elongated cells, 7.5–12.5 μm diam., 10–25 μm long. Cells of surface layer lens-shaped or oval, 2.5–5×5–7.5(–10) μm, lateral pit connections present. Tetrasporangial conceptacles develop on basal crust and projections, slightly convex, with age becoming whitish, 225–500 μm diam. Growing in the low intertidal and upper subtidal zones, on stones, boulders and on shells in semi-sheltered and open areas.

Europe, Asia (China, Japan).