Parviphycus pannosus

Thallus small, consisting of creeping axes bearing simple erect axes, redish-brown сolor. Creeping axes terete, 50–175 μm diam. Erect axes terete to slightly compressed, simple (rarely branching), 1.5–4.7(–7) mm high, 60–135(–170) μm wide, tapering gradually to acute apices. Surface cells rounded-polygonal, 3.5–5×3–7.5 μm. In transverse section, cortex of 2 cell layers, medullary cells thick-walled. Tetrasporangial stichidia terminal, 80–150 μm wide, 200–400(–500) μm long. Tetrasporangia spherical, to 27.5(–30) μm in diam., tetrahedrally divided. Attachment by unicellular rhizoids originating from external cortical cells on ventral side of prostrate axes, 5–7 μm diam., to 80 μm long, non-aggregated. Growing on stones, dead corals in the intertidal to upper subtidal zones.

Europe, Atlantic, Indian and Pacific Oceans.