Ceramium macilentum

Thallus filamentous, to 2 cm high, dark red, initially creeping, giving rise to erect branches. Erect filaments 90-100(-150) μm diam. Branching regular dichotomous, pseudo-dichotomous. Cortical nodes (25-35 μm long) consist of three bands of large (12.5-25 μm) angular cells in the middle and small (7 μm) angular cells above and below. Internodes 100-150 μm long at the lower portion and shortening to 45 μm long at upper. Branch tips circinate, inwardly curved. Rhizoids issuing from nodes of creeping axis, 1-3 rhizoids from each node, 12-15 μm diam., two-celled, ending into blunt or disc-like attachment. Sporangia born abaxially, 1-3 per node, tetrahedrally divided, spherical or subspherical 35-40(-50) μm diam. surrounded by involucres. Growing on rocks, epiphytic in the upper intertidal to shallow subtidal zones.

Note: Potential as antimicrobial and antifungal.

Tropical and subtropical seas of Indian and Pacific Oceans.