Pterocladiella caerulescens

Thallus erect, caespitose, wiry, cartilaginous, gregarious forming dense tangled tufts or turfs, 1.5-2.7(-3.5) cm high, dark grayish-green to dark purple-red. Creeping axes terete, (150-)280-300(-350) mm in diam., give rise to erect, flattened lanceolate blades on short сylindrical stipe, (180)-350 mm diam. Blades 140-180 mm thick, 1.5(-1.8) mm wide, tapering to blunt apices. Branching irregular, opposite or alternate to pinnate in one plane. Tetrasporangial sori develop in mid portions of the blades, spherical to ellipsoidal, to 35 mm diam., cruciate, embedded in the cortical layer. Tight attachment by peg-like rhizoids descending from creeping axes. Growing on dead coral fragments, intertidal to upper subtidal, in sites exposed to strong wave.

Note: A source of agar.

Tropical and subtropical waters of Atlantic, Indian and Pacific Oceans.