Halymenia maculata

Thallus solitary, blade-like, carnose, firm, mucilaginous, blotchy yellowish-red to purple red, with 8–15(–19) cm high, 210–360 μm thick. Blade separated into cuneate strongly dissected ruffled lobes, with margins densely overgrown by irregularly shaped fimbriate proliferations. The surface of blade is undulate, with whitish spots. In transverse section, medulla composed of sparse fusiform filaments, 3–10 mm diam. and rare stellate cells; cortex consists of 2–4 rows of small inner cells and 1 (rarely 2) rows of oblong to elongate outermost cells. Tetrasporangia develop in outer layer of cortex, ovoid or oblong, cruciately divided, 10–20×23–30 μm. Spermatangia are borne on outer cortical cell, covering most of the surface of the blade. Cystocarps scattered over surface of thalli, hemispherical, to 450 μm diam. Attachment by short, thickened discoid holdfast. Growing on subtidal dead corals, rocks and pebbles.

Africa. Common in countries of the Asia-Pacific Region: China, Vietnam, Thailand, Malaysia, Singapore, Indonesia, Philippines, Australia and New Zealand, Pacific Islands.