Sphaerococcus rigens C. Agardh, 1822 [1822–1823]: 332 (type locality: "In mari Japonico'').
Chylocladia rigens (C. Agardh) J. Agardh, 1851 [1851–1863]: 362–363.—Dickie, 1877b: 7.— Hauck, 1886 [1886–1889]: 166–167.— Lawson, 1980: 39.
INDIAN OCEAN DISTRIBUTION: Rodriguez Island, Somalia.