Halimeda cylindracea Decaisne, 1842b: 103 (type locality: Nosy-Bé, Madagascar).—Kützing, 1849: 505.— G. Martens, 1868: 66 (`cylindrica').— J. Agardh, 1887: 87–88.— De Toni, 1889: 524.— Hillis, 1959: 373–374, pl. 4: fig. 3; pl. 5: figs. 22, 23; pl. 6: fig. 19; pl. 7: fig. 13; pl. 12.— Sartoni, 1979: 280, figs. 1a–c, 6A.— Farghaly, 1980: 96.— Hillis-Colinvaux, 1980: 100–101.— E. Drew, 1995: 144.
Taxonomic synonym:
Halimeda polydactylis J. Agardh, 1887: 89 (syntype localities: Australia; Tonga).—Piccone, 1901: 121.— Lawson, 1980: 14.
Misapplied names (fide Hillis, 1959: 373, 374):
Halimeda monile.—Hauck, 1886 [1886–1889]: 168.
Halimeda incrassata forma monilis.—Barton, 1901: 27 (in part, including pl. IV: fig. 40).— A. Gepp & E. Gepp, 1908: 181.— A. Gepp & E. Gepp, 1909: 391.— Weber-van Bosse, 1913a: 123.
INDIAN OCEAN DISTRIBUTION: Amirante Islands, Cargados Carajos, Chagos Archipelago, Djibouti, Indonesia (Rotti and Sawu), Madagascar, Mozambique, Saya de Malha Bank, Seychelles (Coetivy Reef), Somalia.
Note: Halimeda polydactylis is included as a synonym on the authority of Hillis (1959: 373). Djibouti and Mozambique are included in the distribution on the basis of specimens in UC collected by Papenfuss and Scagel and determined by Hillis-Colinvaux.