Fucus pyrifer Linnaeus, 1771: 311–312 (`pyriferus') (type locality: "in oceano Æthiopico'' [South Atlantic Ocean]).
Macrocystis pyrifera (Linnaeus) C. Agardh, 1820a: 47.—De Toni, 1895b: 372–373.— Delépine, 1963a: 10.— Delépine, 1966: 56.— Wynne & Scott, 1989: 25.
Taxonomic synonyms:
Macrocystis pelagica Areschoug in J. Agardh, 1848b: 157 (syntype localities: "in profundiori ponto natans''; Cape of Good Hope, South Africa).—Areschoug, 1851: 32.— Areschoug, 1854b: 358.— Grunow, 1867: 52.— Reichardt, 1871: 22.— Hemsley, 1884: 281.
Macrocystis planicaulis C. Agardh, 1839: 298–300, pl. XXVI: fig. 3; pl. XXVII: fig. 7; pl. XXVIII: fig. 8 (syntype localities: "in Oceano Indico''; "ad Insulas Canarias'').—J. Agardh, 1848b: 155–156.
INDIAN OCEAN DISTRIBUTION: Amsterdam Island, "Oceano Indico'', St. Paul Island.
Note: Macrocystis pelagica and M. planicaulis were placed in the synonymy of this highly variable species by Areschoug (1883: 23). The taxonomic relationship between M. pyrifera and M. angustifolia was discussed by Womersley (1954a; 1987: 327–330).