The following taxon apparently lies within the circumscription of Hincksia hincksiae but has not yet been transferred or reduced to synonymy:
Ectocarpus hincksiae Harvey var. australis Grunow, 1867: 45 (type locality: St. Paul Island).—Reichardt, 1871: 21 (without varietal epithet).— Hemsley, 1884: 281.
INDIAN OCEAN DISTRIBUTION: St. Paul Island.