The following taxon apparently lies within the circumscription of Hydrolithon farinosum but has not yet been transferred or reduced to synonymy:
Melobesia farinosa Lamouroux forma mauritiana Foslie, 1905c: 4–5 (type locality: Mauritius).—De Toni, 1924: 645.— Woelkerling, 1993: 146.
INDIAN OCEAN DISTRIBUTION: Mauritius.