This genus as currently circumscribed is restricted to the Mascarene Islands (Verdcourt 1983; Stone & Davis 2004). Some authors suggested (Capuron, ined. ms.; Schatz, Generic Tree Flora of Madagascar) that Fernelia might better be circumscribed more broadly to include the related genera Flagenium, Canephora, Galiniera, Lemyrea and Gallienia. However Stone & Davis (2004) reviewed all of these genera and provisionally separated and recognized all of them. They distinguished Fernelia by its functionally unisexual flowers, 4-lobed calyx and corolla, and ovary with the ovules attached at the top of the septum; the other genera each differ in one or more of these characters.