Flabellia is a genus of green algae in the family Halimedaceae.

[1] It is a monotypic genus and Flabellia petiolata is the only species; it is found in the eastern Atlantic Ocean and the Mediterranean Sea.

Flabellia petiolata is native to the Mediterranean Sea and also occurs in the Canary Islands and Cape Verde.

It grows in shallow waters with soft sediment.

Researchers are questioning whether this is a relict species, previously overlooked, or a genuine expansion of the range of the alga.