Grateloupia taiwanensis is a leafy red alga consisting of 3 to 5 lance-shaped blades 80-150 mm long, and 20-30 mm wide, red to brown, with fine teeth, and with a soft texture. This alga is native to Vietnam, China, and Taiwan. An unidentified alga, found on lower intertidal and shallow subtidal rocks, in Mobile Bay, Alabama, was compared compared genetically with 20 species of Grateloupia, including the native G. gibbesi. The unidentified alga clustered closely with G, taiwanensis. Twenty one specimens were collected in Moblie Bay, so this alga is beilieved to be introduced and established. However, it has not yet been reported from elsewhere in the Gulf of Mexico, or in North American waters.