Schizymenia dubyi is a red seaweed which is widely distributed in the East Atlantic, Mediterranean, Northwest Pacific, amd Australia, but its native range is unclear. It appears to be a recent introduction in Chile, Argentina, and California. In California, it was collected in Carpinteria in 1957, and in Royal Palms, Los Angeles County, in 1972, and on floating docks in Monterey in 2008–2009. This species has been confused with the natives Schizymenia pacifica and Dilsea californica. The gametophyte plants are oval to pennant-shaped, ruffled, and orange to maroon, up to 400 mm long and 200 mm wide. The thallus was attached to the substrate by a fibrous holdfast. The abundance of this species is unclear, because it is often confused with native species.