ON A JAPANESE SPECIES OF CHONDRUS (GIGART INACEAE, RHODOPHYTAE) ACCIDENTALLY INTRODUCED INTO THE THAU LAGOON (MEDITERRANEAN FRANCE)

Probably in 1993 or early 1994, further to illicit importations of oys ters (Crassostrea gigas) from North Japan, an asiatic Chondrus, C. gig anteus forma flabellatus, has accidentally been introduced in the Medi terranean sea where the genus was hitherto unknown. In september 1995, this alga was common on hard substrates along the north coast of Thau lagoon (Herault, France), and the majority of thalli were in reproduc tion (tetrasporophytes, male plants and female plants with carpogonial branches and carposporophytes). The mediterranean specimens are descr ibed. The implications of this acclimatization in Thau lagoon and the possible spread of this Chondrus elsewhere in Europe are discussed.