Polyopes lancifolius is an introduced species of Halymeniales (Rhodophyta) from Asia, discovered on the North Atlantic coast in 2008. In this study, a first biochemical description of the species from the Gulf of Morbihan (France) is presented. The overall biochemical analysis of the algal raw material showed levels of neutral sugars (25.14% dw), proteins (15.00% dw), lipids (2.30% dw) and ash (12.64% dw) similar to those observed in species of the genera Grateloupia and Halymenia (Halymeniales). The major mycosporin-like amino acids were the shinorine, palythine and porphyra-334. Matrix polysaccharides represented 62% of the alga. The extract contained a high level of 3,6-anhydrogalactose (44.26%) and a low level of sulphates (10.2%). Uronic acids were also identified in the polysaccharide extract (13.03% dw). Galactose (64.54%) and glucose (27.92%) were the two main monosaccharides. Physico-chemical analyses showed that P. lancifolius contained kappa-carrageenan. The chemical and spectrometry results suggested the presence of agarocolloids and glucans with a high diversity of compounds in the extract. The characterization of the polysaccharide families requires future study. [ABSTRACT FROM AUTHOR]