Abstract Six species of macroalgae are newly reported for the Caribbean International Biosphere Reserve Seaflower . All the algae were found growing epiphytically on Thalassia testudinum in shallow (<1 m) meadows around San Andrés Island. Two of these species, Stylonema alsidii and Colaconema hypneae , have been previously reported from Colombian waters, whereas Chroodactylon ornatum , Colaconema dasyae , Colaconema hallandicum and Herposiphonia parca are new records for Colombia.