Observations on the Chromosome Numbers of Porphyra (Bangiales, Rhodophyta) Populations from Long Island Sound to the Canadian Maritimes

As part of an ongoing investigation into the species delineation and distribution of Porphyra from Long Island Sound to the Canadian Maritimes, cytological investigations are being undertaken. A variety of methods have been attempted and of the techniques used, DAPI fluorescent-dye staining was found to be most preferable. Three different Porphyra purpurea (Roth) C. Agardh populations were found within this geographic range, each with different chromosome numbers or arrangements. Different populations of P. leucosticta Thuret in Le Jolis were also delineated using this cytological method. The use of chromosome counts as an aid to traditional taxonomic methods has proved useful in this species-distribution investigation of Porphyra in the Northwest Atlantic.