Karyological studies of five species of Porphyra (Bangiales, Rhodophyta) from the North Atlantic and Mediterranean

Abstract
Chromosome numbers for five species of Porphyra from the warm temperate and tropical North Atlantic and Mediterranean are presented. The basic haploid number found in vegetative cells of the foliose thallus and spermatia is N = 4, with one species having N = 3. Diploid chromosome numbers were determined during divisions leading to carpospore formation only in P. umbilicalis (Linnaeus) J. Agardh. Chromosome numbers have been recorded for conchocelis vegetative cells and conchospores for four of these species. Representative karyotypes were prepared for all five species, and used to discuss possible phylogenetic relationships between Atlantic and Pacific Porphyra species.