Porphyra rediviva sp nov (Rhodophyta): A new species from northeast Pacific salt marshes

A new species, Porphyra rediviva (Bangiales, Rhodophyta), is described from the northeast Pacific based on morphological, cytological, reproductive, ecological, and molecular characters. This species occurs at high intertidal levels in salt marshes along the coasts of Washington, Oregon, and northern California and exhibits a growth optimum at reduced salinity. It is further distinguished by a distinct demarcation between male and female sectors of the gametophytic thalli of epilithic specimens. The species is found most commonly in the drift or trapped in Salicornia beds, but these detached blades never have been found with sporangia or gametangia. Molecular analyses using restriction fragment length polymorphism patterns of polymerase chain reaction-amplified ribosomal DNA (rDNA) show that this salt marsh Porphyra is conspecific throughout its range and is distinct from other Pacific Porphyra species with similar reproductive patterns. Based on molecular data, P. rediviva is related most closely to P, purpurea from the North Atlantic. Fixed rDNA polymorphisms between the two taxa, however, support ecological and cytological evidence that they should be considered different species.