Porphyra birdiae sp. nov. (Bangiales, Rhodophyta): A New Species from the Northwest Atlantic

Recent studies combining biochemical, molecular, and traditional morphological and ecological traits have shown that some currently recognized species of the red algal genus Porphyra are actually form species or complexes comprising several morphologically similar but genetically distinct taxa. Conflicting reports of chromosome numbers and differences in DNA sequences for Porphyra purpurea (Roth) C. Agardh have raised suspicion that more than one taxon has been confused under this name in the Northwest Atlantic. We have identified one of these cryptic taxa and describe it here as a new species, Porphyra birdiae. Like P. purpurea, it has an ovate to broadly elongate, foliose blade with reproductive areas segregated by a distinct line into male and female sectors. While reproductive specimens have historically been confused with P. purpurea, non-reproductive specimens of P. birdiae have been incorrectly identified as P. umbilicalis Kutzing. Although P. birdiae is morphologically similar to both of these species, sequences of SSU (nuclear small subunit rRNA gene) and rbcL (plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene) indicate that it is not closely related to either one. Based on rbcL sequences, P. birdiae is closely related to P. aestivalis Lindstrom et Fredericq, a proposed new species from Alaska.