Phylogenetic Position and ISSR-Estimated Intraspecific Genetic Variation of Bangia Maxima (Bangiales, Rhodophyta)

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Abstract
The red alga Bangia maxima, in addition to its large size (up to 35 cm long × 6 mm in diameter), was found in this study to be distinguishable from other species of Bangia by the character of mature filament apices containing elongate, separated vegetative cells. The phylogenetic position of B. maxima was resolved using both the rbcL and nuclear small subunit rRNA (nSSU rRNA) gene sequences and the genetic variation within a population was studied using an inter-simple sequence repeat (ISSR) polymerase chain reaction (PCR)-based DNA fingerprint analysis. In phylogenetic analyses of the plastid rbcL gene region and nSSU rRNA, B. maxima grouped with local populations of concurrently collected B. vermicularis and B. fuscopurpurea as well as other collections of B. fuscopurpurea from California in a clade of predominantly eastern Pacific isolates. Banding patterns from 13 male filaments from seven littoral boulders for five ISSR primers were used to develop both band presence or absence and distance matrices (using the Dice coefficient). Banding patterns of B. maxima isolates were highly polymorphic among different boulders but consistent among individuals from the same boulder, as demonstrated by multivariate analyses (UPGMA, principal coordinates analysis). UPGMA analysis also indicated a limited genetic transfer among boulders. These results help in clarifying the population genetics of B. maxima and further understanding of genetic diversity within the Bangiales.