Species recognition in New Zealand Porphyra using 18S rDNA sequencing

The long geographic isolation of New Zealand, an archipelago with a large latitudinal range (29 degrees to 54 degrees S) and an extensive coastline, has resulted in a high level of endemism in both land and coastal marine flora. The genus Porphyra in NZ is represented by 5 epiphytic species and a number of epilithic species, many of which are undescribed. Systematic studies aimed at understanding variation in morphology and life history are underway, and have led to the description of a number of new species. The present study uses sequence data from the 18S rDNA locus to investigate genetic variation in New Zealand Porphyra. Sequences have been fully determined for 10 epilithic species. A subset of these data has been shown to be sufficient to distinguish established taxa and to identify new entities. Our data indicate that New Zealand harbours at least 12 epilithic species of Porphyra, establishing the NZ coastline as a repository of diversity for this genus. Phylogenetic trees based on complete 18S rDNA sequence data show a deep division in the genus that is not obviously correlated with existing morphological characters, and indicate that representatives of the New Zealand flora have undergone long reproductive isolation.