Phylogenetic relationships and generic concepts in the red order Bangiales: challenges ahead

Abstract

Wendy A. Nelson, Tracy J. Farr and Judy E.S. Broom. 2006. Phylogenetic relationships and generic concepts in the red order Bengiales: challenges ahead. Phycologia 45: 249–259. DOI: 10.2216/05-26.1Over the past decade molecular sequence data and phylogenetic analyses have provided strong evidence that the order Bangiales is monophyletic, but that Porphyra and Bangia as currently understood are not. Previous research on the Bangiales has focused primarily on taxa from the North Pacific and North Atlantic. Recent exploration of Bangiales diversity in other regions, particularly the southern hemisphere, has revealed deep divergences in the order in phylogenetic analyses employing the slowly evolving 18S rRNA gene. The presence of high diversity in New Zealand raises the prospect that the southern hemisphere, and particularly eastern Gondwana, is not only a centre of diversity but a centre of origin for the Bangiales. Although the need for new generic concepts within this order is clear, it is our conclusion that approaches to revising the Bangiales based solely on regional approaches will not succeed: the completion of a modern and robust taxonomic revision of this order requires a global collaborative effort. Enhanced taxon sampling and verifiable application of names, based on vouchered specimens, will be essential for this to be achieved. The determination of phylogenetic relationships in the Bangiales has implications for the qua.gification of biodiversity. The number of taxa in the evolutionarily diverse Bangiales has been significantly underestimated, and the diversity in this group has been obscured by the recognition of only two genera. Based on the analyses completed to date, in a revised Bangiales there will be at least 10 genera, 5 of which are currently recognised (Bangia, Dione, Minerva, Pseudobangia and Porphyra), as well as further genera yet to be circumscribed. The majority of species currently placed in Porphyra, including species of commercial value, will not remain in Porphyra sensu stricto.