History and advances in the taxonomy of the Bangiaceae (Rhodophyta) and new evidence to support splitting the genus <i>Pyropia</i>

Abstract

The Bangiaceae is an ancient and monophyletic red algal lineage whose origin has been dated back to c. 1047 Mya. More than 200 species have been detected in this family. They are distributed globally from the tropics to the poles, typically occurring in the intertidal, although a few species are found in the subtidal. Several species are economically important and cultivated mainly in East Asian countries, providing food and livelihoods for seaweed farmers and their families in coastal communities. However, with simple and plastic morphology, identification of the Bangiaceae is notoriously difficult using morphological characters alone, which has resulted in a complex taxonomic history. Furthermore, whether the generic ranks should be split or combined has always been a matter of debate and remains controversial amongst taxonomists today. Utilizing molecular approaches to assist in species delimitations poses both opportunities and challenges, with the potential for major changes in the taxonomy of the Bangiaceae. In the first two decades after molecular approaches were routinely introduced for taxonomy in the early 1990s, phycologists split the Bangiaceae from two to 15 genera. However, over the last decade, whether the family should be split further has been controversial. In this paper, we have reviewed the taxonomic history of the Bangiaceae, including paying particular attention to non-English language literature to improve accessibility to readers. We have also summarized the latest phylogenetic advances and have proposed how to proceed further to resolve the taxonomy. The latest evidence from phylogenomics revealed four well-resolved clades in Pyropia sensu lato, which provide strong evidence to split Pyropia. A robust taxonomy and phylogeny of such an ancient lineage that reflects its evolutionary history would be invaluable to underpin research on biogeographic patterns, adaptive evolution and palaeobiogeography events. Resource protection and cultivar breeding would also benefit from it.

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