Splitting blades: why genera need to be more carefully defined; the case for <italic>Pyropia</italic> (Bangiales, Rhodophyta)

Abstract

The trend in naming genera based almost exclusively on molecular data, and not on morphological diagnostic characters, is increasing. In bifurcating phylogenetic trees generic cut-offs are arbitrary, but at the bare minimum nomenclatural changes should be supported by multiple phylogenetic methodologies using appropriate models for all the various gene partitions, strong support with all branch support methods, and should also result in adding to our knowledge of the interrelationships of taxa. We believe that a recent taxonomic treatment of the genus Pyropia (Yang et al. 2020) into several genera is unwarranted. We reanalysed the data presented in the recent article, using additional phylogenetic methods. Our results show that many of the newly established genera are not well supported by all methods, and the new circumscription of the genus Pyropia renders it unsupported. We also tested additional outgroups, which were previously suggested as sister to Pyropia, but this did not substantially change our conclusions. These generic nomenclatural changes of the previously strongly supported genus Pyropia, do not shed light on the evolution of this group and have serious consequences in these commercially important algae, that are also governed by a plethora of regulation and by-laws that now need to be amended. We suggest that the over-splitting of groups based only on poorly produced and modestly supported phylogenies should not be accepted and that the genus Pyropia sensu Sutherland et al. (2011) be restored.

A Taxonomic Assessment of Pyropia hiemalis (Kylin) Varela-Álvarez, Guiry & Serrão, comb. nov. (Bangiaceae, Bangiophyceae)

“…The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. Symbols: * , distinct sequences produced in this study; ** , species nomenclature according to Santiañez & Wynne 2020, Yang et al 2020 and Zuccarello et al 2022.…”

“…Brodie et al 1996Brodie et al , 1998, but also for other red algal species (e.g. Destombe & Doug-las 1991;Maggs et al 1992;Goff et al 1994;Zuccarello et al 1999) -in several isolates of both species in Europe. Herein, we provide an update of the nomenclature status for former P. hiemalis.…”

“…Species identification of these taxa was and is very difficult due to their simple morphologies. Currently, several of these genetic entities have been pooled and renamed (Zuccarello et al 2022). DNA-based methods are now necessary to correctly identify bladed Bangiaceae, and an update of the nomenclature and taxonomy of all the previous species included in the genus Porphyra sensu lato is required.…”

Control of oomycete pathogens during Pyropia farming and processing using calcium propionate

“…The global production of cultivated macroalgae more than doubles every decade, and the production of red algae has overtaken brown algae since 2010, dominating the market (Badis et al 2020b). Production of laver (Pyropia spp., formerly known as Porphyra) (Zuccarello et al 2022) has also doubled during the same period, primarily due to a rapid expansion in China and Korea, but this rapid development of aquaculture is followed by a similarly increasing economic burden of disease outbreaks (Cottier-Cook et al 2016, 2021. Disease management is a growing concern for Pyropia farmers, and now contributes up to half the running cost of a farm (Kim et al 2014).…”

Confirmation of Neoporphyra cf. dentata on Shikinejima, Izu Islands, southcentral Japan, and comparison with co‐occurring Neoporphyra haitanensis

“…Consequently, the bladed Bangiales is now divided into 14 genera, and molecular phylogenetic studies have revealed surprisingly high biodiversity in the bladed Bangiales. Recently, Zuccarello et al (2022) proposed that newly established genera should be restored to Pyropia because of the low confidence of branches in phylogenetic analyses. However, the scientific names in the present study follow Yang et al (2020).…”