Magallana Salvi & Mariottini, 2016

Tan, Koh Siang, , Siong Kiat Tan, , Sherralee S. Lukehurst, Wells, & Fred E., 2024, Assessing the threat of the oyster genus Magallana (Bivalvia: Ostreidae) in Singapore to the Australian marine environment, Raffles Bulletin of Zoology 72, pp. 162-183 : 166-168

Genus Magallana Salvi & Mariottini, 2016

Note. A number of oyster species, both from the Atlantic and Indo-Pacific, have traditionally been included in the genus Crassostrea Sacco, 1897 . Ó Foighil et al. (1995) analysed information from mitochondrial 16S ribosomal gene sequences and demonstrated there were genetic differences between American Atlantic coast Crassostrea and Indo-Pacific species. Further information was subsequently provided by Wang H et al. (2004), Wang Y et al. (2004), and Lam & Morton (2004). Salvi et al. (2014) and Salvi & Mariottini (2016) expanded on this, using extensive genetic data to separate species that had previously been included in Crassostrea into three genera: Crassostrea for Atlantic species, Talonostrea Li & Qi, 1994 , and Magallana Salvi & Mariottini, 2016 for Indo-Pacific species, with M. gigas as the type species of Magallana . The separation of Crassostrea into three genera has been controversial. Bayne et al. (2017, 2019) and Backeljau (2018) argued that the genus Crassostrea is well known, both taxonomically and in the aquaculture industry, and it is important to maintain nomenclatural stability. Backeljau (2018) and Guo et al. (2018) further argued that while there are clades within Crassostrea , the genus is well defined. Although criteria for separation of taxa at species level are clear, there are no agreed criteria for separation of genera. On an extreme basis, each species could be classified into a separate genus. Bayne et al. (2019), in a letter to the editor of the journal ‘Aquaculture’, recommended the continued use of Crassostrea “until a more detailed and comprehensive genomic analysis resolves the correct nomenclature”. This was countered by Salvi & Mariottini (2021), Willan (2021), and Salvi et al. (2022), who argued the separation of the genus Crassostrea into three distinct genera is valid.

Sigwart et al. (2021) further suggested that while extant species included in the three genera are phylogenetically distinct, fossils that are clearly separable into species using shell morphology cannot be placed into Magallana , Crassostrea , or Talonostrea as there are no genetic data available, and not all extant species have been sequenced. They analysed published barcoding data and found that genetic data were insufficient to separate several economically important species. Additionally, more than 5% of the oyster species reported in GenBank were misidentified; an additional misidentified M. gigas was recently reported by Salvi et al. (2021). Accordingly, Sigwart et al. (2021) recognised living species of the three taxa as subgenera of Crassostrea .

However, the World Register of Marine Species (WoRMS) currently recognises only Magallana gigas , not Crassostrea gigas or Crassostrea (Magallana) gigas (MolluscaBase eds., 2023); we have followed the WoRMS designation.