Global controversy in oyster systematics and a newly described species from SE Asia (Bivalvia: Ostreidae: Crassostreinae)

Abstract The diversity of native oysters in many regions is overshadowed by the global dominance a few economically important species. Here we describe Muar Oyster, Crassostrea (Magallana) saidii sp. nov., first reported as an established local fishery renowned for exceptional and distinctive flavour over 160 years ago British colonial officials Malaysia, but yet never formally named or described This new species has subtle clear morphological diagnosis dependent on three-dimensional characters, which long been recognised fishers to differentiate from co-occurring C. ( M.) belcheri (G. B. Sowerby II, 1871). Indo-Pacific clade Magallana Salvi & Mariottini, 2016 Mariottini 2017 phylogenetically distinct group that nonetheless cannot be morphologically separated broader genus Sacco, 1897. Fossils known only shell specimens, though species, classified , Talonostrea Li Qi, 1994, s.s. ; therefore, revise these groups sub-genera within Crassostrea. Our analysis COI barcoding fragment previously published sequences all available found gene not sufficient separate several revealed more than 5% GenBank represent identification errors. genetically, morphologically, gastronomically distinct, one population under potential threat urbanisation. Many remain undescribed. systematics this critical understand oysters, sustainable use grown worldwide centuries our food.