Crassostrea ariakensis and related species in China

The proposed introduction of the non-native oyster Crassostrea ariakensis to Chesapeake Bay has generated considerable interest in this poorly understood species. Based on the literature, the center of distribution for C. ariakensis is apparently China, where it has been referred to as jinjiang (close to river) oyster or C. rivularis. Its reported distribution in China ranged from the border region with Korea in the north to Beihai near Vietnam. Two forms of C. rivularis are recognized; one is referred to as "red meat", and the other as "white meat". We studied the taxonomic status of the two forms of C. rivularis and related species from China by DNA sequencing of three genes, mitochondrial 16S rRNA, cytochrome oxidase I (COI), and nuclear 28S rRNA genes. Our sequence data demonstrate that the red oyster is the same species as C. ariakensis Wakiya 1929, although red oysters from northern and southern China were genetically distinctive. The white oyster is the same species as the newly described species from Hong Kong, C. hongkongensis Lam and Morton 2003. C. ariakensis is sympatric with C. gigas in northern China and with C. hongkongensis and several other species in southern China. At least three species, C. ariakensis, C. gigas and C. hongkongensis, have been misidentified as C. rivularis in the past. A complete reclassification of oyster populations along China's coast is needed in order to understand the true distribution of C. ariakensis in China.