Morphological and Molecular Analysis Identified a Subspecies of (Fujita, 1913) along the Coast of Asia.

(Fujita, 1913) is one of the most important economic and ecological oysters that is naturally distributed along the coast of Asia, separated by the Yangtze River estuary. They are usually compared as different populations, while there is no consensus on whether in northern and southern areas should be considered as two species or subspecies. Here, we analyzed morphological characteristics, , , mitogenome sequences, and species delimitation analysis (ASAP and PTP) to resolve the intraspecific taxonomic status of the . Phylogenetic and ASAP analysis highlight that was divided into N-type and S-type. PTP was unable to differentiate between the two types of . The divergence time of N-type and S-type is estimated to be 1.6 Mya, using the relaxed uncorrelated lognormal clock method. Additionally, significant morphological differences exist between the two groups in terms of the adductor muscle scar color. Despite these differences, the (0.6%) and (0.6%) genetic distance differences between N-type and S-type has not yet reached the interspecific level. These results suggest that N-type and S-type should be treated as different subspecies and renamed as subsp. nov and subsp. nov.