DNA barcoding and phylogeographic analysis of Nipponacmea limpets (Gastropoda: Lottiidae) in China

To identify the Nipponacmea limpets along the coast of China, their taxonomy was investigated with three molecular markers (one mitochondrial gene, COI; two nuclear markers, 28S rDNA and H3). Three species (N. radula, N. fuscoviridis and N. nigrans) were found among 274 individuals collected from 14 sites. Intraspecific variation was far less than interspecific variation and obvious barcoding gaps existed. These results indicate that the three Nipponacmea species can be efficiently identified by DNA barcoding. The phylogeographic patterns of the three species were also analysed using COI sequences. There was clear biogeographic separation between the northern N. radula and the southern two species (N. fuscoviridis and N. nigrans), with the Yangtze River estuary as a barrier. In the southern N. fuscoviridis, there was a star-shaped haplotype network and the dominant haplotype was detected in all populations. In the northern N. radula, there were five main haplotypes; some adjacent populations showed no significant difference according to the pairwise Fst values. The southern N. nigrans showed two main haplotypes. The phylogeographic break between the Nipponacmea species is possibly due to the local and regional hydrographic conditions in the Yangtze River estuary, the large salt marsh in the river delta and difference of temperature between northern and southern China.