Taxonomic status and phylogeographical structure in Pseudonereis sp. East Asia in the East China Sea off the Coast of Zhejiang, China

Abstract

Abstract Pseudonereis variegata is a polychaeteous worm (Annelida: Nereididae) with a cosmopolitan distribution in coastal waters; however, noticeable variations in morphology and genetics raised the question whether individuals from distinct ocean basins belong to the same species. This study evaluated the taxonomic status and phylogeographic structure in Pseudonereis sp. East Asia (as P. variegata) in the East China Sea (ECS) off the Coast of Nanji Islands (NJ) and Zhoushan Islands (ZS), Zhejiang by analyzing a 582bp DNA sequence in mitochondrial cytochrome C oxidase subunit I (COI). A total of 36 haplotypes were scored from 152 specimens, including 40 from ZS and 112 from NJ. Between NJ and ZS, 5 haplotypes were in common. Relatively, the levels of diversity on NJ (Hd = 0.556±0.060, π = 0.149±0.023%) were higher than ZS (Hd = 0.478±0.099, π = 0.110±0.028%). Comparative analyses with morphological characters and COI sequences of congeneric samples derived from other locations indicated that Pseudonereis sp. East Asia in the West Pacific, including the East China Sea/Taiwan Strait (ECS-TS) and Yellow Sea (YS) had a strong and significant divergence from the conspecific specimens in Chile and thus they should be described as a separate species, namely Pseudonereis sp. East Asia. The lack of noticeable phylogeographic structuring observed among populations in Pseudonereis sp. East Asia is probably due to larval transportation and oceanographic connection via the coastal currents. Our study provides basic scientific information for understanding the identity and genetic diversity of Pseudonereis sp. East Asia in the East China Sea off the Coast of Zhejiang, China and neighboring areas.