DNA barcoding reveals cryptic diversity in the peanut worm Sipunculus nudus

Peanut worm (Sipunculus nudus) is a cosmopolitan species mainly distributed in tropical and subtropical coastal waters. Analysis of the mitochondrial cytochrome c oxidase subunit I (COI) gene sequences among S. nudus from GenBank revealed high genetic variation (p-distance, 0.115–0.235; k2p, 0.128–0.297) and paraphyletic relationships. These indicated misidentification and/or cryptic diversity may be present in the genus Sipunculus. To understand the genetic diversity and to manage the recourse of S. nudus, we collected specimens from coastal waters of southern China and Taiwan. In the phylogenetic topology, specimens can be separated into four distinct clades; three of these clades (clade A, B and C) were only represented from this region (southern China and Taiwan), but the clade D grouped with individuals from Central America (Atlantic coast). Furthermore, individuals of clades A and D were collected at the same location, which does not support the hypothesis that this genetic break ...

方格星虫（Sipunculus nudus）是一种广布种，主要分布于热带及亚热带近岸水域。针对GenBank数据库中S. nudus的线粒体细胞色素c氧化酶亚基I（COI）基因序列开展分析，结果显示其遗传变异水平较高（p距离：0.115–0.235；Kimura双参数距离（K2P）：0.128–0.297），且呈现并系亲缘关系。上述结果表明星虫属（Sipunculus）类群中可能存在错误鉴定及/或隐存多样性。为探明方格星虫的遗传多样性并对其资源进行科学管理，本研究从中国南部及中国台湾地区的近岸水域采集了标本。系统发育拓扑结构分析显示，所获标本可划分为4个独立的进化支；其中A、B、C三个进化支仅在本采样区域（中国南部及台湾地区）被检出，而进化支D则与来自中美洲（大西洋沿岸）的个体聚为一支。此外，进化支A与进化支D的个体在同一采样位点被采集到，该结果不支持该遗传分化……的假说。