中国沿海三井卷曲纽虫的分布与COI序列分析

Distribution and Mitochondrial COI Sequence Variation of Emplectonema mitsuii Yamaoka(Nemertea)in China Seas

本研究通过形态和DNA分类相结合的方法确认了三井卷曲纽虫(Emplectonema mitsuii)在中国沿海的分布,共在浙江泗礁山、嵊山岛、枸杞岛、东极岛、大陈岛、南麂岛、柴屿和海南文昌8地发现本种。中国标本的形态与三井卷曲纽虫的原始描述基本一致,但体型、吻针及针座明显较小。COI序列分析显示,中国沿海21个样品间COI序列平均遗传距离为0.0004(未校正p-距离),包含3个单倍型,其中90%的个体共享主单倍型1,平均单倍型多样性Hd为0.186±0.110,平均核苷酸多样性π为0.0004±0.0002,说明其遗传分化很低,可能经历过瓶颈效应或种群是由少数个体通过奠基者效应形成。中国样品与韩国济州岛样品、日本忍路样品间的遗传差异较高(平均p-距离为0.0177)。

Based on morphological and molecular studies on specimens from eight sites of Zhejiang(Sijiao Shan Island,Shengshan Island,Gouqi Island,Dongji Island,Dachen Island,Nanji Island and Chai Yu)and Hainan(Longlou)Provinces,the occurrence of Emplectonema mitsuii Yamaoka,1947(phylum Nemertea)in China seas was confirmed.Present specimens were basically consistent with the original description of E.mitsuii,but body size,stylet and basis were smaller.Based on COI sequences,the overall mean uncorrected p-distance among 21 specimens from China was 0.0004.Three haplotypes were identified,90%of individuals shared the main haplotype(Hap 1).The mean haplotype diversity(Hd)was 0.186±0.110,and the mean nucleotide diversity(π)was 0.0004±0.0002.The very low genetic differentiation may be explained with the fact that the Chinese population(s)may have experienced a bottleneck effect,and/or they may have been established from a small number of individuals with founder effect.The genetic differences between the Chinese samples and the 2 samples from Jeju Island and Oshoro p-distance(0.0177)were much higher.Therefore,it will be an interes-ting project to study the phylogeography of this species based on future intensive sampling across its full distribution range.