Hao Yue, Kajihara Hiroshi, Chernyshev Alexei V, Okazaki Robert K, Sun Shi-Chun
1 institute of Evolution & Marine Biodiversity, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.
2 Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
Zoolog Sci. 2015 Dec;32(6):571-8. doi: 10.2108/zs140275.
Of the 14 nominal species that are now or have ever been assigned to the genus Paranemertes Coe, 1901 , four have been reported to have stylets with a spirally fluted or braided appearance. Although differentiation in color patterns has been documented among species/populations, these nemerteans share similar external characters. Using the sequence datasets of mitochondrial cytochrome c oxidase subunit I (COI), 16S rRNA, and nuclear 28S rRNA genes of specimens from 14 localities of Canada, USA, Russia, Japan, and China, we analyzed the genetic differentiation and reconstructed the phylogenetic trees for these nemerteans. In conjunction with the external characters, we discuss their taxonomy and species delimitation. An analysis based on COI dataset showed high genetic variations among populations and even among worms from the same geographic area. The analyzed 111 individuals were assigned into seven networks by statistical parsimony analysis. The inter-network uncorrected p-distances ranged from 0.044 to 0.172 and the mean intra-network uncorrected p-distances varied from 0.001 to 0.005. With the exception of two networks that contain specimens from the East China Sea, all networks were well-supported by the results of Bayesian and neighbor-joining analyses on the COI data. Phylogenetic trees based on 16S rRNA and 28S rRNA datasets were basically similar to the COI trees, but specimens in some networks were merged into larger clades. Present molecular analyses support the validity of P. sanjuanensis and the synonymization of P. cylindracea with P. peregrina. Nemerteans previously recorded as P. peregrina may contain several species and sympatric speciation might have been occurred in this nemertean group.
在目前或曾经被归入1901年Coe所建立的拟纽虫属（Paranemertes）的14个名义物种中，有4种被报道具有呈螺旋状凹槽或编织状外观的吻针。尽管已记录到不同物种/种群之间在颜色模式上存在差异，但这些纽虫具有相似的外部特征。我们利用来自加拿大、美国、俄罗斯、日本和中国14个地点的标本的线粒体细胞色素c氧化酶亚基I（COI）、16S rRNA和核28S rRNA基因的序列数据集，分析了这些纽虫的遗传分化，并重建了它们的系统发育树。结合外部特征，我们讨论了它们的分类学和物种界定。基于COI数据集的分析表明，种群之间甚至来自同一地理区域的个体之间都存在高度的遗传变异。通过统计简约分析，将分析的111个个体分为7个网络。网络间未校正的p距离在0.044至0.172之间，网络内平均未校正的p距离在0.001至0.005之间。除了两个包含来自中国东海标本的网络外，所有网络都得到了基于COI数据的贝叶斯分析和邻接法分析结果的有力支持。基于16S rRNA和28S rRNA数据集的系统发育树与基于COI的树基本相似，但一些网络中的标本被合并为更大的分支。目前的分子分析支持圣胡安拟纽虫（P. sanjuanensis）的有效性以及圆柱形拟纽虫（P. cylindracea）与奇异拟纽虫（P. peregrina）的同义关系。以前记录为奇异拟纽虫的纽虫可能包含几个物种，并且在这个纽虫群体中可能已经发生了同域物种形成。
