Strand Malin, Sundberg Per
Göteborg University, Department of Zoology, Gothenborg, Sweden.
Mol Phylogenet Evol. 2005 Oct;37(1):144-52. doi: 10.1016/j.ympev.2005.02.006. Epub 2005 Mar 17.
We investigated the monophyletic status of the hoplonemertean taxon Tetrastemma by reconstructing the phylogeny for 22 specimens assigned to this genus, together with another 25 specimens from closely related hoplonemertean genera. The phylogeny was based on partial 18S rRNA sequences using Bayesian and maximum likelihood analyses. The included Tetrastemma-species formed a well-supported clade, although the within-taxon relationships were unsettled. We conclude that the name Tetrastemma refers to a monophyletic taxon, but that it cannot be defined by morphological synapomorphies, and our results do not imply that all the over 100 species assigned to this genus belong to it. The results furthermore indicate that the genera Amphiporus and Emplectonema are non-monophyletic.
我们通过重建22个归属于该属的标本以及另外25个来自近缘刺吻纽虫属的标本的系统发育关系，研究了刺吻纽虫分类单元Tetrastemma的单系性。该系统发育关系基于部分18S rRNA序列，采用贝叶斯分析和最大似然分析。尽管分类单元内部的关系尚未确定，但所包含的Tetrastemma物种形成了一个得到充分支持的分支。我们得出结论，Tetrastemma这个名称指的是一个单系分类单元，但它不能由形态共衍征来定义，而且我们的结果并不意味着所有归属于该属的100多个物种都属于它。此外，结果表明Amphiporus属和Emplectonema属是非单系的。
