舌鳎亚科鱼类单系起源和同种异名的线粒体DNA证据

舌鳎亚科鱼类因形态特征的特殊性, 其分类及系统发育关系一直存在争议。本研究测定了中国沿海14种舌鳎亚科鱼类线粒体DNA的16S rRNA和Cyt b基因的部分片段。两个基因构建的舌鳎亚科系统发育树结果显示, 中国沿海舌鳎亚科鱼类为明显的单系群, 但舌鳎亚科鱼类内部的系统发育关系与形态分类划分的亚属并不完全一致, 日本须鳎(Paraplagusis japonica)与其他舌鳎属(Cynoglossus)种类并未形成不同的分支。虽然舌鳎属内的舌鳎亚属(Cynoglossus)、拟舌鳎亚属(Cynoglossoides)和三线舌鳎亚属(Areliscus)均可以聚为独立分支, 但长吻红舌鳎(C. lighti)与短吻红舌鳎(C. joyneri)、短吻三线舌鳎(C. abbreviatus)与紫斑舌鳎(C. purpureomaculatus)、半滑舌鳎(C. semilaevis)与窄体舌鳎(C. gracilis)及褐斑三线舌鳎(C. trigrammus)这三组物种可能存在同种异名现象。这一结果提示, 基于形态学对舌鳎亚科的种属分类鉴定尚存在不足, 线粒体DNA的系统发育关系可为其分类的修订提供有意义的参考和佐证。

Monophyletic origin and synonymic phenomena in the sub-family Cynoglossinae inferred from mitochondrial DNA sequences

Morphological taxonomy in the fish sub-family Cynoglossinae is complicated and contentious. To clarify these ambiguities, the molecular phylogenic relationships among 14 Cynoglossinae species were studied by analyzing partial 16S rRNA and Cyt b mitochondrial gene sequences. Similar phylogentic topology inferred from both gene fragments demonstrated that Cynoglossinae is a monophyletic group. However, the phylogenetic relationships revealed by the mitochondrial DNA sequence analyses were not consistent with those inferred from morphological classification. In contrast with morphological classification, reciprocal monophyly was not detected between Paraplagusis japonica and the species in the genus Cynoglossus. Neighbor-Joining (NJ) and Maximum Parsimony (MP) trees showed that those species in the three sub-genera Cynoglossus, Cynoglossoides and Areliscus clustered on an independent branch. Also, synonymic phenomena possibly existed in the following three groups of species: C. lighti andC. joyner, C. abbreviatus and C. purpureomaculatus, as well as in C. semilaevis, C. gracilis and C. trigrammus. Our results highlight the open questions surrounding the morphological classification of Cynoglossinae species. Information on molecular phylogenic relationships will likely be of help in revising the morphological classification of Cynoglossinae species.