The genus Ciona is an interesting ‘taxonomic case’ because its evolutionary history and taxonomy have not yet been resolved completely. In this study, we present new findings, describing specimens of an unidentified Ciona species collected along the north-eastern coasts of Sardinia (Tyrrhenian Sea, Mediterranean Sea). Applying an integrative taxonomic approach, based on the joint examination of morphological and molecular traits, we identify these specimens as a new species, Ciona intermedia sp. nov. Morphological comparisons and peculiarities of the habitat first revealed that these Ciona specimens have intermediate characters compared with other Ciona species. Molecular characterization (based on three mitochondrial regions: two already used for discriminating Ciona cryptic species and a newly developed one) confirmed that our specimens could not be assigned to any previously molecularly-characterized species. Both molecular phylogenetic reconstructions and morphological data clearly indicate C. intermedia as sister clade of Ciona edwardsi. Our findings add further complexity to the taxonomy of Ciona, underlying the importance of an integrative taxonomic approach for the study of the evolutionary history of this enigmatic genus.

中文翻译：

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研究Ciona（Ascidiacea）属和描述新物种Ciona intermedia的综合分类学框架

Ciona属是一个有趣的“分类案例”，因为其进化历史和分类学尚未完全解决。在这项研究中，我们提出了新的发现，描述了在撒丁岛（第勒尼安海，地中海）的东北海岸收集的一个身份不明的Ciona物种的标本。应用综合分类学方法，基于形态和分子特征的共同检查，我们将这些标本鉴定为新物种，Ciona intermedia sp。十一月 栖息地的形态学比较和特殊性首先表明，与其他Ciona相比，这些Ciona标本具有中间特征种类。分子表征（基于三个线粒体区域：两个已经用于区分Ciona隐性物种和一个新近发展的物种）证实了我们的标本无法分配给任何以前的分子表征的物种。分子系统发育重建和形态学数据均清楚地证明中间隐孢子虫是爱德华犬的姐妹进化枝。我们的发现为Ciona的分类法增加了进一步的复杂性，这为研究该神秘属的进化史提供了一种综合的分类学方法的重要性。