ABSTRACT Molecular phylogenetic analyses based on mitochondrial cox1 and cox3 and chloroplast rbcL gene sequences revealed that the morphospecies of the brown alga Planosiphon gracilis (Scytosiphonaceae, Ectocarpales) from Japan is a complex of three distinct lineages (lineages I–III). Specimens from these lineages had the typical morphology of Pl. gracilis (i.e. flattened, linear, hollow, and gregarious erect thalli); thus, morphological discrimination among them was difficult in many cases. We observed large genetic divergences among the three lineages (c. 10% in cox1 and cox3). Moreover, we observed a reproductive isolating barrier between lineages I and II, despite the wide overlap in their geographic distribution. Our data, therefore, suggest that these three lineages are distinct species. Since lineage I included the holotype specimen of Pl. gracilis, this lineage was attributed to Pl. gracilis. Lineage III was phylogenetically close to Pl. complanatus from Canada with a 4.1% divergence in cox1. For lineage II, a new species name, Pl. nakamurae sp. nov., was proposed. This new species was also found in Argentina.

中文翻译：

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来自日本的 Planosiphon gracilis morphospecies (Scytosiphonaceae, Phaeophyceae) 的物种定界和 Pl 的描述。中村江公司 十一月

摘要 基于线粒体 cox1 和 cox3 以及叶绿体 rbcL 基因序列的分子系统发育分析表明，来自日本的褐藻 Planosiphon gracilis（Scytosiphonaceae，Ectocarpales）的形态种是三个不同谱系（谱系 I-III）的复合体。来自这些谱系的标本具有典型的 Pl 形态。股薄（即扁平的、线性的、中空的和群居的直立菌体）；因此，在许多情况下，它们之间的形态区分是困难的。我们观察到三个谱系之间存在很大的遗传差异（在 cox1 和 cox3 中约为 10%）。此外，我们观察到谱系 I 和 II 之间存在生殖隔离障碍，尽管它们的地理分布有很大的重叠。因此，我们的数据表明这三个谱系是不同的物种。由于世系，我包括了 Pl 的正模标本。gracilis，这个血统归因于Pl。薄薄的。谱系 III 在系统发育上与 Pl 接近。来自加拿大的 complanatus 与 cox1 的差异为 4.1%。对于谱系 II，一个新的物种名称，Pl。中村江公司 11 月，提出。这个新物种也在阿根廷被发现。