To evaluate the specific validity of the Caspian pipefish Syngnathus caspius, we used a comparative molecular species delimitation method on a COI barcode library of Syngnathus, as well as principles of genealogical concordance. Comparative species delimitation allowed us to delineate putative species without a priori assignment of individuals to nominal species, while genealogical concordance extended our species delimitation results to multiple genes, multiple codistributed species, and comparisons with biogeographic evidence. All species delimitation analyses including two topology‐based, one network‐based, and one distance‐based analysis showed genetically isolated lineages of pipefish in the Black and Caspian Sea, corresponding to S. abaster and S. caspius, respectively. Mean evolutionary divergence between the two lineages (0.029) was within the range separating species of Syngnathus (0.024–0.217). The interclade/intraclade ratio of variation was comparable to the operational criterion of divergence between clades greater or equal to 10 × the level within clades to recognize separate species. Our argument on taxonomic validity of S. caspius is also supported by the principles of genealogical concordance as a conceptual basis for recognition of biological species. As a second objective, using a limited number of S. caspius specimens from two semi‐confined water bodies along the Caspian Sea south coastal zone (i.e., Anzali Wetland in the west and Gorgan Bay in the east), we searched for a possible matrilineal structure. The retrieved phylogeographic pattern was characterized by a shallow genealogy and lineage distributions varied, most probably caused by low to modest contemporary gene flow between populations of S. caspius across the southern Caspian Sea that are linked tightly through history.

中文翻译：

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族谱一致性，比较物种定界和里氏pipe鱼Syngnathus caspius（Teleostei：Syngnathidae）的特定状态

为了评估里海管鱼Syngnathus caspius的特定有效性，我们在Syngnathus的COI条码文库中使用了比较分子物种定界方法，以及家谱一致性原则。比较物种定界使我们能够在没有先验地将个体分配给标称物种的情况下描述推定物种，而族谱一致性将我们的物种定界结果扩展到多个基因，多个共同分布的物种以及与生物地理证据的比较。所有物种定界分析，包括两种基于拓扑的分析，一种基于网络的分析和一种基于距离的分析，显示了黑海和里海的pipe鱼遗传分离的谱系，分别对应于苦参和S. caspius分别。两个谱系之间的平均进化差异（0.029）在分离Syngnathus（0.024–0.217）的范围内。进化枝间/进化枝内的比率与进化枝之间的差异大于或等于进化枝内的水平以识别不同物种的操作标准相当。家谱链球菌的分类学有效性的论点也得到家谱一致性原则的支持，这是识别生物物种的概念基础。第二个目标，是使用数量有限的葡萄球菌我们从里海南部沿海地区（即西部的安扎利湿地和东部的Gorgan湾）的两个半封闭水体中提取了标本，我们寻找了可能的母系结构。检索到的植物学特征是谱系浅，谱系分布多样，最有可能是由于当代里海链球菌跨南里海的种群之间的基因流低至中等而形成的，这些历史流与历史紧密相关。