Lampreys are jawless fishes belonging to the order Petromyzontiformes. Geotria australis is the sole representative lamprey species of the Geotriidae family and is widely distributed around South America, Australia, New Zealand, and sub-Antarctic Islands. In South America, the presence and distribution of G. australis are well characterized in Western Patagonia, in rivers flowing into the Pacific Ocean. In contrast, there is scarce information about the presence of this species in Eastern Patagonia, in rivers flowing into the Atlantic Ocean. Here, we provide the first report on the distribution of lamprey at the extreme south of Patagonia and suggest the occurrence of a new lamprey species. We developed an environmental DNA (eDNA) method to detect G. australis from water samples and obtained positive results in five basins flowing into the Atlantic Ocean and one river basin flowing into the Beagle Channel. Lampreys were captured from two eDNA-positive basins and used for genetic analysis. An 875 bp-sequence of the cytochrome b mitochondrial gene was obtained, and a phylogenetic analysis was carried out with this sequence and those available in GenBank, revealing Argentinean lamprey reported here, as a sister species of G. australis from Chile, Australia, and New Zealand. Also, the genetic distance values between lamprey reported here and G. australis were consistent with the genetic distances between species of different genera. Our results suggest that the Argentinean lamprey corresponds to a new specific taxon that could represent a new monotypic genus in Geotriidae.

中文翻译：

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通过环境 DNA (eDNA) 和新物种的分子证据在南美洲最南端检测七鳃鳗

七鳃鳗是属于石斑鱼目的无颚鱼。Geotria australis 是七鳃鳗科唯一的代表性七鳃鳗物种，广泛分布于南美洲、澳大利亚、新西兰和亚南极群岛。在南美洲，G. australis 的存在和分布在巴塔哥尼亚西部流入太平洋的河流中得到了很好的表征。相比之下，关于该物种在巴塔哥尼亚东部流入大西洋的河流中存在的信息很少。在这里，我们提供了关于巴塔哥尼亚最南端七鳃鳗分布的第一份报告，并提出了一种新的七鳃鳗物种的出现。我们开发了一种环境 DNA (eDNA) 方法来检测 G. australis 从水样中提取，并在流入大西洋的五个流域和流入比格尔海峡的流域中获得了阳性结果。从两个 eDNA 阳性盆地捕获七鳃鳗并用于遗传分析。获得了细胞色素 b 线粒体基因的 875 bp 序列，并对该序列和 GenBank 中可用的序列进行了系统发育分析，揭示了此处报道的阿根廷七鳃鳗是来自智利、澳大利亚和澳大利亚的 G. australis 的姐妹种。新西兰。此外，这里报道的七鳃鳗和 G. australis 之间的遗传距离值与不同属物种之间的遗传距离一致。我们的结果表明，阿根廷七鳃鳗对应于一种新的特定分类群，可以代表 Geotriidae 中的一个新的单型属。