The Pakaraima Mountains are an ancient mountain range along the borders of Guyana, Brazil and Venezuela. The high plateau is drained by multiple river systems in all directions. Although hypotheses have been presented for the biogeographical relationships of lowland rivers, the interconnectivity of rivers on the top of the plateau is unknown. With multiple complex rivers in a small, upland area, we predicted a high level of endemism for stream fishes and complex biogeographical relationships. We explored this with the incredibly diverse pencil catfish genus Trichomycterus. Using collections from recent expeditions to the Pakaraima Mountains of Guyana, we amplified three mitochondrial (16S, COI and Cytb) and one nuclear marker (rag2). We constructed individual gene trees and a concatenated tree to determine the placement of these taxa within the Trichomycterus of the trans-Andean/Amazonian clade. Herein, we identify six endemic lineages of Trichomycterus from the highlands of the Pakaraima Mountains. Of the identified lineages, we find two species occupying multiple basins, suggesting that Pakaraima streams either maintain connectivity or had some degree of recent connectivity.

中文翻译：

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顶部是一个热点：圭亚那高地的河流拥有丰富的地方性笔形cat鱼（Teleostei：Ostariophysi：Siluriformes）

Pakaraima山是圭亚那，巴西和委内瑞拉边界的古老山脉。高原流经各个方向的多条河流。尽管已经提出了有关低地河流生物地理关系的假设，但高原顶部的河流之间的相互联系仍是未知的。在一个小的高地地区，由于有多条复杂的河流，我们预计溪流鱼类和复杂的生物地理关系的地方特有性很高。我们用种类繁多的铅笔cat鱼Trichomycterus进行了探索。使用最近对圭亚那Pakaraima山脉的考察收集的数据，我们扩增了三个线粒体（16S，COI和Cytb）和一个核标记（rag2）。）。我们构建了单独的基因树和一棵级联树，以确定这些分类单元在安第斯山脉/亚马逊河流域进化支的毛线虫中的位置。在此，我们确定六个地方性谱系Trichomycterus从帕卡赖马山脉的高地。在确定的谱系中，我们发现两个物种占据了多个盆地，这表明Pakaraima流要么保持连通性，要么具有某种程度的近期连通性。