Asymmetrical rates of cladogenesis and extinction abound in the tree of life, resulting in numerous minute clades that are dwarfed by larger sister groups. Such taxa are commonly regarded as phylogenetic relicts or “living fossils” when they exhibit an ancient first appearance in the fossil record and prolonged external morphological stasis, particularly in comparison to their more diversified sister groups. Due to their special status, various phylogenetic relicts tend to be well-studied and prioritized for conservation. A notable exception to this trend is found within Amblypygi (“whip spiders”), a visually striking order of functionally hexapodous arachnids that are notable for their antenniform first walking leg pair (the eponymous “whips”). Paleoamblypygi, the putative sister group to the remaining Amblypygi, is known from Late Carboniferous and Eocene deposits but is survived by a single living species, Paracharon caecusHansen (1921), that was last collected in 1899. Due to the absence of genomic sequence-grade tissue for this vital taxon, there is no global molecular phylogeny for Amblypygi to date, nor a fossil-calibrated estimation of divergences within the group. Here, we report a previously unknown species of Paleoamblypygi from a cave site in Colombia. Capitalizing upon this discovery, we generated the first molecular phylogeny of Amblypygi, integrating ultraconserved element sequencing with legacy Sanger datasets and including described extant genera. To quantify the impact of sampling Paleoamblypygi on divergence time estimation, we performed in silico experiments with pruning of Paracharon. We demonstrate that the omission of relicts has a significant impact on the accuracy of node dating approaches that outweighs the impact of excluding ingroup fossils, which bears upon the ancestral range reconstruction for the group. Our results underscore the imperative for biodiversity discovery efforts in elucidating the phylogenetic relationships of “dark taxa,” and especially phylogenetic relicts in tropical and subtropical habitats. The lack of reciprocal monophyly for Charontidae and Charinidae leads us to subsume them into one family, Charontidae, new synonymy.

中文翻译：

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遗物的重新发现解锁了鞭蜘蛛 （Amblypygi） 的首个全球系统发育


在生命之树中，不对称的分支发生和灭绝速度比比皆是，导致许多微小的分支与更大的姐妹群相比相形见绌。当这些分类群在化石记录中表现出古老的首次出现和长时间的外部形态停滞时，它们通常被视为系统发育遗迹或“活化石”，特别是与它们更多样化的姐妹群相比。由于其特殊地位，各种系统发育遗迹往往得到充分研究并优先进行保护。这一趋势的一个显着例外是在 Amblypygi（“鞭子蜘蛛”）中发现的，这是一个视觉上引人注目的功能性六足蜘蛛目，以其 antenniform 第一对行走腿（同名的“鞭子”）而著称。Paleoamblypygi 是其余 Amblypygi 的推定姊妹群，已知于晚石炭世和始新世矿床，但幸存下来的是一个现存物种，Paracharon caecusHansen（1921 年），最后一次收集是在 1899 年。由于缺乏这一重要分类单元的基因组序列级组织，迄今为止还没有 Amblypygi 的全球分子系统发育，也没有对该类群内部差异的化石校准估计。在这里，我们报告了来自哥伦比亚洞穴遗址的一种以前未知的 Paleoamblypygi 物种。利用这一发现，我们生成了 Amblypygi 的第一个分子系统发育，将超保守元件测序与传统的 Sanger 数据集相结合，并包括已描述的现存属。为了量化采样 Paleoamblypygi 对发散时间估计的影响，我们进行了修剪 Paracharon 的计算机实验。 我们证明，遗漏遗迹对节点测年方法的准确性有重大影响，超过了排除内群化石的影响，后者对该群的祖先范围重建有影响。我们的结果强调了生物多样性发现工作在阐明“暗类群”的系统发育关系方面的必要性，尤其是热带和亚热带栖息地的系统发育遗迹。Charontidae 和 Charinidae 缺乏互惠的单系性，导致我们将它们归入一个科，Charontidae，新的同义词。