Pallenopsis patagonica (Hoek, 1881) is a morphologically and genetically variable sea spider species whose taxonomic classification is challenging. Currently, it is considered as a species complex including several genetic lineages, many of which have not been formally described as species. Members of this species complex occur on the Patagonian and Antarctic continental shelves as well as around sub-Antarctic islands. These habitats have been strongly influenced by historical large-scale glaciations and previous studies suggested that communities were limited to very few refugia during glacial maxima. Therefore, allopatric speciation in these independent refugia is regarded as a common mechanism leading to high biodiversity of marine benthic taxa in the high-latitude Southern Hemisphere. However, other mechanisms such as ecological speciation have rarely been considered or tested. Therefore, we conducted an integrative morphological and genetic study on the P. patagonica species complex to i) resolve species diversity using a target hybrid enrichment approach to obtain multiple genomic markers, ii) find morphological characters and analyze morphometric measurements to distinguish species, and iii) investigate the speciation processes that led to multiple lineages within the species complex. Phylogenomic results support most of the previously reported lineages within the P. patagonica species complex and morphological data show that several lineages are distinct species with diagnostic characters. Two lineages are proposed as new species, P. aulaeturcarum sp. nov. Dömel & Melzer, 2019 and P. obstaculumsuperavit sp. nov. Dömel, 2019, respectively. However, not all lineages could be distinguished morphologically and thus likely represent cryptic species that can only be identified with genetic tools. Further, morphometric data of 135 measurements showed a high amount of variability within and between species without clear support of adaptive divergence in sympatry. We generated an unprecedented molecular data set for members of the P. patagonica sea spider species complex with a target hybrid enrichment approach, which we combined with extensive morphological and morphometric analyses to investigate the taxonomy, phylogeny and biogeography of this group. The extensive data set enabled us to delineate species boundaries, on the basis of which we formally described two new species. No consistent evidence for positive selection was found, rendering speciation in allopatric glacial refugia as the most likely model of speciation.

中文翻译：

---

结合形态学和基因组证据来解决物种多样性并研究 Pycnogonida 物种复合体的物种形成过程

Pallenopsis patagonica (Hoek, 1881) 是一种形态和基因可变的海蜘蛛物种，其分类学分类具有挑战性。目前，它被认为是一个包括多个遗传谱系的物种复合体，其中许多尚未被正式描述为物种。该物种复合体的成员分布在巴塔哥尼亚和南极大陆架以及亚南极岛屿周围。这些栖息地受到历史上大规模冰川作用的强烈影响，之前的研究表明，在冰川盛期期间，群落仅限于很少的避难所。因此，这些独立保护区的异域物种形成被认为是导致南半球高纬度海洋底栖类群高度生物多样性的共同机制。然而，生态物种形成等其他机制却很少被考虑或测试。因此，我们对 P. patagonica 物种复合体进行了综合形态学和遗传学研究，以 i) 使用目标混合富集方法解决物种多样性以获得多个基因组标记，ii) 查找形态特征并分析形态测量以区分物种，以及 iii ）研究导致物种复合体内多个谱系的物种形成过程。系统基因组结果支持先前报道的 P. patagonica 物种复合体中的大多数谱系，形态学数据表明几个谱系是具有诊断特征的不同物种。两个谱系被提议为新种：P. aulaeturcarum sp。十一月 Dömel & Melzer，2019 和 P. obstaculumsuperavit sp。十一月 多梅尔，分别为 2019 年。然而，并非所有谱系都可以在形态上区分，因此可能代表只能通过遗传工具识别的神秘物种。此外，135 次测量的形态测量数据显示，物种内部和物种之间存在大量变异，但没有明确支持同域性的适应性分歧。我们通过目标混合富集方法为 P. patagonica 海蜘蛛物种复合体的成员生成了前所未有的分子数据集，并将其与广泛的形态学和形态计量分析相结合，以研究该群体的分类学、系统发育和生物地理学。广泛的数据集使我们能够划定物种边界，在此基础上我们正式描述了两个新物种。没有发现积极选择的一致证据，使得异域冰川避难所中的物种形成成为最有可能的物种形成模型。