The systematics of Subantarctic and Antarctic near-shore marine benthic invertebrates requires major revision and highlights the necessity to incorporate additional sources of information in the specimen identification chart in the Southern Ocean (SO). In this study, we aim to improve our understanding of the biodiversity of Kidderia (Dall 1876) through molecular and morphological comparisons of Antarctic and Subantarctic taxa. The microbivalves of the genus Kidderia are small brooding organisms that inhabit intertidal and shallow subtidal rocky ecosystems. This genus represents an interesting model to test the vicariance and dispersal hypothesis in the biogeography of the SO. However, the description of Kidderia species relies on a few morphological characters and biogeographic records that raise questions about the true diversity in the group. Here we will define the specimens collected with genetic tools, delimiting their respective boundaries across provinces of the SO, validating the presence of two species of Kidderia. Through the revision of taxonomic issues and species delimitation, it was possible to report that the Antarctic species is Kidderia subquadrata and the species recorded in the Subantarctic islands Diego Ramirez, South Georgia and the Kerguelen Archipelago is Kidderia minuta. The divergence time estimation suggests the origin and diversification of Kidderia lineages are related to historical vicariant processes probably associated with the separation of the continental landmasses close to the late Eocene.

亚南极和南极近岸海洋底栖无脊椎动物的系统学需要进行重大修订，并强调有必要在南大洋 (SO) 的标本识别图中纳入额外的信息来源。在这项研究中，我们旨在通过对南极和亚南极分类群的分子和形态学比较，提高我们对Kidderia (Dall 1876) 生物多样性的理解。Kidderia属的微生物是栖息在潮间带和浅潮下带岩石生态系统中的小型育雏生物。该属代表了一个有趣的模型，用于测试 SO 生物地理学中的变异和分散假设。然而，对Kidderia的描述物种依赖于一些形态特征和生物地理记录，这些记录对群体的真正多样性提出了质疑。在这里，我们将定义用遗传工具收集的标本，划定它们在 SO 各省之间的各自边界，验证两种Kidderia的存在。通过对分类问题和物种划分的修订，可以报告南极物种为Kidderia subquadrata，亚南极岛屿迭戈拉米雷斯、南乔治亚岛和Kerguelen群岛记录的物种为Kidderia minuta。发散时间估计暗示了Kidderia的起源和多样化谱系与可能与接近始新世晚期的大陆陆块分离有关的历史变迁过程有关。