The South African coastline can be divided into at least four temperature-defined marine bioregions, including the tropical north-east coast, the subtropical east coast, the warm-temperate south coast, and the cool-temperate west coast. There are also two biogeographical transition zones, the south-west coast and the south-east coast (or Wild Coast). The former is sometimes considered a distinct marine bioregion, but no such status has yet been suggested for the Wild Coast. Previous data on the distribution of a recently described but very common coastal crab, Hymenosoma longicrure, indicated that this species could be a Wild Coast endemic. If confirmed, this would be a first indication that this region harbours unique fauna, and that additional research is required to determine whether the Wild Coast constitutes a distinct bioregion that needs to be managed separately from other coastal regions. In the present study, we generated novel genetic data for H. longicrure and compared the species’ range with that of its southern African congeners. We found that H. longicrure occurs north of the Wild Coast, where its range overlaps with that of H. projectum. This finding rejects the idea that the Wild Coast harbours endemic fauna and suggests that the ranges of the two species may be linked to the subtropical and tropical bioregions, respectively, with some southward dispersal facilitated by the southward-flowing Agulhas Current. We conclude that there is as yet no compelling evidence that the Wild Coast is a distinct marine bioregion, and concur with previous biogeographical studies which have suggested that the Wild Coast is an area in which species from the subtropical and warm-temperate bioregions have overlapping ranges. Nonetheless, that fact that no biological information is available for the majority of the region’s estuaries highlights the necessity of comprehensively documenting the biodiversity of this understudied region to fully resolve this issue.

中文翻译：

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南非东部的野生海岸是一个独特的海洋生物区吗？

南非的海岸线可以分为至少四个温度定义的海洋生物区，包括热带东北海岸，亚热带东海岸，温带南海岸和冷温西海岸。还有两个生物地理过渡区，西南海岸和东南海岸（或野生海岸）。前者有时被认为是一个独特的海洋生物区，但是对于野生海岸，尚未提出这样的地位。关于最近描述的但非常常见的沿海蟹，Hymenosoma longicrure分布的先前数据表明，该物种可能是野生海岸特有种。如果得到确认，则将首次表明该地区拥有独特的动物区系，并且需要进行更多的研究来确定野生海岸是否构成一个需要与其他沿海地区分开管理的独特生物地区。在当前的研究中，我们产生了长双孢菌的新的遗传数据，并将该物种的范围与其南部非洲同类物种的范围进行了比较。我们发现H. longicrure发生在野生海岸的北部，其范围与H. projectum的范围重叠。这一发现拒绝了野生海岸具有地方性动物区系的想法，并暗示了这两个物种的范围可能分别与亚热带和热带生物区域有关，而向南流动的阿古拉斯海流促进了向南的扩散。我们得出的结论是，目前还没有令人信服的证据表明野生海岸是一个独特的海洋生物区，并与先前的生物地理研究一致，这些研究表明，狂野海岸是亚热带和温带生物区域物种重叠范围的区域。但是，该地区大部分河口没有生物学信息这一事实凸显了全面记录该被研究区域的生物多样性以充分解决这一问题的必要性。