The definition, as well as the existence of cryptic species, is still a subject of controversial debates. Some scientists claim that cryptic diversity is a real phenomenon that should be extensively studied while others argue that cryptic species do not exist as they are nothing more than an incompatibility of species concepts. We investigated the enigmatic case of two widely distributed Caribbean intertidal oribatid mites, Carinozetes bermudensis and Carinozetes mangrovi, consisting of five distinct genetic lineages. Morphological features allowing to clearly distinguish between these lineages are absent, and despite certain congruence with genetic data, comprehensive morphometric analyses also do not show clear separation. Species delimitation analyses based on COI sequence data, on the other hand, suggest five distinct genetic species. Despite the lack of diagnostic characters for these suggested species, the lineages can be classified at least into two morphological groups, the bermudensis and the mangrovi group which can only be distinguished by the arrangement of cuticular ventral carinae. Specimens within a group show nearly identical phenotypes, impeding morphological identification and hence rendering the found diversity cryptic. Stabilizing selection caused by the extreme conditions of the intertidal environment is suggested to be responsible for the found morphological stasis. The genetic lineages show more or less clear geographic patterns; in C. mangrovi, there is a northern, an Antillean, and a Pacific lineage, whereas in C. bermudensis, there is a Bermudian and a Caribbean lineage. In a few places, e.g., the Bahamas and Panama, distributions may overlap. Neither the found biogeographic pattern nor the observed ecological needs could explain the reason for the genetic diversification of Caribbean Carinozetes.

中文翻译：

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加勒比海之谜：潮间带螨（Arachnida、Acari、Oribatida）中存在不寻常的隐秘多样性

定义，以及隐性物种的存在，仍然是一个有争议的话题。一些科学家声称隐性多样性是一种真实的现象，应该被广泛研究，而另一些科学家则认为隐性物种不存在，因为它们只不过是物种概念的不兼容。我们调查了两种广泛分布的加勒比海潮间带螨类、Carinozetes bermudensis 和 Carinozetes mangrovi 的神秘案例，它们由五个不同的遗传谱系组成。没有能够清楚地区分这些谱系的形态特征，尽管与遗传数据有一定的一致性，但综合形态测量分析也没有显示出明显的分离。另一方面，基于 COI 序列数据的物种定界分析表明有五种不同的遗传物种。尽管缺乏这些建议物种的诊断特征，但这些谱系至少可以分为两个形态组，百慕大和红树组，只能通过表皮腹隆突的排列来区分。一组内的标本显示出几乎相同的表型，阻碍了形态学鉴定，从而使发现的多样性变得神秘。由潮间带环境的极端条件引起的稳定选择被认为是造成所发现的形态停滞的原因。遗传谱系或多或少显示出清晰的地理模式；在 C. mangrovi 中，有北部、安的列斯和太平洋血统，而在 C. bermudensis 中，有百慕大和加勒比血统。在一些地方，例如巴哈马和巴拿马，分布可能会重叠。