Coral reefs are highly threatened ecosystems, yet there are numerous challenges in conducting inventories of their vanishing biodiversity, partly because many taxa remain difficult to detect and describe. Genetic species delimitation methods provide a standardized means for taxonomic classification including of cryptic, rare, or elusive groups, but results can vary by analytical method and genetic marker. In this study, a combination of morphological and genetic identification methods was used to estimate species richness and identify taxonomic units in true crabs (Infraorder Brachyura; n = 200) from coral reefs of Palmyra Atoll, Central Pacific. Genetic identification was based on matches between mitochondrial 16S ribosomal RNA (16S rRNA) and/or cytochrome c oxidase subunit I (COI) sequences to GenBank data, while morphological work relied on the taxonomic literature. Broad agreement in the number of candidate species delimited by genetic distance thresholds and tree-based approaches was found, although the multi-rate Poisson tree process (mPTP) was less appropriate for this dataset. The COI sequence data identified 30–32 provisional species and the 16S data revealed 34–35. The occurrence of 10 families, 20 genera, and 19 species of brachyurans at Palmyra was corroborated by at least two methods. Diversity levels within Chlorodiella laevissima indicated possible undescribed or cryptic species in currently lumped taxa. These results illustrate the efficacy of DNA sequences in identifying organisms and detecting cryptic variation, and underscore the importance of using appropriate genetic markers and multiple species delimitation analyses, with applications for future species descriptions.

珊瑚礁是受到高度威胁的生态系统，但是在清查其消失的生物多样性方面面临许多挑战，部分原因是许多生物分类仍然难以发现和描述。遗传物种定界方法为分类学分类提供了标准化的方法，包括神秘，稀有或难以捉摸的组，但结果可能因分析方法和遗传标记而异。在这项研究中，结合了形态学和遗传学鉴定方法来估计物种丰富度，并鉴定中太平洋帕尔米拉环礁珊瑚礁真蟹（Infraorder Brachyura； n = 200）中的分类单位。遗传鉴定基于线粒体16S核糖体RNA（16S rRNA）和/或细胞色素c氧化酶亚基I（COI）序列到GenBank数据，而形态学工作则依赖于分类学文献。尽管通过多速率泊松树过程（mPTP）不太适合此数据集，但是发现了由遗传距离阈值和基于树的方法界定的候选物种数量上的广泛共识。COI序列数据确定了30–32种临时物种，而16S数据揭示了34–35种。至少有两种方法证实了在巴尔米拉有10个科，20个属和19个腕类动物的发生。Laevissima小球藻内的多样性水平表示当前集中的分类单元中可能没有描述的或隐秘的物种。这些结果说明了DNA序列在识别生物体和检测隐性变异中的功效，并强调了使用适当的遗传标记和多种物种定界分析的重要性，并为将来的物种描述提供了应用。