Integrative taxonomy provides evidence for a cryptic lineage in the velvet worm <i>Peripatopsis birgeri</i> species complex (Onychophora: Peripatopsidae) in KwaZulu-Natal, South Africa

During the present study, species boundaries in the velvet worm <i>Peripatopsis birgeri</i> species complex in KwaZulu-Natal, South Africa, were examined with the use of DNA sequence data, gross morphology, scanning electron microscopy (SEM) and ecological niche modelling. Mitochondrial <i>CO1</i> and nuclear <i>18S</i> rRNA sequence data were used to generate a phylogeny using both a Bayesian inference and maximum likelihood approaches. Both the <i>CO1</i> sequence data and the combined DNA sequence topology (<i>CO1</i> +<i> 18S</i> rRNA) revealed the presence of two geographically distinct clades within the <i>P. birgeri</i> species complex. Results from three species delimitation methods (GMYC, PTP and ASAP), were incongruent in determining the number of species within the species complex and generally overestimated the number of operational taxonomic units. The latter result can be attributed to the marked genetic structure within the species complex, a result corroborated by the <i>CO1</i> haplotype network and statistically significant <i>F</i>_ST values. Divergence time estimation suggests that the two clades diverged during the Plio/Pleistocene. Niche modelling revealed that the two clades were differentially impacted by bioclimatic variables and occupied different habitats. Gross morphological characteristics, such as leg pair numbers and colour revealed no fixed differences between the two clades, however, a creamy white headband/collar occurred exclusively in specimens of clade 1 (<i>P. birgeri</i>). In contrast, SEM revealed fixed dorsal and ventral scale rank differences between the two clades. The results corroborate the presence of a novel species within the <i>P. birgeri s.s.</i> species complex. <i>Peripatopsis birgeri s.s.</i> is revised and restricted to the southern Drakensberg and a new species, <i>P. polychroma</i> sp. nov. (clade 2), from the northern Drakensberg and adjacent Afrotemperate forests in the interior of KwaZulu-Natal is described. https://zoobank.org/urn:lsid:zoobank:org:pub:569557AB-8BC8-49B6-B8AA-96507371297B本研究针对南非夸祖鲁-纳塔尔省的天鹅绒虫*Peripatopsis birgeri*物种复合群的物种边界展开考察，采用DNA序列数据、大体形态学、扫描电子显微镜（scanning electron microscopy, SEM）以及生态位建模技术。研究借助线粒体CO1基因与核18S rRNA序列数据，分别通过贝叶斯推断法与最大似然法构建系统发育树。线粒体CO1序列数据以及联合序列拓扑结构（CO1+18S rRNA）均显示，*P. birgeri*物种复合群内存在两个地理分化的演化支。三种物种界定方法（GMYC、PTP与ASAP）的结果在该物种复合群的物种数量判定上存在不一致性，且普遍高估了操作分类单元（operational taxonomic unit, OTU）的数量。该结果可归因于该物种复合群内显著的遗传结构，这一结论得到了CO1单倍型网络以及具有统计学显著性的*F*_ST值的佐证。分化时间估算结果显示，两个演化支的分化发生在上新世/更新世时期。生态位建模结果表明，两个演化支受到生物气候变量的影响存在差异，且占据了不同的栖息生境。大体形态学特征（如足对数与体色）未显示两个演化支间存在稳定差异，但乳白头部带/颈环仅存在于演化支1（*P. birgeri*）的标本中。与之相反，扫描电子显微镜结果显示两个演化支间存在稳定的背侧与腹侧鳞片列差异。本研究结果证实，*P. birgeri* s.s.物种复合群内存在一个新物种。研究对狭义*Peripatopsis birgeri*进行了修订，并将其分布范围限定于南德拉肯斯堡地区；同时描述了一个新物种——*P. polychroma* sp. nov.（演化支2），该物种分布于北德拉肯斯堡以及夸祖鲁-纳塔尔省内陆邻近的非洲温带森林中。https://zoobank.org/urn:lsid:zoobank:org:pub:569557AB-8BC8-49B6-B8AA-96507371297B