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

During the present study, species boundaries in the velvet worm Peripatopsis birgeri 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 CO1 and nuclear 18S rRNA sequence data were used to generate a phylogeny using both a Bayesian inference and maximum likelihood approaches. Both the CO1 sequence data and the combined DNA sequence topology (CO1 + 18S rRNA) revealed the presence of two geographically distinct clades within the P. birgeri 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 CO1 haplotype network and statistically significant FST 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 (P. birgeri). 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 P. birgeri s.s. species complex. Peripatopsis birgeri s.s. is revised and restricted to the southern Drakensberg and a new species, P. polychroma 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物种复合群的物种界限展开探究，采用DNA序列数据、大体形态学、扫描电子显微镜（SEM）以及生态位建模等方法开展分析。研究使用线粒体CO1基因与核18S rRNA序列数据，借助贝叶斯推断法与最大似然法构建系统发育树。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）在该复合群的物种数量判定上结果不一致，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FST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。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固定差异，但乳白色头带/颈领仅存在于演化支1的标本（即P. birgeri）中。与之相反，扫描电子显微镜（SEM）结果显示两个演化支间存在固定的背侧与腹侧鳞片排列等级差异。本研究结果证实，P. birgeri s.s.物种复合群内存在一个新物种。本研究对狭义Peripatopsis birgeri类群进行了修订，将其限定在南德拉肯斯堡地区，并描述了一个新物种P. polychroma sp. nov.（演化支2），其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。https://zoobank.org/urn:lsid:zoobank:org:pub:569557AB-8BC8-49B6-B8AA-96507371297B