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