Cyrtarachninae are moth-specialized orb-weaving spiders whose unique web architectures have attracted considerable interest from evolutionary biologists and material scientists. Despite this attention, their taxonomy remains poorly resolved owing to extreme female-biased sexual size dimorphism and cryptic lifestyles. We revise the Taiwanese Cyrtarachninae using an integrative approach combining morphological and molecular evidence. Whereas previous studies recognized only four species, we document 15 species in four genera, including three previously recorded species, nine newly recorded species, and three species new to science: Pasilobus bifurcatus sp. nov., Pasilobus albosignatus sp. nov., and Cyrtarachne tricornis sp. nov. This total excludes the previously misidentified Pasilobus bufoninus (Simon, 1867). We also report the first Taiwanese record of the genus Ordgarius. Molecular analyses reveal that the previously described male of Cyrtarachne inaequalis was misidentified, and we provide a formal description of the true male. Phylogenetic analyses based on COI and 28S support the monophyly of most morphologically defined species, but species-delimitation methods reveal several incongruences between molecular and morphological datasets. Furthermore, the phylogeny suggests that some currently recognized genera may not represent natural groups, with Cyrtarachne recovered as non-monophyletic and Pasilobus nested within one of its principal clades. These results highlight the limitations of species delimitation and generic circumscription based on morphology or a small number of genetic markers alone. Our study nearly quadruples the known diversity of Taiwanese Cyrtarachninae and provides a foundation for future phylogenomic investigations aimed at resolving species boundaries, generic relationships, and the evolutionary history of this remarkable spider lineage.
Integrative taxonomy, Species delimitation, Island biodiversity, Phylogeny, Moth-specialized spider, Orb-weaving spiders