Abstract

The Laufeia clade is a peculiar lineage of euophryine jumping spiders showing rapid divergence of male genital structures, especially the embolic complex that directly interacts with female genitalia during sperm transfer. With the rapid growth of species discovery and the perplexing morphology of male genitalia in the Laufeia clade, the controversy in its classification has become a crucial problem. In this study, we applied a phylogenomic approach using ultra-conserved elements data to infer the phylogeny of the Laufeia clade with extensive taxon sampling. A comparative morphological study was performed to evaluate diagnostic characters and understand the evolution of the male embolic complex within the Laufeia clade. The evolution of microhabitats (foliage, tree trunk, rock and surface litter) was also investigated to uncover the potential link between the microhabitat shifts and male embolic complex divergence. The results provide a strongly supported phylogenetic framework and updated generic concepts for the Laufeia clade. The synapomorphies for the updated genera within the Laufeia clade were identified through character mapping on the phylogeny. Ancestral state reconstruction analyses revealed that the Type I embolic complex (characterized by a disc-like embolic disc with a lamina as its outer edge) was ancestral and gradually evolved into the Type II (without lamina of embolic disc, base of embolic complex often modified into a functional "conductor") and Type III (lacking lamina of embolic disc and base of embolic complex) embolic complex, and that some embolic shapes evolved multiple times independently in different lineages of the Laufeia clade. The shift from foliage-dwelling to tree trunk-dwelling in the common ancestor of the Laufeia clade may have facilitated the divergent evolution of male embolic complex in the Laufeia clade. This study provides a solid foundation for future studies of systematics and evolution of this group.