A. Markee, L. J. Davis, D. D. Davis, J. S. Edgerly, E. L. Stanley, J. L. Ware, A. Y. Kawahara, A. Powell, C. Y. Hayashi, R. H. Baker, P. B. Frandsen
Webspinners (Insecta: Embioptera) are an unusual insect order that are known for their subsocial behavior and prolific silk-production. Due to their unique foreleg silk glands, and spider-like ability to produce silk throughout their entire life cycle, webspinners are hypothesized to have evolved silk independently from other arthropod lineages. To date, there are no reference-quality genomes available for the order, preventing the study of their silk gene origination and diversification. Here, we assembled PacBio HiFi reference genomes and characterized the silk genes present in two webspinner species, Aposthonia ceylonica and Oligotoma nigra. The genomes reveal multiple full-length copies of the primary Embioptera silk gene, e-fibroin, that have undergone both ancestral and recent gene duplications within the group. For both species, all e-fibroin paralogs show the presence of complex repeat units consisting of multiple exons and introns that are remarkably homogenized across each gene. We also used 7CT-scanning of the internal silk glands to provide details concerning the localization of silk production in foreleg tarsi, and interspecific morphology.