Taxon sampling
Genomes of selected gastropods, including the aplysiid Aplysia californica (base genome), the sacoglossan Elysia chlorotica , the hygrophilid Radix auricularia , and the caenogastropodPomacea canaliculata (used as outgroup), and transcriptomes of the cephalaspidean Haminoea antillarum and the umbraculidTylodina fungina were downloaded from NCBI. Additional transcriptomes across Heterobranchia, including Acochlidia, Acteonida, Architectonicoidea, Ellobiida, Nudibranchia, Pleurobranchida, Pteropoda, Pylopulmonata, and Rissoelloidea, were downloaded for the in silico test of the bait set. Finally, two Caenogastropoda were downloaded for matrix construction and for rooting the phylogenetic trees (Table 1, S1).
Specimens for the in vitro test of the bait set were obtained from the Museum of Comparative Zoology (MCZ) and the University Museum of Bergen (Department of Natural History; ZMBN, Norway) (Table 2). Most of the material was freshly collected from the Maldives in 2019, preserved at 95% EtOH and kept at –20 °C. The remaining samples were gathered from museum collections, mostly preserved in 70% EtOH and kept at room temperature, sometimes for several years, and are thus considered ‘degraded’ samples.