Phylogenetic Diversity and Venom Gland Transcriptomics of Palauan Cone Snails (Conidae)

Cone snails (genus Conus Linnaeus, 1758) represent one of the most species-rich lineages of venomous marine snails, producing diverse and highly specialized toxins. While Conus diversity is particularly high in the Indo-Pacific, some regions, such as the archipelago of Palau, remain poorly studied. Here, we combine mitochondrial marker gene sequencing (COI, 12S, and 16S) and venom-gland transcriptomics to investigate the phylogenetic relationships and venom gene diversity of Palauan Conus species. We sampled 27 species, recovering mitochondrial sequences for 34-41 individuals per gene. Maximum-likelihood phylogenetic analysis revealed that most individuals group with known species, although several lineages show notable divergence from reference sequences. We additionally sequenced venom gland transcriptomes from 21 individuals representing 14 species, including three species for which no previous venom data exist. Comparative analysis showed largely consistent expression patterns at the superfamily level within species collected from different biogeographical regions, supporting conserved venom gene expression profiles. These results contribute foundational data for future studies of Conus evolution, biogeography, and toxin diversification in an underexplored biodiversity hotspot.