A phylogeny-aware approach reveals unexpected venom components in divergent lineages of cone snails

Marine gastropods of the genusConusare renowned for their remarkable diversity and deadly venoms. WhileConusvenoms are increasingly well studied for their biomedical applications, we know surprisingly little about venom composition in other lineages of Conidae. We performed comprehensive venom transcriptomic profiling forConasprella coriolisiandPygmaeconus traillii, first time for both respective genera. We complemented reference-based transcriptome annotation by ade novotoxin prediction guided by phylogeny, which involved transcriptomic data on two additional ‘divergent’ cone snail lineages,Profundiconus, andCaliforniconus. We identified toxin clusters (SSCs) shared among all or some of the four analysed genera based on the identity of the signal region—a molecular tag present in toxins. In total, 116 and 98 putative toxins represent 29 and 28 toxin gene superfamilies inConasprellaandPygmaeconus, respectively; about quarter of these only found by semi-manual annotation of the SSCs. Two rare gene superfamilies, originally identified from fish-hunting cone snails, were detected outsideConusrather unexpectedly, so we further investigated their distribution across Conidae radiation. We demonstrate that both these, in fact, are ubiquitous in Conidae, sometimes with extremely high expression. Our findings demonstrate how a phylogeny-aware approach circumvents methodological caveats of similarity-based transcriptome annotation.