Chromosome-level genome assembly of the Asian tramp snail Bradybaena similaris (Stylommatophora: Camaenidae)

While terrestrial land snails have long been subjected to evolutionary research, a lack of high-quality genomic resources has impeded recent progress. Bradybaena snails in particular have numerous intriguing traits that make them a good model for studying evolution, including shell pattern polymorphism and convergent evolution. They are also introduced and invasive across the world. In this study, we present a chromosome-level genome assembly of the Asian tramp snail Bradybaena similaris utilizing 88-fold Illumina short-read sequences, 125-fold Nanopore long-read sequences, 63-fold PacBio HiFi sequences, and 47-fold Hi-C sequences. The assembled genome of 2.18 Gb is anchored to 28 chromosomes, and exhibits high completeness (98.8% metazoan BUSCO completeness) and contiguity (N50 of 75.6 Mb). Additionally, we also obtained a high-quality transcriptome for annotation. This resource represents the first chromosome-level assembly for snails in the superfamily Helicoidea, which includes more than 5,000 species of terrestrial snails, and will facilitate genomic study in Bradybaena and, more broadly, in the superfamily Helicoidea. SIGNIFICANCE STATEMENTWhile the Helicoidea is the largest land snail superfamily, consisting of more than 5,000 species, many of interest to evolutionary studies, no chromosome-level assembly has been available for any species. Previously, the genus Bradybaena in the Helicoidea has been studied in the context of speciation, adaptation and invasive biology, and thereby has high potential for further research. In this study, we present a chromosome-level assembly and transcriptome of the Asian tramp snail Bradybaena similaris. These high-quality genomic resources will facilitate research on related species, and eventually enhance our understanding of many areas of evolutionary biology.