Hao Song

The Pleurotomarioidea, commonly referred to as slit shells, constitute one of the most ancient and enduring lineages within the phylum Mollusca, with its fossil record tracing back to the Upper Cambrian epoch. Its rareness and evolutionary antiquity surpass even that of the nautilus. In this study, we conducted the first transcriptome sequencing and analyses of Entemnotrochus rumphii (Schepman, 1879), a representative species of Pleurotomarioidea. Full-length transcriptome sequencing of E. rumphii was performed using the PacBio Sequel II platform with SMRT technology. A total of 64.38 gigabytes of data and 964,550 polymerase reads were generated, resulting in 28,068,998 subreads after data filtering. After de-duplication, correction, and clustering, we identified 19,273 genes. Additionally, next-generation sequencing was performed on 11 tissues of E. rumphii. This investigation provides a detailed portrayal and analytical scrutiny of its transcriptomic landscape.

Pleurotomarioidea represents a truly isolated and basally diverging lineage in Vetigastropoda (Mollusca: Gastropoda) whose fossil record can date back to the late Cambrian, thus providing rare insights into the evolutionary history of molluscs. Here, we sequenced and assembled the complete mitochondrial genome of one representative species from Pleurotomarioidea—Entemnotrochus rumphii (Schepman, 1879)—of which the mitogenome is 15,795 bp in length, including 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. The nucleotide composition was biased toward AT, and A + T content reached 65.2%. E. rumphii was recovered as sister to all other living vetigastropods according to mitogenome-based phylogenetic analysis. The mitochondrial gene order was consistent with major vetigastropods and the hypothetical ancestral gastropoda, suggesting the deep conservation of mitogenome arrangement in Vetigastropoda.