SRA

Here we describe four new species of Xenoturbella from deep waters of the eastern Pacific Ocean. One species, found near a whalefall at 600 m depth in Monterey Canyon (California), is similar to the Swedish Xenoturbella at 2.5 cm in length. The second species is much larger (over 20 cm), and was found in a vesicomyid clam field at ~3000 m depth in Monterey Canyon and near a chemosynthetic habitat at ~1700 m in the Gulf of California, Mexico. The third species, also large, was also found at the same site in the Gulf of California at ~1700 m. The fourth species, reaching 15 cm in length, was found at over 3700 meters depth near a hydrothermal vent in the Gulf of California. Analysis of whole mitochondrial genomes places the three new deep sea sea species as a clade that is sister to the smaller and more shallow-water Xenoturbella species. Phylogenomic analysis of transcriptomic data for one of the new Xenoturbella species supports the placement of it with Acoelomorpha and them both as sister to Nephrozoa.