Wooden steps to shallow depths: A new bathymodiolin mussel, Vadumodiolus teredinicola, inhabits shipworm burrows in an ancient submarine forest

Large mussels of the mytilid subfamily Bathymodiolinae are common inhabitants of deep-sea hydrothermal vents and cold seeps, where gill-borne symbionts allow them to utilize energy-rich compounds such as hydrogen sulfide and methane to support abundant growth. This subfamily also includes smaller symbiont-bearing mussels found on deep-sea wood and organic deposits. Phylogenetic analyses suggest that wood association is ancestral to bathymodiolin evolution. This observation led to the “wooden steps” hypothesis, which proposed that wood and other large organic deposits have acted as evolutionary steppingstones, introducing the progenitors of the modern vent and seep Bathymodiolinae to their remote environments. Although this hypothesis implies an evolutionary trajectory from shallow to deep water, no bathymodiolin species that grows and reproduces at depths less than 100 m has yet been formally described. Here we describe a new bathymodiolin genus and species, Vadumodiolus teredinicola, f..., To search for evidence of bacterial symbionts in the tissues of Vadumodiolus teredinicola, we sequenced the gill metagenomes of three specimens, assembled contigs and sorted contigs of predicted bacterial origin into bins reflecting individual predicted bacterial MAGs using SPADES and metaBAT2. Reads of bacterial origin were sparsely represented in the three individual gill metagenome datasets. However, by combining reads from all three gill metagenome sequences during SPADES assembly, a single, though highly fragmented, bacterial MAG was assembled. MetaBAT2 uses tetranucleotide composition information to perform binning. MetaBAT2 takes a metagenome assembly and the reads that produced the assembly and organizes the contigs into putative genomes, called \"bins\". Because metaBAT2 only uses contigs longer than 1.5 kbp during binning, we performed BLASTn searches using the 16S rRNA genes, 23S rRNA genes, and coding sequences (CDS) of Bathymodiolus thermophilus thioautotrophic gill symbiont ..., , # Wooden steps to shallow depths: a new bathymodiolin mussel, Vadumodiolus teredinicola, inhabits shipworm burrows in an ancient submarine forest

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Files included:

* DRYAD : Vt_gill_bac_5288ABC_2023-05-05_NCBI_decontam.fsa.fasta
* ZENODO: Altamia et al._2023-1212_supplement.1.reordered.final.pdf
* ZENODO: Vadumodiolus_teredinicola_Supplementary_Video_SV1.MP4
* ZENODO: Vadumodiolus_teredinicola_Supplementary_Video_SV2.mp4

## Description of the data and file structure

* Vt_gill_bac_5288ABC_2023-05-05_NCBI_decontam.fsa.fasta
Draft metagenome assembled genome of Vadumodiolus teredinicola gill bacterium in FASTA format

Wooden steps to shallow depths: a new bathymodiolin mussel, Vadumodiolus teredinicola, inhabits shipworm burrows in an ancient submarine forest

Marvin A. Altamia, Hannah J. Appiah-Madson, Rosalia Falco Poulin, Bruno Huettel, Maxim Rubin-Blum,
Nicole Dubilier, Harald R. Gruber-Vodicka, Nikolaus Leisch, and Daniel L. Distel*

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