An anaerobic, salt-tolerant, rod-shaped bacterium, strain JL216-2
T
, was isolated from the shell of the hydrothermal gastropod
Alviniconcha marisindica
in the Tianxiu hydrothermal field on the Carlsberg Ridge, Indian Ocean. Cells of strain JL216-2
T
were motile and 0.5×3–6 µm in size. Strain JL216-2
T
grew at 10–32 °C (optimal 28 °C), pH 6.0–9.0 (optimal pH 7.0) and 0.5–12.0% (w/v) sodium chloride(NaCl, optimal 2.5%). Strain JL216-2
T
exhibited metabolic versatility, being capable of heterotrophic growth on complex organic compounds. It also performed autotrophic growth by utilizing carbon dioxide (CO₂) fixation or sodium bicarbonate (NaHCO
3
) as the sole carbon source, driven by hydrogen oxidation coupled with Fe(III) reduction. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain was most closely related to
Helicovermis profundi
S502
T
(90.43% sequence similarity). The genome size of strain JL216-2
T
was 4.91 Mb, with a G+C content of 39.54 mol%. Phylogenomic analysis and overall genome relatedness indices values indicated a close relatedness of strain JL216-2
T
to
H. profundi
S502
T
and
Fusibacter
spp. The combined genotypic and phenotypic data showed that strain JL216-2
T
represents a novel genus within the order
Eubacteriales
. The type strain is JL216-2
T
(=MCCC M30262
T
=KACC 23553
T
).