Abstract
This study reports the discovery of two novel ciliate species – Dysteria brevicauda sp. nov. and Dysteria parasemilunaris sp. nov. – inhabiting unique environments in recently explored hydrothermal vent fields at the Onnuri and Onbada vents (1978 m and 2523 m depths, respectively) along the Central Indian Ridge in the Indian Ocean. The species were identified using a combination of morphological and molecular approaches. The morphology of D. brevicauda sp. nov. (65–110 × 20–30 μm) is characterized by a protruding dorso-anterior part, a short tail-like structure, converging outer two right kineties at the posterior end, and two frontoventral kineties with a few gaps in the anterior part. D. parasemilunaris sp. nov. (50–70 × 25–35 μm) can be recognized by its elongated oval shape with a dorsoapical collar-like protrusion, a terminally positioned stout podite, and five right kineties, including two frontoventral kineties. D. parasemilunaris sp. nov., which inhabits both the Onnuri and Onbada vents, is morphologically almost identical to Dysteria sp. collected from another hydrothermal vent, Clam Acres, in 1985. Thus, these are considered conspecific species. Phylogenetic analysis based on SSU rDNA sequences places the two new species within Dysteria Group III and V clades, respectively. D. brevicauda sp. nov. is positioned between Spirodysteria kahli (97.3% similarity) and D. subtropica (97.1% similarity). Meanwhile, D. parasemilunaris sp. nov. forms a cluster with D. semilunaris (95.3% similarity) and branches off from D. lanceolata (94.3% similarity). These findings contribute to the understanding of ciliate biodiversity in deep-sea hydrothermal vents. http:zoobank.org/urn:lsid:zoobank.org:pub:FE45985A-C0C1-4BAC-9471-3CC5D6180FEC.
Published Version
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