A barotolerant ciliate isolated from the abyssal deep sea of the North Atlantic: Euplotes dominicanus sp. n. (Ciliophora, Euplotia)

A new Euplotes species, isolated from abyssal depths (>4000 m) of the North Atlantic Ocean, was described based on morphology, ciliary pattern and molecular data. Euplotes dominicanus sp. n. is characterized by a small body size (29–40 × 17–27 μm in vivo), 18–22 adoral membranelles, 10 frontoventral, five transverse and two left marginal cirri and one caudal cirrus, five or six dorsolateral kineties with 7–9 dikinetids in mid-dorsolateral kinety (DK3), and dorsal silverline system of the double-eurystomus type. Phylogenetic analyses inferred from 18S rRNA sequences show that Euplotes dominicanus sp. n. is most closely related to E. curdsi, with a sequence similarity of 97.6 %. Euplotes dominicanus sp. n. was able to survive hydrostatic pressures up to 500 bar indicating its barotolerance. Metabarcoding data demonstrate the presence of E. dominicanus sp. n. in sediments of several deep-sea basins.