Taxonomy and SSU rDNA-based phylogeny of three new Euplotes species (Protozoa, Ciliophora) from China seas

Abstract As widely accepted, Euplotid ciliates, a unique mono-cellular organisms, play important roles in ecological, environmental, evolutionary and basic biological studies. We investigate the living morphology, infraciliature and silverline system of three new marine Euplotes found from China in this study: Euplotes bergeri n. sp., E. weissei n. sp. and E. shini n. sp. The new species Euplotes bergeri is characterized by its dominant adoral zone of membranelles, ten frontoventral cirri, three or four caudal cirri, 12–14 dorsal kineties with 14–20 dikinetids in the mid-dorsal row, and a dorsal silverline system of the double-eurystomus type. Euplotes weissei can be recognized by its tiny size, having two conspicuous dorsal grooves, nine frontoventral cirri, one marginal cirri, six or seven dorsal kineties, ca. 10 basal bodies in the mid-dorsal row and a mix single-double silverline system. Euplotes shini is a medium-sized form with the ciliary and silverline pattern of the well-known E. minuta but differs from the latter mainly in SSU rDNA gene sequences and usually different-sized marginal cirri. Phylogenetic analyses based on molecular data documented the systematic positions of those new taxa and support the validity of all three organism as distinct species.