Ciliates constitute a vital component of eukaryotic diversity, playing an essential trophic role in aquatic ecosystems by mediating carbon and nutrient cycling. As specialized primary consumers in biofilms, cyrtophorian ciliates (Class Phyllopharyngea de Puytorac et al., 1974) are ubiquitous in periphytic habitats; yet, their biodiversity remains significantly underestimated compared to well-studied model groups. Here we document three species from the urban-adjacent coastal waters in East China. Integrative studies suggest that one of them represents a novel species and the other two are rare species. Morphological and molecular investigations were conducted on three species belonging to the order Dysteriida Deroux, 1976, Dysteria armata Huxley, 1857, Dysteria bella sp. nov., and Orthotrochilia agamalievi Deroux, 1976. For Dysteria armata (the type species of the genus), detailed morphometric data and an improved diagnosis are provided based on a Chinese population. The new species is characterized by size in vivo 75–110 × 40–60 μm, body long obovate, and seven right kineties including five frontoventral kineties. The SSU rRNA gene sequences were first obtained for all three species. Phylogenetic analyses reveal that Dysteria bella sp. nov. and D. armata form a fully supported sister clade. Consistent with morphological diversity, the molecular topology shows the non-monophyly of the genus Dysteria. Furthermore, the first molecular data for Orthotrochilia confirms its evolutionary distinctiveness from the genus Trochilioides. By providing detailed morphological and molecular characterizations of one new and two poorly known marine cyrtophorian species, this work not only advances our knowledge of the biodiversity within this specialized ciliate group but also resolves the systematic placement of the type species D. armata. Additionally, the acquisition of these sequences supplies essential genetic markers, filling critical gaps in molecular databases.
Wang et al. (Tue,) studied this question.