Diversity of free-living marine ciliates (Alveolata, Ciliophora): Faunal studies in coastal waters of China during the years 2011–2016

In the period 2011–2016, a series of investigations were carried out on the marine and brackish free-living ciliate fauna of the temperate–tropical coastal waters of China. About 210 morphotypes including over 100 new species within six groups (cyrtophorians, hypotrichs s.l., karyorelicteans, oligotrichs, pleurostomatids, and scuticociliates) were isolated and described in detail from observations of live cells and silver-stained specimens. Based on their morphology, morphogenesis and molecular phylogeny, three new families (Wilbertomorphidae, Kentrophyllidae, Protolitonotidae) and 22 new genera (Apotrachelocerca, Wilbertomorpha, Protolitonotus, Paracyrtophoron, Heterohartmannula, Aporthotrochilia, Falcicyclidium, Paramesanophrys, Pseudodiophrys, Monocoronella, Neourostylopsis, Apobakuella, Parabistichella, Heterokeronopsis, Heterotachysoma, Antiokeronopsis, Apoholosticha, Pseudogastrostyla, Antestrombidium, Sinistrostrombidium, Williophrya, and Varistrombidium) were established. In the present review, we summarize these studies which show there is a large, undiscovered diversity of ciliates, especially in undersampled habitats, such as subtropical/tropical coastal waters, mangrove wetlands, estuaries and aquaculture ponds. We also highlight the importance of integrative approaches, combining morphology, morphogenesis and molecular phylogeny, in order to understand ciliate systematics and ecosystem function.