Molecular phylogeny and taxonomy of four Remanella species(Protozoa, Ciliophora): A flagship genus of karyorelictean ciliates, with descriptions of two new species

During faunal studies of psammophilic ciliates along the coast of Qingdao, China, several marine karyorelictean species were isolated. Among them,four species within the genus Remanella were investigated, including two species new to science:i.e., R. rugosa, Remanella elongata sp. nov.,Remanella aposinica sp. nov.,and R.unicorpusculata. Remanella rugosa has been reported several times, but this study is the first to provide detailed morphological characters and phylogenetics. Remanella elongata sp. nov. can be distinguished from its congeners by the presence of complex cortical granules, fewer macronuclei, and longer body size. Remanella aposinica sp. nov.differs from its congeners by having 14–17 right lateral ciliary rows and 24–37 dikinetids of intrabuccal kinety. Poorly known Remanella rugosa var. unicorpusculata(Kahl, 1933) Foissner, 1996should be elevated from subspecies to species level,Remanella unicorpusculata(Foissner, 1996) stat.nov., based on detailed redescriptions with statistical data, living morphology, infraciliature, and species definitions. Small subunit(SSU) rDNA was sequenced for the four species, and phylogenetic analysis revealed that all known taxa in Remanella formed the outline branch to the genus Loxodes with moderate to high bootstrap support among Remanella lineages.

Doublets of the unicellular organism Euplotes vannus(Alveolata,Ciliophora,Euplotida):the morphogenetic patterns of the ciliary and nuclear apparatuses associated with cell division

Ciliated protists are one of the most diverse and highly differentiated group among unicellular organisms.Doublets occur in ciliates when two cells fuse into a single individual.Doublets contain two major cellular components(either cell in a doublet)and have traditionally been considered as developmental anomalies.Nevertheless,doublets can divide or even conjugate effectively,which may represent dispersal forms of the life stages.In addition,morphogenesis,as an important process in the life cycle,will provide important insights into the complex differentiation mechanism and various physiological phenomena.However,morphogenetic studies focusing on doublets of ciliates are very limited,which has become an obstacle to understand their complete life history.Here we isolated a doublet strain from the marine species Euplotes vannus(Müller,1786)Diesing,1850 and investigated its morphogenetic events during asexual reproduction.Our results indicate that:(1)the opisthe’s oral primordium develops de novo beneath the cortex;(2)the frontoventral and transverse cirral anlagen,cirrus I/1,and marginal anlagen in both dividers develop de novo separately;(3)the dorsal kinety anlagen,the three rightmost ones of which produce three caudal cirri for the proter,occur within the parental structures in the mid-body region;(4)the opisthe acquires two caudal cirri,one from the end of each two rightmost kineties;and(5)there are two macronuclei and one micronucleus in the doublet and they divide amitotically and mitotically,respectively.Finally,we speculate that this special differentiation may be an adaptive form to adverse environments.