Zhenzhen Yi

The morphology and morphogenesis of two populations of the soil hypotrichous ciliate, Parakahliella macrostoma (Foissner, 1982) Berger et al. 1985, isolated from northwest China, were investigated based on specimens examined in vivo and stained with protargol. Our populations resemble the original one in terms of their live characters and cirral pattern. The main events during binary fission are as follows: (1) the parental adoral zone of membranelles is retained completely by the proter; (2) both in the proter and in the opisthe five frontal-ventral cirral anlagen are recognizable; (3) the marginal rows and dorsal kineties develop intrakinetally. In addition, the SSU rRNA gene was sequenced for the genus Parakahliella for the first time. Molecular phylogenetic analyses suggest that two populations of the genus Parakahliella cluster together and have a close relationship with species of Oxytrichidae. 

In order to better understand phylogenetic relationships among tintinnid ciliated protozoa, we sequenced and analyzed the SSU rDNA and ITS1-5.8S-ITS2 regions of 10 species belonging to five genera in the order Tintinnida. The secondary structures of the ITS2 region were compared among 8 closely related genera, revealing two stable helices of the palm. In addition, we identified a bulge absence in position II of the ITS2 putative secondary structures of species in basal positions in phylogenetic trees, suggesting the absence bulge might be an ancestral character in the order Tintinnida. Phylogenetic analyses based on SSU rDNA and ITS1-5.8S-ITS2 regions sequence show 1) divergences within the family Tintinnidae are higher than that among other four families (Codonellidae, Ptychocylididae, Metacylididae and Codonellopsidae), suggesting the subdivision of the this family; 2) the family Ptychocylididae is polyphyletic; 3) the subdivision of Tintinnopsis are suggested, because the Tintinnopsis spp. scatter into different clades; 4) species with agglutinated loricae are not clearly separated from that with hyaline ones.

Living observation and silver impregnation methods were used to investigate the morphology and infraciliature of three Frontonia ciliates (F. guangdongensis spec. nov., F. ocularis Bullington, 1939 and F. schaefferi Bullington, 1939) that were isolated from coastal waters of the South China Sea. Frontonia guangdongensis spec. nov. may be recognized by the combination of the following characteristics: cells about 160 × 35 μm in vivo; elongated body with right margin depressed in anterior third; length to width ratio 4:1 to 5:1; three or four vestibular and four or five postoral kineties; peniculi 1 and 2 each with four rows of kineties, peniculus 3 with two rows; one contractile vacuole in mid-body region right of cell median; brackish water habitat. A key based on morphological data for fourteen marine or brackish water Frontonia species found in China is also provided. In addition, the small subunit (SSU) rDNA gene was sequenced for F. ocularis Bullington, 1939. Our phylogenetic analyses support the contention that the genus Frontonia is not monophyletic.