Weiwei Liu

As a follow-up part of our studies of the tropical ciliate fauna carried out in the last decade, we investigated the morphology and phylogeny of three choreotrich ciliates, viz, Parastrombidinopsis costalis sp. n., P. pelagica (Fauré-Fremiet, 1924) comb. n. and P. minima Tsai et al., 2008. The new species is characterized by its unique asymmetrical cell shape, 19–21 collar membranelles, one buccal membrane, and eight unevenly distributed somatic kineties.An improved diagnosis of P. pelagica(Fauré-Fremiet, 1924) comb. n.is given based on the original and current studies, the species is characterized by a large cell size, an elongate obconical cell shape, 31–36 collar membranelles and 13–15 somatic kineties. The species P. minimais redescribed based on a new population with some new features supplemented.SSU rRNA genes of both the new species and P. minima were sequenced and a phylogenetic review of related taxa obtained has been performed in order to reveal their systematic relationships. The monophyly of the genus Parastrombidinopsis is highly supported in our phylogenetic analyses.

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.