Morphology and Phylogeny of Three New Loxophyllum Species (Ciliophora, Pleurostomatida) from Mangrove Wetlands of Southern China

Three new pleurostomatid ciliates, Loxophyllum meridionale sp. n., L. salinum sp. n., and L. planum sp. n., isolated from brackish waters of mangrove wetlands in southern China, were investigated using live observation and protargol impregnation. The main characteristic feature of L. meridionale sp. n. is the presence of three contractile vacuoles (CVs) along its dorsal margin. Loxophyllum salinum sp. n. can be identified by the presence of three closely spaced CVs along the ventral margin and 1215 right and four to six left kineties. Loxophyllum planum sp. n. is characterized by the combination of two macronuclei, a single, subterminal CV, and the absence of cortical granules. Phylogenetic trees based on the small subunit rDNA sequence data recovered Loxophyllum as a monophyletic group within the pleurostomatids. Loxophyllum meridionale sp. n., L. salinum sp. n., and L. planum sp. n. were all nested within the Loxophyllum clade. Based on its ciliary pattern and general morphological features, Loxophyllum asetosum is transferred to the genus Amphileptus and a new combination is suggested: Amphileptus asetosus (Burkovsky 1970) comb. n. [basionym L. asetosum Burkovsky 1970].