Morphology and SSU rRNA gene sequences of three Frontonia species, including a description of F. subtropica spec. nov. (Ciliophora, Peniculida)

The morphology and infraciliature of three Frontonia species, F. subtropica spec. nov., F. canadensis Roque and Puytorac, 1972, and F. magna Fan et al., 2011, isolated from coastal waters in southern China sea, were investigated using living observation and silver impregnation methods. Frontonia subtropica spec. nov. is recognized by the combination of the following characters: body elliptical in outline with right margin depressed in anterior third, about 180–230 μm × 60–80 μm in vivo; 104–114 somatic kineties; peniculi 1–3 each with four kineties; five vestibular and five postoral kineties; one centrally located elongate-elliptical macronucleus; single contractile vacuole located left-dorsally in posterior third of body. We also provide improved diagnoses for F. canadensis and F. magna based on current and previous reports. The small subunit (SSU) rRNA gene was sequenced for all three species. Comparisons with sequences of morphologically similar congeners clearly support the validity each species.