Morphology and taxonomy of a new species of a rare genus Paracolpidium (Ciliophora, Oligohymenophorea), P. harbinense sp. nov. from Northeast China

The morphology and ciliary pattern of a new hymenostomatid ciliate, Paracolpidium harbinense sp. nov., collected from the Songhua River, northeast China, was investigated based on living observation and silver staining. Paracolpidium harbinense sp. nov. is characterized by the following features: body size in vivo about 47-56 μm × 17-26 μm in vivo; cell shape ovate with silghtly curved anterior body end; buccal field about 17 % of body length; 18-20 somatic kineties; oral ciliature consisting of a single paroral membrane and three adoral membranelles; macronucleus globular and accompanied by a single micronucleus; silverline system composed of primary meridians. Phylogenetic analyses based on small subunit ribosomal RNA (SSU rRNA) gene sequences suggest the genus Paracolpidium is closely related to Dexiostoma.