Taxonomic Study Of Five Freshwater Parasitic Ciliates

During 2012-2013, 5 species of freshwater parasitic ciliates were collected from Hubei province and Tibet and described with morphological and molecular methods. The main results are as follows:1. Chilodonella pisicicola Zacharias, 1894(syn. Chilodonella cyprini) is collected from the surface of Schizothorax o’connori and Oxygymnocypris stewartii. The body of C. piscicola is oval. Somatic kineties usually contain seven right kineties and nine left kineties. Terminal fragment kinety is linear and on the top left of dorsal side. Two parallel circumoral kineties revolve round the cyrtos, and one preoral kinety extends to the anterior end of the fourth left-most kinety. Sequence alignments revealed that the present SSU r DNA and ITS1-5.8S-ITS2 sequences are both most similar to the sequences of C. uncinata with the similarities of 98.2%(over 1593 bp) and 99.5%(over 424 bp). The phylogenetic analyses show that C. piscicola is sister to other Chilodonella species, whereas C. cyprini(FJ873805) clusters with Tetrahymena species. Molecular analysis shows that the ITS1-5.8S-ITS2 sequence of C. cyprini in Gen Bank is unreliable.2. Tokophrya huangmeiensis n. sp. is a new suctorian ciliate which can cause high mortality in redclaw crayfish Cherax quadricarinatus. It aggregates into colonies distributing the whole surface of carapace and gills of the host. Adult form of this parasitic species comprises a body borne upon a long stalk. The body is elongated, pyramid shaped, corrugate, and having aggregate in two fascicles of tentacles in cell apical part. The stalk is transparent and has lot of longitudinal tubules inside. Inside the body an elongate ρ-shaped macronucleus is centrally located and a single contractile vacuole is located in apical region. Transmission electron microscopy shows that bud of T. huangmeiensis is also connect to parent plasma membrane by ribbon-forms. Sequence alignments revealed that the SSU r DNA of T. huangmeiensis is most similar to the sequences of T. infusionum(JQ723984, 95.5% over 1,648 bp). Phylogenetic analyses show that the subclass Suctoria is monophyletic and T. huangmeiensis falls within the Endogenina subgroup and form the sister species with Tokophrya species.3. Trichodina paranigra Tang et al, 2005 is collected from the gill of Micropercops swinhonis. The body is wheel-shaped, oral surface and aboral surface are round. Central zone of adhesive disc is clear and without granules. Blade is almost rhomboid. Apex of blade always extending past Y+1 axis. Apophysis of blade and posterior projection are absent. Central part is well developed with rounded point fitting into preceding denticle. Ray is well developed and nearly parallel to Y axis, slightly Slanted backward. Molecular analysis revealed that the present SSU r DNA sequences is most similar to that of T. heterodentata(AY788099, 97.5% over 1,602 bp). T. reticulata Hirschman & Partsch, 1955 is also collected from the gill of Micropercops swinhonis. The body is calyptrate in lateral view. Central zone of adhesive disc relatively clear and with 8- 14 uniform and irregular granules, fitting tightly into each other. Blade is broad and fills most of space between Yaxes. Apophysis of blade and posterior projection are absent. Central part is well developed with rounded point fitting tightly into preceding denticle. Ray is relatively stumpy and parallel to Y axis. Sequence alignments revealed that the present SSU r DNA sequence is most similar to that of T. reticulate(AY741784, 99.6% over 1,618 bp). T. acuta Lom, 1961 is collected from the surface of Misgurnus anguillicaudatus. The body is saucer-shaped in lateral view. Central zone of adhesive disc is clear and with single irregular rounded granule. Blade is broad and falcate, with a sharp point. Apophysis of blade and posterior projection are absent. Central part is broad and well developed, with round point fitting tightly into preceding denticle. Ray connection is undistinguishable from ray. Ray is well developed and slightly bent with sharp point. Adoral ciliary spiral turns about 390° around peristomial. BLAST searches indicated that T.acuta was most similar to that of T.nobilis(AY102172, 97.1% over 1,703 bp). Phylogenetic analyses show that these three species fall in the Mobilida clade and cluster with other Trichodina species.