Trichodina johniusi sp. n. (Ciliophora: Trichodinidae) from Johnius coitor (Hamilton, 1822) in the Shitalakshya River, Bangladesh

During a survey on species diversity of trichodinid ciliates from freshwater fishes in the Shitalakshya River of Gazipur district, Bangladesh, a new species of ciliate was identified and described using the silver nitrate impregnation method. The species is described from the gills of Johnius coitor in the Shitalakshya River of Gazipur district. Trichodina johniusi sp. n. may be characterised by having broad, rounded and slightly curved blades with shallow semilunar curve; relatively short, slim rays having parallel borders, but ill defined ray apophysis; ray tip never touches a well defined, undivided central circle, encircled by undulated perimeter, interspersed with black patches or granules; and the adoral cilia described a turn of approximately 400°. Based on these characters and the unique shape and absence of variability of the denticles among the silver impregnated specimens of the present species, it may be said that to a lesser extent, resembles T. domerguei.