Trichodinid ciliates (Ciliophora: Trichodinidae) of selected freshwater fishes of Hakaluki Haor, Bangladesh

Abstract

This dissertation presents a comprehensive study on the occurrence of trichodinid ciliates parasitizing freshwater fishes from Hakaluki Haor, Sylhet, Bangladesh, conducted between April 2018 and March 2022. A total of 44 host fish species, belonging to 8 orders, 18 families, and 32 genera, were examined; among them, 16 species were infested with trichodinid ciliates. Altogether, 29 species of trichodinid ciliates were identified belonging to three genera: Trichodina Ehrenberg, 1830; Trichodinella (Raabe, 1950) Šrámek-Hušek, 1953; and Tripartiella Lom, 1959. Twenty-four species of Trichodina were identified, of which 22 are redescribed, viz., T. acuta, T. ahmedi, T. anabasi, T. cancilae, T. caspialosae, T. cobitis, T. cubanensis, T. domerguei, T. glossogobae, T. gulshae, T. hafizuddini, T. heterodentata, T. hoffmani, T. japonica, T. kupermani, T. modesta, T. molae, T. nigra, T. notopterusi, T. ovonucleata, T. siluri and T. sylhetensis. Two species of Trichodina are described and new to science, viz., Trichodina sp. 1 n. sp. and sp. 2 n. sp. Two species of Trichodinella, viz., Trichodinella epizootica and Trichodinella sunderbanensis, were recorded, along with three species of Tripartiella, viz., Tripartiella bulbosa, Tripartiella copiosa, and Tripartiella obtusa. Among the 29 species, eight (T. ahmedi, T. cubanensis, T. caspialosae, T. glossogobae, T. kupermani, T. notopterusi, T. ovonucleata, and Trichodinella sunderbanensis) are recorded for the first time from Bangladesh. Taxonomic identification followed the protocols of Lom (1958), Wellborn (1967), Arthur and Lom (1984), and Van As and Basson (1989, 1992). All species descriptions were based on dry silver nitrate impregnated specimens following Klein (1958). Photomicrographs captured at 1000× magnification, detailed morphometric data for each trichodinid species, and diagrammatic illustrations of denticles for selected taxa are included. Observations on host specificity, distribution patterns, and seasonal incidence of infection contribute valuable insights into the diversity and ecology of trichodinid ciliates in freshwater ecosystems of Hakaluki Haor. This study significantly enhances knowledge of trichodinid diversity, distribution, and ecological interactions in Bangladesh, providing essential baseline data for future parasitological research and management strategies.