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.
