Morphometric and molecular characterization of Thelohanellus catlae infecting the gills of Indian major carp catla, Catla catla (Hamilton, 1822) from West Bengal, India

The morphometric and molecular characterization of Thelohanellus catlae a new myxozoan belonging to genus Thelohanellus Kudo, 1933 (Myxosporea:Bivalvulida) infecting the gills of Catla catla were described in this study. The infection was observed as irregular, milky whitish, cyst-like plasmodia (up to 2.0-3.0 mm in diameter) attached to the gill filaments of the host fish. Each spore has a single pyriform polar capsule. Spores measured about 20.4 +/- 0.69 (19.3-21.4) x mu M long and 11.5 +/- 0.63 (10.7-12.4) mu m wide. The polar capsule was 12.3 +/- 0.70 (10.7- 13.9) mu m long and 10.95 +/- 0.28 (9.7-12.9) mu m wide. Sequencing of 18S rRNA gene of the new myxozoan revealed 98% sequence homology between the 18S rRNA gene of T.cattae. Phylogenetic analysis showed T. catlae within the clade of gill infecting myxosporeans and closed together with T. catlae. The importance of myxosporeans introduction to new locations along with infected cultured host is emphasized.